Make git-pack-objects a builtin

Signed-off-by: Matthias Kestenholz <matthias@spinlock.ch>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Makefile b/Makefile
index 132c9cf012c02647399b47890d67f64acb3ff1f5..4fd62bcf6dc5a71526fd7d81a6138e8456171a14 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -177,7 +177,7 @@ PROGRAMS = \
        git-convert-objects$X git-fetch-pack$X git-fsck-objects$X \
        git-hash-object$X git-index-pack$X git-local-fetch$X \
        git-merge-base$X \
-       git-merge-index$X git-mktag$X git-mktree$X git-pack-objects$X git-patch-id$X \
+       git-merge-index$X git-mktag$X git-mktree$X git-patch-id$X \
        git-peek-remote$X git-receive-pack$X \
        git-send-pack$X git-shell$X \
        git-show-index$X git-ssh-fetch$X \
@@ -198,7 +198,7 @@ BUILT_INS = git-log$X git-whatchanged$X git-show$X git-update-ref$X \
        git-apply$X git-show-branch$X git-diff-files$X git-update-index$X \
        git-diff-index$X git-diff-stages$X git-diff-tree$X git-cat-file$X \
        git-fmt-merge-msg$X git-prune$X git-mv$X git-prune-packed$X \
-       git-repo-config$X git-name-rev$X
+       git-repo-config$X git-name-rev$X git-pack-objects$X
 
 # what 'all' will build and 'install' will install, in gitexecdir
 ALL_PROGRAMS = $(PROGRAMS) $(SIMPLE_PROGRAMS) $(SCRIPTS)
@@ -256,7 +256,7 @@ BUILTIN_OBJS = \
        builtin-cat-file.o builtin-mailsplit.o builtin-stripspace.o \
        builtin-update-ref.o builtin-fmt-merge-msg.o builtin-prune.o \
        builtin-mv.o builtin-prune-packed.o builtin-repo-config.o \
-       builtin-name-rev.o
+       builtin-name-rev.o builtin-pack-objects.o
 
 GITLIBS = $(LIB_FILE) $(XDIFF_LIB)
 LIBS = $(GITLIBS) -lz

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
new file mode 100644 (file)
index 0000000..2301cd5
--- /dev/null
+++ b/builtin-pack-objects.c
@@ -0,0 +1,1376 @@
+#include "builtin.h"
+#include "cache.h"
+#include "object.h"
+#include "blob.h"
+#include "commit.h"
+#include "tag.h"
+#include "tree.h"
+#include "delta.h"
+#include "pack.h"
+#include "csum-file.h"
+#include "tree-walk.h"
+#include <sys/time.h>
+#include <signal.h>
+
+static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
+
+struct object_entry {
+       unsigned char sha1[20];
+       unsigned long size;     /* uncompressed size */
+       unsigned long offset;   /* offset into the final pack file;
+                                * nonzero if already written.
+                                */
+       unsigned int depth;     /* delta depth */
+       unsigned int delta_limit;       /* base adjustment for in-pack delta */
+       unsigned int hash;      /* name hint hash */
+       enum object_type type;
+       enum object_type in_pack_type;  /* could be delta */
+       unsigned long delta_size;       /* delta data size (uncompressed) */
+       struct object_entry *delta;     /* delta base object */
+       struct packed_git *in_pack;     /* already in pack */
+       unsigned int in_pack_offset;
+       struct object_entry *delta_child; /* deltified objects who bases me */
+       struct object_entry *delta_sibling; /* other deltified objects who
+                                            * uses the same base as me
+                                            */
+       int preferred_base;     /* we do not pack this, but is encouraged to
+                                * be used as the base objectto delta huge
+                                * objects against.
+                                */
+};
+
+/*
+ * Objects we are going to pack are collected in objects array (dynamically
+ * expanded).  nr_objects & nr_alloc controls this array.  They are stored
+ * in the order we see -- typically rev-list --objects order that gives us
+ * nice "minimum seek" order.
+ *
+ * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
+ * elements in the objects array.  The former is used to build the pack
+ * index (lists object names in the ascending order to help offset lookup),
+ * and the latter is used to group similar things together by try_delta()
+ * heuristics.
+ */
+
+static unsigned char object_list_sha1[20];
+static int non_empty = 0;
+static int no_reuse_delta = 0;
+static int local = 0;
+static int incremental = 0;
+static struct object_entry **sorted_by_sha, **sorted_by_type;
+static struct object_entry *objects = NULL;
+static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
+static const char *base_name;
+static unsigned char pack_file_sha1[20];
+static int progress = 1;
+static volatile sig_atomic_t progress_update = 0;
+static int window = 10;
+
+/*
+ * The object names in objects array are hashed with this hashtable,
+ * to help looking up the entry by object name.  Binary search from
+ * sorted_by_sha is also possible but this was easier to code and faster.
+ * This hashtable is built after all the objects are seen.
+ */
+static int *object_ix = NULL;
+static int object_ix_hashsz = 0;
+
+/*
+ * Pack index for existing packs give us easy access to the offsets into
+ * corresponding pack file where each object's data starts, but the entries
+ * do not store the size of the compressed representation (uncompressed
+ * size is easily available by examining the pack entry header).  We build
+ * a hashtable of existing packs (pack_revindex), and keep reverse index
+ * here -- pack index file is sorted by object name mapping to offset; this
+ * pack_revindex[].revindex array is an ordered list of offsets, so if you
+ * know the offset of an object, next offset is where its packed
+ * representation ends.
+ */
+struct pack_revindex {
+       struct packed_git *p;
+       unsigned long *revindex;
+} *pack_revindex = NULL;
+static int pack_revindex_hashsz = 0;
+
+/*
+ * stats
+ */
+static int written = 0;
+static int written_delta = 0;
+static int reused = 0;
+static int reused_delta = 0;
+
+static int pack_revindex_ix(struct packed_git *p)
+{
+       unsigned long ui = (unsigned long)p;
+       int i;
+
+       ui = ui ^ (ui >> 16); /* defeat structure alignment */
+       i = (int)(ui % pack_revindex_hashsz);
+       while (pack_revindex[i].p) {
+               if (pack_revindex[i].p == p)
+                       return i;
+               if (++i == pack_revindex_hashsz)
+                       i = 0;
+       }
+       return -1 - i;
+}
+
+static void prepare_pack_ix(void)
+{
+       int num;
+       struct packed_git *p;
+       for (num = 0, p = packed_git; p; p = p->next)
+               num++;
+       if (!num)
+               return;
+       pack_revindex_hashsz = num * 11;
+       pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
+       for (p = packed_git; p; p = p->next) {
+               num = pack_revindex_ix(p);
+               num = - 1 - num;
+               pack_revindex[num].p = p;
+       }
+       /* revindex elements are lazily initialized */
+}
+
+static int cmp_offset(const void *a_, const void *b_)
+{
+       unsigned long a = *(unsigned long *) a_;
+       unsigned long b = *(unsigned long *) b_;
+       if (a < b)
+               return -1;
+       else if (a == b)
+               return 0;
+       else
+               return 1;
+}
+
+/*
+ * Ordered list of offsets of objects in the pack.
+ */
+static void prepare_pack_revindex(struct pack_revindex *rix)
+{
+       struct packed_git *p = rix->p;
+       int num_ent = num_packed_objects(p);
+       int i;
+       void *index = p->index_base + 256;
+
+       rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
+       for (i = 0; i < num_ent; i++) {
+               unsigned int hl = *((unsigned int *)((char *) index + 24*i));
+               rix->revindex[i] = ntohl(hl);
+       }
+       /* This knows the pack format -- the 20-byte trailer
+        * follows immediately after the last object data.
+        */
+       rix->revindex[num_ent] = p->pack_size - 20;
+       qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
+}
+
+static unsigned long find_packed_object_size(struct packed_git *p,
+                                            unsigned long ofs)
+{
+       int num;
+       int lo, hi;
+       struct pack_revindex *rix;
+       unsigned long *revindex;
+       num = pack_revindex_ix(p);
+       if (num < 0)
+               die("internal error: pack revindex uninitialized");
+       rix = &pack_revindex[num];
+       if (!rix->revindex)
+               prepare_pack_revindex(rix);
+       revindex = rix->revindex;
+       lo = 0;
+       hi = num_packed_objects(p) + 1;
+       do {
+               int mi = (lo + hi) / 2;
+               if (revindex[mi] == ofs) {
+                       return revindex[mi+1] - ofs;
+               }
+               else if (ofs < revindex[mi])
+                       hi = mi;
+               else
+                       lo = mi + 1;
+       } while (lo < hi);
+       die("internal error: pack revindex corrupt");
+}
+
+static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
+{
+       unsigned long othersize, delta_size;
+       char type[10];
+       void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
+       void *delta_buf;
+
+       if (!otherbuf)
+               die("unable to read %s", sha1_to_hex(entry->delta->sha1));
+        delta_buf = diff_delta(otherbuf, othersize,
+                              buf, size, &delta_size, 0);
+        if (!delta_buf || delta_size != entry->delta_size)
+               die("delta size changed");
+        free(buf);
+        free(otherbuf);
+       return delta_buf;
+}
+
+/*
+ * The per-object header is a pretty dense thing, which is
+ *  - first byte: low four bits are "size", then three bits of "type",
+ *    and the high bit is "size continues".
+ *  - each byte afterwards: low seven bits are size continuation,
+ *    with the high bit being "size continues"
+ */
+static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
+{
+       int n = 1;
+       unsigned char c;
+
+       if (type < OBJ_COMMIT || type > OBJ_DELTA)
+               die("bad type %d", type);
+
+       c = (type << 4) | (size & 15);
+       size >>= 4;
+       while (size) {
+               *hdr++ = c | 0x80;
+               c = size & 0x7f;
+               size >>= 7;
+               n++;
+       }
+       *hdr = c;
+       return n;
+}
+
+static unsigned long write_object(struct sha1file *f,
+                                 struct object_entry *entry)
+{
+       unsigned long size;
+       char type[10];
+       void *buf;
+       unsigned char header[10];
+       unsigned hdrlen, datalen;
+       enum object_type obj_type;
+       int to_reuse = 0;
+
+       if (entry->preferred_base)
+               return 0;
+
+       obj_type = entry->type;
+       if (! entry->in_pack)
+               to_reuse = 0;   /* can't reuse what we don't have */
+       else if (obj_type == OBJ_DELTA)
+               to_reuse = 1;   /* check_object() decided it for us */
+       else if (obj_type != entry->in_pack_type)
+               to_reuse = 0;   /* pack has delta which is unusable */
+       else if (entry->delta)
+               to_reuse = 0;   /* we want to pack afresh */
+       else
+               to_reuse = 1;   /* we have it in-pack undeltified,
+                                * and we do not need to deltify it.
+                                */
+
+       if (! to_reuse) {
+               buf = read_sha1_file(entry->sha1, type, &size);
+               if (!buf)
+                       die("unable to read %s", sha1_to_hex(entry->sha1));
+               if (size != entry->size)
+                       die("object %s size inconsistency (%lu vs %lu)",
+                           sha1_to_hex(entry->sha1), size, entry->size);
+               if (entry->delta) {
+                       buf = delta_against(buf, size, entry);
+                       size = entry->delta_size;
+                       obj_type = OBJ_DELTA;
+               }
+               /*
+                * The object header is a byte of 'type' followed by zero or
+                * more bytes of length.  For deltas, the 20 bytes of delta
+                * sha1 follows that.
+                */
+               hdrlen = encode_header(obj_type, size, header);
+               sha1write(f, header, hdrlen);
+
+               if (entry->delta) {
+                       sha1write(f, entry->delta, 20);
+                       hdrlen += 20;
+               }
+               datalen = sha1write_compressed(f, buf, size);
+               free(buf);
+       }
+       else {
+               struct packed_git *p = entry->in_pack;
+               use_packed_git(p);
+
+               datalen = find_packed_object_size(p, entry->in_pack_offset);
+               buf = (char *) p->pack_base + entry->in_pack_offset;
+               sha1write(f, buf, datalen);
+               unuse_packed_git(p);
+               hdrlen = 0; /* not really */
+               if (obj_type == OBJ_DELTA)
+                       reused_delta++;
+               reused++;
+       }
+       if (obj_type == OBJ_DELTA)
+               written_delta++;
+       written++;
+       return hdrlen + datalen;
+}
+
+static unsigned long write_one(struct sha1file *f,
+                              struct object_entry *e,
+                              unsigned long offset)
+{
+       if (e->offset)
+               /* offset starts from header size and cannot be zero
+                * if it is written already.
+                */
+               return offset;
+       e->offset = offset;
+       offset += write_object(f, e);
+       /* if we are deltified, write out its base object. */
+       if (e->delta)
+               offset = write_one(f, e->delta, offset);
+       return offset;
+}
+
+static void write_pack_file(void)
+{
+       int i;
+       struct sha1file *f;
+       unsigned long offset;
+       struct pack_header hdr;
+       unsigned last_percent = 999;
+       int do_progress = 0;
+
+       if (!base_name)
+               f = sha1fd(1, "<stdout>");
+       else {
+               f = sha1create("%s-%s.%s", base_name,
+                              sha1_to_hex(object_list_sha1), "pack");
+               do_progress = progress;
+       }
+       if (do_progress)
+               fprintf(stderr, "Writing %d objects.\n", nr_result);
+
+       hdr.hdr_signature = htonl(PACK_SIGNATURE);
+       hdr.hdr_version = htonl(PACK_VERSION);
+       hdr.hdr_entries = htonl(nr_result);
+       sha1write(f, &hdr, sizeof(hdr));
+       offset = sizeof(hdr);
+       if (!nr_result)
+               goto done;
+       for (i = 0; i < nr_objects; i++) {
+               offset = write_one(f, objects + i, offset);
+               if (do_progress) {
+                       unsigned percent = written * 100 / nr_result;
+                       if (progress_update || percent != last_percent) {
+                               fprintf(stderr, "%4u%% (%u/%u) done\r",
+                                       percent, written, nr_result);
+                               progress_update = 0;
+                               last_percent = percent;
+                       }
+               }
+       }
+       if (do_progress)
+               fputc('\n', stderr);
+ done:
+       sha1close(f, pack_file_sha1, 1);
+}
+
+static void write_index_file(void)
+{
+       int i;
+       struct sha1file *f = sha1create("%s-%s.%s", base_name,
+                                       sha1_to_hex(object_list_sha1), "idx");
+       struct object_entry **list = sorted_by_sha;
+       struct object_entry **last = list + nr_result;
+       unsigned int array[256];
+
+       /*
+        * Write the first-level table (the list is sorted,
+        * but we use a 256-entry lookup to be able to avoid
+        * having to do eight extra binary search iterations).
+        */
+       for (i = 0; i < 256; i++) {
+               struct object_entry **next = list;
+               while (next < last) {
+                       struct object_entry *entry = *next;
+                       if (entry->sha1[0] != i)
+                               break;
+                       next++;
+               }
+               array[i] = htonl(next - sorted_by_sha);
+               list = next;
+       }
+       sha1write(f, array, 256 * sizeof(int));
+
+       /*
+        * Write the actual SHA1 entries..
+        */
+       list = sorted_by_sha;
+       for (i = 0; i < nr_result; i++) {
+               struct object_entry *entry = *list++;
+               unsigned int offset = htonl(entry->offset);
+               sha1write(f, &offset, 4);
+               sha1write(f, entry->sha1, 20);
+       }
+       sha1write(f, pack_file_sha1, 20);
+       sha1close(f, NULL, 1);
+}
+
+static int locate_object_entry_hash(const unsigned char *sha1)
+{
+       int i;
+       unsigned int ui;
+       memcpy(&ui, sha1, sizeof(unsigned int));
+       i = ui % object_ix_hashsz;
+       while (0 < object_ix[i]) {
+               if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
+                       return i;
+               if (++i == object_ix_hashsz)
+                       i = 0;
+       }
+       return -1 - i;
+}
+
+static struct object_entry *locate_object_entry(const unsigned char *sha1)
+{
+       int i;
+
+       if (!object_ix_hashsz)
+               return NULL;
+
+       i = locate_object_entry_hash(sha1);
+       if (0 <= i)
+               return &objects[object_ix[i]-1];
+       return NULL;
+}
+
+static void rehash_objects(void)
+{
+       int i;
+       struct object_entry *oe;
+
+       object_ix_hashsz = nr_objects * 3;
+       if (object_ix_hashsz < 1024)
+               object_ix_hashsz = 1024;
+       object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
+       memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
+       for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
+               int ix = locate_object_entry_hash(oe->sha1);
+               if (0 <= ix)
+                       continue;
+               ix = -1 - ix;
+               object_ix[ix] = i + 1;
+       }
+}
+
+static unsigned name_hash(const char *name)
+{
+       unsigned char c;
+       unsigned hash = 0;
+
+       /*
+        * This effectively just creates a sortable number from the
+        * last sixteen non-whitespace characters. Last characters
+        * count "most", so things that end in ".c" sort together.
+        */
+       while ((c = *name++) != 0) {
+               if (isspace(c))
+                       continue;
+               hash = (hash >> 2) + (c << 24);
+       }
+       return hash;
+}
+
+static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
+{
+       unsigned int idx = nr_objects;
+       struct object_entry *entry;
+       struct packed_git *p;
+       unsigned int found_offset = 0;
+       struct packed_git *found_pack = NULL;
+       int ix, status = 0;
+
+       if (!exclude) {
+               for (p = packed_git; p; p = p->next) {
+                       struct pack_entry e;
+                       if (find_pack_entry_one(sha1, &e, p)) {
+                               if (incremental)
+                                       return 0;
+                               if (local && !p->pack_local)
+                                       return 0;
+                               if (!found_pack) {
+                                       found_offset = e.offset;
+                                       found_pack = e.p;
+                               }
+                       }
+               }
+       }
+       if ((entry = locate_object_entry(sha1)) != NULL)
+               goto already_added;
+
+       if (idx >= nr_alloc) {
+               unsigned int needed = (idx + 1024) * 3 / 2;
+               objects = xrealloc(objects, needed * sizeof(*entry));
+               nr_alloc = needed;
+       }
+       entry = objects + idx;
+       nr_objects = idx + 1;
+       memset(entry, 0, sizeof(*entry));
+       memcpy(entry->sha1, sha1, 20);
+       entry->hash = hash;
+
+       if (object_ix_hashsz * 3 <= nr_objects * 4)
+               rehash_objects();
+       else {
+               ix = locate_object_entry_hash(entry->sha1);
+               if (0 <= ix)
+                       die("internal error in object hashing.");
+               object_ix[-1 - ix] = idx + 1;
+       }
+       status = 1;
+
+ already_added:
+       if (progress_update) {
+               fprintf(stderr, "Counting objects...%d\r", nr_objects);
+               progress_update = 0;
+       }
+       if (exclude)
+               entry->preferred_base = 1;
+       else {
+               if (found_pack) {
+                       entry->in_pack = found_pack;
+                       entry->in_pack_offset = found_offset;
+               }
+       }
+       return status;
+}
+
+struct pbase_tree_cache {
+       unsigned char sha1[20];
+       int ref;
+       int temporary;
+       void *tree_data;
+       unsigned long tree_size;
+};
+
+static struct pbase_tree_cache *(pbase_tree_cache[256]);
+static int pbase_tree_cache_ix(const unsigned char *sha1)
+{
+       return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
+}
+static int pbase_tree_cache_ix_incr(int ix)
+{
+       return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
+}
+
+static struct pbase_tree {
+       struct pbase_tree *next;
+       /* This is a phony "cache" entry; we are not
+        * going to evict it nor find it through _get()
+        * mechanism -- this is for the toplevel node that
+        * would almost always change with any commit.
+        */
+       struct pbase_tree_cache pcache;
+} *pbase_tree;
+
+static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
+{
+       struct pbase_tree_cache *ent, *nent;
+       void *data;
+       unsigned long size;
+       char type[20];
+       int neigh;
+       int my_ix = pbase_tree_cache_ix(sha1);
+       int available_ix = -1;
+
+       /* pbase-tree-cache acts as a limited hashtable.
+        * your object will be found at your index or within a few
+        * slots after that slot if it is cached.
+        */
+       for (neigh = 0; neigh < 8; neigh++) {
+               ent = pbase_tree_cache[my_ix];
+               if (ent && !memcmp(ent->sha1, sha1, 20)) {
+                       ent->ref++;
+                       return ent;
+               }
+               else if (((available_ix < 0) && (!ent || !ent->ref)) ||
+                        ((0 <= available_ix) &&
+                         (!ent && pbase_tree_cache[available_ix])))
+                       available_ix = my_ix;
+               if (!ent)
+                       break;
+               my_ix = pbase_tree_cache_ix_incr(my_ix);
+       }
+
+       /* Did not find one.  Either we got a bogus request or
+        * we need to read and perhaps cache.
+        */
+       data = read_sha1_file(sha1, type, &size);
+       if (!data)
+               return NULL;
+       if (strcmp(type, tree_type)) {
+               free(data);
+               return NULL;
+       }
+
+       /* We need to either cache or return a throwaway copy */
+
+       if (available_ix < 0)
+               ent = NULL;
+       else {
+               ent = pbase_tree_cache[available_ix];
+               my_ix = available_ix;
+       }
+
+       if (!ent) {
+               nent = xmalloc(sizeof(*nent));
+               nent->temporary = (available_ix < 0);
+       }
+       else {
+               /* evict and reuse */
+               free(ent->tree_data);
+               nent = ent;
+       }
+       memcpy(nent->sha1, sha1, 20);
+       nent->tree_data = data;
+       nent->tree_size = size;
+       nent->ref = 1;
+       if (!nent->temporary)
+               pbase_tree_cache[my_ix] = nent;
+       return nent;
+}
+
+static void pbase_tree_put(struct pbase_tree_cache *cache)
+{
+       if (!cache->temporary) {
+               cache->ref--;
+               return;
+       }
+       free(cache->tree_data);
+       free(cache);
+}
+
+static int name_cmp_len(const char *name)
+{
+       int i;
+       for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
+               ;
+       return i;
+}
+
+static void add_pbase_object(struct tree_desc *tree,
+                            const char *name,
+                            int cmplen,
+                            const char *fullname)
+{
+       struct name_entry entry;
+
+       while (tree_entry(tree,&entry)) {
+               unsigned long size;
+               char type[20];
+
+               if (entry.pathlen != cmplen ||
+                   memcmp(entry.path, name, cmplen) ||
+                   !has_sha1_file(entry.sha1) ||
+                   sha1_object_info(entry.sha1, type, &size))
+                       continue;
+               if (name[cmplen] != '/') {
+                       unsigned hash = name_hash(fullname);
+                       add_object_entry(entry.sha1, hash, 1);
+                       return;
+               }
+               if (!strcmp(type, tree_type)) {
+                       struct tree_desc sub;
+                       struct pbase_tree_cache *tree;
+                       const char *down = name+cmplen+1;
+                       int downlen = name_cmp_len(down);
+
+                       tree = pbase_tree_get(entry.sha1);
+                       if (!tree)
+                               return;
+                       sub.buf = tree->tree_data;
+                       sub.size = tree->tree_size;
+
+                       add_pbase_object(&sub, down, downlen, fullname);
+                       pbase_tree_put(tree);
+               }
+       }
+}
+
+static unsigned *done_pbase_paths;
+static int done_pbase_paths_num;
+static int done_pbase_paths_alloc;
+static int done_pbase_path_pos(unsigned hash)
+{
+       int lo = 0;
+       int hi = done_pbase_paths_num;
+       while (lo < hi) {
+               int mi = (hi + lo) / 2;
+               if (done_pbase_paths[mi] == hash)
+                       return mi;
+               if (done_pbase_paths[mi] < hash)
+                       hi = mi;
+               else
+                       lo = mi + 1;
+       }
+       return -lo-1;
+}
+
+static int check_pbase_path(unsigned hash)
+{
+       int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
+       if (0 <= pos)
+               return 1;
+       pos = -pos - 1;
+       if (done_pbase_paths_alloc <= done_pbase_paths_num) {
+               done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
+               done_pbase_paths = xrealloc(done_pbase_paths,
+                                           done_pbase_paths_alloc *
+                                           sizeof(unsigned));
+       }
+       done_pbase_paths_num++;
+       if (pos < done_pbase_paths_num)
+               memmove(done_pbase_paths + pos + 1,
+                       done_pbase_paths + pos,
+                       (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
+       done_pbase_paths[pos] = hash;
+       return 0;
+}
+
+static void add_preferred_base_object(char *name, unsigned hash)
+{
+       struct pbase_tree *it;
+       int cmplen = name_cmp_len(name);
+
+       if (check_pbase_path(hash))
+               return;
+
+       for (it = pbase_tree; it; it = it->next) {
+               if (cmplen == 0) {
+                       hash = name_hash("");
+                       add_object_entry(it->pcache.sha1, hash, 1);
+               }
+               else {
+                       struct tree_desc tree;
+                       tree.buf = it->pcache.tree_data;
+                       tree.size = it->pcache.tree_size;
+                       add_pbase_object(&tree, name, cmplen, name);
+               }
+       }
+}
+
+static void add_preferred_base(unsigned char *sha1)
+{
+       struct pbase_tree *it;
+       void *data;
+       unsigned long size;
+       unsigned char tree_sha1[20];
+
+       data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
+       if (!data)
+               return;
+
+       for (it = pbase_tree; it; it = it->next) {
+               if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
+                       free(data);
+                       return;
+               }
+       }
+
+       it = xcalloc(1, sizeof(*it));
+       it->next = pbase_tree;
+       pbase_tree = it;
+
+       memcpy(it->pcache.sha1, tree_sha1, 20);
+       it->pcache.tree_data = data;
+       it->pcache.tree_size = size;
+}
+
+static void check_object(struct object_entry *entry)
+{
+       char type[20];
+
+       if (entry->in_pack && !entry->preferred_base) {
+               unsigned char base[20];
+               unsigned long size;
+               struct object_entry *base_entry;
+
+               /* We want in_pack_type even if we do not reuse delta.
+                * There is no point not reusing non-delta representations.
+                */
+               check_reuse_pack_delta(entry->in_pack,
+                                      entry->in_pack_offset,
+                                      base, &size,
+                                      &entry->in_pack_type);
+
+               /* Check if it is delta, and the base is also an object
+                * we are going to pack.  If so we will reuse the existing
+                * delta.
+                */
+               if (!no_reuse_delta &&
+                   entry->in_pack_type == OBJ_DELTA &&
+                   (base_entry = locate_object_entry(base)) &&
+                   (!base_entry->preferred_base)) {
+
+                       /* Depth value does not matter - find_deltas()
+                        * will never consider reused delta as the
+                        * base object to deltify other objects
+                        * against, in order to avoid circular deltas.
+                        */
+
+                       /* uncompressed size of the delta data */
+                       entry->size = entry->delta_size = size;
+                       entry->delta = base_entry;
+                       entry->type = OBJ_DELTA;
+
+                       entry->delta_sibling = base_entry->delta_child;
+                       base_entry->delta_child = entry;
+
+                       return;
+               }
+               /* Otherwise we would do the usual */
+       }
+
+       if (sha1_object_info(entry->sha1, type, &entry->size))
+               die("unable to get type of object %s",
+                   sha1_to_hex(entry->sha1));
+
+       if (!strcmp(type, commit_type)) {
+               entry->type = OBJ_COMMIT;
+       } else if (!strcmp(type, tree_type)) {
+               entry->type = OBJ_TREE;
+       } else if (!strcmp(type, blob_type)) {
+               entry->type = OBJ_BLOB;
+       } else if (!strcmp(type, tag_type)) {
+               entry->type = OBJ_TAG;
+       } else
+               die("unable to pack object %s of type %s",
+                   sha1_to_hex(entry->sha1), type);
+}
+
+static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
+{
+       struct object_entry *child = me->delta_child;
+       unsigned int m = n;
+       while (child) {
+               unsigned int c = check_delta_limit(child, n + 1);
+               if (m < c)
+                       m = c;
+               child = child->delta_sibling;
+       }
+       return m;
+}
+
+static void get_object_details(void)
+{
+       int i;
+       struct object_entry *entry;
+
+       prepare_pack_ix();
+       for (i = 0, entry = objects; i < nr_objects; i++, entry++)
+               check_object(entry);
+
+       if (nr_objects == nr_result) {
+               /*
+                * Depth of objects that depend on the entry -- this
+                * is subtracted from depth-max to break too deep
+                * delta chain because of delta data reusing.
+                * However, we loosen this restriction when we know we
+                * are creating a thin pack -- it will have to be
+                * expanded on the other end anyway, so do not
+                * artificially cut the delta chain and let it go as
+                * deep as it wants.
+                */
+               for (i = 0, entry = objects; i < nr_objects; i++, entry++)
+                       if (!entry->delta && entry->delta_child)
+                               entry->delta_limit =
+                                       check_delta_limit(entry, 1);
+       }
+}
+
+typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
+
+static entry_sort_t current_sort;
+
+static int sort_comparator(const void *_a, const void *_b)
+{
+       struct object_entry *a = *(struct object_entry **)_a;
+       struct object_entry *b = *(struct object_entry **)_b;
+       return current_sort(a,b);
+}
+
+static struct object_entry **create_sorted_list(entry_sort_t sort)
+{
+       struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
+       int i;
+
+       for (i = 0; i < nr_objects; i++)
+               list[i] = objects + i;
+       current_sort = sort;
+       qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
+       return list;
+}
+
+static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
+{
+       return memcmp(a->sha1, b->sha1, 20);
+}
+
+static struct object_entry **create_final_object_list(void)
+{
+       struct object_entry **list;
+       int i, j;
+
+       for (i = nr_result = 0; i < nr_objects; i++)
+               if (!objects[i].preferred_base)
+                       nr_result++;
+       list = xmalloc(nr_result * sizeof(struct object_entry *));
+       for (i = j = 0; i < nr_objects; i++) {
+               if (!objects[i].preferred_base)
+                       list[j++] = objects + i;
+       }
+       current_sort = sha1_sort;
+       qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
+       return list;
+}
+
+static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
+{
+       if (a->type < b->type)
+               return -1;
+       if (a->type > b->type)
+               return 1;
+       if (a->hash < b->hash)
+               return -1;
+       if (a->hash > b->hash)
+               return 1;
+       if (a->preferred_base < b->preferred_base)
+               return -1;
+       if (a->preferred_base > b->preferred_base)
+               return 1;
+       if (a->size < b->size)
+               return -1;
+       if (a->size > b->size)
+               return 1;
+       return a < b ? -1 : (a > b);
+}
+
+struct unpacked {
+       struct object_entry *entry;
+       void *data;
+       struct delta_index *index;
+};
+
+/*
+ * We search for deltas _backwards_ in a list sorted by type and
+ * by size, so that we see progressively smaller and smaller files.
+ * That's because we prefer deltas to be from the bigger file
+ * to the smaller - deletes are potentially cheaper, but perhaps
+ * more importantly, the bigger file is likely the more recent
+ * one.
+ */
+static int try_delta(struct unpacked *trg, struct unpacked *src,
+                    unsigned max_depth)
+{
+       struct object_entry *trg_entry = trg->entry;
+       struct object_entry *src_entry = src->entry;
+       unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
+       char type[10];
+       void *delta_buf;
+
+       /* Don't bother doing diffs between different types */
+       if (trg_entry->type != src_entry->type)
+               return -1;
+
+       /* We do not compute delta to *create* objects we are not
+        * going to pack.
+        */
+       if (trg_entry->preferred_base)
+               return -1;
+
+       /*
+        * We do not bother to try a delta that we discarded
+        * on an earlier try, but only when reusing delta data.
+        */
+       if (!no_reuse_delta && trg_entry->in_pack &&
+           trg_entry->in_pack == src_entry->in_pack)
+               return 0;
+
+       /*
+        * If the current object is at pack edge, take the depth the
+        * objects that depend on the current object into account --
+        * otherwise they would become too deep.
+        */
+       if (trg_entry->delta_child) {
+               if (max_depth <= trg_entry->delta_limit)
+                       return 0;
+               max_depth -= trg_entry->delta_limit;
+       }
+       if (src_entry->depth >= max_depth)
+               return 0;
+
+       /* Now some size filtering heuristics. */
+       trg_size = trg_entry->size;
+       max_size = trg_size/2 - 20;
+       max_size = max_size * (max_depth - src_entry->depth) / max_depth;
+       if (max_size == 0)
+               return 0;
+       if (trg_entry->delta && trg_entry->delta_size <= max_size)
+               max_size = trg_entry->delta_size-1;
+       src_size = src_entry->size;
+       sizediff = src_size < trg_size ? trg_size - src_size : 0;
+       if (sizediff >= max_size)
+               return 0;
+
+       /* Load data if not already done */
+       if (!trg->data) {
+               trg->data = read_sha1_file(trg_entry->sha1, type, &sz);
+               if (sz != trg_size)
+                       die("object %s inconsistent object length (%lu vs %lu)",
+                           sha1_to_hex(trg_entry->sha1), sz, trg_size);
+       }
+       if (!src->data) {
+               src->data = read_sha1_file(src_entry->sha1, type, &sz);
+               if (sz != src_size)
+                       die("object %s inconsistent object length (%lu vs %lu)",
+                           sha1_to_hex(src_entry->sha1), sz, src_size);
+       }
+       if (!src->index) {
+               src->index = create_delta_index(src->data, src_size);
+               if (!src->index)
+                       die("out of memory");
+       }
+
+       delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
+       if (!delta_buf)
+               return 0;
+
+       trg_entry->delta = src_entry;
+       trg_entry->delta_size = delta_size;
+       trg_entry->depth = src_entry->depth + 1;
+       free(delta_buf);
+       return 1;
+}
+
+static void progress_interval(int signum)
+{
+       progress_update = 1;
+}
+
+static void find_deltas(struct object_entry **list, int window, int depth)
+{
+       int i, idx;
+       unsigned int array_size = window * sizeof(struct unpacked);
+       struct unpacked *array = xmalloc(array_size);
+       unsigned processed = 0;
+       unsigned last_percent = 999;
+
+       memset(array, 0, array_size);
+       i = nr_objects;
+       idx = 0;
+       if (progress)
+               fprintf(stderr, "Deltifying %d objects.\n", nr_result);
+
+       while (--i >= 0) {
+               struct object_entry *entry = list[i];
+               struct unpacked *n = array + idx;
+               int j;
+
+               if (!entry->preferred_base)
+                       processed++;
+
+               if (progress) {
+                       unsigned percent = processed * 100 / nr_result;
+                       if (percent != last_percent || progress_update) {
+                               fprintf(stderr, "%4u%% (%u/%u) done\r",
+                                       percent, processed, nr_result);
+                               progress_update = 0;
+                               last_percent = percent;
+                       }
+               }
+
+               if (entry->delta)
+                       /* This happens if we decided to reuse existing
+                        * delta from a pack.  "!no_reuse_delta &&" is implied.
+                        */
+                       continue;
+
+               if (entry->size < 50)
+                       continue;
+               free_delta_index(n->index);
+               n->index = NULL;
+               free(n->data);
+               n->data = NULL;
+               n->entry = entry;
+
+               j = window;
+               while (--j > 0) {
+                       unsigned int other_idx = idx + j;
+                       struct unpacked *m;
+                       if (other_idx >= window)
+                               other_idx -= window;
+                       m = array + other_idx;
+                       if (!m->entry)
+                               break;
+                       if (try_delta(n, m, depth) < 0)
+                               break;
+               }
+               /* if we made n a delta, and if n is already at max
+                * depth, leaving it in the window is pointless.  we
+                * should evict it first.
+                */
+               if (entry->delta && depth <= entry->depth)
+                       continue;
+
+               idx++;
+               if (idx >= window)
+                       idx = 0;
+       }
+
+       if (progress)
+               fputc('\n', stderr);
+
+       for (i = 0; i < window; ++i) {
+               free_delta_index(array[i].index);
+               free(array[i].data);
+       }
+       free(array);
+}
+
+static void prepare_pack(int window, int depth)
+{
+       get_object_details();
+       sorted_by_type = create_sorted_list(type_size_sort);
+       if (window && depth)
+               find_deltas(sorted_by_type, window+1, depth);
+}
+
+static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
+{
+       static const char cache[] = "pack-cache/pack-%s.%s";
+       char *cached_pack, *cached_idx;
+       int ifd, ofd, ifd_ix = -1;
+
+       cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
+       ifd = open(cached_pack, O_RDONLY);
+       if (ifd < 0)
+               return 0;
+
+       if (!pack_to_stdout) {
+               cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
+               ifd_ix = open(cached_idx, O_RDONLY);
+               if (ifd_ix < 0) {
+                       close(ifd);
+                       return 0;
+               }
+       }
+
+       if (progress)
+               fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
+                       sha1_to_hex(sha1));
+
+       if (pack_to_stdout) {
+               if (copy_fd(ifd, 1))
+                       exit(1);
+               close(ifd);
+       }
+       else {
+               char name[PATH_MAX];
+               snprintf(name, sizeof(name),
+                        "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
+               ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
+               if (ofd < 0)
+                       die("unable to open %s (%s)", name, strerror(errno));
+               if (copy_fd(ifd, ofd))
+                       exit(1);
+               close(ifd);
+
+               snprintf(name, sizeof(name),
+                        "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
+               ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
+               if (ofd < 0)
+                       die("unable to open %s (%s)", name, strerror(errno));
+               if (copy_fd(ifd_ix, ofd))
+                       exit(1);
+               close(ifd_ix);
+               puts(sha1_to_hex(sha1));
+       }
+
+       return 1;
+}
+
+static void setup_progress_signal(void)
+{
+       struct sigaction sa;
+       struct itimerval v;
+
+       memset(&sa, 0, sizeof(sa));
+       sa.sa_handler = progress_interval;
+       sigemptyset(&sa.sa_mask);
+       sa.sa_flags = SA_RESTART;
+       sigaction(SIGALRM, &sa, NULL);
+
+       v.it_interval.tv_sec = 1;
+       v.it_interval.tv_usec = 0;
+       v.it_value = v.it_interval;
+       setitimer(ITIMER_REAL, &v, NULL);
+}
+
+static int git_pack_config(const char *k, const char *v)
+{
+       if(!strcmp(k, "pack.window")) {
+               window = git_config_int(k, v);
+               return 0;
+       }
+       return git_default_config(k, v);
+}
+
+int cmd_pack_objects(int argc, const char **argv, const char *prefix)
+{
+       SHA_CTX ctx;
+       char line[40 + 1 + PATH_MAX + 2];
+       int depth = 10, pack_to_stdout = 0;
+       struct object_entry **list;
+       int num_preferred_base = 0;
+       int i;
+
+       git_config(git_pack_config);
+
+       progress = isatty(2);
+       for (i = 1; i < argc; i++) {
+               const char *arg = argv[i];
+
+               if (*arg == '-') {
+                       if (!strcmp("--non-empty", arg)) {
+                               non_empty = 1;
+                               continue;
+                       }
+                       if (!strcmp("--local", arg)) {
+                               local = 1;
+                               continue;
+                       }
+                       if (!strcmp("--progress", arg)) {
+                               progress = 1;
+                               continue;
+                       }
+                       if (!strcmp("--incremental", arg)) {
+                               incremental = 1;
+                               continue;
+                       }
+                       if (!strncmp("--window=", arg, 9)) {
+                               char *end;
+                               window = strtoul(arg+9, &end, 0);
+                               if (!arg[9] || *end)
+                                       usage(pack_usage);
+                               continue;
+                       }
+                       if (!strncmp("--depth=", arg, 8)) {
+                               char *end;
+                               depth = strtoul(arg+8, &end, 0);
+                               if (!arg[8] || *end)
+                                       usage(pack_usage);
+                               continue;
+                       }
+                       if (!strcmp("--progress", arg)) {
+                               progress = 1;
+                               continue;
+                       }
+                       if (!strcmp("-q", arg)) {
+                               progress = 0;
+                               continue;
+                       }
+                       if (!strcmp("--no-reuse-delta", arg)) {
+                               no_reuse_delta = 1;
+                               continue;
+                       }
+                       if (!strcmp("--stdout", arg)) {
+                               pack_to_stdout = 1;
+                               continue;
+                       }
+                       usage(pack_usage);
+               }
+               if (base_name)
+                       usage(pack_usage);
+               base_name = arg;
+       }
+
+       if (pack_to_stdout != !base_name)
+               usage(pack_usage);
+
+       prepare_packed_git();
+
+       if (progress) {
+               fprintf(stderr, "Generating pack...\n");
+               setup_progress_signal();
+       }
+
+       for (;;) {
+               unsigned char sha1[20];
+               unsigned hash;
+
+               if (!fgets(line, sizeof(line), stdin)) {
+                       if (feof(stdin))
+                               break;
+                       if (!ferror(stdin))
+                               die("fgets returned NULL, not EOF, not error!");
+                       if (errno != EINTR)
+                               die("fgets: %s", strerror(errno));
+                       clearerr(stdin);
+                       continue;
+               }
+
+               if (line[0] == '-') {
+                       if (get_sha1_hex(line+1, sha1))
+                               die("expected edge sha1, got garbage:\n %s",
+                                   line+1);
+                       if (num_preferred_base++ < window)
+                               add_preferred_base(sha1);
+                       continue;
+               }
+               if (get_sha1_hex(line, sha1))
+                       die("expected sha1, got garbage:\n %s", line);
+               hash = name_hash(line+41);
+               add_preferred_base_object(line+41, hash);
+               add_object_entry(sha1, hash, 0);
+       }
+       if (progress)
+               fprintf(stderr, "Done counting %d objects.\n", nr_objects);
+       sorted_by_sha = create_final_object_list();
+       if (non_empty && !nr_result)
+               return 0;
+
+       SHA1_Init(&ctx);
+       list = sorted_by_sha;
+       for (i = 0; i < nr_result; i++) {
+               struct object_entry *entry = *list++;
+               SHA1_Update(&ctx, entry->sha1, 20);
+       }
+       SHA1_Final(object_list_sha1, &ctx);
+       if (progress && (nr_objects != nr_result))
+               fprintf(stderr, "Result has %d objects.\n", nr_result);
+
+       if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
+               ;
+       else {
+               if (nr_result)
+                       prepare_pack(window, depth);
+               if (progress && pack_to_stdout) {
+                       /* the other end usually displays progress itself */
+                       struct itimerval v = {{0,},};
+                       setitimer(ITIMER_REAL, &v, NULL);
+                       signal(SIGALRM, SIG_IGN );
+                       progress_update = 0;
+               }
+               write_pack_file();
+               if (!pack_to_stdout) {
+                       write_index_file();
+                       puts(sha1_to_hex(object_list_sha1));
+               }
+       }
+       if (progress)
+               fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
+                       nr_result, written, written_delta, reused, reused_delta);
+       return 0;
+}

diff --git a/builtin.h b/builtin.h
index d1d9dc14f9ea688ef0a924f08e094f33b0ae0d5f..bc57a04c053689e470b66bd9b7a3674a7ca0c950 100644 (file)
--- a/builtin.h
+++ b/builtin.h
@@ -50,6 +50,7 @@ extern int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix);
 extern int cmd_mv(int argc, const char **argv, const char *prefix);
 extern int cmd_repo_config(int argc, const char **argv, const char *prefix);
 extern int cmd_name_rev(int argc, const char **argv, const char *prefix);
+extern int cmd_pack_objects(int argc, const char **argv, const char *prefix);
 
 extern int cmd_write_tree(int argc, const char **argv, const char *prefix);
 extern int write_tree(unsigned char *sha1, int missing_ok, const char *prefix);

diff --git a/git.c b/git.c
index 501a7815fce71c3bd3368d1b4afc4f540ddfbc64..5d58946f41684f2df2d98222a2c0bd076a9ada4a 100644 (file)
--- a/git.c
+++ b/git.c
@@ -266,6 +266,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
                { "prune-packed", cmd_prune_packed, NEEDS_PREFIX },
                { "repo-config", cmd_repo_config },
                { "name-rev", cmd_name_rev, NEEDS_PREFIX },
+               { "pack-objects", cmd_pack_objects, NEEDS_PREFIX },
        };
        int i;
 

diff --git a/pack-objects.c b/pack-objects.c
deleted file mode 100644 (file)
index 861c7f0..0000000
--- a/pack-objects.c
+++ /dev/null
@@ -1,1376 +0,0 @@
-#include "cache.h"
-#include "object.h"
-#include "blob.h"
-#include "commit.h"
-#include "tag.h"
-#include "tree.h"
-#include "delta.h"
-#include "pack.h"
-#include "csum-file.h"
-#include "tree-walk.h"
-#include <sys/time.h>
-#include <signal.h>
-
-static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
-
-struct object_entry {
-       unsigned char sha1[20];
-       unsigned long size;     /* uncompressed size */
-       unsigned long offset;   /* offset into the final pack file;
-                                * nonzero if already written.
-                                */
-       unsigned int depth;     /* delta depth */
-       unsigned int delta_limit;       /* base adjustment for in-pack delta */
-       unsigned int hash;      /* name hint hash */
-       enum object_type type;
-       enum object_type in_pack_type;  /* could be delta */
-       unsigned long delta_size;       /* delta data size (uncompressed) */
-       struct object_entry *delta;     /* delta base object */
-       struct packed_git *in_pack;     /* already in pack */
-       unsigned int in_pack_offset;
-       struct object_entry *delta_child; /* deltified objects who bases me */
-       struct object_entry *delta_sibling; /* other deltified objects who
-                                            * uses the same base as me
-                                            */
-       int preferred_base;     /* we do not pack this, but is encouraged to
-                                * be used as the base objectto delta huge
-                                * objects against.
-                                */
-};
-
-/*
- * Objects we are going to pack are collected in objects array (dynamically
- * expanded).  nr_objects & nr_alloc controls this array.  They are stored
- * in the order we see -- typically rev-list --objects order that gives us
- * nice "minimum seek" order.
- *
- * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
- * elements in the objects array.  The former is used to build the pack
- * index (lists object names in the ascending order to help offset lookup),
- * and the latter is used to group similar things together by try_delta()
- * heuristics.
- */
-
-static unsigned char object_list_sha1[20];
-static int non_empty = 0;
-static int no_reuse_delta = 0;
-static int local = 0;
-static int incremental = 0;
-static struct object_entry **sorted_by_sha, **sorted_by_type;
-static struct object_entry *objects = NULL;
-static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
-static const char *base_name;
-static unsigned char pack_file_sha1[20];
-static int progress = 1;
-static volatile sig_atomic_t progress_update = 0;
-static int window = 10;
-
-/*
- * The object names in objects array are hashed with this hashtable,
- * to help looking up the entry by object name.  Binary search from
- * sorted_by_sha is also possible but this was easier to code and faster.
- * This hashtable is built after all the objects are seen.
- */
-static int *object_ix = NULL;
-static int object_ix_hashsz = 0;
-
-/*
- * Pack index for existing packs give us easy access to the offsets into
- * corresponding pack file where each object's data starts, but the entries
- * do not store the size of the compressed representation (uncompressed
- * size is easily available by examining the pack entry header).  We build
- * a hashtable of existing packs (pack_revindex), and keep reverse index
- * here -- pack index file is sorted by object name mapping to offset; this
- * pack_revindex[].revindex array is an ordered list of offsets, so if you
- * know the offset of an object, next offset is where its packed
- * representation ends.
- */
-struct pack_revindex {
-       struct packed_git *p;
-       unsigned long *revindex;
-} *pack_revindex = NULL;
-static int pack_revindex_hashsz = 0;
-
-/*
- * stats
- */
-static int written = 0;
-static int written_delta = 0;
-static int reused = 0;
-static int reused_delta = 0;
-
-static int pack_revindex_ix(struct packed_git *p)
-{
-       unsigned long ui = (unsigned long)p;
-       int i;
-
-       ui = ui ^ (ui >> 16); /* defeat structure alignment */
-       i = (int)(ui % pack_revindex_hashsz);
-       while (pack_revindex[i].p) {
-               if (pack_revindex[i].p == p)
-                       return i;
-               if (++i == pack_revindex_hashsz)
-                       i = 0;
-       }
-       return -1 - i;
-}
-
-static void prepare_pack_ix(void)
-{
-       int num;
-       struct packed_git *p;
-       for (num = 0, p = packed_git; p; p = p->next)
-               num++;
-       if (!num)
-               return;
-       pack_revindex_hashsz = num * 11;
-       pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
-       for (p = packed_git; p; p = p->next) {
-               num = pack_revindex_ix(p);
-               num = - 1 - num;
-               pack_revindex[num].p = p;
-       }
-       /* revindex elements are lazily initialized */
-}
-
-static int cmp_offset(const void *a_, const void *b_)
-{
-       unsigned long a = *(unsigned long *) a_;
-       unsigned long b = *(unsigned long *) b_;
-       if (a < b)
-               return -1;
-       else if (a == b)
-               return 0;
-       else
-               return 1;
-}
-
-/*
- * Ordered list of offsets of objects in the pack.
- */
-static void prepare_pack_revindex(struct pack_revindex *rix)
-{
-       struct packed_git *p = rix->p;
-       int num_ent = num_packed_objects(p);
-       int i;
-       void *index = p->index_base + 256;
-
-       rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
-       for (i = 0; i < num_ent; i++) {
-               unsigned int hl = *((unsigned int *)((char *) index + 24*i));
-               rix->revindex[i] = ntohl(hl);
-       }
-       /* This knows the pack format -- the 20-byte trailer
-        * follows immediately after the last object data.
-        */
-       rix->revindex[num_ent] = p->pack_size - 20;
-       qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
-}
-
-static unsigned long find_packed_object_size(struct packed_git *p,
-                                            unsigned long ofs)
-{
-       int num;
-       int lo, hi;
-       struct pack_revindex *rix;
-       unsigned long *revindex;
-       num = pack_revindex_ix(p);
-       if (num < 0)
-               die("internal error: pack revindex uninitialized");
-       rix = &pack_revindex[num];
-       if (!rix->revindex)
-               prepare_pack_revindex(rix);
-       revindex = rix->revindex;
-       lo = 0;
-       hi = num_packed_objects(p) + 1;
-       do {
-               int mi = (lo + hi) / 2;
-               if (revindex[mi] == ofs) {
-                       return revindex[mi+1] - ofs;
-               }
-               else if (ofs < revindex[mi])
-                       hi = mi;
-               else
-                       lo = mi + 1;
-       } while (lo < hi);
-       die("internal error: pack revindex corrupt");
-}
-
-static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
-{
-       unsigned long othersize, delta_size;
-       char type[10];
-       void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
-       void *delta_buf;
-
-       if (!otherbuf)
-               die("unable to read %s", sha1_to_hex(entry->delta->sha1));
-        delta_buf = diff_delta(otherbuf, othersize,
-                              buf, size, &delta_size, 0);
-        if (!delta_buf || delta_size != entry->delta_size)
-               die("delta size changed");
-        free(buf);
-        free(otherbuf);
-       return delta_buf;
-}
-
-/*
- * The per-object header is a pretty dense thing, which is
- *  - first byte: low four bits are "size", then three bits of "type",
- *    and the high bit is "size continues".
- *  - each byte afterwards: low seven bits are size continuation,
- *    with the high bit being "size continues"
- */
-static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
-{
-       int n = 1;
-       unsigned char c;
-
-       if (type < OBJ_COMMIT || type > OBJ_DELTA)
-               die("bad type %d", type);
-
-       c = (type << 4) | (size & 15);
-       size >>= 4;
-       while (size) {
-               *hdr++ = c | 0x80;
-               c = size & 0x7f;
-               size >>= 7;
-               n++;
-       }
-       *hdr = c;
-       return n;
-}
-
-static unsigned long write_object(struct sha1file *f,
-                                 struct object_entry *entry)
-{
-       unsigned long size;
-       char type[10];
-       void *buf;
-       unsigned char header[10];
-       unsigned hdrlen, datalen;
-       enum object_type obj_type;
-       int to_reuse = 0;
-
-       if (entry->preferred_base)
-               return 0;
-
-       obj_type = entry->type;
-       if (! entry->in_pack)
-               to_reuse = 0;   /* can't reuse what we don't have */
-       else if (obj_type == OBJ_DELTA)
-               to_reuse = 1;   /* check_object() decided it for us */
-       else if (obj_type != entry->in_pack_type)
-               to_reuse = 0;   /* pack has delta which is unusable */
-       else if (entry->delta)
-               to_reuse = 0;   /* we want to pack afresh */
-       else
-               to_reuse = 1;   /* we have it in-pack undeltified,
-                                * and we do not need to deltify it.
-                                */
-
-       if (! to_reuse) {
-               buf = read_sha1_file(entry->sha1, type, &size);
-               if (!buf)
-                       die("unable to read %s", sha1_to_hex(entry->sha1));
-               if (size != entry->size)
-                       die("object %s size inconsistency (%lu vs %lu)",
-                           sha1_to_hex(entry->sha1), size, entry->size);
-               if (entry->delta) {
-                       buf = delta_against(buf, size, entry);
-                       size = entry->delta_size;
-                       obj_type = OBJ_DELTA;
-               }
-               /*
-                * The object header is a byte of 'type' followed by zero or
-                * more bytes of length.  For deltas, the 20 bytes of delta
-                * sha1 follows that.
-                */
-               hdrlen = encode_header(obj_type, size, header);
-               sha1write(f, header, hdrlen);
-
-               if (entry->delta) {
-                       sha1write(f, entry->delta, 20);
-                       hdrlen += 20;
-               }
-               datalen = sha1write_compressed(f, buf, size);
-               free(buf);
-       }
-       else {
-               struct packed_git *p = entry->in_pack;
-               use_packed_git(p);
-
-               datalen = find_packed_object_size(p, entry->in_pack_offset);
-               buf = (char *) p->pack_base + entry->in_pack_offset;
-               sha1write(f, buf, datalen);
-               unuse_packed_git(p);
-               hdrlen = 0; /* not really */
-               if (obj_type == OBJ_DELTA)
-                       reused_delta++;
-               reused++;
-       }
-       if (obj_type == OBJ_DELTA)
-               written_delta++;
-       written++;
-       return hdrlen + datalen;
-}
-
-static unsigned long write_one(struct sha1file *f,
-                              struct object_entry *e,
-                              unsigned long offset)
-{
-       if (e->offset)
-               /* offset starts from header size and cannot be zero
-                * if it is written already.
-                */
-               return offset;
-       e->offset = offset;
-       offset += write_object(f, e);
-       /* if we are deltified, write out its base object. */
-       if (e->delta)
-               offset = write_one(f, e->delta, offset);
-       return offset;
-}
-
-static void write_pack_file(void)
-{
-       int i;
-       struct sha1file *f;
-       unsigned long offset;
-       struct pack_header hdr;
-       unsigned last_percent = 999;
-       int do_progress = 0;
-
-       if (!base_name)
-               f = sha1fd(1, "<stdout>");
-       else {
-               f = sha1create("%s-%s.%s", base_name,
-                              sha1_to_hex(object_list_sha1), "pack");
-               do_progress = progress;
-       }
-       if (do_progress)
-               fprintf(stderr, "Writing %d objects.\n", nr_result);
-
-       hdr.hdr_signature = htonl(PACK_SIGNATURE);
-       hdr.hdr_version = htonl(PACK_VERSION);
-       hdr.hdr_entries = htonl(nr_result);
-       sha1write(f, &hdr, sizeof(hdr));
-       offset = sizeof(hdr);
-       if (!nr_result)
-               goto done;
-       for (i = 0; i < nr_objects; i++) {
-               offset = write_one(f, objects + i, offset);
-               if (do_progress) {
-                       unsigned percent = written * 100 / nr_result;
-                       if (progress_update || percent != last_percent) {
-                               fprintf(stderr, "%4u%% (%u/%u) done\r",
-                                       percent, written, nr_result);
-                               progress_update = 0;
-                               last_percent = percent;
-                       }
-               }
-       }
-       if (do_progress)
-               fputc('\n', stderr);
- done:
-       sha1close(f, pack_file_sha1, 1);
-}
-
-static void write_index_file(void)
-{
-       int i;
-       struct sha1file *f = sha1create("%s-%s.%s", base_name,
-                                       sha1_to_hex(object_list_sha1), "idx");
-       struct object_entry **list = sorted_by_sha;
-       struct object_entry **last = list + nr_result;
-       unsigned int array[256];
-
-       /*
-        * Write the first-level table (the list is sorted,
-        * but we use a 256-entry lookup to be able to avoid
-        * having to do eight extra binary search iterations).
-        */
-       for (i = 0; i < 256; i++) {
-               struct object_entry **next = list;
-               while (next < last) {
-                       struct object_entry *entry = *next;
-                       if (entry->sha1[0] != i)
-                               break;
-                       next++;
-               }
-               array[i] = htonl(next - sorted_by_sha);
-               list = next;
-       }
-       sha1write(f, array, 256 * sizeof(int));
-
-       /*
-        * Write the actual SHA1 entries..
-        */
-       list = sorted_by_sha;
-       for (i = 0; i < nr_result; i++) {
-               struct object_entry *entry = *list++;
-               unsigned int offset = htonl(entry->offset);
-               sha1write(f, &offset, 4);
-               sha1write(f, entry->sha1, 20);
-       }
-       sha1write(f, pack_file_sha1, 20);
-       sha1close(f, NULL, 1);
-}
-
-static int locate_object_entry_hash(const unsigned char *sha1)
-{
-       int i;
-       unsigned int ui;
-       memcpy(&ui, sha1, sizeof(unsigned int));
-       i = ui % object_ix_hashsz;
-       while (0 < object_ix[i]) {
-               if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
-                       return i;
-               if (++i == object_ix_hashsz)
-                       i = 0;
-       }
-       return -1 - i;
-}
-
-static struct object_entry *locate_object_entry(const unsigned char *sha1)
-{
-       int i;
-
-       if (!object_ix_hashsz)
-               return NULL;
-
-       i = locate_object_entry_hash(sha1);
-       if (0 <= i)
-               return &objects[object_ix[i]-1];
-       return NULL;
-}
-
-static void rehash_objects(void)
-{
-       int i;
-       struct object_entry *oe;
-
-       object_ix_hashsz = nr_objects * 3;
-       if (object_ix_hashsz < 1024)
-               object_ix_hashsz = 1024;
-       object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
-       memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
-       for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
-               int ix = locate_object_entry_hash(oe->sha1);
-               if (0 <= ix)
-                       continue;
-               ix = -1 - ix;
-               object_ix[ix] = i + 1;
-       }
-}
-
-static unsigned name_hash(const char *name)
-{
-       unsigned char c;
-       unsigned hash = 0;
-
-       /*
-        * This effectively just creates a sortable number from the
-        * last sixteen non-whitespace characters. Last characters
-        * count "most", so things that end in ".c" sort together.
-        */
-       while ((c = *name++) != 0) {
-               if (isspace(c))
-                       continue;
-               hash = (hash >> 2) + (c << 24);
-       }
-       return hash;
-}
-
-static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
-{
-       unsigned int idx = nr_objects;
-       struct object_entry *entry;
-       struct packed_git *p;
-       unsigned int found_offset = 0;
-       struct packed_git *found_pack = NULL;
-       int ix, status = 0;
-
-       if (!exclude) {
-               for (p = packed_git; p; p = p->next) {
-                       struct pack_entry e;
-                       if (find_pack_entry_one(sha1, &e, p)) {
-                               if (incremental)
-                                       return 0;
-                               if (local && !p->pack_local)
-                                       return 0;
-                               if (!found_pack) {
-                                       found_offset = e.offset;
-                                       found_pack = e.p;
-                               }
-                       }
-               }
-       }
-       if ((entry = locate_object_entry(sha1)) != NULL)
-               goto already_added;
-
-       if (idx >= nr_alloc) {
-               unsigned int needed = (idx + 1024) * 3 / 2;
-               objects = xrealloc(objects, needed * sizeof(*entry));
-               nr_alloc = needed;
-       }
-       entry = objects + idx;
-       nr_objects = idx + 1;
-       memset(entry, 0, sizeof(*entry));
-       memcpy(entry->sha1, sha1, 20);
-       entry->hash = hash;
-
-       if (object_ix_hashsz * 3 <= nr_objects * 4)
-               rehash_objects();
-       else {
-               ix = locate_object_entry_hash(entry->sha1);
-               if (0 <= ix)
-                       die("internal error in object hashing.");
-               object_ix[-1 - ix] = idx + 1;
-       }
-       status = 1;
-
- already_added:
-       if (progress_update) {
-               fprintf(stderr, "Counting objects...%d\r", nr_objects);
-               progress_update = 0;
-       }
-       if (exclude)
-               entry->preferred_base = 1;
-       else {
-               if (found_pack) {
-                       entry->in_pack = found_pack;
-                       entry->in_pack_offset = found_offset;
-               }
-       }
-       return status;
-}
-
-struct pbase_tree_cache {
-       unsigned char sha1[20];
-       int ref;
-       int temporary;
-       void *tree_data;
-       unsigned long tree_size;
-};
-
-static struct pbase_tree_cache *(pbase_tree_cache[256]);
-static int pbase_tree_cache_ix(const unsigned char *sha1)
-{
-       return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
-}
-static int pbase_tree_cache_ix_incr(int ix)
-{
-       return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
-}
-
-static struct pbase_tree {
-       struct pbase_tree *next;
-       /* This is a phony "cache" entry; we are not
-        * going to evict it nor find it through _get()
-        * mechanism -- this is for the toplevel node that
-        * would almost always change with any commit.
-        */
-       struct pbase_tree_cache pcache;
-} *pbase_tree;
-
-static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
-{
-       struct pbase_tree_cache *ent, *nent;
-       void *data;
-       unsigned long size;
-       char type[20];
-       int neigh;
-       int my_ix = pbase_tree_cache_ix(sha1);
-       int available_ix = -1;
-
-       /* pbase-tree-cache acts as a limited hashtable.
-        * your object will be found at your index or within a few
-        * slots after that slot if it is cached.
-        */
-       for (neigh = 0; neigh < 8; neigh++) {
-               ent = pbase_tree_cache[my_ix];
-               if (ent && !memcmp(ent->sha1, sha1, 20)) {
-                       ent->ref++;
-                       return ent;
-               }
-               else if (((available_ix < 0) && (!ent || !ent->ref)) ||
-                        ((0 <= available_ix) &&
-                         (!ent && pbase_tree_cache[available_ix])))
-                       available_ix = my_ix;
-               if (!ent)
-                       break;
-               my_ix = pbase_tree_cache_ix_incr(my_ix);
-       }
-
-       /* Did not find one.  Either we got a bogus request or
-        * we need to read and perhaps cache.
-        */
-       data = read_sha1_file(sha1, type, &size);
-       if (!data)
-               return NULL;
-       if (strcmp(type, tree_type)) {
-               free(data);
-               return NULL;
-       }
-
-       /* We need to either cache or return a throwaway copy */
-
-       if (available_ix < 0)
-               ent = NULL;
-       else {
-               ent = pbase_tree_cache[available_ix];
-               my_ix = available_ix;
-       }
-
-       if (!ent) {
-               nent = xmalloc(sizeof(*nent));
-               nent->temporary = (available_ix < 0);
-       }
-       else {
-               /* evict and reuse */
-               free(ent->tree_data);
-               nent = ent;
-       }
-       memcpy(nent->sha1, sha1, 20);
-       nent->tree_data = data;
-       nent->tree_size = size;
-       nent->ref = 1;
-       if (!nent->temporary)
-               pbase_tree_cache[my_ix] = nent;
-       return nent;
-}
-
-static void pbase_tree_put(struct pbase_tree_cache *cache)
-{
-       if (!cache->temporary) {
-               cache->ref--;
-               return;
-       }
-       free(cache->tree_data);
-       free(cache);
-}
-
-static int name_cmp_len(const char *name)
-{
-       int i;
-       for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
-               ;
-       return i;
-}
-
-static void add_pbase_object(struct tree_desc *tree,
-                            const char *name,
-                            int cmplen,
-                            const char *fullname)
-{
-       struct name_entry entry;
-
-       while (tree_entry(tree,&entry)) {
-               unsigned long size;
-               char type[20];
-
-               if (entry.pathlen != cmplen ||
-                   memcmp(entry.path, name, cmplen) ||
-                   !has_sha1_file(entry.sha1) ||
-                   sha1_object_info(entry.sha1, type, &size))
-                       continue;
-               if (name[cmplen] != '/') {
-                       unsigned hash = name_hash(fullname);
-                       add_object_entry(entry.sha1, hash, 1);
-                       return;
-               }
-               if (!strcmp(type, tree_type)) {
-                       struct tree_desc sub;
-                       struct pbase_tree_cache *tree;
-                       const char *down = name+cmplen+1;
-                       int downlen = name_cmp_len(down);
-
-                       tree = pbase_tree_get(entry.sha1);
-                       if (!tree)
-                               return;
-                       sub.buf = tree->tree_data;
-                       sub.size = tree->tree_size;
-
-                       add_pbase_object(&sub, down, downlen, fullname);
-                       pbase_tree_put(tree);
-               }
-       }
-}
-
-static unsigned *done_pbase_paths;
-static int done_pbase_paths_num;
-static int done_pbase_paths_alloc;
-static int done_pbase_path_pos(unsigned hash)
-{
-       int lo = 0;
-       int hi = done_pbase_paths_num;
-       while (lo < hi) {
-               int mi = (hi + lo) / 2;
-               if (done_pbase_paths[mi] == hash)
-                       return mi;
-               if (done_pbase_paths[mi] < hash)
-                       hi = mi;
-               else
-                       lo = mi + 1;
-       }
-       return -lo-1;
-}
-
-static int check_pbase_path(unsigned hash)
-{
-       int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
-       if (0 <= pos)
-               return 1;
-       pos = -pos - 1;
-       if (done_pbase_paths_alloc <= done_pbase_paths_num) {
-               done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
-               done_pbase_paths = xrealloc(done_pbase_paths,
-                                           done_pbase_paths_alloc *
-                                           sizeof(unsigned));
-       }
-       done_pbase_paths_num++;
-       if (pos < done_pbase_paths_num)
-               memmove(done_pbase_paths + pos + 1,
-                       done_pbase_paths + pos,
-                       (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
-       done_pbase_paths[pos] = hash;
-       return 0;
-}
-
-static void add_preferred_base_object(char *name, unsigned hash)
-{
-       struct pbase_tree *it;
-       int cmplen = name_cmp_len(name);
-
-       if (check_pbase_path(hash))
-               return;
-
-       for (it = pbase_tree; it; it = it->next) {
-               if (cmplen == 0) {
-                       hash = name_hash("");
-                       add_object_entry(it->pcache.sha1, hash, 1);
-               }
-               else {
-                       struct tree_desc tree;
-                       tree.buf = it->pcache.tree_data;
-                       tree.size = it->pcache.tree_size;
-                       add_pbase_object(&tree, name, cmplen, name);
-               }
-       }
-}
-
-static void add_preferred_base(unsigned char *sha1)
-{
-       struct pbase_tree *it;
-       void *data;
-       unsigned long size;
-       unsigned char tree_sha1[20];
-
-       data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
-       if (!data)
-               return;
-
-       for (it = pbase_tree; it; it = it->next) {
-               if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
-                       free(data);
-                       return;
-               }
-       }
-
-       it = xcalloc(1, sizeof(*it));
-       it->next = pbase_tree;
-       pbase_tree = it;
-
-       memcpy(it->pcache.sha1, tree_sha1, 20);
-       it->pcache.tree_data = data;
-       it->pcache.tree_size = size;
-}
-
-static void check_object(struct object_entry *entry)
-{
-       char type[20];
-
-       if (entry->in_pack && !entry->preferred_base) {
-               unsigned char base[20];
-               unsigned long size;
-               struct object_entry *base_entry;
-
-               /* We want in_pack_type even if we do not reuse delta.
-                * There is no point not reusing non-delta representations.
-                */
-               check_reuse_pack_delta(entry->in_pack,
-                                      entry->in_pack_offset,
-                                      base, &size,
-                                      &entry->in_pack_type);
-
-               /* Check if it is delta, and the base is also an object
-                * we are going to pack.  If so we will reuse the existing
-                * delta.
-                */
-               if (!no_reuse_delta &&
-                   entry->in_pack_type == OBJ_DELTA &&
-                   (base_entry = locate_object_entry(base)) &&
-                   (!base_entry->preferred_base)) {
-
-                       /* Depth value does not matter - find_deltas()
-                        * will never consider reused delta as the
-                        * base object to deltify other objects
-                        * against, in order to avoid circular deltas.
-                        */
-
-                       /* uncompressed size of the delta data */
-                       entry->size = entry->delta_size = size;
-                       entry->delta = base_entry;
-                       entry->type = OBJ_DELTA;
-
-                       entry->delta_sibling = base_entry->delta_child;
-                       base_entry->delta_child = entry;
-
-                       return;
-               }
-               /* Otherwise we would do the usual */
-       }
-
-       if (sha1_object_info(entry->sha1, type, &entry->size))
-               die("unable to get type of object %s",
-                   sha1_to_hex(entry->sha1));
-
-       if (!strcmp(type, commit_type)) {
-               entry->type = OBJ_COMMIT;
-       } else if (!strcmp(type, tree_type)) {
-               entry->type = OBJ_TREE;
-       } else if (!strcmp(type, blob_type)) {
-               entry->type = OBJ_BLOB;
-       } else if (!strcmp(type, tag_type)) {
-               entry->type = OBJ_TAG;
-       } else
-               die("unable to pack object %s of type %s",
-                   sha1_to_hex(entry->sha1), type);
-}
-
-static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
-{
-       struct object_entry *child = me->delta_child;
-       unsigned int m = n;
-       while (child) {
-               unsigned int c = check_delta_limit(child, n + 1);
-               if (m < c)
-                       m = c;
-               child = child->delta_sibling;
-       }
-       return m;
-}
-
-static void get_object_details(void)
-{
-       int i;
-       struct object_entry *entry;
-
-       prepare_pack_ix();
-       for (i = 0, entry = objects; i < nr_objects; i++, entry++)
-               check_object(entry);
-
-       if (nr_objects == nr_result) {
-               /*
-                * Depth of objects that depend on the entry -- this
-                * is subtracted from depth-max to break too deep
-                * delta chain because of delta data reusing.
-                * However, we loosen this restriction when we know we
-                * are creating a thin pack -- it will have to be
-                * expanded on the other end anyway, so do not
-                * artificially cut the delta chain and let it go as
-                * deep as it wants.
-                */
-               for (i = 0, entry = objects; i < nr_objects; i++, entry++)
-                       if (!entry->delta && entry->delta_child)
-                               entry->delta_limit =
-                                       check_delta_limit(entry, 1);
-       }
-}
-
-typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
-
-static entry_sort_t current_sort;
-
-static int sort_comparator(const void *_a, const void *_b)
-{
-       struct object_entry *a = *(struct object_entry **)_a;
-       struct object_entry *b = *(struct object_entry **)_b;
-       return current_sort(a,b);
-}
-
-static struct object_entry **create_sorted_list(entry_sort_t sort)
-{
-       struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
-       int i;
-
-       for (i = 0; i < nr_objects; i++)
-               list[i] = objects + i;
-       current_sort = sort;
-       qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
-       return list;
-}
-
-static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
-{
-       return memcmp(a->sha1, b->sha1, 20);
-}
-
-static struct object_entry **create_final_object_list(void)
-{
-       struct object_entry **list;
-       int i, j;
-
-       for (i = nr_result = 0; i < nr_objects; i++)
-               if (!objects[i].preferred_base)
-                       nr_result++;
-       list = xmalloc(nr_result * sizeof(struct object_entry *));
-       for (i = j = 0; i < nr_objects; i++) {
-               if (!objects[i].preferred_base)
-                       list[j++] = objects + i;
-       }
-       current_sort = sha1_sort;
-       qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
-       return list;
-}
-
-static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
-{
-       if (a->type < b->type)
-               return -1;
-       if (a->type > b->type)
-               return 1;
-       if (a->hash < b->hash)
-               return -1;
-       if (a->hash > b->hash)
-               return 1;
-       if (a->preferred_base < b->preferred_base)
-               return -1;
-       if (a->preferred_base > b->preferred_base)
-               return 1;
-       if (a->size < b->size)
-               return -1;
-       if (a->size > b->size)
-               return 1;
-       return a < b ? -1 : (a > b);
-}
-
-struct unpacked {
-       struct object_entry *entry;
-       void *data;
-       struct delta_index *index;
-};
-
-/*
- * We search for deltas _backwards_ in a list sorted by type and
- * by size, so that we see progressively smaller and smaller files.
- * That's because we prefer deltas to be from the bigger file
- * to the smaller - deletes are potentially cheaper, but perhaps
- * more importantly, the bigger file is likely the more recent
- * one.
- */
-static int try_delta(struct unpacked *trg, struct unpacked *src,
-                    unsigned max_depth)
-{
-       struct object_entry *trg_entry = trg->entry;
-       struct object_entry *src_entry = src->entry;
-       unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
-       char type[10];
-       void *delta_buf;
-
-       /* Don't bother doing diffs between different types */
-       if (trg_entry->type != src_entry->type)
-               return -1;
-
-       /* We do not compute delta to *create* objects we are not
-        * going to pack.
-        */
-       if (trg_entry->preferred_base)
-               return -1;
-
-       /*
-        * We do not bother to try a delta that we discarded
-        * on an earlier try, but only when reusing delta data.
-        */
-       if (!no_reuse_delta && trg_entry->in_pack &&
-           trg_entry->in_pack == src_entry->in_pack)
-               return 0;
-
-       /*
-        * If the current object is at pack edge, take the depth the
-        * objects that depend on the current object into account --
-        * otherwise they would become too deep.
-        */
-       if (trg_entry->delta_child) {
-               if (max_depth <= trg_entry->delta_limit)
-                       return 0;
-               max_depth -= trg_entry->delta_limit;
-       }
-       if (src_entry->depth >= max_depth)
-               return 0;
-
-       /* Now some size filtering heuristics. */
-       trg_size = trg_entry->size;
-       max_size = trg_size/2 - 20;
-       max_size = max_size * (max_depth - src_entry->depth) / max_depth;
-       if (max_size == 0)
-               return 0;
-       if (trg_entry->delta && trg_entry->delta_size <= max_size)
-               max_size = trg_entry->delta_size-1;
-       src_size = src_entry->size;
-       sizediff = src_size < trg_size ? trg_size - src_size : 0;
-       if (sizediff >= max_size)
-               return 0;
-
-       /* Load data if not already done */
-       if (!trg->data) {
-               trg->data = read_sha1_file(trg_entry->sha1, type, &sz);
-               if (sz != trg_size)
-                       die("object %s inconsistent object length (%lu vs %lu)",
-                           sha1_to_hex(trg_entry->sha1), sz, trg_size);
-       }
-       if (!src->data) {
-               src->data = read_sha1_file(src_entry->sha1, type, &sz);
-               if (sz != src_size)
-                       die("object %s inconsistent object length (%lu vs %lu)",
-                           sha1_to_hex(src_entry->sha1), sz, src_size);
-       }
-       if (!src->index) {
-               src->index = create_delta_index(src->data, src_size);
-               if (!src->index)
-                       die("out of memory");
-       }
-
-       delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
-       if (!delta_buf)
-               return 0;
-
-       trg_entry->delta = src_entry;
-       trg_entry->delta_size = delta_size;
-       trg_entry->depth = src_entry->depth + 1;
-       free(delta_buf);
-       return 1;
-}
-
-static void progress_interval(int signum)
-{
-       progress_update = 1;
-}
-
-static void find_deltas(struct object_entry **list, int window, int depth)
-{
-       int i, idx;
-       unsigned int array_size = window * sizeof(struct unpacked);
-       struct unpacked *array = xmalloc(array_size);
-       unsigned processed = 0;
-       unsigned last_percent = 999;
-
-       memset(array, 0, array_size);
-       i = nr_objects;
-       idx = 0;
-       if (progress)
-               fprintf(stderr, "Deltifying %d objects.\n", nr_result);
-
-       while (--i >= 0) {
-               struct object_entry *entry = list[i];
-               struct unpacked *n = array + idx;
-               int j;
-
-               if (!entry->preferred_base)
-                       processed++;
-
-               if (progress) {
-                       unsigned percent = processed * 100 / nr_result;
-                       if (percent != last_percent || progress_update) {
-                               fprintf(stderr, "%4u%% (%u/%u) done\r",
-                                       percent, processed, nr_result);
-                               progress_update = 0;
-                               last_percent = percent;
-                       }
-               }
-
-               if (entry->delta)
-                       /* This happens if we decided to reuse existing
-                        * delta from a pack.  "!no_reuse_delta &&" is implied.
-                        */
-                       continue;
-
-               if (entry->size < 50)
-                       continue;
-               free_delta_index(n->index);
-               n->index = NULL;
-               free(n->data);
-               n->data = NULL;
-               n->entry = entry;
-
-               j = window;
-               while (--j > 0) {
-                       unsigned int other_idx = idx + j;
-                       struct unpacked *m;
-                       if (other_idx >= window)
-                               other_idx -= window;
-                       m = array + other_idx;
-                       if (!m->entry)
-                               break;
-                       if (try_delta(n, m, depth) < 0)
-                               break;
-               }
-               /* if we made n a delta, and if n is already at max
-                * depth, leaving it in the window is pointless.  we
-                * should evict it first.
-                */
-               if (entry->delta && depth <= entry->depth)
-                       continue;
-
-               idx++;
-               if (idx >= window)
-                       idx = 0;
-       }
-
-       if (progress)
-               fputc('\n', stderr);
-
-       for (i = 0; i < window; ++i) {
-               free_delta_index(array[i].index);
-               free(array[i].data);
-       }
-       free(array);
-}
-
-static void prepare_pack(int window, int depth)
-{
-       get_object_details();
-       sorted_by_type = create_sorted_list(type_size_sort);
-       if (window && depth)
-               find_deltas(sorted_by_type, window+1, depth);
-}
-
-static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
-{
-       static const char cache[] = "pack-cache/pack-%s.%s";
-       char *cached_pack, *cached_idx;
-       int ifd, ofd, ifd_ix = -1;
-
-       cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
-       ifd = open(cached_pack, O_RDONLY);
-       if (ifd < 0)
-               return 0;
-
-       if (!pack_to_stdout) {
-               cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
-               ifd_ix = open(cached_idx, O_RDONLY);
-               if (ifd_ix < 0) {
-                       close(ifd);
-                       return 0;
-               }
-       }
-
-       if (progress)
-               fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
-                       sha1_to_hex(sha1));
-
-       if (pack_to_stdout) {
-               if (copy_fd(ifd, 1))
-                       exit(1);
-               close(ifd);
-       }
-       else {
-               char name[PATH_MAX];
-               snprintf(name, sizeof(name),
-                        "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
-               ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
-               if (ofd < 0)
-                       die("unable to open %s (%s)", name, strerror(errno));
-               if (copy_fd(ifd, ofd))
-                       exit(1);
-               close(ifd);
-
-               snprintf(name, sizeof(name),
-                        "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
-               ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
-               if (ofd < 0)
-                       die("unable to open %s (%s)", name, strerror(errno));
-               if (copy_fd(ifd_ix, ofd))
-                       exit(1);
-               close(ifd_ix);
-               puts(sha1_to_hex(sha1));
-       }
-
-       return 1;
-}
-
-static void setup_progress_signal(void)
-{
-       struct sigaction sa;
-       struct itimerval v;
-
-       memset(&sa, 0, sizeof(sa));
-       sa.sa_handler = progress_interval;
-       sigemptyset(&sa.sa_mask);
-       sa.sa_flags = SA_RESTART;
-       sigaction(SIGALRM, &sa, NULL);
-
-       v.it_interval.tv_sec = 1;
-       v.it_interval.tv_usec = 0;
-       v.it_value = v.it_interval;
-       setitimer(ITIMER_REAL, &v, NULL);
-}
-
-static int git_pack_config(const char *k, const char *v)
-{
-       if(!strcmp(k, "pack.window")) {
-               window = git_config_int(k, v);
-               return 0;
-       }
-       return git_default_config(k, v);
-}
-
-int main(int argc, char **argv)
-{
-       SHA_CTX ctx;
-       char line[40 + 1 + PATH_MAX + 2];
-       int depth = 10, pack_to_stdout = 0;
-       struct object_entry **list;
-       int num_preferred_base = 0;
-       int i;
-
-       setup_git_directory();
-       git_config(git_pack_config);
-
-       progress = isatty(2);
-       for (i = 1; i < argc; i++) {
-               const char *arg = argv[i];
-
-               if (*arg == '-') {
-                       if (!strcmp("--non-empty", arg)) {
-                               non_empty = 1;
-                               continue;
-                       }
-                       if (!strcmp("--local", arg)) {
-                               local = 1;
-                               continue;
-                       }
-                       if (!strcmp("--progress", arg)) {
-                               progress = 1;
-                               continue;
-                       }
-                       if (!strcmp("--incremental", arg)) {
-                               incremental = 1;
-                               continue;
-                       }
-                       if (!strncmp("--window=", arg, 9)) {
-                               char *end;
-                               window = strtoul(arg+9, &end, 0);
-                               if (!arg[9] || *end)
-                                       usage(pack_usage);
-                               continue;
-                       }
-                       if (!strncmp("--depth=", arg, 8)) {
-                               char *end;
-                               depth = strtoul(arg+8, &end, 0);
-                               if (!arg[8] || *end)
-                                       usage(pack_usage);
-                               continue;
-                       }
-                       if (!strcmp("--progress", arg)) {
-                               progress = 1;
-                               continue;
-                       }
-                       if (!strcmp("-q", arg)) {
-                               progress = 0;
-                               continue;
-                       }
-                       if (!strcmp("--no-reuse-delta", arg)) {
-                               no_reuse_delta = 1;
-                               continue;
-                       }
-                       if (!strcmp("--stdout", arg)) {
-                               pack_to_stdout = 1;
-                               continue;
-                       }
-                       usage(pack_usage);
-               }
-               if (base_name)
-                       usage(pack_usage);
-               base_name = arg;
-       }
-
-       if (pack_to_stdout != !base_name)
-               usage(pack_usage);
-
-       prepare_packed_git();
-
-       if (progress) {
-               fprintf(stderr, "Generating pack...\n");
-               setup_progress_signal();
-       }
-
-       for (;;) {
-               unsigned char sha1[20];
-               unsigned hash;
-
-               if (!fgets(line, sizeof(line), stdin)) {
-                       if (feof(stdin))
-                               break;
-                       if (!ferror(stdin))
-                               die("fgets returned NULL, not EOF, not error!");
-                       if (errno != EINTR)
-                               die("fgets: %s", strerror(errno));
-                       clearerr(stdin);
-                       continue;
-               }
-
-               if (line[0] == '-') {
-                       if (get_sha1_hex(line+1, sha1))
-                               die("expected edge sha1, got garbage:\n %s",
-                                   line+1);
-                       if (num_preferred_base++ < window)
-                               add_preferred_base(sha1);
-                       continue;
-               }
-               if (get_sha1_hex(line, sha1))
-                       die("expected sha1, got garbage:\n %s", line);
-               hash = name_hash(line+41);
-               add_preferred_base_object(line+41, hash);
-               add_object_entry(sha1, hash, 0);
-       }
-       if (progress)
-               fprintf(stderr, "Done counting %d objects.\n", nr_objects);
-       sorted_by_sha = create_final_object_list();
-       if (non_empty && !nr_result)
-               return 0;
-
-       SHA1_Init(&ctx);
-       list = sorted_by_sha;
-       for (i = 0; i < nr_result; i++) {
-               struct object_entry *entry = *list++;
-               SHA1_Update(&ctx, entry->sha1, 20);
-       }
-       SHA1_Final(object_list_sha1, &ctx);
-       if (progress && (nr_objects != nr_result))
-               fprintf(stderr, "Result has %d objects.\n", nr_result);
-
-       if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
-               ;
-       else {
-               if (nr_result)
-                       prepare_pack(window, depth);
-               if (progress && pack_to_stdout) {
-                       /* the other end usually displays progress itself */
-                       struct itimerval v = {{0,},};
-                       setitimer(ITIMER_REAL, &v, NULL);
-                       signal(SIGALRM, SIG_IGN );
-                       progress_update = 0;
-               }
-               write_pack_file();
-               if (!pack_to_stdout) {
-                       write_index_file();
-                       puts(sha1_to_hex(object_list_sha1));
-               }
-       }
-       if (progress)
-               fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
-                       nr_result, written, written_delta, reused, reused_delta);
-       return 0;
-}