[PATCH] Teach read_sha1_file() and friends about packed git object store.

GIT_OBJECT_DIRECTORY and GIT_ALTERNATE_OBJECT_DIRECTORIES can
have the "pack" subdirectory that houses "packed GIT" files
produced by git-pack-objects (e.g. .git/objects/pack/foo.pack
and .git/objects/pack/foo.idx; always store them as pairs).  The
following functions in sha1_file.c can then read object contents
from such packed file:

 - sha1_object_info()
 - has_sha1_file()
 - read_sha1_file()

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/sha1_file.c b/sha1_file.c
index 4225c67c5b3f76ec8c20a4878e519a82a8b1ccae..7e4a3df3ad9f7be666256e3219651a5296da7aca 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -6,7 +6,10 @@
  * This handles basic git sha1 object files - packing, unpacking,
  * creation etc.
  */
+#include <sys/types.h>
+#include <dirent.h>
 #include "cache.h"
+#include "delta.h"
 
 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
@@ -265,6 +268,184 @@ static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
        return NULL;
 }
 
+#define PACK_MAX_SZ (1<<26)
+static int pack_used_ctr;
+static unsigned long pack_mapped;
+static struct packed_git {
+       struct packed_git *next;
+       unsigned long index_size;
+       unsigned long pack_size;
+       unsigned int *index_base;
+       void *pack_base;
+       unsigned int pack_last_used;
+       char pack_name[0]; /* something like ".git/objects/pack/xxxxx.pack" */
+} *packed_git;
+
+struct pack_entry {
+       unsigned int offset;
+       unsigned char sha1[20];
+       struct packed_git *p;
+};
+
+static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
+                               void **idx_map_)
+{
+       void *idx_map;
+       unsigned int *index;
+       unsigned long idx_size;
+       int nr, i;
+       int fd = open(path, O_RDONLY);
+       struct stat st;
+       if (fd < 0)
+               return -1;
+       if (fstat(fd, &st)) {
+               close(fd);
+               return -1;
+       }
+       idx_size = st.st_size;
+       idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
+       close(fd);
+       if (idx_map == MAP_FAILED)
+               return -1;
+
+       index = idx_map;
+
+       /* check index map */
+       if (idx_size < 4*256 + 20)
+               return error("index file too small");
+       nr = 0;
+       for (i = 0; i < 256; i++) {
+               unsigned int n = ntohl(index[i]);
+               if (n < nr)
+                       return error("non-monotonic index");
+               nr = n;
+       }
+
+       /*
+        * Total size:
+        *  - 256 index entries 4 bytes each
+        *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
+        *  - 20-byte SHA1 of the packfile
+        *  - 20-byte SHA1 file checksum
+        */
+       if (idx_size != 4*256 + nr * 24 + 20 + 20)
+               return error("wrong index file size");
+
+       *idx_map_ = idx_map;
+       *idx_size_ = idx_size;
+       return 0;
+}
+
+static void unuse_one_packed_git(void)
+{
+       /* NOTYET */
+}
+
+static int use_packed_git(struct packed_git *p)
+{
+       if (!p->pack_base) {
+               int fd;
+               struct stat st;
+               void *map;
+
+               pack_mapped += p->pack_size;
+               while (PACK_MAX_SZ < pack_mapped)
+                       unuse_one_packed_git();
+               fd = open(p->pack_name, O_RDONLY);
+               if (fd < 0)
+                       return -1;
+               if (fstat(fd, &st)) {
+                       close(fd);
+                       return -1;
+               }
+               if (st.st_size != p->pack_size)
+                       return -1;
+               map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
+               close(fd);
+               if (map == MAP_FAILED)
+                       return -1;
+               p->pack_base = map;
+       }
+       p->pack_last_used = pack_used_ctr++;
+       return 0;
+}
+
+static struct packed_git *add_packed_git(char *path, int path_len)
+{
+       struct stat st;
+       struct packed_git *p;
+       unsigned long idx_size;
+       void *idx_map;
+
+       if (check_packed_git_idx(path, &idx_size, &idx_map))
+               return NULL;
+
+       /* do we have a corresponding .pack file? */
+       strcpy(path + path_len - 4, ".pack");
+       if (stat(path, &st) || !S_ISREG(st.st_mode)) {
+               munmap(idx_map, idx_size);
+               return NULL;
+       }
+       /* ok, it looks sane as far as we can check without
+        * actually mapping the pack file.
+        */
+       p = xmalloc(sizeof(*p) + path_len + 2);
+       strcpy(p->pack_name, path);
+       p->index_size = idx_size;
+       p->pack_size = st.st_size;
+       p->index_base = idx_map;
+       p->next = NULL;
+       p->pack_last_used = 0;
+       return p;
+}
+
+static void prepare_packed_git_one(char *objdir)
+{
+       char path[PATH_MAX];
+       int len;
+       DIR *dir;
+       struct dirent *de;
+
+       sprintf(path, "%s/pack", objdir);
+       len = strlen(path);
+       dir = opendir(path);
+       if (!dir)
+               return;
+       path[len++] = '/';
+       while ((de = readdir(dir)) != NULL) {
+               int namelen = strlen(de->d_name);
+               struct packed_git *p;
+
+               if (strcmp(de->d_name + namelen - 4, ".idx"))
+                       continue;
+
+               /* we have .idx.  Is it a file we can map? */
+               strcpy(path + len, de->d_name);
+               p = add_packed_git(path, len + namelen);
+               if (!p)
+                       continue;
+               p->next = packed_git;
+               packed_git = p;
+       }
+}
+
+static void prepare_packed_git(void)
+{
+       int i;
+       static int run_once = 0;
+
+       if (run_once++)
+               return;
+
+       prepare_packed_git_one(get_object_directory());
+       if (!alt_odb)
+               prepare_alt_odb();
+       for (i = 0; alt_odb[i].base != NULL; i++) {
+               alt_odb[i].name[0] = 0;
+               prepare_packed_git_one(alt_odb[i].base);
+       }
+}
+
 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 {
        char header[100];
@@ -278,7 +459,9 @@ int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long siz
        return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 }
 
-void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+static void *map_sha1_file_internal(const unsigned char *sha1,
+                                   unsigned long *size,
+                                   int say_error)
 {
        struct stat st;
        void *map;
@@ -286,7 +469,8 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
        char *filename = find_sha1_file(sha1, &st);
 
        if (!filename) {
-               error("cannot map sha1 file %s", sha1_to_hex(sha1));
+               if (say_error)
+                       error("cannot map sha1 file %s", sha1_to_hex(sha1));
                return NULL;
        }
 
@@ -300,11 +484,14 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
                                break;
                /* Fallthrough */
                case 0:
-                       perror(filename);
+                       if (say_error)
+                               perror(filename);
                        return NULL;
                }
 
-               /* If it failed once, it will probably fail again. Stop using O_NOATIME */
+               /* If it failed once, it will probably fail again.
+                * Stop using O_NOATIME
+                */
                sha1_file_open_flag = 0;
        }
        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
@@ -315,6 +502,11 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
        return map;
 }
 
+void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+{
+       return map_sha1_file_internal(sha1, size, 1);
+}
+
 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 {
        /* Get the data stream */
@@ -409,6 +601,191 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
        return unpack_sha1_rest(&stream, hdr, *size);
 }
 
+/* Returns 0 on fast-path success, returns 1 on deltified
+ * and need to unpack to see info.
+ */
+static int packed_object_info(struct pack_entry *entry,
+                             char *type, unsigned long *sizep)
+{
+       struct packed_git *p = entry->p;
+       unsigned long offset, size, left;
+       unsigned char *pack;
+
+       offset = entry->offset;
+       if (p->pack_size - 5 < offset)
+               die("object offset outside of pack file");
+       pack = p->pack_base + offset;
+       size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
+       left = p->pack_size - offset - 5;
+       switch (*pack) {
+       case 'D':
+               return 1;
+               break;
+       case 'C':
+               strcpy(type, "commit");
+               break;
+       case 'T':
+               strcpy(type, "tree");
+               break;
+       case 'B':
+               strcpy(type, "blob");
+               break;
+       default:
+               die("corrupted pack file");
+       }
+       *sizep = size;
+       return 0;
+}
+
+/* forward declaration for a mutually recursive function */
+static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
+
+static void *unpack_delta_entry(unsigned char *base_sha1,
+                               unsigned long delta_size,
+                               unsigned long left,
+                               char *type,
+                               unsigned long *sizep)
+{
+       void *data, *delta_data, *result, *base;
+       unsigned long data_size, result_size, base_size;
+       z_stream stream;
+       int st;
+
+       if (left < 20)
+               die("truncated pack file");
+       data = base_sha1 + 20;
+       data_size = left - 20;
+       delta_data = xmalloc(delta_size);
+
+       memset(&stream, 0, sizeof(stream));
+
+       stream.next_in = data;
+       stream.avail_in = data_size;
+       stream.next_out = delta_data;
+       stream.avail_out = delta_size;
+
+       inflateInit(&stream);
+       st = inflate(&stream, Z_FINISH);
+       inflateEnd(&stream);
+       if ((st != Z_STREAM_END) || stream.total_out != delta_size)
+               die("delta data unpack failed");
+
+       /* This may recursively unpack the base, which is what we want */
+       base = read_sha1_file(base_sha1, type, &base_size);
+       if (!base)
+               die("failed to read delta-pack base object %s",
+                   sha1_to_hex(base_sha1));
+       result = patch_delta(base, base_size,
+                            delta_data, delta_size,
+                            &result_size);
+       if (!result)
+               die("failed to apply delta");
+       free(delta_data);
+       free(base);
+       *sizep = result_size;
+       return result;
+}
+
+static void *unpack_non_delta_entry(unsigned char *data,
+                                   unsigned long size,
+                                   unsigned long left)
+{
+       int st;
+       z_stream stream;
+       char *buffer;
+
+       buffer = xmalloc(size + 1);
+       buffer[size] = 0;
+       memset(&stream, 0, sizeof(stream));
+       stream.next_in = data;
+       stream.avail_in = left;
+       stream.next_out = buffer;
+       stream.avail_out = size;
+
+       inflateInit(&stream);
+       st = inflate(&stream, Z_FINISH);
+       inflateEnd(&stream);
+       if ((st != Z_STREAM_END) || stream.total_out != size) {
+               free(buffer);
+               return NULL;
+       }
+
+       return buffer;
+}
+
+static void *unpack_entry(struct pack_entry *entry,
+                         char *type, unsigned long *sizep)
+{
+       struct packed_git *p = entry->p;
+       unsigned long offset, size, left;
+       unsigned char *pack;
+
+       offset = entry->offset;
+       if (p->pack_size - 5 < offset)
+               die("object offset outside of pack file");
+
+       if (use_packed_git(p))
+               die("cannot map packed file");
+
+       pack = p->pack_base + offset;
+       size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
+       left = p->pack_size - offset - 5;
+       switch (*pack) {
+       case 'D':
+               return unpack_delta_entry(pack+5, size, left, type, sizep);
+       case 'C':
+               strcpy(type, "commit");
+               break;
+       case 'T':
+               strcpy(type, "tree");
+               break;
+       case 'B':
+               strcpy(type, "blob");
+               break;
+       default:
+               die("corrupted pack file");
+       }
+       *sizep = size;
+       return unpack_non_delta_entry(pack+5, size, left);
+}
+
+static int find_pack_entry_1(const unsigned char *sha1,
+                            struct pack_entry *e, struct packed_git *p)
+{
+       int *level1_ofs = p->index_base;
+       int hi = ntohl(level1_ofs[*sha1]);
+       int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
+       void *index = p->index_base + 256;
+
+       do {
+               int mi = (lo + hi) / 2;
+               int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
+               if (!cmp) {
+                       e->offset = ntohl(*((int*)(index + 24 * mi)));
+                       memcpy(e->sha1, sha1, 20);
+                       e->p = p;
+                       return 1;
+               }
+               if (cmp > 0)
+                       hi = mi;
+               else
+                       lo = mi+1;
+       } while (lo < hi);
+       return 0;
+}
+
+static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
+{
+       struct packed_git *p;
+       prepare_packed_git();
+
+       for (p = packed_git; p; p = p->next) {
+               if (find_pack_entry_1(sha1, e, p))
+                       return 1;
+       }
+       return 0;
+}
+
 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
 {
        int status;
@@ -417,9 +794,19 @@ int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep
        z_stream stream;
        char hdr[128];
 
-       map = map_sha1_file(sha1, &mapsize);
-       if (!map)
-               return error("unable to map %s", sha1_to_hex(sha1));
+       map = map_sha1_file_internal(sha1, &mapsize, 0);
+       if (!map) {
+               struct pack_entry e;
+
+               if (!find_pack_entry(sha1, &e))
+                       return error("unable to find %s", sha1_to_hex(sha1));
+               if (!packed_object_info(&e, type, sizep))
+                       return 0;
+               /* sheesh */
+               map = unpack_entry(&e, type, sizep);
+               free(map);
+               return (map == NULL) ? 0 : -1;
+       }
        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
                status = error("unable to unpack %s header",
                               sha1_to_hex(sha1));
@@ -434,18 +821,29 @@ int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep
        return status;
 }
 
+static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
+{
+       struct pack_entry e;
+
+       if (!find_pack_entry(sha1, &e)) {
+               error("cannot read sha1_file for %s", sha1_to_hex(sha1));
+               return NULL;
+       }
+       return unpack_entry(&e, type, size);
+}
+
 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 {
        unsigned long mapsize;
        void *map, *buf;
 
-       map = map_sha1_file(sha1, &mapsize);
+       map = map_sha1_file_internal(sha1, &mapsize, 0);
        if (map) {
                buf = unpack_sha1_file(map, mapsize, type, size);
                munmap(map, mapsize);
                return buf;
        }
-       return NULL;
+       return read_packed_sha1(sha1, type, size);
 }
 
 void *read_object_with_reference(const unsigned char *sha1,
@@ -664,7 +1062,11 @@ int write_sha1_from_fd(const unsigned char *sha1, int fd)
 int has_sha1_file(const unsigned char *sha1)
 {
        struct stat st;
-       return !!find_sha1_file(sha1, &st);
+       struct pack_entry e;
+
+       if (find_sha1_file(sha1, &st))
+               return 1;
+       return find_pack_entry(sha1, &e);
 }
 
 int index_fd(unsigned char *sha1, int fd, struct stat *st)

diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 171af643e50768e4ccf4a45b142fbf70be9f04d6..901653656a3d73fb8f0a6d736e3dd712792e8b22 100755 (executable)
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -19,10 +19,19 @@ test_expect_success \
             git-update-cache --add $i || exit
      done &&
      cat c >d && echo foo >>d && git-update-cache --add d &&
-     tree=`git-write-tree` && {
+     tree=`git-write-tree` &&
+     commit=`git-commit-tree $tree </dev/null` && {
         echo $tree &&
+        echo $commit &&
         git-ls-tree $tree | sed -e "s/.* \\([0-9a-f]*\\)       .*/\\1/"
-     } >obj-list'
+     } >obj-list && {
+        git-diff-tree --root -p $commit &&
+        while read object
+        do
+           t=`git-cat-file -t $object` &&
+           git-cat-file $t $object || exit 1
+        done <obj-list
+     } >expect'
 
 test_expect_success \
     'pack without delta' \
@@ -82,4 +91,39 @@ test_expect_success \
      done'
 cd $TRASH
 
+rm -fr .git2
+mkdir .git2
+
+test_expect_success \
+    'use packed objects' \
+    'GIT_OBJECT_DIRECTORY=.git2/objects &&
+     export GIT_OBJECT_DIRECTORY &&
+     git-init-db &&
+     mkdir .git2/objects/pack &&
+     cp test-1.pack test-1.idx .git2/objects/pack && {
+        git-diff-tree --root -p $commit &&
+        while read object
+        do
+           t=`git-cat-file -t $object` &&
+           git-cat-file $t $object || exit 1
+        done <obj-list
+    } >current &&
+    diff expect current'
+
+
+test_expect_success \
+    'use packed deltified objects' \
+    'GIT_OBJECT_DIRECTORY=.git2/objects &&
+     export GIT_OBJECT_DIRECTORY &&
+     rm -f .git2/objects/pack/test-?.idx &&
+     cp test-2.pack test-2.idx .git2/objects/pack && {
+        git-diff-tree --root -p $commit &&
+        while read object
+        do
+           t=`git-cat-file -t $object` &&
+           git-cat-file $t $object || exit 1
+        done <obj-list
+    } >current &&
+    diff expect current'
+
 test_done