Make read-cache.c "the_index" free.

This makes all low-level functions defined in read-cache.c to
take an explicit index_state structure as their first parameter,
to specify which index to work on.  These functions
traditionally operated on "the_index" and were named foo_cache();
the counterparts this patch introduces are called foo_index().

The traditional foo_cache() functions are made into macros that
give "the_index" to their corresponding foo_index() functions.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/cache.h b/cache.h
index 4841c9a16187f12e9815b81fd8283cd8fd7ead1a..74e47dffa270f15bbc8157f88493bb184ce650b0 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -154,12 +154,27 @@ struct index_state {
 
 extern struct index_state the_index;
 
+#ifndef NO_THE_INDEX_COMPATIBILITY_MACROS
 #define active_cache (the_index.cache)
 #define active_nr (the_index.cache_nr)
 #define active_alloc (the_index.cache_alloc)
 #define active_cache_changed (the_index.cache_changed)
 #define active_cache_tree (the_index.cache_tree)
 
+#define read_cache() read_index(&the_index)
+#define read_cache_from(path) read_index_from(&the_index, (path))
+#define write_cache(newfd, cache, entries) write_index(&the_index, (newfd))
+#define discard_cache() discard_index(&the_index)
+#define cache_name_pos(name, namelen) index_name_pos(&the_index,(name),(namelen))
+#define add_cache_entry(ce, option) add_index_entry(&the_index, (ce), (option))
+#define remove_cache_entry_at(pos) remove_index_entry_at(&the_index, (pos))
+#define remove_file_from_cache(path) remove_file_from_index(&the_index, (path))
+#define add_file_to_cache(path, verbose) add_file_to_index(&the_index, (path), (verbose))
+#define refresh_cache(flags) refresh_index(&the_index, flags)
+#define ce_match_stat(ce, st, really) ie_match_stat(&the_index, (ce), (st), (really))
+#define ce_modified(ce, st, really) ie_modified(&the_index, (ce), (st), (really))
+#endif
+
 enum object_type {
        OBJ_BAD = -1,
        OBJ_NONE = 0,
@@ -208,23 +223,23 @@ extern void verify_non_filename(const char *prefix, const char *name);
 #define alloc_nr(x) (((x)+16)*3/2)
 
 /* Initialize and use the cache information */
-extern int read_cache(void);
-extern int read_cache_from(const char *path);
-extern int write_cache(int newfd, struct cache_entry **cache, int entries);
-extern int discard_cache(void);
+extern int read_index(struct index_state *);
+extern int read_index_from(struct index_state *, const char *path);
+extern int write_index(struct index_state *, int newfd);
+extern int discard_index(struct index_state *);
 extern int verify_path(const char *path);
-extern int cache_name_pos(const char *name, int namelen);
+extern int index_name_pos(struct index_state *, const char *name, int namelen);
 #define ADD_CACHE_OK_TO_ADD 1          /* Ok to add */
 #define ADD_CACHE_OK_TO_REPLACE 2      /* Ok to replace file/directory */
 #define ADD_CACHE_SKIP_DFCHECK 4       /* Ok to skip DF conflict checks */
-extern int add_cache_entry(struct cache_entry *ce, int option);
+extern int add_index_entry(struct index_state *, struct cache_entry *ce, int option);
 extern struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really);
-extern int remove_cache_entry_at(int pos);
-extern int remove_file_from_cache(const char *path);
-extern int add_file_to_cache(const char *path, int verbose);
+extern int remove_index_entry_at(struct index_state *, int pos);
+extern int remove_file_from_index(struct index_state *, const char *path);
+extern int add_file_to_index(struct index_state *, const char *path, int verbose);
 extern int ce_same_name(struct cache_entry *a, struct cache_entry *b);
-extern int ce_match_stat(struct cache_entry *ce, struct stat *st, int);
-extern int ce_modified(struct cache_entry *ce, struct stat *st, int);
+extern int ie_match_stat(struct index_state *, struct cache_entry *, struct stat *, int);
+extern int ie_modified(struct index_state *, struct cache_entry *, struct stat *, int);
 extern int ce_path_match(const struct cache_entry *ce, const char **pathspec);
 extern int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, enum object_type type, const char *path);
 extern int read_pipe(int fd, char** return_buf, unsigned long* return_size);
@@ -236,7 +251,7 @@ extern void fill_stat_cache_info(struct cache_entry *ce, struct stat *st);
 #define REFRESH_UNMERGED       0x0002  /* allow unmerged */
 #define REFRESH_QUIET          0x0004  /* be quiet about it */
 #define REFRESH_IGNORE_MISSING 0x0008  /* ignore non-existent */
-extern int refresh_cache(unsigned int flags);
+extern int refresh_index(struct index_state *, unsigned int flags);
 
 struct lock_file {
        struct lock_file *next;

diff --git a/read-cache.c b/read-cache.c
index 9b4385ea5cfd23ac07b460557cf296650983794d..e04e99112d4c4b19dc1b6e1dcab89600bb30b57a 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -3,6 +3,7 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
+#define NO_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "cache-tree.h"
 #include "refs.h"
@@ -20,9 +21,6 @@
 #define CACHE_EXT_TREE 0x54524545      /* "TREE" */
 
 struct index_state the_index;
-#define index_file_timestamp (the_index.timestamp)
-#define cache_mmap (the_index.mmap)
-#define cache_mmap_size (the_index.mmap_size)
 
 /*
  * This only updates the "non-critical" parts of the directory
@@ -192,7 +190,8 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
        return changed;
 }
 
-int ce_match_stat(struct cache_entry *ce, struct stat *st, int options)
+int ie_match_stat(struct index_state *istate,
+                 struct cache_entry *ce, struct stat *st, int options)
 {
        unsigned int changed;
        int ignore_valid = options & 01;
@@ -224,8 +223,8 @@ int ce_match_stat(struct cache_entry *ce, struct stat *st, int options)
         * carefully than others.
         */
        if (!changed &&
-           index_file_timestamp &&
-           index_file_timestamp <= ntohl(ce->ce_mtime.sec)) {
+           istate->timestamp &&
+           istate->timestamp <= ntohl(ce->ce_mtime.sec)) {
                if (assume_racy_is_modified)
                        changed |= DATA_CHANGED;
                else
@@ -235,10 +234,11 @@ int ce_match_stat(struct cache_entry *ce, struct stat *st, int options)
        return changed;
 }
 
-int ce_modified(struct cache_entry *ce, struct stat *st, int really)
+int ie_modified(struct index_state *istate,
+               struct cache_entry *ce, struct stat *st, int really)
 {
        int changed, changed_fs;
-       changed = ce_match_stat(ce, st, really);
+       changed = ie_match_stat(istate, ce, st, really);
        if (!changed)
                return 0;
        /*
@@ -306,15 +306,15 @@ int cache_name_compare(const char *name1, int flags1, const char *name2, int fla
        return 0;
 }
 
-int cache_name_pos(const char *name, int namelen)
+int index_name_pos(struct index_state *istate, const char *name, int namelen)
 {
        int first, last;
 
        first = 0;
-       last = active_nr;
+       last = istate->cache_nr;
        while (last > first) {
                int next = (last + first) >> 1;
-               struct cache_entry *ce = active_cache[next];
+               struct cache_entry *ce = istate->cache[next];
                int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
                if (!cmp)
                        return next;
@@ -328,27 +328,29 @@ int cache_name_pos(const char *name, int namelen)
 }
 
 /* Remove entry, return true if there are more entries to go.. */
-int remove_cache_entry_at(int pos)
+int remove_index_entry_at(struct index_state *istate, int pos)
 {
-       active_cache_changed = 1;
-       active_nr--;
-       if (pos >= active_nr)
+       istate->cache_changed = 1;
+       istate->cache_nr--;
+       if (pos >= istate->cache_nr)
                return 0;
-       memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
+       memmove(istate->cache + pos,
+               istate->cache + pos + 1,
+               (istate->cache_nr - pos) * sizeof(struct cache_entry *));
        return 1;
 }
 
-int remove_file_from_cache(const char *path)
+int remove_file_from_index(struct index_state *istate, const char *path)
 {
-       int pos = cache_name_pos(path, strlen(path));
+       int pos = index_name_pos(istate, path, strlen(path));
        if (pos < 0)
                pos = -pos-1;
-       while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
-               remove_cache_entry_at(pos);
+       while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
+               remove_index_entry_at(istate, pos);
        return 0;
 }
 
-int add_file_to_cache(const char *path, int verbose)
+int add_file_to_index(struct index_state *istate, const char *path, int verbose)
 {
        int size, namelen;
        struct stat st;
@@ -378,19 +380,19 @@ int add_file_to_cache(const char *path, int verbose)
                 * from it, otherwise assume unexecutable regular file.
                 */
                struct cache_entry *ent;
-               int pos = cache_name_pos(path, namelen);
+               int pos = index_name_pos(istate, path, namelen);
 
-               ent = (0 <= pos) ? active_cache[pos] : NULL;
+               ent = (0 <= pos) ? istate->cache[pos] : NULL;
                ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
        }
 
        if (index_path(ce->sha1, path, &st, 1))
                die("unable to index file %s", path);
-       if (add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
+       if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
                die("unable to add %s to index",path);
        if (verbose)
                printf("add '%s'\n", path);
-       cache_tree_invalidate_path(active_cache_tree, path);
+       cache_tree_invalidate_path(istate->cache_tree, path);
        return 0;
 }
 
@@ -494,15 +496,16 @@ inside:
  * Do we have another file that has the beginning components being a
  * proper superset of the name we're trying to add?
  */
-static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
+static int has_file_name(struct index_state *istate,
+                        const struct cache_entry *ce, int pos, int ok_to_replace)
 {
        int retval = 0;
        int len = ce_namelen(ce);
        int stage = ce_stage(ce);
        const char *name = ce->name;
 
-       while (pos < active_nr) {
-               struct cache_entry *p = active_cache[pos++];
+       while (pos < istate->cache_nr) {
+               struct cache_entry *p = istate->cache[pos++];
 
                if (len >= ce_namelen(p))
                        break;
@@ -517,7 +520,7 @@ static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replac
                retval = -1;
                if (!ok_to_replace)
                        break;
-               remove_cache_entry_at(--pos);
+               remove_index_entry_at(istate, --pos);
        }
        return retval;
 }
@@ -526,7 +529,8 @@ static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replac
  * Do we have another file with a pathname that is a proper
  * subset of the name we're trying to add?
  */
-static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
+static int has_dir_name(struct index_state *istate,
+                       const struct cache_entry *ce, int pos, int ok_to_replace)
 {
        int retval = 0;
        int stage = ce_stage(ce);
@@ -544,7 +548,7 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
                }
                len = slash - name;
 
-               pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
+               pos = index_name_pos(istate, name, ntohs(create_ce_flags(len, stage)));
                if (pos >= 0) {
                        /*
                         * Found one, but not so fast.  This could
@@ -554,11 +558,11 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
                         * it is Ok to have a directory at the same
                         * path.
                         */
-                       if (stage || active_cache[pos]->ce_mode) {
+                       if (stage || istate->cache[pos]->ce_mode) {
                                retval = -1;
                                if (!ok_to_replace)
                                        break;
-                               remove_cache_entry_at(pos);
+                               remove_index_entry_at(istate, pos);
                                continue;
                        }
                }
@@ -570,8 +574,8 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
                 * already matches the sub-directory, then we know
                 * we're ok, and we can exit.
                 */
-               while (pos < active_nr) {
-                       struct cache_entry *p = active_cache[pos];
+               while (pos < istate->cache_nr) {
+                       struct cache_entry *p = istate->cache[pos];
                        if ((ce_namelen(p) <= len) ||
                            (p->name[len] != '/') ||
                            memcmp(p->name, name, len))
@@ -598,7 +602,9 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
  * from the cache so the caller should recompute the insert position.
  * When this happens, we return non-zero.
  */
-static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
+static int check_file_directory_conflict(struct index_state *istate,
+                                        const struct cache_entry *ce,
+                                        int pos, int ok_to_replace)
 {
        int retval;
 
@@ -613,28 +619,28 @@ static int check_file_directory_conflict(const struct cache_entry *ce, int pos,
         * first, since removing those will not change the position
         * in the array.
         */
-       retval = has_file_name(ce, pos, ok_to_replace);
+       retval = has_file_name(istate, ce, pos, ok_to_replace);
 
        /*
         * Then check if the path might have a clashing sub-directory
         * before it.
         */
-       return retval + has_dir_name(ce, pos, ok_to_replace);
+       return retval + has_dir_name(istate, ce, pos, ok_to_replace);
 }
 
-int add_cache_entry(struct cache_entry *ce, int option)
+int add_index_entry(struct index_state *istate, struct cache_entry *ce, int option)
 {
        int pos;
        int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
        int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
        int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
 
-       pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
+       pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags));
 
        /* existing match? Just replace it. */
        if (pos >= 0) {
-               active_cache_changed = 1;
-               active_cache[pos] = ce;
+               istate->cache_changed = 1;
+               istate->cache[pos] = ce;
                return 0;
        }
        pos = -pos-1;
@@ -643,10 +649,10 @@ int add_cache_entry(struct cache_entry *ce, int option)
         * Inserting a merged entry ("stage 0") into the index
         * will always replace all non-merged entries..
         */
-       if (pos < active_nr && ce_stage(ce) == 0) {
-               while (ce_same_name(active_cache[pos], ce)) {
+       if (pos < istate->cache_nr && ce_stage(ce) == 0) {
+               while (ce_same_name(istate->cache[pos], ce)) {
                        ok_to_add = 1;
-                       if (!remove_cache_entry_at(pos))
+                       if (!remove_index_entry_at(istate, pos))
                                break;
                }
        }
@@ -657,25 +663,29 @@ int add_cache_entry(struct cache_entry *ce, int option)
                return -1;
 
        if (!skip_df_check &&
-           check_file_directory_conflict(ce, pos, ok_to_replace)) {
+           check_file_directory_conflict(istate, ce, pos, ok_to_replace)) {
                if (!ok_to_replace)
-                       return error("'%s' appears as both a file and as a directory", ce->name);
-               pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
+                       return error("'%s' appears as both a file and as a directory",
+                                    ce->name);
+               pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags));
                pos = -pos-1;
        }
 
        /* Make sure the array is big enough .. */
-       if (active_nr == active_alloc) {
-               active_alloc = alloc_nr(active_alloc);
-               active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
+       if (istate->cache_nr == istate->cache_alloc) {
+               istate->cache_alloc = alloc_nr(istate->cache_alloc);
+               istate->cache = xrealloc(istate->cache,
+                                       istate->cache_alloc * sizeof(struct cache_entry *));
        }
 
        /* Add it in.. */
-       active_nr++;
-       if (active_nr > pos)
-               memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
-       active_cache[pos] = ce;
-       active_cache_changed = 1;
+       istate->cache_nr++;
+       if (istate->cache_nr > pos)
+               memmove(istate->cache + pos + 1,
+                       istate->cache + pos,
+                       (istate->cache_nr - pos - 1) * sizeof(ce));
+       istate->cache[pos] = ce;
+       istate->cache_changed = 1;
        return 0;
 }
 
@@ -690,7 +700,8 @@ int add_cache_entry(struct cache_entry *ce, int option)
  * For example, you'd want to do this after doing a "git-read-tree",
  * to link up the stat cache details with the proper files.
  */
-static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really, int *err)
+static struct cache_entry *refresh_cache_ent(struct index_state *istate,
+                                            struct cache_entry *ce, int really, int *err)
 {
        struct stat st;
        struct cache_entry *updated;
@@ -702,7 +713,7 @@ static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really,
                return NULL;
        }
 
-       changed = ce_match_stat(ce, &st, really);
+       changed = ie_match_stat(istate, ce, &st, really);
        if (!changed) {
                if (really && assume_unchanged &&
                    !(ce->ce_flags & htons(CE_VALID)))
@@ -711,7 +722,7 @@ static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really,
                        return ce;
        }
 
-       if (ce_modified(ce, &st, really)) {
+       if (ie_modified(istate, ce, &st, really)) {
                if (err)
                        *err = EINVAL;
                return NULL;
@@ -734,7 +745,7 @@ static struct cache_entry *refresh_cache_ent(struct cache_entry *ce, int really,
        return updated;
 }
 
-int refresh_cache(unsigned int flags)
+int refresh_index(struct index_state *istate, unsigned int flags)
 {
        int i;
        int has_errors = 0;
@@ -743,14 +754,14 @@ int refresh_cache(unsigned int flags)
        int quiet = (flags & REFRESH_QUIET) != 0;
        int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
 
-       for (i = 0; i < active_nr; i++) {
+       for (i = 0; i < istate->cache_nr; i++) {
                struct cache_entry *ce, *new;
                int cache_errno = 0;
 
-               ce = active_cache[i];
+               ce = istate->cache[i];
                if (ce_stage(ce)) {
-                       while ((i < active_nr) &&
-                              ! strcmp(active_cache[i]->name, ce->name))
+                       while ((i < istate->cache_nr) &&
+                              ! strcmp(istate->cache[i]->name, ce->name))
                                i++;
                        i--;
                        if (allow_unmerged)
@@ -760,7 +771,7 @@ int refresh_cache(unsigned int flags)
                        continue;
                }
 
-               new = refresh_cache_ent(ce, really, &cache_errno);
+               new = refresh_cache_ent(istate, ce, really, &cache_errno);
                if (new == ce)
                        continue;
                if (!new) {
@@ -771,7 +782,7 @@ int refresh_cache(unsigned int flags)
                                 * means the index is not valid anymore.
                                 */
                                ce->ce_flags &= ~htons(CE_VALID);
-                               active_cache_changed = 1;
+                               istate->cache_changed = 1;
                        }
                        if (quiet)
                                continue;
@@ -779,18 +790,18 @@ int refresh_cache(unsigned int flags)
                        has_errors = 1;
                        continue;
                }
-               active_cache_changed = 1;
-               /* You can NOT just free active_cache[i] here, since it
+               istate->cache_changed = 1;
+               /* You can NOT just free istate->cache[i] here, since it
                 * might not be necessarily malloc()ed but can also come
                 * from mmap(). */
-               active_cache[i] = new;
+               istate->cache[i] = new;
        }
        return has_errors;
 }
 
 struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
 {
-       return refresh_cache_ent(ce, really, NULL);
+       return refresh_cache_ent(&the_index, ce, really, NULL);
 }
 
 static int verify_hdr(struct cache_header *hdr, unsigned long size)
@@ -810,11 +821,12 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
        return 0;
 }
 
-static int read_index_extension(const char *ext, void *data, unsigned long sz)
+static int read_index_extension(struct index_state *istate,
+                               const char *ext, void *data, unsigned long sz)
 {
        switch (CACHE_EXT(ext)) {
        case CACHE_EXT_TREE:
-               active_cache_tree = cache_tree_read(data, sz);
+               istate->cache_tree = cache_tree_read(data, sz);
                break;
        default:
                if (*ext < 'A' || 'Z' < *ext)
@@ -826,13 +838,13 @@ static int read_index_extension(const char *ext, void *data, unsigned long sz)
        return 0;
 }
 
-int read_cache(void)
+int read_index(struct index_state *istate)
 {
-       return read_cache_from(get_index_file());
+       return read_index_from(istate, get_index_file());
 }
 
 /* remember to discard_cache() before reading a different cache! */
-int read_cache_from(const char *path)
+int read_index_from(struct index_state *istate, const char *path)
 {
        int fd, i;
        struct stat st;
@@ -840,11 +852,11 @@ int read_cache_from(const char *path)
        struct cache_header *hdr;
 
        errno = EBUSY;
-       if (cache_mmap)
-               return active_nr;
+       if (istate->mmap)
+               return istate->cache_nr;
 
        errno = ENOENT;
-       index_file_timestamp = 0;
+       istate->timestamp = 0;
        fd = open(path, O_RDONLY);
        if (fd < 0) {
                if (errno == ENOENT)
@@ -853,32 +865,35 @@ int read_cache_from(const char *path)
        }
 
        if (!fstat(fd, &st)) {
-               cache_mmap_size = xsize_t(st.st_size);
+               istate->mmap_size = xsize_t(st.st_size);
                errno = EINVAL;
-               if (cache_mmap_size >= sizeof(struct cache_header) + 20)
-                       cache_mmap = xmmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+               if (istate->mmap_size >= sizeof(struct cache_header) + 20)
+                       istate->mmap = xmmap(NULL, istate->mmap_size,
+                                           PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
                else
                        die("index file smaller than expected");
        } else
                die("cannot stat the open index (%s)", strerror(errno));
        close(fd);
 
-       hdr = cache_mmap;
-       if (verify_hdr(hdr, cache_mmap_size) < 0)
+       hdr = istate->mmap;
+       if (verify_hdr(hdr, istate->mmap_size) < 0)
                goto unmap;
 
-       active_nr = ntohl(hdr->hdr_entries);
-       active_alloc = alloc_nr(active_nr);
-       active_cache = xcalloc(active_alloc, sizeof(struct cache_entry *));
+       istate->cache_nr = ntohl(hdr->hdr_entries);
+       istate->cache_alloc = alloc_nr(istate->cache_nr);
+       istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
 
        offset = sizeof(*hdr);
-       for (i = 0; i < active_nr; i++) {
-               struct cache_entry *ce = (struct cache_entry *) ((char *) cache_mmap + offset);
+       for (i = 0; i < istate->cache_nr; i++) {
+               struct cache_entry *ce;
+
+               ce = (struct cache_entry *)((char *)(istate->mmap) + offset);
                offset = offset + ce_size(ce);
-               active_cache[i] = ce;
+               istate->cache[i] = ce;
        }
-       index_file_timestamp = st.st_mtime;
-       while (offset <= cache_mmap_size - 20 - 8) {
+       istate->timestamp = st.st_mtime;
+       while (offset <= istate->mmap_size - 20 - 8) {
                /* After an array of active_nr index entries,
                 * there can be arbitrary number of extended
                 * sections, each of which is prefixed with
@@ -886,35 +901,37 @@ int read_cache_from(const char *path)
                 * in 4-byte network byte order.
                 */
                unsigned long extsize;
-               memcpy(&extsize, (char *) cache_mmap + offset + 4, 4);
+               memcpy(&extsize, (char *)(istate->mmap) + offset + 4, 4);
                extsize = ntohl(extsize);
-               if (read_index_extension(((const char *) cache_mmap) + offset,
-                                        (char *) cache_mmap + offset + 8,
+               if (read_index_extension(istate,
+                                        ((const char *) (istate->mmap)) + offset,
+                                        (char *) (istate->mmap) + offset + 8,
                                         extsize) < 0)
                        goto unmap;
                offset += 8;
                offset += extsize;
        }
-       return active_nr;
+       return istate->cache_nr;
 
 unmap:
-       munmap(cache_mmap, cache_mmap_size);
+       munmap(istate->mmap, istate->mmap_size);
        errno = EINVAL;
        die("index file corrupt");
 }
 
-int discard_cache(void)
+int discard_index(struct index_state *istate)
 {
        int ret;
 
-       active_nr = active_cache_changed = 0;
-       index_file_timestamp = 0;
-       cache_tree_free(&active_cache_tree);
-       if (cache_mmap == NULL)
+       istate->cache_nr = 0;
+       istate->cache_changed = 0;
+       istate->timestamp = 0;
+       cache_tree_free(&(istate->cache_tree));
+       if (istate->mmap == NULL)
                return 0;
-       ret = munmap(cache_mmap, cache_mmap_size);
-       cache_mmap = NULL;
-       cache_mmap_size = 0;
+       ret = munmap(istate->mmap, istate->mmap_size);
+       istate->mmap = NULL;
+       istate->mmap_size = 0;
 
        /* no need to throw away allocated active_cache */
        return ret;
@@ -1033,11 +1050,13 @@ static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
        }
 }
 
-int write_cache(int newfd, struct cache_entry **cache, int entries)
+int write_index(struct index_state *istate, int newfd)
 {
        SHA_CTX c;
        struct cache_header hdr;
        int i, removed;
+       struct cache_entry **cache = istate->cache;
+       int entries = istate->cache_nr;
 
        for (i = removed = 0; i < entries; i++)
                if (!cache[i]->ce_mode)
@@ -1055,17 +1074,17 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
                struct cache_entry *ce = cache[i];
                if (!ce->ce_mode)
                        continue;
-               if (index_file_timestamp &&
-                   index_file_timestamp <= ntohl(ce->ce_mtime.sec))
+               if (istate->timestamp &&
+                   istate->timestamp <= ntohl(ce->ce_mtime.sec))
                        ce_smudge_racily_clean_entry(ce);
                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
                        return -1;
        }
 
        /* Write extension data here */
-       if (active_cache_tree) {
+       if (istate->cache_tree) {
                unsigned long sz;
-               void *data = cache_tree_write(active_cache_tree, &sz);
+               void *data = cache_tree_write(istate->cache_tree, &sz);
                if (data &&
                    !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) &&
                    !ce_write(&c, newfd, data, sz))