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-rw-r--r--sha1_file.c146
1 files changed, 81 insertions, 65 deletions
diff --git a/sha1_file.c b/sha1_file.c
index 8d189d4..2d109f9 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -222,84 +222,100 @@ char *sha1_pack_index_name(const unsigned char *sha1)
return base;
}
-struct alternate_object_database *alt_odb;
+struct alternate_object_database *alt_odb_list;
+static struct alternate_object_database **alt_odb_tail;
/*
* Prepare alternate object database registry.
- * alt_odb points at an array of struct alternate_object_database.
- * This array is terminated with an element that has both its base
- * and name set to NULL. alt_odb[n] comes from n'th non-empty
- * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
- * variable, and its base points at a statically allocated buffer
- * that contains "/the/directory/corresponding/to/.git/objects/...",
- * while its name points just after the slash at the end of
- * ".git/objects/" in the example above, and has enough space to hold
- * 40-byte hex SHA1, an extra slash for the first level indirection,
- * and the terminating NUL.
- * This function allocates the alt_odb array and all the strings
- * pointed by base fields of the array elements with one xmalloc();
- * the string pool immediately follows the array.
+ *
+ * The variable alt_odb_list points at the list of struct
+ * alternate_object_database. The elements on this list come from
+ * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
+ * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
+ * whose contents is exactly in the same format as that environment
+ * variable. Its base points at a statically allocated buffer that
+ * contains "/the/directory/corresponding/to/.git/objects/...", while
+ * its name points just after the slash at the end of ".git/objects/"
+ * in the example above, and has enough space to hold 40-byte hex
+ * SHA1, an extra slash for the first level indirection, and the
+ * terminating NUL.
*/
-void prepare_alt_odb(void)
+static void link_alt_odb_entries(const char *alt, const char *ep)
{
- int pass, totlen, i;
const char *cp, *last;
- char *op = NULL;
- const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
+ struct alternate_object_database *ent;
+
+ last = alt;
+ do {
+ for (cp = last; cp < ep && *cp != ':'; cp++)
+ ;
+ if (last != cp) {
+ /* 43 = 40-byte + 2 '/' + terminating NUL */
+ int pfxlen = cp - last;
+ int entlen = pfxlen + 43;
+
+ ent = xmalloc(sizeof(*ent) + entlen);
+ *alt_odb_tail = ent;
+ alt_odb_tail = &(ent->next);
+ ent->next = NULL;
+
+ memcpy(ent->base, last, pfxlen);
+ ent->name = ent->base + pfxlen + 1;
+ ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
+ ent->base[entlen-1] = 0;
+ }
+ while (cp < ep && *cp == ':')
+ cp++;
+ last = cp;
+ } while (cp < ep);
+}
- if (alt_odb)
+void prepare_alt_odb(void)
+{
+ char path[PATH_MAX];
+ char *map, *ep;
+ int fd;
+ struct stat st;
+ char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
+
+ sprintf(path, "%s/info/alternates", get_object_directory());
+ if (alt_odb_tail)
+ return;
+ alt_odb_tail = &alt_odb_list;
+ link_alt_odb_entries(alt, alt + strlen(alt));
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return;
+ if (fstat(fd, &st) || (st.st_size == 0)) {
+ close(fd);
return;
- /* The first pass counts how large an area to allocate to
- * hold the entire alt_odb structure, including array of
- * structs and path buffers for them. The second pass fills
- * the structure and prepares the path buffers for use by
- * fill_sha1_path().
- */
- for (totlen = pass = 0; pass < 2; pass++) {
- last = alt;
- i = 0;
- do {
- cp = strchr(last, ':') ? : last + strlen(last);
- if (last != cp) {
- /* 43 = 40-byte + 2 '/' + terminating NUL */
- int pfxlen = cp - last;
- int entlen = pfxlen + 43;
- if (pass == 0)
- totlen += entlen;
- else {
- alt_odb[i].base = op;
- alt_odb[i].name = op + pfxlen + 1;
- memcpy(op, last, pfxlen);
- op[pfxlen] = op[pfxlen + 3] = '/';
- op[entlen-1] = 0;
- op += entlen;
- }
- i++;
- }
- while (*cp && *cp == ':')
- cp++;
- last = cp;
- } while (*cp);
- if (pass)
- break;
- alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
- alt_odb[i].base = alt_odb[i].name = NULL;
- op = (char*)(&alt_odb[i+1]);
}
+ map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ close(fd);
+ if (map == MAP_FAILED)
+ return;
+
+ /* Remove the trailing newline */
+ for (ep = map + st.st_size - 1; map < ep && ep[-1] == '\n'; ep--)
+ ;
+ link_alt_odb_entries(map, ep);
+ munmap(map, st.st_size);
}
static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
{
- int i;
char *name = sha1_file_name(sha1);
+ struct alternate_object_database *alt;
if (!stat(name, st))
return name;
prepare_alt_odb();
- for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
+ for (alt = alt_odb_list; alt; alt = alt->next) {
+ name = alt->name;
fill_sha1_path(name, sha1);
- if (!stat(alt_odb[i].base, st))
- return alt_odb[i].base;
+ if (!stat(alt->base, st))
+ return alt->base;
}
return NULL;
}
@@ -522,18 +538,18 @@ static void prepare_packed_git_one(char *objdir)
void prepare_packed_git(void)
{
- int i;
static int run_once = 0;
+ struct alternate_object_database *alt;
- if (run_once++)
+ if (run_once)
return;
-
prepare_packed_git_one(get_object_directory());
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);
+ for (alt = alt_odb_list; alt; alt = alt->next) {
+ alt->name[0] = 0;
+ prepare_packed_git_one(alt->base);
}
+ run_once = 1;
}
int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)