Teach revision walking machinery to walk multiple times sequencially

diff --git a/sha1_file.c b/sha1_file.c
index 88f2151ff31870138a53e40f99f5ae9928b09545..f9f8d5e91c278000e5869f49ba6a79ddfaf13145 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -54,6 +54,8 @@ static struct cached_object empty_tree = {
        0
 };
 
+static struct packed_git *last_found_pack;
+
 static struct cached_object *find_cached_object(const unsigned char *sha1)
 {
        int i;
@@ -720,6 +722,8 @@ void free_pack_by_name(const char *pack_name)
                        close_pack_index(p);
                        free(p->bad_object_sha1);
                        *pp = p->next;
+                       if (last_found_pack == p)
+                               last_found_pack = NULL;
                        free(p);
                        return;
                }
@@ -1202,6 +1206,11 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 
                if (!fstat(fd, &st)) {
                        *size = xsize_t(st.st_size);
+                       if (!*size) {
+                               /* mmap() is forbidden on empty files */
+                               error("object file %s is empty", sha1_file_name(sha1));
+                               return NULL;
+                       }
                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
                }
                close(fd);
@@ -2010,54 +2019,58 @@ int is_pack_valid(struct packed_git *p)
        return !open_packed_git(p);
 }
 
+static int fill_pack_entry(const unsigned char *sha1,
+                          struct pack_entry *e,
+                          struct packed_git *p)
+{
+       off_t offset;
+
+       if (p->num_bad_objects) {
+               unsigned i;
+               for (i = 0; i < p->num_bad_objects; i++)
+                       if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
+                               return 0;
+       }
+
+       offset = find_pack_entry_one(sha1, p);
+       if (!offset)
+               return 0;
+
+       /*
+        * We are about to tell the caller where they can locate the
+        * requested object.  We better make sure the packfile is
+        * still here and can be accessed before supplying that
+        * answer, as it may have been deleted since the index was
+        * loaded!
+        */
+       if (!is_pack_valid(p)) {
+               warning("packfile %s cannot be accessed", p->pack_name);
+               return 0;
+       }
+       e->offset = offset;
+       e->p = p;
+       hashcpy(e->sha1, sha1);
+       return 1;
+}
+
 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 {
-       static struct packed_git *last_found = (void *)1;
        struct packed_git *p;
-       off_t offset;
 
        prepare_packed_git();
        if (!packed_git)
                return 0;
-       p = (last_found == (void *)1) ? packed_git : last_found;
 
-       do {
-               if (p->num_bad_objects) {
-                       unsigned i;
-                       for (i = 0; i < p->num_bad_objects; i++)
-                               if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
-                                       goto next;
-               }
+       if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
+               return 1;
 
-               offset = find_pack_entry_one(sha1, p);
-               if (offset) {
-                       /*
-                        * We are about to tell the caller where they can
-                        * locate the requested object.  We better make
-                        * sure the packfile is still here and can be
-                        * accessed before supplying that answer, as
-                        * it may have been deleted since the index
-                        * was loaded!
-                        */
-                       if (!is_pack_valid(p)) {
-                               warning("packfile %s cannot be accessed", p->pack_name);
-                               goto next;
-                       }
-                       e->offset = offset;
-                       e->p = p;
-                       hashcpy(e->sha1, sha1);
-                       last_found = p;
-                       return 1;
-               }
+       for (p = packed_git; p; p = p->next) {
+               if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
+                       continue;
 
-               next:
-               if (p == last_found)
-                       p = packed_git;
-               else
-                       p = p->next;
-               if (p == last_found)
-                       p = p->next;
-       } while (p);
+               last_found_pack = p;
+               return 1;
+       }
        return 0;
 }