"rebase -i": support special-purpose editor to edit insn sheet
[gitweb.git] / sha1_file.c
index 92e87ee2254b6e7a675ad2bdf5111ef7a9b8b5ec..e002056b85ce89c089dd09c1300461d60d81dffa 100644 (file)
@@ -380,7 +380,7 @@ void add_to_alternates_file(const char *reference)
 {
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
        int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
-       char *alt = mkpath("%s/objects\n", reference);
+       char *alt = mkpath("%s\n", reference);
        write_or_die(fd, alt, strlen(alt));
        if (commit_lock_file(lock))
                die("could not close alternates file");
@@ -1186,7 +1186,7 @@ static int open_sha1_file(const unsigned char *sha1)
        return -1;
 }
 
-static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 {
        void *map;
        int fd;
@@ -1217,14 +1217,34 @@ static int experimental_loose_object(unsigned char *map)
        unsigned int word;
 
        /*
-        * Is it a zlib-compressed buffer? If so, the first byte
-        * must be 0x78 (15-bit window size, deflated), and the
-        * first 16-bit word is evenly divisible by 31. If so,
-        * we are looking at the official format, not the experimental
-        * one.
+        * We must determine if the buffer contains the standard
+        * zlib-deflated stream or the experimental format based
+        * on the in-pack object format. Compare the header byte
+        * for each format:
+        *
+        * RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
+        * Experimental pack-based : Stttssss : ttt = 1,2,3,4
+        *
+        * If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
+        * in standard loose-object format, UNLESS it is a Git-pack
+        * format object *exactly* 8 bytes in size when inflated.
+        *
+        * However, RFC1950 also specifies that the 1st 16-bit word
+        * must be divisible by 31 - this checksum tells us our buffer
+        * is in the standard format, giving a false positive only if
+        * the 1st word of the Git-pack format object happens to be
+        * divisible by 31, ie:
+        *      ((byte0 * 256) + byte1) % 31 = 0
+        *   =>        0ttt10000www1000 % 31 = 0
+        *
+        * As it happens, this case can only arise for www=3 & ttt=1
+        * - ie, a Commit object, which would have to be 8 bytes in
+        * size. As no Commit can be that small, we find that the
+        * combination of these two criteria (bitmask & checksum)
+        * can always correctly determine the buffer format.
         */
        word = (map[0] << 8) + map[1];
-       if (map[0] == 0x78 && !(word % 31))
+       if ((map[0] & 0x8F) == 0x08 && !(word % 31))
                return 0;
        else
                return 1;
@@ -1254,7 +1274,7 @@ unsigned long unpack_object_header_buffer(const unsigned char *buf,
        return used;
 }
 
-static int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
+int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 {
        unsigned long size, used;
        static const char valid_loose_object_type[8] = {
@@ -1346,7 +1366,7 @@ static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long s
  * too permissive for what we want to check. So do an anal
  * object header parse by hand.
  */
-static int parse_sha1_header(const char *hdr, unsigned long *sizep)
+int parse_sha1_header(const char *hdr, unsigned long *sizep)
 {
        char type[10];
        int i;
@@ -1485,7 +1505,7 @@ static off_t get_delta_base(struct packed_git *p,
 
 /* forward declaration for a mutually recursive function */
 static int packed_object_info(struct packed_git *p, off_t offset,
-                             unsigned long *sizep);
+                             unsigned long *sizep, int *rtype);
 
 static int packed_delta_info(struct packed_git *p,
                             struct pack_window **w_curs,
@@ -1499,7 +1519,7 @@ static int packed_delta_info(struct packed_git *p,
        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
        if (!base_offset)
                return OBJ_BAD;
-       type = packed_object_info(p, base_offset, NULL);
+       type = packed_object_info(p, base_offset, NULL, NULL);
        if (type <= OBJ_NONE) {
                struct revindex_entry *revidx;
                const unsigned char *base_sha1;
@@ -1527,10 +1547,10 @@ static int packed_delta_info(struct packed_git *p,
        return type;
 }
 
-static int unpack_object_header(struct packed_git *p,
-                               struct pack_window **w_curs,
-                               off_t *curpos,
-                               unsigned long *sizep)
+int unpack_object_header(struct packed_git *p,
+                        struct pack_window **w_curs,
+                        off_t *curpos,
+                        unsigned long *sizep)
 {
        unsigned char *base;
        unsigned long left;
@@ -1553,63 +1573,8 @@ static int unpack_object_header(struct packed_git *p,
        return type;
 }
 
-const char *packed_object_info_detail(struct packed_git *p,
-                                     off_t obj_offset,
-                                     unsigned long *size,
-                                     unsigned long *store_size,
-                                     unsigned int *delta_chain_length,
-                                     unsigned char *base_sha1)
-{
-       struct pack_window *w_curs = NULL;
-       off_t curpos;
-       unsigned long dummy;
-       unsigned char *next_sha1;
-       enum object_type type;
-       struct revindex_entry *revidx;
-
-       *delta_chain_length = 0;
-       curpos = obj_offset;
-       type = unpack_object_header(p, &w_curs, &curpos, size);
-
-       revidx = find_pack_revindex(p, obj_offset);
-       *store_size = revidx[1].offset - obj_offset;
-
-       for (;;) {
-               switch (type) {
-               default:
-                       die("pack %s contains unknown object type %d",
-                           p->pack_name, type);
-               case OBJ_COMMIT:
-               case OBJ_TREE:
-               case OBJ_BLOB:
-               case OBJ_TAG:
-                       unuse_pack(&w_curs);
-                       return typename(type);
-               case OBJ_OFS_DELTA:
-                       obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
-                       if (!obj_offset)
-                               die("pack %s contains bad delta base reference of type %s",
-                                   p->pack_name, typename(type));
-                       if (*delta_chain_length == 0) {
-                               revidx = find_pack_revindex(p, obj_offset);
-                               hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
-                       }
-                       break;
-               case OBJ_REF_DELTA:
-                       next_sha1 = use_pack(p, &w_curs, curpos, NULL);
-                       if (*delta_chain_length == 0)
-                               hashcpy(base_sha1, next_sha1);
-                       obj_offset = find_pack_entry_one(next_sha1, p);
-                       break;
-               }
-               (*delta_chain_length)++;
-               curpos = obj_offset;
-               type = unpack_object_header(p, &w_curs, &curpos, &dummy);
-       }
-}
-
 static int packed_object_info(struct packed_git *p, off_t obj_offset,
-                             unsigned long *sizep)
+                             unsigned long *sizep, int *rtype)
 {
        struct pack_window *w_curs = NULL;
        unsigned long size;
@@ -1617,6 +1582,8 @@ static int packed_object_info(struct packed_git *p, off_t obj_offset,
        enum object_type type;
 
        type = unpack_object_header(p, &w_curs, &curpos, &size);
+       if (rtype)
+               *rtype = type; /* representation type */
 
        switch (type) {
        case OBJ_OFS_DELTA:
@@ -1699,6 +1666,13 @@ static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
        return hash % MAX_DELTA_CACHE;
 }
 
+static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
+{
+       unsigned long hash = pack_entry_hash(p, base_offset);
+       struct delta_base_cache_entry *ent = delta_base_cache + hash;
+       return (ent->data && ent->p == p && ent->base_offset == base_offset);
+}
+
 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
        unsigned long *base_size, enum object_type *type, int keep_cache)
 {
@@ -1843,6 +1817,24 @@ static void *unpack_delta_entry(struct packed_git *p,
        return result;
 }
 
+static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
+{
+       static FILE *log_file;
+
+       if (!log_file) {
+               log_file = fopen(log_pack_access, "w");
+               if (!log_file) {
+                       error("cannot open pack access log '%s' for writing: %s",
+                             log_pack_access, strerror(errno));
+                       log_pack_access = NULL;
+                       return;
+               }
+       }
+       fprintf(log_file, "%s %"PRIuMAX"\n",
+               p->pack_name, (uintmax_t)obj_offset);
+       fflush(log_file);
+}
+
 int do_check_packed_object_crc;
 
 void *unpack_entry(struct packed_git *p, off_t obj_offset,
@@ -1852,6 +1844,9 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
        off_t curpos = obj_offset;
        void *data;
 
+       if (log_pack_access)
+               write_pack_access_log(p, obj_offset);
+
        if (do_check_packed_object_crc && p->index_version > 1) {
                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
                unsigned long len = revidx[1].offset - obj_offset;
@@ -2097,24 +2092,28 @@ static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *size
        return status;
 }
 
-int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
+/* returns enum object_type or negative */
+int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
 {
        struct cached_object *co;
        struct pack_entry e;
-       int status;
+       int status, rtype;
 
        co = find_cached_object(sha1);
        if (co) {
-               if (sizep)
-                       *sizep = co->size;
+               if (oi->sizep)
+                       *(oi->sizep) = co->size;
+               oi->whence = OI_CACHED;
                return co->type;
        }
 
        if (!find_pack_entry(sha1, &e)) {
                /* Most likely it's a loose object. */
-               status = sha1_loose_object_info(sha1, sizep);
-               if (status >= 0)
+               status = sha1_loose_object_info(sha1, oi->sizep);
+               if (status >= 0) {
+                       oi->whence = OI_LOOSE;
                        return status;
+               }
 
                /* Not a loose object; someone else may have just packed it. */
                reprepare_packed_git();
@@ -2122,15 +2121,31 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
                        return status;
        }
 
-       status = packed_object_info(e.p, e.offset, sizep);
+       status = packed_object_info(e.p, e.offset, oi->sizep, &rtype);
        if (status < 0) {
                mark_bad_packed_object(e.p, sha1);
-               status = sha1_object_info(sha1, sizep);
+               status = sha1_object_info_extended(sha1, oi);
+       } else if (in_delta_base_cache(e.p, e.offset)) {
+               oi->whence = OI_DBCACHED;
+       } else {
+               oi->whence = OI_PACKED;
+               oi->u.packed.offset = e.offset;
+               oi->u.packed.pack = e.p;
+               oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
+                                        rtype == OBJ_OFS_DELTA);
        }
 
        return status;
 }
 
+int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
+{
+       struct object_info oi;
+
+       oi.sizep = sizep;
+       return sha1_object_info_extended(sha1, &oi);
+}
+
 static void *read_packed_sha1(const unsigned char *sha1,
                              enum object_type *type, unsigned long *size)
 {
@@ -2708,7 +2723,7 @@ static int index_stream(unsigned char *sha1, int fd, size_t size,
        while (size) {
                char buf[10240];
                size_t sz = size < sizeof(buf) ? size : sizeof(buf);
-               size_t actual;
+               ssize_t actual;
 
                actual = read_in_full(fd, buf, sz);
                if (actual < 0)