packfile: abstract away hash constant values

There are several instances of the constant 20 and 20-based values in
the packfile code.  Abstract away dependence on SHA-1 by using the
values from the_hash_algo instead.

Use unsigned values for temporary constants to provide the compiler with
more information about what kinds of values it should expect.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/packfile.c b/packfile.c
index 84acd405e015414f04ff0dae7bc199d90dfe95cb..b7bc4eab17c736345b3757a7ad656ff4da8a9c94 100644 (file)
--- a/packfile.c
+++ b/packfile.c
@@ -84,6 +84,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
        uint32_t version, nr, i, *index;
        int fd = git_open(path);
        struct stat st;
        uint32_t version, nr, i, *index;
        int fd = git_open(path);
        struct stat st;

+       const unsigned int hashsz = the_hash_algo->rawsz;

 
        if (fd < 0)
                return -1;
 
        if (fd < 0)
                return -1;


@@ -92,7 +93,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
                return -1;
        }
        idx_size = xsize_t(st.st_size);
                return -1;
        }
        idx_size = xsize_t(st.st_size);

-       if (idx_size < 4 * 256 + 20 + 20) {
+       if (idx_size < 4 * 256 + hashsz + hashsz) {

                close(fd);
                return error("index file %s is too small", path);
        }
                close(fd);
                return error("index file %s is too small", path);
        }


@@ -129,11 +130,11 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
                /*
                 * Total size:
                 *  - 256 index entries 4 bytes each
                /*
                 * 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
+                *  - 24-byte entries * nr (object ID + 4-byte offset)
+                *  - hash of the packfile
+                *  - file checksum

                 */
                 */

-               if (idx_size != 4*256 + nr * 24 + 20 + 20) {
+               if (idx_size != 4*256 + nr * (hashsz + 4) + hashsz + hashsz) {

                        munmap(idx_map, idx_size);
                        return error("wrong index v1 file size in %s", path);
                }
                        munmap(idx_map, idx_size);
                        return error("wrong index v1 file size in %s", path);
                }


@@ -142,16 +143,16 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
                 * Minimum size:
                 *  - 8 bytes of header
                 *  - 256 index entries 4 bytes each
                 * Minimum size:
                 *  - 8 bytes of header
                 *  - 256 index entries 4 bytes each

-                *  - 20-byte sha1 entry * nr
+                *  - object ID entry * nr

                 *  - 4-byte crc entry * nr
                 *  - 4-byte offset entry * nr
                 *  - 4-byte crc entry * nr
                 *  - 4-byte offset entry * nr

-                *  - 20-byte SHA1 of the packfile
-                *  - 20-byte SHA1 file checksum
+                *  - hash of the packfile
+                *  - file checksum

                 * And after the 4-byte offset table might be a
                 * variable sized table containing 8-byte entries
                 * for offsets larger than 2^31.
                 */
                 * And after the 4-byte offset table might be a
                 * variable sized table containing 8-byte entries
                 * for offsets larger than 2^31.
                 */

-               unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
+               unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;

                unsigned long max_size = min_size;
                if (nr)
                        max_size += (nr - 1)*8;
                unsigned long max_size = min_size;
                if (nr)
                        max_size += (nr - 1)*8;


@@ -444,10 +445,11 @@ static int open_packed_git_1(struct packed_git *p)
 {
        struct stat st;
        struct pack_header hdr;
 {
        struct stat st;
        struct pack_header hdr;

-       unsigned char sha1[20];
-       unsigned char *idx_sha1;
+       unsigned char hash[GIT_MAX_RAWSZ];
+       unsigned char *idx_hash;

        long fd_flag;
        ssize_t read_result;
        long fd_flag;
        ssize_t read_result;

+       const unsigned hashsz = the_hash_algo->rawsz;

 
        if (!p->index_data && open_pack_index(p))
                return error("packfile %s index unavailable", p->pack_name);
 
        if (!p->index_data && open_pack_index(p))
                return error("packfile %s index unavailable", p->pack_name);


@@ -507,15 +509,15 @@ static int open_packed_git_1(struct packed_git *p)
                             " while index indicates %"PRIu32" objects",
                             p->pack_name, ntohl(hdr.hdr_entries),
                             p->num_objects);
                             " while index indicates %"PRIu32" objects",
                             p->pack_name, ntohl(hdr.hdr_entries),
                             p->num_objects);

-       if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
+       if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)

                return error("end of packfile %s is unavailable", p->pack_name);
                return error("end of packfile %s is unavailable", p->pack_name);

-       read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
+       read_result = read_in_full(p->pack_fd, hash, hashsz);

        if (read_result < 0)
                return error_errno("error reading from %s", p->pack_name);
        if (read_result < 0)
                return error_errno("error reading from %s", p->pack_name);

-       if (read_result != sizeof(sha1))
+       if (read_result != hashsz)

                return error("packfile %s signature is unavailable", p->pack_name);
                return error("packfile %s signature is unavailable", p->pack_name);

-       idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
-       if (hashcmp(sha1, idx_sha1))
+       idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
+       if (hashcmp(hash, idx_hash))

                return error("packfile %s does not match index", p->pack_name);
        return 0;
 }
                return error("packfile %s does not match index", p->pack_name);
        return 0;
 }


@@ -530,7 +532,7 @@ static int open_packed_git(struct packed_git *p)
 
 static int in_window(struct pack_window *win, off_t offset)
 {
 
 static int in_window(struct pack_window *win, off_t offset)
 {

-       /* We must promise at least 20 bytes (one hash) after the
+       /* We must promise at least one full hash after the

         * offset is available from this window, otherwise the offset
         * is not actually in this window and a different window (which
         * has that one hash excess) must be used.  This is to support
         * offset is available from this window, otherwise the offset
         * is not actually in this window and a different window (which
         * has that one hash excess) must be used.  This is to support


@@ -538,7 +540,7 @@ static int in_window(struct pack_window *win, off_t offset)
         */
        off_t win_off = win->offset;
        return win_off <= offset
         */
        off_t win_off = win->offset;
        return win_off <= offset

-               && (offset + 20) <= (win_off + win->len);
+               && (offset + the_hash_algo->rawsz) <= (win_off + win->len);

 }
 
 unsigned char *use_pack(struct packed_git *p,
 }
 
 unsigned char *use_pack(struct packed_git *p,


@@ -555,7 +557,7 @@ unsigned char *use_pack(struct packed_git *p,
         */
        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
                die("packfile %s cannot be accessed", p->pack_name);
         */
        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
                die("packfile %s cannot be accessed", p->pack_name);

-       if (offset > (p->pack_size - 20))
+       if (offset > (p->pack_size - the_hash_algo->rawsz))

                die("offset beyond end of packfile (truncated pack?)");
        if (offset < 0)
                die(_("offset before end of packfile (broken .idx?)"));
                die("offset beyond end of packfile (truncated pack?)");
        if (offset < 0)
                die(_("offset before end of packfile (broken .idx?)"));


@@ -675,7 +677,8 @@ struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
        p->pack_size = st.st_size;
        p->pack_local = local;
        p->mtime = st.st_mtime;
        p->pack_size = st.st_size;
        p->pack_local = local;
        p->mtime = st.st_mtime;

-       if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
+       if (path_len < the_hash_algo->hexsz ||
+           get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))

                hashclr(p->sha1);
        return p;
 }
                hashclr(p->sha1);
        return p;
 }


@@ -1028,7 +1031,8 @@ const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
 
        for (p = the_repository->objects->packed_git; p; p = p->next)
                for (i = 0; i < p->num_bad_objects; i++)
 
        for (p = the_repository->objects->packed_git; p; p = p->next)
                for (i = 0; i < p->num_bad_objects; i++)

-                       if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
+                       if (!hashcmp(sha1,
+                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))

                                return p;
        return NULL;
 }
                                return p;
        return NULL;
 }


@@ -1066,7 +1070,7 @@ static off_t get_delta_base(struct packed_git *p,
        } else if (type == OBJ_REF_DELTA) {
                /* The base entry _must_ be in the same pack */
                base_offset = find_pack_entry_one(base_info, p);
        } else if (type == OBJ_REF_DELTA) {
                /* The base entry _must_ be in the same pack */
                base_offset = find_pack_entry_one(base_info, p);

-               *curpos += 20;
+               *curpos += the_hash_algo->rawsz;

        } else
                die("I am totally screwed");
        return base_offset;
        } else
                die("I am totally screwed");
        return base_offset;


@@ -1671,6 +1675,7 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
 {
        const unsigned char *index_fanout = p->index_data;
        const unsigned char *index_lookup;
 {
        const unsigned char *index_fanout = p->index_data;
        const unsigned char *index_lookup;

+       const unsigned int hashsz = the_hash_algo->rawsz;

        int index_lookup_width;
 
        if (!index_fanout)
        int index_lookup_width;
 
        if (!index_fanout)


@@ -1678,10 +1683,10 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32
 
        index_lookup = index_fanout + 4 * 256;
        if (p->index_version == 1) {
 
        index_lookup = index_fanout + 4 * 256;
        if (p->index_version == 1) {

-               index_lookup_width = 24;
+               index_lookup_width = hashsz + 4;

                index_lookup += 4;
        } else {
                index_lookup += 4;
        } else {

-               index_lookup_width = 20;
+               index_lookup_width = hashsz;

                index_fanout += 8;
                index_lookup += 8;
        }
                index_fanout += 8;
                index_lookup += 8;
        }


@@ -1694,6 +1699,7 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
                                            uint32_t n)
 {
        const unsigned char *index = p->index_data;
                                            uint32_t n)
 {
        const unsigned char *index = p->index_data;

+       const unsigned int hashsz = the_hash_algo->rawsz;

        if (!index) {
                if (open_pack_index(p))
                        return NULL;
        if (!index) {
                if (open_pack_index(p))
                        return NULL;


@@ -1703,10 +1709,10 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
                return NULL;
        index += 4 * 256;
        if (p->index_version == 1) {
                return NULL;
        index += 4 * 256;
        if (p->index_version == 1) {

-               return index + 24 * n + 4;
+               return index + (hashsz + 4) * n + 4;

        } else {
                index += 8;
        } else {
                index += 8;

-               return index + 20 * n;
+               return index + hashsz * n;

        }
 }
 
        }
 }
 


@@ -1738,12 +1744,13 @@ void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
 {
        const unsigned char *index = p->index_data;
 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
 {
        const unsigned char *index = p->index_data;

+       const unsigned int hashsz = the_hash_algo->rawsz;

        index += 4 * 256;
        if (p->index_version == 1) {
        index += 4 * 256;
        if (p->index_version == 1) {

-               return ntohl(*((uint32_t *)(index + 24 * n)));
+               return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));

        } else {
                uint32_t off;
        } else {
                uint32_t off;

-               index += 8 + p->num_objects * (20 + 4);
+               index += 8 + p->num_objects * (hashsz + 4);

                off = ntohl(*((uint32_t *)(index + 4 * n)));
                if (!(off & 0x80000000))
                        return off;
                off = ntohl(*((uint32_t *)(index + 4 * n)));
                if (!(off & 0x80000000))
                        return off;


@@ -1814,7 +1821,8 @@ static int fill_pack_entry(const struct object_id *oid,
        if (p->num_bad_objects) {
                unsigned i;
                for (i = 0; i < p->num_bad_objects; i++)
        if (p->num_bad_objects) {
                unsigned i;
                for (i = 0; i < p->num_bad_objects; i++)

-                       if (!hashcmp(oid->hash, p->bad_object_sha1 + 20 * i))
+                       if (!hashcmp(oid->hash,
+                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))

                                return 0;
        }
 
                                return 0;
        }