Fix object packing/unpacking.

This actually successfully packed and unpacked a git archive down to
1.3MB (17MB unpacked).

Right now unpacking is way too noisy, lots of debug messages left.

diff --git a/pack-objects.c b/pack-objects.c
index 3900df3..aa6cb6d 100644 (file)
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -96,7 +96,7 @@ static unsigned long write_object(FILE *f, struct object_entry *entry)
        unsigned long size;
        char type[10];
        void *buf = read_sha1_file(entry->sha1, type, &size);
-       char header[21];
+       char header[25];
        unsigned hdrlen, datalen;
 
        if (!buf)
@@ -110,16 +110,16 @@ static unsigned long write_object(FILE *f, struct object_entry *entry)
         * instead.
         */
        header[0] = ".CTB"[entry->type];
-       datalen = htonl(size);
-       memcpy(header+1, &datalen, 4);
        hdrlen = 5;
        if (entry->delta) {
                header[0] = 'D';
-               memcpy(header+1, entry->delta, 20);
+               memcpy(header+5, entry->delta, 20);
                buf = delta_against(buf, size, entry);
                size = entry->delta_size;
-               hdrlen = 21;
+               hdrlen = 25;
        }
+       datalen = htonl(size);
+       memcpy(header+1, &datalen, 4);
        fwrite(header, hdrlen, 1, f);
        datalen = fwrite_compressed(buf, size, f);
        free(buf);

diff --git a/unpack-objects.c b/unpack-objects.c
index a7b8df0..a62eeb4 100644 (file)
--- a/unpack-objects.c
+++ b/unpack-objects.c
@@ -88,26 +88,26 @@ static int check_index(void)
 }
 
 static int unpack_non_delta_entry(struct pack_entry *entry,
-                                 unsigned char *pack)
+                                 int kind,
+                                 unsigned char *data,
+                                 unsigned long size,
+                                 unsigned long left)
 {
-       int st, kind;
-       unsigned long size;
+       int st;
        z_stream stream;
        char *buffer;
        unsigned char sha1[20];
        char *type_s;
-       unsigned long offset = ntohl(entry->offset);
 
-       kind = pack[0];
-       size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
        printf("%s %c %lu\n", sha1_to_hex(entry->sha1), kind, size);
-       pack += 5;
+       if (dry_run)
+               return 0;
 
        buffer = xmalloc(size + 1);
        buffer[size] = 0;
        memset(&stream, 0, sizeof(stream));
-       stream.next_in = pack;
-       stream.avail_in = pack_size - offset; /* sheesh. */
+       stream.next_in = data;
+       stream.avail_in = left;
        stream.next_out = buffer;
        stream.avail_out = size;
 
@@ -148,14 +148,15 @@ static int find_pack_entry(unsigned char *sha1, struct pack_entry **ent)
        do {
                int mi = (lo + hi) / 2;
                int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
+printf("lo=%d mi=%d hi=%d cmp=%d\n", lo, mi, hi, cmp);
                if (!cmp) {
                        *ent = index + 24 * mi;
                        return 1;
                }
-               if (cmp < 0)
+               if (cmp > 0)
                        hi = mi;
                else
-                       lo = mi;
+                       lo = mi+1;
        } while (lo < hi);
        return 0;
 }
@@ -163,70 +164,55 @@ static int find_pack_entry(unsigned char *sha1, struct pack_entry **ent)
 /* forward declaration for a mutually recursive function */
 static void unpack_entry(struct pack_entry *);
 
-static int unpack_delta_entry(struct pack_entry *entry, unsigned char *pack)
+static int unpack_delta_entry(struct pack_entry *entry,
+                             unsigned char *base_sha1,
+                             unsigned long delta_size,
+                             unsigned long left)
 {
-       void *delta_data, *result, *base;
-       unsigned long delta_alloc, delta_size, result_size, base_size;
+       void *data, *delta_data, *result, *base;
+       unsigned long data_size, result_size, base_size;
        z_stream stream;
        int st;
        char type[20];
        unsigned char sha1[20];
 
-       printf("%s D", sha1_to_hex(entry->sha1));
-       printf(" %s\n", sha1_to_hex(pack+1));
+       if (left < 20)
+               die("truncated pack file");
+       data = base_sha1 + 20;
+       data_size = left - 20;
+       printf("%s D %lu", sha1_to_hex(entry->sha1), delta_size);
+       printf(" %s\n", sha1_to_hex(base_sha1));
+
+       if (dry_run)
+               return 0;
 
-       /* pack+1 is the base sha1, unless we have it, we need to
+       /* pack+5 is the base sha1, unless we have it, we need to
         * unpack it first.
         */
-       if (!has_sha1_file(pack+1)) {
+       if (!has_sha1_file(base_sha1)) {
                struct pack_entry *base;
-               if (!find_pack_entry(pack+1, &base))
+               if (!find_pack_entry(base_sha1, &base))
                        die("cannot find delta-pack base object");
                unpack_entry(base);
        }
-
-       /* pack+1 thru pack+20 is the base sha1 and
-        * pack+21 thru unknown number is the delta data.
-        * we do not even have size of the delta data uncompressed.
-        * sheesh!
-        */
-       delta_alloc = 1024;
-       delta_data = xmalloc(delta_alloc);
+       delta_data = xmalloc(delta_size);
 
        memset(&stream, 0, sizeof(stream));
 
-       stream.next_in = pack + 21;
-       stream.avail_in = pack_size - ntohl(entry->offset); /* sheesh. */
+       stream.next_in = data;
+       stream.avail_in = data_size;
        stream.next_out = delta_data;
-       stream.avail_out = delta_alloc;
-       delta_size = 0;
+       stream.avail_out = delta_size;
 
        inflateInit(&stream);
-       while (1) {
-               st = inflate(&stream, Z_FINISH);
-               if (st == Z_STREAM_END) {
-                       delta_size = stream.total_out;
-                       break;
-               }
-               if (st < 0)
-                       break;
-
-               if (delta_alloc <= stream.total_out) {
-                       delta_alloc = (delta_alloc +1024) * 3 / 2;
-                       delta_data = xrealloc(delta_data, delta_alloc);
-                       stream.next_out = delta_data + stream.total_out;
-                       stream.avail_out = delta_alloc - stream.total_out;
-               }
-       }
+       st = inflate(&stream, Z_FINISH);
        inflateEnd(&stream);
-       if (st != Z_STREAM_END) {
-               free(delta_data);
-               return -1;
-       }
+       if ((st != Z_STREAM_END) || stream.total_out != delta_size)
+               die("delta data unpack failed");
 
-       base = read_sha1_file(pack+1, type, &base_size);
+       base = read_sha1_file(base_sha1, type, &base_size);
        if (!base)
-               die("failed to read delta-pack base object");
+               die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
        result = patch_delta(base, base_size,
                             delta_data, delta_size,
                             &result_size);
@@ -246,7 +232,7 @@ static int unpack_delta_entry(struct pack_entry *entry, unsigned char *pack)
 
 static void unpack_entry(struct pack_entry *entry)
 {
-       unsigned long offset;
+       unsigned long offset, size, left;
        unsigned char *pack;
 
        /* Have we done this one already due to deltas based on it? */
@@ -257,13 +243,14 @@ static void unpack_entry(struct pack_entry *entry)
        if (offset > pack_size - 5)
                die("object offset outside of pack file");
        pack = pack_base + offset;
-       offset = pack_size - offset;
+       size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
+       left = pack_size - offset - 5;
        switch (*pack) {
        case 'C': case 'T': case 'B':
-               unpack_non_delta_entry(entry, pack);
+               unpack_non_delta_entry(entry, *pack, pack+5, size, left);
                break;
        case 'D':
-               unpack_delta_entry(entry, pack);
+               unpack_delta_entry(entry, pack+5, size, left);
                break;
        default:
                die("corrupted pack file");