mirror of
https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
![Peter Eriksen](/assets/img/avatar_default.png)
This replaces occurences of "blob", "commit", "tag", and "tree", where they're really used as type specifiers, which we already have defined global constants for. Signed-off-by: Peter Eriksen <s022018@student.dtu.dk> Signed-off-by: Junio C Hamano <junkio@cox.net>
473 lines
12 KiB
C
473 lines
12 KiB
C
#include "cache.h"
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#include "delta.h"
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#include "pack.h"
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#include "csum-file.h"
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#include "blob.h"
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#include "commit.h"
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#include "tag.h"
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#include "tree.h"
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static const char index_pack_usage[] =
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"git-index-pack [-o index-file] pack-file";
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struct object_entry
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{
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unsigned long offset;
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enum object_type type;
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enum object_type real_type;
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unsigned char sha1[20];
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};
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struct delta_entry
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{
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struct object_entry *obj;
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unsigned char base_sha1[20];
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};
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static const char *pack_name;
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static unsigned char *pack_base;
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static unsigned long pack_size;
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static struct object_entry *objects;
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static struct delta_entry *deltas;
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static int nr_objects;
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static int nr_deltas;
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static void open_pack_file(void)
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{
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int fd;
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struct stat st;
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fd = open(pack_name, O_RDONLY);
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if (fd < 0)
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die("cannot open packfile '%s': %s", pack_name,
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strerror(errno));
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if (fstat(fd, &st)) {
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int err = errno;
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close(fd);
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die("cannot fstat packfile '%s': %s", pack_name,
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strerror(err));
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}
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pack_size = st.st_size;
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pack_base = mmap(NULL, pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
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if (pack_base == MAP_FAILED) {
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int err = errno;
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close(fd);
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die("cannot mmap packfile '%s': %s", pack_name,
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strerror(err));
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}
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close(fd);
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}
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static void parse_pack_header(void)
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{
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const struct pack_header *hdr;
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unsigned char sha1[20];
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SHA_CTX ctx;
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/* Ensure there are enough bytes for the header and final SHA1 */
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if (pack_size < sizeof(struct pack_header) + 20)
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die("packfile '%s' is too small", pack_name);
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/* Header consistency check */
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hdr = (void *)pack_base;
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if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
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die("packfile '%s' signature mismatch", pack_name);
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if (!pack_version_ok(hdr->hdr_version))
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die("packfile '%s' version %d unsupported",
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pack_name, ntohl(hdr->hdr_version));
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nr_objects = ntohl(hdr->hdr_entries);
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/* Check packfile integrity */
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SHA1_Init(&ctx);
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SHA1_Update(&ctx, pack_base, pack_size - 20);
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SHA1_Final(sha1, &ctx);
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if (memcmp(sha1, pack_base + pack_size - 20, 20))
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die("packfile '%s' SHA1 mismatch", pack_name);
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}
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static void bad_object(unsigned long offset, const char *format,
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...) NORETURN __attribute__((format (printf, 2, 3)));
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static void bad_object(unsigned long offset, const char *format, ...)
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{
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va_list params;
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char buf[1024];
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va_start(params, format);
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vsnprintf(buf, sizeof(buf), format, params);
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va_end(params);
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die("packfile '%s': bad object at offset %lu: %s",
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pack_name, offset, buf);
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}
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static void *unpack_entry_data(unsigned long offset,
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unsigned long *current_pos, unsigned long size)
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{
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unsigned long pack_limit = pack_size - 20;
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unsigned long pos = *current_pos;
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z_stream stream;
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void *buf = xmalloc(size);
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memset(&stream, 0, sizeof(stream));
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stream.next_out = buf;
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stream.avail_out = size;
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stream.next_in = pack_base + pos;
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stream.avail_in = pack_limit - pos;
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inflateInit(&stream);
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for (;;) {
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int ret = inflate(&stream, 0);
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if (ret == Z_STREAM_END)
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break;
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if (ret != Z_OK)
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bad_object(offset, "inflate returned %d", ret);
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}
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inflateEnd(&stream);
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if (stream.total_out != size)
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bad_object(offset, "size mismatch (expected %lu, got %lu)",
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size, stream.total_out);
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*current_pos = pack_limit - stream.avail_in;
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return buf;
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}
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static void *unpack_raw_entry(unsigned long offset,
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enum object_type *obj_type,
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unsigned long *obj_size,
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unsigned char *delta_base,
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unsigned long *next_obj_offset)
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{
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unsigned long pack_limit = pack_size - 20;
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unsigned long pos = offset;
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unsigned char c;
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unsigned long size;
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unsigned shift;
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enum object_type type;
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void *data;
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c = pack_base[pos++];
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type = (c >> 4) & 7;
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size = (c & 15);
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shift = 4;
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while (c & 0x80) {
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if (pos >= pack_limit)
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bad_object(offset, "object extends past end of pack");
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c = pack_base[pos++];
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size += (c & 0x7fUL) << shift;
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shift += 7;
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}
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switch (type) {
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case OBJ_DELTA:
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if (pos + 20 >= pack_limit)
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bad_object(offset, "object extends past end of pack");
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memcpy(delta_base, pack_base + pos, 20);
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pos += 20;
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/* fallthru */
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case OBJ_COMMIT:
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case OBJ_TREE:
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case OBJ_BLOB:
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case OBJ_TAG:
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data = unpack_entry_data(offset, &pos, size);
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break;
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default:
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bad_object(offset, "bad object type %d", type);
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}
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*obj_type = type;
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*obj_size = size;
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*next_obj_offset = pos;
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return data;
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}
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static int find_delta(const unsigned char *base_sha1)
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{
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int first = 0, last = nr_deltas;
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while (first < last) {
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int next = (first + last) / 2;
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struct delta_entry *delta = &deltas[next];
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int cmp;
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cmp = memcmp(base_sha1, delta->base_sha1, 20);
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if (!cmp)
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return next;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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return -first-1;
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}
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static int find_deltas_based_on_sha1(const unsigned char *base_sha1,
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int *first_index, int *last_index)
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{
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int first = find_delta(base_sha1);
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int last = first;
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int end = nr_deltas - 1;
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if (first < 0)
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return -1;
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while (first > 0 && !memcmp(deltas[first-1].base_sha1, base_sha1, 20))
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--first;
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while (last < end && !memcmp(deltas[last+1].base_sha1, base_sha1, 20))
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++last;
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*first_index = first;
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*last_index = last;
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return 0;
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}
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static void sha1_object(const void *data, unsigned long size,
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enum object_type type, unsigned char *sha1)
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{
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SHA_CTX ctx;
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char header[50];
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int header_size;
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const char *type_str;
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switch (type) {
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case OBJ_COMMIT: type_str = commit_type; break;
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case OBJ_TREE: type_str = tree_type; break;
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case OBJ_BLOB: type_str = blob_type; break;
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case OBJ_TAG: type_str = tag_type; break;
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default:
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die("bad type %d", type);
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}
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header_size = sprintf(header, "%s %lu", type_str, size) + 1;
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SHA1_Init(&ctx);
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SHA1_Update(&ctx, header, header_size);
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SHA1_Update(&ctx, data, size);
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SHA1_Final(sha1, &ctx);
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}
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static void resolve_delta(struct delta_entry *delta, void *base_data,
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unsigned long base_size, enum object_type type)
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{
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struct object_entry *obj = delta->obj;
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void *delta_data;
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unsigned long delta_size;
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void *result;
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unsigned long result_size;
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enum object_type delta_type;
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unsigned char base_sha1[20];
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unsigned long next_obj_offset;
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int j, first, last;
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obj->real_type = type;
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delta_data = unpack_raw_entry(obj->offset, &delta_type,
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&delta_size, base_sha1,
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&next_obj_offset);
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result = patch_delta(base_data, base_size, delta_data, delta_size,
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&result_size);
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free(delta_data);
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if (!result)
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bad_object(obj->offset, "failed to apply delta");
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sha1_object(result, result_size, type, obj->sha1);
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if (!find_deltas_based_on_sha1(obj->sha1, &first, &last)) {
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for (j = first; j <= last; j++)
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resolve_delta(&deltas[j], result, result_size, type);
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}
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free(result);
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}
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static int compare_delta_entry(const void *a, const void *b)
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{
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const struct delta_entry *delta_a = a;
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const struct delta_entry *delta_b = b;
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return memcmp(delta_a->base_sha1, delta_b->base_sha1, 20);
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}
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static void parse_pack_objects(void)
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{
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int i;
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unsigned long offset = sizeof(struct pack_header);
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unsigned char base_sha1[20];
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void *data;
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unsigned long data_size;
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/*
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* First pass:
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* - find locations of all objects;
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* - calculate SHA1 of all non-delta objects;
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* - remember base SHA1 for all deltas.
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*/
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for (i = 0; i < nr_objects; i++) {
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struct object_entry *obj = &objects[i];
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obj->offset = offset;
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data = unpack_raw_entry(offset, &obj->type, &data_size,
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base_sha1, &offset);
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obj->real_type = obj->type;
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if (obj->type == OBJ_DELTA) {
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struct delta_entry *delta = &deltas[nr_deltas++];
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delta->obj = obj;
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memcpy(delta->base_sha1, base_sha1, 20);
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} else
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sha1_object(data, data_size, obj->type, obj->sha1);
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free(data);
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}
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if (offset != pack_size - 20)
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die("packfile '%s' has junk at the end", pack_name);
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/* Sort deltas by base SHA1 for fast searching */
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qsort(deltas, nr_deltas, sizeof(struct delta_entry),
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compare_delta_entry);
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/*
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* Second pass:
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* - for all non-delta objects, look if it is used as a base for
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* deltas;
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* - if used as a base, uncompress the object and apply all deltas,
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* recursively checking if the resulting object is used as a base
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* for some more deltas.
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*/
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for (i = 0; i < nr_objects; i++) {
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struct object_entry *obj = &objects[i];
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int j, first, last;
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if (obj->type == OBJ_DELTA)
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continue;
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if (find_deltas_based_on_sha1(obj->sha1, &first, &last))
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continue;
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data = unpack_raw_entry(obj->offset, &obj->type, &data_size,
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base_sha1, &offset);
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for (j = first; j <= last; j++)
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resolve_delta(&deltas[j], data, data_size, obj->type);
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free(data);
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}
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/* Check for unresolved deltas */
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for (i = 0; i < nr_deltas; i++) {
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if (deltas[i].obj->real_type == OBJ_DELTA)
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die("packfile '%s' has unresolved deltas", pack_name);
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}
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}
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static int sha1_compare(const void *_a, const void *_b)
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{
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struct object_entry *a = *(struct object_entry **)_a;
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struct object_entry *b = *(struct object_entry **)_b;
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return memcmp(a->sha1, b->sha1, 20);
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}
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static void write_index_file(const char *index_name, unsigned char *sha1)
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{
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struct sha1file *f;
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struct object_entry **sorted_by_sha, **list, **last;
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unsigned int array[256];
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int i;
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SHA_CTX ctx;
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if (nr_objects) {
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sorted_by_sha =
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xcalloc(nr_objects, sizeof(struct object_entry *));
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list = sorted_by_sha;
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last = sorted_by_sha + nr_objects;
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for (i = 0; i < nr_objects; ++i)
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sorted_by_sha[i] = &objects[i];
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qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
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sha1_compare);
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}
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else
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sorted_by_sha = list = last = NULL;
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unlink(index_name);
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f = sha1create("%s", index_name);
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/*
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* Write the first-level table (the list is sorted,
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* but we use a 256-entry lookup to be able to avoid
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* having to do eight extra binary search iterations).
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*/
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for (i = 0; i < 256; i++) {
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struct object_entry **next = list;
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while (next < last) {
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struct object_entry *obj = *next;
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if (obj->sha1[0] != i)
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break;
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next++;
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}
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array[i] = htonl(next - sorted_by_sha);
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list = next;
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}
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sha1write(f, array, 256 * sizeof(int));
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/* recompute the SHA1 hash of sorted object names.
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* currently pack-objects does not do this, but that
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* can be fixed.
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*/
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SHA1_Init(&ctx);
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/*
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* Write the actual SHA1 entries..
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*/
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list = sorted_by_sha;
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for (i = 0; i < nr_objects; i++) {
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struct object_entry *obj = *list++;
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unsigned int offset = htonl(obj->offset);
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sha1write(f, &offset, 4);
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sha1write(f, obj->sha1, 20);
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SHA1_Update(&ctx, obj->sha1, 20);
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}
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sha1write(f, pack_base + pack_size - 20, 20);
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sha1close(f, NULL, 1);
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free(sorted_by_sha);
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SHA1_Final(sha1, &ctx);
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}
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int main(int argc, char **argv)
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{
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int i;
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char *index_name = NULL;
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char *index_name_buf = NULL;
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unsigned char sha1[20];
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for (i = 1; i < argc; i++) {
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const char *arg = argv[i];
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if (*arg == '-') {
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if (!strcmp(arg, "-o")) {
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if (index_name || (i+1) >= argc)
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usage(index_pack_usage);
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index_name = argv[++i];
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} else
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usage(index_pack_usage);
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continue;
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}
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if (pack_name)
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usage(index_pack_usage);
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pack_name = arg;
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}
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if (!pack_name)
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usage(index_pack_usage);
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if (!index_name) {
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int len = strlen(pack_name);
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if (len < 5 || strcmp(pack_name + len - 5, ".pack"))
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die("packfile name '%s' does not end with '.pack'",
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pack_name);
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index_name_buf = xmalloc(len);
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memcpy(index_name_buf, pack_name, len - 5);
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strcpy(index_name_buf + len - 5, ".idx");
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index_name = index_name_buf;
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}
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open_pack_file();
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parse_pack_header();
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objects = xcalloc(nr_objects, sizeof(struct object_entry));
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deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
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parse_pack_objects();
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free(deltas);
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write_index_file(index_name, sha1);
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free(objects);
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free(index_name_buf);
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printf("%s\n", sha1_to_hex(sha1));
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return 0;
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}
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