https://github.com/git/git
Revision d0f7dcbf424e1739437ffe477d87088ca6cb3432 authored by Junio C Hamano on 09 March 2011, 00:58:19 UTC, committed by Junio C Hamano on 09 March 2011, 05:35:22 UTC
Earlier, 47afed5 (SubmittingPatches: itemize and reflect upon well written changes, 2009-04-28) added a discussion on the contents of the commit log message, but the last part of the new paragraph didn't make much sense. Reword it slightly to make it more readable. Update the "quicklist" to clarify what we mean by "motivation" and "contrast". Also mildly discourage external references. Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent e0adb84
Tip revision: d0f7dcbf424e1739437ffe477d87088ca6cb3432 authored by Junio C Hamano on 09 March 2011, 00:58:19 UTC
SubmittingPatches: clarify the expected commit log description
SubmittingPatches: clarify the expected commit log description
Tip revision: d0f7dcb
pack-check.c
#include "cache.h"
#include "pack.h"
#include "pack-revindex.h"
struct idx_entry
{
off_t offset;
const unsigned char *sha1;
unsigned int nr;
};
static int compare_entries(const void *e1, const void *e2)
{
const struct idx_entry *entry1 = e1;
const struct idx_entry *entry2 = e2;
if (entry1->offset < entry2->offset)
return -1;
if (entry1->offset > entry2->offset)
return 1;
return 0;
}
int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
off_t offset, off_t len, unsigned int nr)
{
const uint32_t *index_crc;
uint32_t data_crc = crc32(0, Z_NULL, 0);
do {
unsigned int avail;
void *data = use_pack(p, w_curs, offset, &avail);
if (avail > len)
avail = len;
data_crc = crc32(data_crc, data, avail);
offset += avail;
len -= avail;
} while (len);
index_crc = p->index_data;
index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
return data_crc != ntohl(*index_crc);
}
static int verify_packfile(struct packed_git *p,
struct pack_window **w_curs)
{
off_t index_size = p->index_size;
const unsigned char *index_base = p->index_data;
git_SHA_CTX ctx;
unsigned char sha1[20], *pack_sig;
off_t offset = 0, pack_sig_ofs = 0;
uint32_t nr_objects, i;
int err = 0;
struct idx_entry *entries;
/* Note that the pack header checks are actually performed by
* use_pack when it first opens the pack file. If anything
* goes wrong during those checks then the call will die out
* immediately.
*/
git_SHA1_Init(&ctx);
do {
unsigned int remaining;
unsigned char *in = use_pack(p, w_curs, offset, &remaining);
offset += remaining;
if (!pack_sig_ofs)
pack_sig_ofs = p->pack_size - 20;
if (offset > pack_sig_ofs)
remaining -= (unsigned int)(offset - pack_sig_ofs);
git_SHA1_Update(&ctx, in, remaining);
} while (offset < pack_sig_ofs);
git_SHA1_Final(sha1, &ctx);
pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
if (hashcmp(sha1, pack_sig))
err = error("%s SHA1 checksum mismatch",
p->pack_name);
if (hashcmp(index_base + index_size - 40, pack_sig))
err = error("%s SHA1 does not match its index",
p->pack_name);
unuse_pack(w_curs);
/* Make sure everything reachable from idx is valid. Since we
* have verified that nr_objects matches between idx and pack,
* we do not do scan-streaming check on the pack file.
*/
nr_objects = p->num_objects;
entries = xmalloc((nr_objects + 1) * sizeof(*entries));
entries[nr_objects].offset = pack_sig_ofs;
/* first sort entries by pack offset, since unpacking them is more efficient that way */
for (i = 0; i < nr_objects; i++) {
entries[i].sha1 = nth_packed_object_sha1(p, i);
if (!entries[i].sha1)
die("internal error pack-check nth-packed-object");
entries[i].offset = nth_packed_object_offset(p, i);
entries[i].nr = i;
}
qsort(entries, nr_objects, sizeof(*entries), compare_entries);
for (i = 0; i < nr_objects; i++) {
void *data;
enum object_type type;
unsigned long size;
if (p->index_version > 1) {
off_t offset = entries[i].offset;
off_t len = entries[i+1].offset - offset;
unsigned int nr = entries[i].nr;
if (check_pack_crc(p, w_curs, offset, len, nr))
err = error("index CRC mismatch for object %s "
"from %s at offset %"PRIuMAX"",
sha1_to_hex(entries[i].sha1),
p->pack_name, (uintmax_t)offset);
}
data = unpack_entry(p, entries[i].offset, &type, &size);
if (!data) {
err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
sha1_to_hex(entries[i].sha1), p->pack_name,
(uintmax_t)entries[i].offset);
break;
}
if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) {
err = error("packed %s from %s is corrupt",
sha1_to_hex(entries[i].sha1), p->pack_name);
free(data);
break;
}
free(data);
}
free(entries);
return err;
}
int verify_pack_index(struct packed_git *p)
{
off_t index_size;
const unsigned char *index_base;
git_SHA_CTX ctx;
unsigned char sha1[20];
int err = 0;
if (open_pack_index(p))
return error("packfile %s index not opened", p->pack_name);
index_size = p->index_size;
index_base = p->index_data;
/* Verify SHA1 sum of the index file */
git_SHA1_Init(&ctx);
git_SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20));
git_SHA1_Final(sha1, &ctx);
if (hashcmp(sha1, index_base + index_size - 20))
err = error("Packfile index for %s SHA1 mismatch",
p->pack_name);
return err;
}
int verify_pack(struct packed_git *p)
{
int err = 0;
struct pack_window *w_curs = NULL;
err |= verify_pack_index(p);
if (!p->index_data)
return -1;
err |= verify_packfile(p, &w_curs);
unuse_pack(&w_curs);
return err;
}
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