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bundle: add new version for use with SHA-256

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Currently we detect the hash algorithm in use by the length of the
object ID.  This is inelegant and prevents us from using a different
hash algorithm that is also 256 bits in length.

Since we cannot extend the v2 format in a backward-compatible way, let's
add a v3 format, which is identical, except for the addition of
capabilities, which are prefixed by an at sign.  We add "object-format"
as the only capability and reject unknown capabilities, since we do not
have a network connection and therefore cannot negotiate with the other
side.

For compatibility, default to the v2 format for SHA-1 and require v3
for SHA-256.

In t5510, always use format v3 so we can be sure we produce consistent
results across hash algorithms.  Since head -n N lists the top N lines
instead of the Nth line, let's run our output through sed to normalize
it and compare it against a fixed value, which will make sure we get
exactly what we're expecting.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson
2020-07-29 23:14:20 +00:00
committed by Junio C Hamano
parent e74b606d47
commit c5aecfc866
7 changed files with 147 additions and 31 deletions
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83
bundle.c
View File

@ -12,7 +12,16 @@
#include "refs.h"
#include "argv-array.h"
static const char bundle_signature[] = "# v2 git bundle\n";
static const char v2_bundle_signature[] = "# v2 git bundle\n";
static const char v3_bundle_signature[] = "# v3 git bundle\n";
static struct {
int version;
const char *signature;
} bundle_sigs[] = {
{ 2, v2_bundle_signature },
{ 3, v3_bundle_signature },
};
static void add_to_ref_list(const struct object_id *oid, const char *name,
struct ref_list *list)
@ -23,15 +32,30 @@ static void add_to_ref_list(const struct object_id *oid, const char *name,
list->nr++;
}
static const struct git_hash_algo *detect_hash_algo(struct strbuf *buf)
static int parse_capability(struct bundle_header *header, const char *capability)
{
size_t len = strcspn(buf->buf, " \n");
int algo;
const char *arg;
if (skip_prefix(capability, "object-format=", &arg)) {
int algo = hash_algo_by_name(arg);
if (algo == GIT_HASH_UNKNOWN)
return error(_("unrecognized bundle hash algorithm: %s"), arg);
header->hash_algo = &hash_algos[algo];
return 0;
}
return error(_("unknown capability '%s'"), capability);
}
algo = hash_algo_by_length(len / 2);
if (algo == GIT_HASH_UNKNOWN)
return NULL;
return &hash_algos[algo];
static int parse_bundle_signature(struct bundle_header *header, const char *line)
{
int i;
for (i = 0; i < ARRAY_SIZE(bundle_sigs); i++) {
if (!strcmp(line, bundle_sigs[i].signature)) {
header->version = bundle_sigs[i].version;
return 0;
}
}
return -1;
}
static int parse_bundle_header(int fd, struct bundle_header *header,
@ -42,14 +66,16 @@ static int parse_bundle_header(int fd, struct bundle_header *header,
/* The bundle header begins with the signature */
if (strbuf_getwholeline_fd(&buf, fd, '\n') ||
strcmp(buf.buf, bundle_signature)) {
parse_bundle_signature(header, buf.buf)) {
if (report_path)
error(_("'%s' does not look like a v2 bundle file"),
error(_("'%s' does not look like a v2 or v3 bundle file"),
report_path);
status = -1;
goto abort;
}
header->hash_algo = the_hash_algo;
/* The bundle header ends with an empty line */
while (!strbuf_getwholeline_fd(&buf, fd, '\n') &&
buf.len && buf.buf[0] != '\n') {
@ -57,19 +83,19 @@ static int parse_bundle_header(int fd, struct bundle_header *header,
int is_prereq = 0;
const char *p;
if (*buf.buf == '-') {
is_prereq = 1;
strbuf_remove(&buf, 0, 1);
}
strbuf_rtrim(&buf);
if (!header->hash_algo) {
header->hash_algo = detect_hash_algo(&buf);
if (!header->hash_algo) {
error(_("unknown hash algorithm length"));
if (header->version == 3 && *buf.buf == '@') {
if (parse_capability(header, buf.buf + 1)) {
status = -1;
break;
}
continue;
}
if (*buf.buf == '-') {
is_prereq = 1;
strbuf_remove(&buf, 0, 1);
}
/*
@ -449,13 +475,14 @@ static int write_bundle_refs(int bundle_fd, struct rev_info *revs)
}
int create_bundle(struct repository *r, const char *path,
int argc, const char **argv, struct argv_array *pack_options)
int argc, const char **argv, struct argv_array *pack_options, int version)
{
struct lock_file lock = LOCK_INIT;
int bundle_fd = -1;
int bundle_to_stdout;
int ref_count = 0;
struct rev_info revs;
int min_version = the_hash_algo == &hash_algos[GIT_HASH_SHA1] ? 2 : 3;
bundle_to_stdout = !strcmp(path, "-");
if (bundle_to_stdout)
@ -464,8 +491,22 @@ int create_bundle(struct repository *r, const char *path,
bundle_fd = hold_lock_file_for_update(&lock, path,
LOCK_DIE_ON_ERROR);
/* write signature */
write_or_die(bundle_fd, bundle_signature, strlen(bundle_signature));
if (version == -1)
version = min_version;
if (version < 2 || version > 3) {
die(_("unsupported bundle version %d"), version);
} else if (version < min_version) {
die(_("cannot write bundle version %d with algorithm %s"), version, the_hash_algo->name);
} else if (version == 2) {
write_or_die(bundle_fd, v2_bundle_signature, strlen(v2_bundle_signature));
} else {
const char *capability = "@object-format=";
write_or_die(bundle_fd, v3_bundle_signature, strlen(v3_bundle_signature));
write_or_die(bundle_fd, capability, strlen(capability));
write_or_die(bundle_fd, the_hash_algo->name, strlen(the_hash_algo->name));
write_or_die(bundle_fd, "\n", 1);
}
/* init revs to list objects for pack-objects later */
save_commit_buffer = 0;