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fast-export, fast-import: add support for signed-commits

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fast-export has a --signed-tags= option that controls how to handle tag
signatures.  However, there is no equivalent for commit signatures; it
just silently strips the signature out of the commit (analogously to
--signed-tags=strip).

While signatures are generally problematic for fast-export/fast-import
(because hashes are likely to change), if they're going to support tag
signatures, there's no reason to not also support commit signatures.

So, implement a --signed-commits= option that mirrors the --signed-tags=
option.

On the fast-export side, try to be as much like signed-tags as possible,
in both implementation and in user-interface.  This will change the
default behavior to '--signed-commits=abort' from what is now
'--signed-commits=strip'.  In order to provide an escape hatch for users
of third-party tools that call fast-export and do not yet know of the
--signed-commits= option, add an environment variable
'FAST_EXPORT_SIGNED_COMMITS_NOABORT=1' that changes the default to
'--signed-commits=warn-strip'.

Signed-off-by: Luke Shumaker <lukeshu@datawire.io>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Luke Shumaker
2025-03-10 16:57:46 +01:00
committed by Junio C Hamano
parent dda9bff3c5
commit d9cb0e6ff8
5 changed files with 253 additions and 20 deletions
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123
builtin/fast-export.c
View File

@@ -35,8 +35,11 @@ static const char *fast_export_usage[] = {
NULL
};
enum sign_mode { SIGN_ABORT, SIGN_VERBATIM, SIGN_STRIP, SIGN_WARN_VERBATIM, SIGN_WARN_STRIP };
static int progress;
static enum signed_tag_mode { SIGNED_TAG_ABORT, VERBATIM, WARN_VERBATIM, WARN_STRIP, STRIP } signed_tag_mode = SIGNED_TAG_ABORT;
static enum sign_mode signed_tag_mode = SIGN_ABORT;
static enum sign_mode signed_commit_mode = SIGN_ABORT;
static enum tag_of_filtered_mode { TAG_FILTERING_ABORT, DROP, REWRITE } tag_of_filtered_mode = TAG_FILTERING_ABORT;
static enum reencode_mode { REENCODE_ABORT, REENCODE_YES, REENCODE_NO } reencode_mode = REENCODE_ABORT;
static int fake_missing_tagger;
@@ -53,23 +56,24 @@ static int anonymize;
static struct hashmap anonymized_seeds;
static struct revision_sources revision_sources;
static int parse_opt_signed_tag_mode(const struct option *opt,
static int parse_opt_sign_mode(const struct option *opt,
const char *arg, int unset)
{
enum signed_tag_mode *val = opt->value;
if (unset || !strcmp(arg, "abort"))
*val = SIGNED_TAG_ABORT;
enum sign_mode *val = opt->value;
if (unset)
return 0;
else if (!strcmp(arg, "abort"))
*val = SIGN_ABORT;
else if (!strcmp(arg, "verbatim") || !strcmp(arg, "ignore"))
*val = VERBATIM;
*val = SIGN_VERBATIM;
else if (!strcmp(arg, "warn-verbatim") || !strcmp(arg, "warn"))
*val = WARN_VERBATIM;
*val = SIGN_WARN_VERBATIM;
else if (!strcmp(arg, "warn-strip"))
*val = WARN_STRIP;
*val = SIGN_WARN_STRIP;
else if (!strcmp(arg, "strip"))
*val = STRIP;
*val = SIGN_STRIP;
else
return error("Unknown signed-tags mode: %s", arg);
return error("Unknown %s mode: %s", opt->long_name, arg);
return 0;
}
@@ -611,6 +615,43 @@ static void anonymize_ident_line(const char **beg, const char **end)
*end = out->buf + out->len;
}
/*
* find_commit_multiline_header is similar to find_commit_header,
* except that it handles multi-line headers, rather than simply
* returning the first line of the header.
*
* The returned string has had the ' ' line continuation markers
* removed, and points to allocated memory that must be free()d (not
* to memory within 'msg').
*
* If the header is found, then *end is set to point at the '\n' in
* msg that immediately follows the header value.
*/
static const char *find_commit_multiline_header(const char *msg,
const char *key,
const char **end)
{
struct strbuf val = STRBUF_INIT;
const char *bol, *eol;
size_t len;
bol = find_commit_header(msg, key, &len);
if (!bol)
return NULL;
eol = bol + len;
strbuf_add(&val, bol, len);
while (eol[0] == '\n' && eol[1] == ' ') {
bol = eol + 2;
eol = strchrnul(bol, '\n');
strbuf_addch(&val, '\n');
strbuf_add(&val, bol, eol - bol);
}
*end = eol;
return strbuf_detach(&val, NULL);
}
static void handle_commit(struct commit *commit, struct rev_info *rev,
struct string_list *paths_of_changed_objects)
{
@@ -619,6 +660,7 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
const char *author, *author_end, *committer, *committer_end;
const char *encoding = NULL;
size_t encoding_len;
const char *signature_alg = NULL, *signature = NULL;
const char *message;
char *reencoded = NULL;
struct commit_list *p;
@@ -645,17 +687,25 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
commit_buffer_cursor = committer_end = strchrnul(committer, '\n');
/*
* find_commit_header() gets a `+ 1` because
* commit_buffer_cursor points at the trailing "\n" at the end
* of the previous line, but find_commit_header() wants a
* find_commit_header() and find_commit_multiline_header() get
* a `+ 1` because commit_buffer_cursor points at the trailing
* "\n" at the end of the previous line, but they want a
* pointer to the beginning of the next line.
*/
if (*commit_buffer_cursor == '\n') {
encoding = find_commit_header(commit_buffer_cursor + 1, "encoding", &encoding_len);
if (encoding)
commit_buffer_cursor = encoding + encoding_len;
}
if (*commit_buffer_cursor == '\n') {
if ((signature = find_commit_multiline_header(commit_buffer_cursor + 1, "gpgsig", &commit_buffer_cursor)))
signature_alg = "sha1";
else if ((signature = find_commit_multiline_header(commit_buffer_cursor + 1, "gpgsig-sha256", &commit_buffer_cursor)))
signature_alg = "sha256";
}
message = strstr(commit_buffer_cursor, "\n\n");
if (message)
message += 2;
@@ -719,6 +769,31 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
printf("%.*s\n%.*s\n",
(int)(author_end - author), author,
(int)(committer_end - committer), committer);
if (signature) {
switch (signed_commit_mode) {
case SIGN_ABORT:
die("encountered signed commit %s; use "
"--signed-commits=<mode> to handle it",
oid_to_hex(&commit->object.oid));
case SIGN_WARN_VERBATIM:
warning("exporting signed commit %s",
oid_to_hex(&commit->object.oid));
/* fallthru */
case SIGN_VERBATIM:
printf("gpgsig %s\ndata %u\n%s",
signature_alg,
(unsigned)strlen(signature),
signature);
break;
case SIGN_WARN_STRIP:
warning("stripping signature from commit %s",
oid_to_hex(&commit->object.oid));
/* fallthru */
case SIGN_STRIP:
break;
}
free((char *)signature);
}
if (!reencoded && encoding)
printf("encoding %.*s\n", (int)encoding_len, encoding);
printf("data %u\n%s",
@@ -834,21 +909,21 @@ static void handle_tag(const char *name, struct tag *tag)
"\n-----BEGIN PGP SIGNATURE-----\n");
if (signature)
switch (signed_tag_mode) {
case SIGNED_TAG_ABORT:
case SIGN_ABORT:
die("encountered signed tag %s; use "
"--signed-tags=<mode> to handle it",
oid_to_hex(&tag->object.oid));
case WARN_VERBATIM:
case SIGN_WARN_VERBATIM:
warning("exporting signed tag %s",
oid_to_hex(&tag->object.oid));
/* fallthru */
case VERBATIM:
case SIGN_VERBATIM:
break;
case WARN_STRIP:
case SIGN_WARN_STRIP:
warning("stripping signature from tag %s",
oid_to_hex(&tag->object.oid));
/* fallthru */
case STRIP:
case SIGN_STRIP:
message_size = signature + 1 - message;
break;
}
@@ -1194,6 +1269,7 @@ int cmd_fast_export(int argc,
const char *prefix,
struct repository *repo UNUSED)
{
const char *env_signed_commits_noabort;
struct rev_info revs;
struct commit *commit;
char *export_filename = NULL,
@@ -1207,7 +1283,10 @@ int cmd_fast_export(int argc,
N_("show progress after <n> objects")),
OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, N_("mode"),
N_("select handling of signed tags"),
parse_opt_signed_tag_mode),
parse_opt_sign_mode),
OPT_CALLBACK(0, "signed-commits", &signed_commit_mode, N_("mode"),
N_("select handling of signed commits"),
parse_opt_sign_mode),
OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, N_("mode"),
N_("select handling of tags that tag filtered objects"),
parse_opt_tag_of_filtered_mode),
@@ -1248,6 +1327,10 @@ int cmd_fast_export(int argc,
if (argc == 1)
usage_with_options (fast_export_usage, options);
env_signed_commits_noabort = getenv("FAST_EXPORT_SIGNED_COMMITS_NOABORT");
if (env_signed_commits_noabort && *env_signed_commits_noabort)
signed_commit_mode = SIGN_WARN_STRIP;
/* we handle encodings */
git_config(git_default_config, NULL);