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git/builtin/tag.c

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/*
* Builtin "git tag"
*
* Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>,
* Carlos Rica <jasampler@gmail.com>
* Based on git-tag.sh and mktag.c by Linus Torvalds.
*/
#include "cache.h"
#include "builtin.h"
#include "refs.h"
#include "tag.h"
#include "run-command.h"
#include "parse-options.h"
#include "diff.h"
#include "revision.h"
static const char * const git_tag_usage[] = {
"git tag [-a|-s|-u <key-id>] [-f] [-m <msg>|-F <file>] <tagname> [<head>]",
"git tag -d <tagname>...",
"git tag -l [-n[<num>]] [<pattern>...]",
"git tag -v <tagname>...",
NULL
};
static char signingkey[1000];
struct tag_filter {
const char **patterns;
int lines;
struct commit_list *with_commit;
};
static int match_pattern(const char **patterns, const char *ref)
{
/* no pattern means match everything */
if (!*patterns)
return 1;
for (; *patterns; patterns++)
if (!fnmatch(*patterns, ref, 0))
return 1;
return 0;
}
static int in_commit_list(const struct commit_list *want, struct commit *c)
{
for (; want; want = want->next)
if (!hashcmp(want->item->object.sha1, c->object.sha1))
return 1;
return 0;
}
static int contains_recurse(struct commit *candidate,
const struct commit_list *want)
{
struct commit_list *p;
/* was it previously marked as containing a want commit? */
if (candidate->object.flags & TMP_MARK)
return 1;
/* or marked as not possibly containing a want commit? */
if (candidate->object.flags & UNINTERESTING)
return 0;
/* or are we it? */
if (in_commit_list(want, candidate))
return 1;
if (parse_commit(candidate) < 0)
return 0;
/* Otherwise recurse and mark ourselves for future traversals. */
for (p = candidate->parents; p; p = p->next) {
if (contains_recurse(p->item, want)) {
candidate->object.flags |= TMP_MARK;
return 1;
}
}
candidate->object.flags |= UNINTERESTING;
return 0;
}
static int contains(struct commit *candidate, const struct commit_list *want)
{
return contains_recurse(candidate, want);
}
static int show_reference(const char *refname, const unsigned char *sha1,
int flag, void *cb_data)
{
struct tag_filter *filter = cb_data;
if (match_pattern(filter->patterns, refname)) {
int i;
unsigned long size;
enum object_type type;
char *buf, *sp, *eol;
size_t len;
if (filter->with_commit) {
struct commit *commit;
commit = lookup_commit_reference_gently(sha1, 1);
if (!commit)
return 0;
if (!contains(commit, filter->with_commit))
return 0;
}
if (!filter->lines) {
printf("%s\n", refname);
return 0;
}
printf("%-15s ", refname);
buf = read_sha1_file(sha1, &type, &size);
if (!buf || !size)
return 0;
/* skip header */
sp = strstr(buf, "\n\n");
if (!sp) {
free(buf);
return 0;
}
/* only take up to "lines" lines, and strip the signature */
size = parse_signature(buf, size);
for (i = 0, sp += 2;
i < filter->lines && sp < buf + size;
i++) {
if (i)
printf("\n ");
eol = memchr(sp, '\n', size - (sp - buf));
len = eol ? eol - sp : size - (sp - buf);
fwrite(sp, len, 1, stdout);
if (!eol)
break;
sp = eol + 1;
}
putchar('\n');
free(buf);
}
return 0;
}
static int list_tags(const char **patterns, int lines,
struct commit_list *with_commit)
{
struct tag_filter filter;
filter.patterns = patterns;
filter.lines = lines;
filter.with_commit = with_commit;
for_each_tag_ref(show_reference, (void *) &filter);
return 0;
}
typedef int (*each_tag_name_fn)(const char *name, const char *ref,
const unsigned char *sha1);
static int for_each_tag_name(const char **argv, each_tag_name_fn fn)
{
const char **p;
char ref[PATH_MAX];
int had_error = 0;
unsigned char sha1[20];
for (p = argv; *p; p++) {
if (snprintf(ref, sizeof(ref), "refs/tags/%s", *p)
>= sizeof(ref)) {
error(_("tag name too long: %.*s..."), 50, *p);
had_error = 1;
continue;
}
if (!resolve_ref(ref, sha1, 1, NULL)) {
error(_("tag '%s' not found."), *p);
had_error = 1;
continue;
}
if (fn(*p, ref, sha1))
had_error = 1;
}
return had_error;
}
static int delete_tag(const char *name, const char *ref,
const unsigned char *sha1)
{
if (delete_ref(ref, sha1, 0))
return 1;
printf(_("Deleted tag '%s' (was %s)\n"), name, find_unique_abbrev(sha1, DEFAULT_ABBREV));
return 0;
}
static int verify_tag(const char *name, const char *ref,
const unsigned char *sha1)
{
const char *argv_verify_tag[] = {"verify-tag",
"-v", "SHA1_HEX", NULL};
argv_verify_tag[2] = sha1_to_hex(sha1);
if (run_command_v_opt(argv_verify_tag, RUN_GIT_CMD))
return error(_("could not verify the tag '%s'"), name);
return 0;
}
static int do_sign(struct strbuf *buffer)
{
struct child_process gpg;
const char *args[4];
char *bracket;
int len;
int i, j;
if (!*signingkey) {
Re-fix "builtin-commit: fix --signoff" An earlier fix to the said commit was incomplete; it mixed up the meaning of the flag parameter passed to the internal fmt_ident() function, so this corrects it. git_author_info() and git_committer_info() can be told to issue a warning when no usable user information is found, and optionally can be told to error out. Operations that actually use the information to record a new commit or a tag will still error out, but the caller to leave reflog record will just silently use bogus user information. Not warning on misconfigured user information while writing a reflog entry is somewhat debatable, but it is probably nicer to the users to silently let it pass, because the only information you are losing is who checked out the branch. * git_author_info() and git_committer_info() used to take 1 (positive int) to error out with a warning on misconfiguration; this is now signalled with a symbolic constant IDENT_ERROR_ON_NO_NAME. * These functions used to take -1 (negative int) to warn but continue; this is now signalled with a symbolic constant IDENT_WARN_ON_NO_NAME. * fmt_ident() function implements the above error reporting behaviour common to git_author_info() and git_committer_info(). A symbolic constant IDENT_NO_DATE can be or'ed in to the flag parameter to make it return only the "Name <email@address.xz>". * fmt_name() is a thin wrapper around fmt_ident() that always passes IDENT_ERROR_ON_NO_NAME and IDENT_NO_DATE. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-12-09 02:32:08 +01:00
if (strlcpy(signingkey, git_committer_info(IDENT_ERROR_ON_NO_NAME),
sizeof(signingkey)) > sizeof(signingkey) - 1)
return error(_("committer info too long."));
bracket = strchr(signingkey, '>');
if (bracket)
bracket[1] = '\0';
}
git-tag -s must fail if gpg cannot sign the tag. Most of this patch code and message was written by Shawn O. Pearce. I made some tests to know what the problem was, and then I changed the code related with the SIGPIPE signal. If the user has misconfigured `user.signingkey` in their .git/config or just doesn't have any secret keys on their keyring and they ask for a signed tag with `git tag -s` we better make sure the resulting tag was actually signed by gpg. Prior versions of builtin git-tag allowed this failure to slip by without error as they were not checking the return value of the finish_command() so they did not notice when gpg exited with an error exit status. They also did not fail if gpg produced an empty output or if read_in_full received an error from the read system call while trying to read the pipe back from gpg. Finally, we did not actually honor any return value from the do_sign function as it returns ssize_t but was being stored into an unsigned long. This caused the compiler to optimize out the die condition, allowing git-tag to continue along and create the tag object. However, when gpg gets a wrong username, it exits before any read was done and then the writing process receives SIGPIPE and program is terminated. By ignoring this signal, anyway, the function write_or_die gets EPIPE from write_in_full and exits returning 0 to the system without a message. Here we better call to write_in_full directly so we can fail printing a message and return safely to the caller. With these issues fixed `git-tag -s` will now fail to create the tag and will report a non-zero exit status to its caller, thereby allowing automated helper scripts to detect (and recover from) failure if gpg is not working properly. Proposed-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Carlos Rica <jasampler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 02:39:29 +02:00
/* When the username signingkey is bad, program could be terminated
* because gpg exits without reading and then write gets SIGPIPE. */
signal(SIGPIPE, SIG_IGN);
memset(&gpg, 0, sizeof(gpg));
gpg.argv = args;
gpg.in = -1;
gpg.out = -1;
args[0] = "gpg";
args[1] = "-bsau";
args[2] = signingkey;
args[3] = NULL;
if (start_command(&gpg))
return error(_("could not run gpg."));
if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
git-tag -s must fail if gpg cannot sign the tag. Most of this patch code and message was written by Shawn O. Pearce. I made some tests to know what the problem was, and then I changed the code related with the SIGPIPE signal. If the user has misconfigured `user.signingkey` in their .git/config or just doesn't have any secret keys on their keyring and they ask for a signed tag with `git tag -s` we better make sure the resulting tag was actually signed by gpg. Prior versions of builtin git-tag allowed this failure to slip by without error as they were not checking the return value of the finish_command() so they did not notice when gpg exited with an error exit status. They also did not fail if gpg produced an empty output or if read_in_full received an error from the read system call while trying to read the pipe back from gpg. Finally, we did not actually honor any return value from the do_sign function as it returns ssize_t but was being stored into an unsigned long. This caused the compiler to optimize out the die condition, allowing git-tag to continue along and create the tag object. However, when gpg gets a wrong username, it exits before any read was done and then the writing process receives SIGPIPE and program is terminated. By ignoring this signal, anyway, the function write_or_die gets EPIPE from write_in_full and exits returning 0 to the system without a message. Here we better call to write_in_full directly so we can fail printing a message and return safely to the caller. With these issues fixed `git-tag -s` will now fail to create the tag and will report a non-zero exit status to its caller, thereby allowing automated helper scripts to detect (and recover from) failure if gpg is not working properly. Proposed-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Carlos Rica <jasampler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 02:39:29 +02:00
close(gpg.in);
close(gpg.out);
git-tag -s must fail if gpg cannot sign the tag. Most of this patch code and message was written by Shawn O. Pearce. I made some tests to know what the problem was, and then I changed the code related with the SIGPIPE signal. If the user has misconfigured `user.signingkey` in their .git/config or just doesn't have any secret keys on their keyring and they ask for a signed tag with `git tag -s` we better make sure the resulting tag was actually signed by gpg. Prior versions of builtin git-tag allowed this failure to slip by without error as they were not checking the return value of the finish_command() so they did not notice when gpg exited with an error exit status. They also did not fail if gpg produced an empty output or if read_in_full received an error from the read system call while trying to read the pipe back from gpg. Finally, we did not actually honor any return value from the do_sign function as it returns ssize_t but was being stored into an unsigned long. This caused the compiler to optimize out the die condition, allowing git-tag to continue along and create the tag object. However, when gpg gets a wrong username, it exits before any read was done and then the writing process receives SIGPIPE and program is terminated. By ignoring this signal, anyway, the function write_or_die gets EPIPE from write_in_full and exits returning 0 to the system without a message. Here we better call to write_in_full directly so we can fail printing a message and return safely to the caller. With these issues fixed `git-tag -s` will now fail to create the tag and will report a non-zero exit status to its caller, thereby allowing automated helper scripts to detect (and recover from) failure if gpg is not working properly. Proposed-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Carlos Rica <jasampler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 02:39:29 +02:00
finish_command(&gpg);
return error(_("gpg did not accept the tag data"));
git-tag -s must fail if gpg cannot sign the tag. Most of this patch code and message was written by Shawn O. Pearce. I made some tests to know what the problem was, and then I changed the code related with the SIGPIPE signal. If the user has misconfigured `user.signingkey` in their .git/config or just doesn't have any secret keys on their keyring and they ask for a signed tag with `git tag -s` we better make sure the resulting tag was actually signed by gpg. Prior versions of builtin git-tag allowed this failure to slip by without error as they were not checking the return value of the finish_command() so they did not notice when gpg exited with an error exit status. They also did not fail if gpg produced an empty output or if read_in_full received an error from the read system call while trying to read the pipe back from gpg. Finally, we did not actually honor any return value from the do_sign function as it returns ssize_t but was being stored into an unsigned long. This caused the compiler to optimize out the die condition, allowing git-tag to continue along and create the tag object. However, when gpg gets a wrong username, it exits before any read was done and then the writing process receives SIGPIPE and program is terminated. By ignoring this signal, anyway, the function write_or_die gets EPIPE from write_in_full and exits returning 0 to the system without a message. Here we better call to write_in_full directly so we can fail printing a message and return safely to the caller. With these issues fixed `git-tag -s` will now fail to create the tag and will report a non-zero exit status to its caller, thereby allowing automated helper scripts to detect (and recover from) failure if gpg is not working properly. Proposed-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Carlos Rica <jasampler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 02:39:29 +02:00
}
close(gpg.in);
len = strbuf_read(buffer, gpg.out, 1024);
close(gpg.out);
git-tag -s must fail if gpg cannot sign the tag. Most of this patch code and message was written by Shawn O. Pearce. I made some tests to know what the problem was, and then I changed the code related with the SIGPIPE signal. If the user has misconfigured `user.signingkey` in their .git/config or just doesn't have any secret keys on their keyring and they ask for a signed tag with `git tag -s` we better make sure the resulting tag was actually signed by gpg. Prior versions of builtin git-tag allowed this failure to slip by without error as they were not checking the return value of the finish_command() so they did not notice when gpg exited with an error exit status. They also did not fail if gpg produced an empty output or if read_in_full received an error from the read system call while trying to read the pipe back from gpg. Finally, we did not actually honor any return value from the do_sign function as it returns ssize_t but was being stored into an unsigned long. This caused the compiler to optimize out the die condition, allowing git-tag to continue along and create the tag object. However, when gpg gets a wrong username, it exits before any read was done and then the writing process receives SIGPIPE and program is terminated. By ignoring this signal, anyway, the function write_or_die gets EPIPE from write_in_full and exits returning 0 to the system without a message. Here we better call to write_in_full directly so we can fail printing a message and return safely to the caller. With these issues fixed `git-tag -s` will now fail to create the tag and will report a non-zero exit status to its caller, thereby allowing automated helper scripts to detect (and recover from) failure if gpg is not working properly. Proposed-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Carlos Rica <jasampler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-09 02:39:29 +02:00
if (finish_command(&gpg) || !len || len < 0)
return error(_("gpg failed to sign the tag"));
/* Strip CR from the line endings, in case we are on Windows. */
for (i = j = 0; i < buffer->len; i++)
if (buffer->buf[i] != '\r') {
if (i != j)
buffer->buf[j] = buffer->buf[i];
j++;
}
strbuf_setlen(buffer, j);
return 0;
}
static const char tag_template[] =
N_("\n"
"#\n"
"# Write a tag message\n"
"#\n");
static void set_signingkey(const char *value)
{
if (strlcpy(signingkey, value, sizeof(signingkey)) >= sizeof(signingkey))
die(_("signing key value too long (%.10s...)"), value);
}
static int git_tag_config(const char *var, const char *value, void *cb)
{
if (!strcmp(var, "user.signingkey")) {
if (!value)
return config_error_nonbool(var);
set_signingkey(value);
return 0;
}
return git_default_config(var, value, cb);
}
static void write_tag_body(int fd, const unsigned char *sha1)
{
unsigned long size;
enum object_type type;
char *buf, *sp;
buf = read_sha1_file(sha1, &type, &size);
if (!buf)
return;
/* skip header */
sp = strstr(buf, "\n\n");
if (!sp || !size || type != OBJ_TAG) {
free(buf);
return;
}
sp += 2; /* skip the 2 LFs */
write_or_die(fd, sp, parse_signature(sp, buf + size - sp));
free(buf);
}
static int build_tag_object(struct strbuf *buf, int sign, unsigned char *result)
{
if (sign && do_sign(buf) < 0)
return error(_("unable to sign the tag"));
if (write_sha1_file(buf->buf, buf->len, tag_type, result) < 0)
return error(_("unable to write tag file"));
return 0;
}
static void create_tag(const unsigned char *object, const char *tag,
struct strbuf *buf, int message, int sign,
unsigned char *prev, unsigned char *result)
{
enum object_type type;
char header_buf[1024];
int header_len;
char *path = NULL;
type = sha1_object_info(object, NULL);
if (type <= OBJ_NONE)
die(_("bad object type."));
header_len = snprintf(header_buf, sizeof(header_buf),
"object %s\n"
"type %s\n"
"tag %s\n"
"tagger %s\n\n",
sha1_to_hex(object),
typename(type),
tag,
Re-fix "builtin-commit: fix --signoff" An earlier fix to the said commit was incomplete; it mixed up the meaning of the flag parameter passed to the internal fmt_ident() function, so this corrects it. git_author_info() and git_committer_info() can be told to issue a warning when no usable user information is found, and optionally can be told to error out. Operations that actually use the information to record a new commit or a tag will still error out, but the caller to leave reflog record will just silently use bogus user information. Not warning on misconfigured user information while writing a reflog entry is somewhat debatable, but it is probably nicer to the users to silently let it pass, because the only information you are losing is who checked out the branch. * git_author_info() and git_committer_info() used to take 1 (positive int) to error out with a warning on misconfiguration; this is now signalled with a symbolic constant IDENT_ERROR_ON_NO_NAME. * These functions used to take -1 (negative int) to warn but continue; this is now signalled with a symbolic constant IDENT_WARN_ON_NO_NAME. * fmt_ident() function implements the above error reporting behaviour common to git_author_info() and git_committer_info(). A symbolic constant IDENT_NO_DATE can be or'ed in to the flag parameter to make it return only the "Name <email@address.xz>". * fmt_name() is a thin wrapper around fmt_ident() that always passes IDENT_ERROR_ON_NO_NAME and IDENT_NO_DATE. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-12-09 02:32:08 +01:00
git_committer_info(IDENT_ERROR_ON_NO_NAME));
if (header_len > sizeof(header_buf) - 1)
die(_("tag header too big."));
if (!message) {
int fd;
/* write the template message before editing: */
path = git_pathdup("TAG_EDITMSG");
fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
if (fd < 0)
die_errno(_("could not create file '%s'"), path);
if (!is_null_sha1(prev))
write_tag_body(fd, prev);
else
write_or_die(fd, _(tag_template), strlen(_(tag_template)));
close(fd);
if (launch_editor(path, buf, NULL)) {
fprintf(stderr,
_("Please supply the message using either -m or -F option.\n"));
exit(1);
}
}
stripspace(buf, 1);
if (!message && !buf->len)
die(_("no tag message?"));
strbuf_insert(buf, 0, header_buf, header_len);
if (build_tag_object(buf, sign, result) < 0) {
if (path)
fprintf(stderr, _("The tag message has been left in %s\n"),
path);
exit(128);
}
if (path) {
unlink_or_warn(path);
free(path);
}
}
struct msg_arg {
int given;
struct strbuf buf;
};
static int parse_msg_arg(const struct option *opt, const char *arg, int unset)
{
struct msg_arg *msg = opt->value;
if (!arg)
return -1;
if (msg->buf.len)
strbuf_addstr(&(msg->buf), "\n\n");
strbuf_addstr(&(msg->buf), arg);
msg->given = 1;
return 0;
}
static int strbuf_check_tag_ref(struct strbuf *sb, const char *name)
{
if (name[0] == '-')
return CHECK_REF_FORMAT_ERROR;
strbuf_reset(sb);
strbuf_addf(sb, "refs/tags/%s", name);
return check_ref_format(sb->buf);
}
int cmd_tag(int argc, const char **argv, const char *prefix)
{
struct strbuf buf = STRBUF_INIT;
struct strbuf ref = STRBUF_INIT;
unsigned char object[20], prev[20];
const char *object_ref, *tag;
struct ref_lock *lock;
int annotate = 0, sign = 0, force = 0, lines = -1,
list = 0, delete = 0, verify = 0;
const char *msgfile = NULL, *keyid = NULL;
struct msg_arg msg = { 0, STRBUF_INIT };
struct commit_list *with_commit = NULL;
struct option options[] = {
OPT_BOOLEAN('l', NULL, &list, "list tag names"),
{ OPTION_INTEGER, 'n', NULL, &lines, "n",
"print <n> lines of each tag message",
PARSE_OPT_OPTARG, NULL, 1 },
OPT_BOOLEAN('d', NULL, &delete, "delete tags"),
OPT_BOOLEAN('v', NULL, &verify, "verify tags"),
OPT_GROUP("Tag creation options"),
OPT_BOOLEAN('a', NULL, &annotate,
"annotated tag, needs a message"),
OPT_CALLBACK('m', NULL, &msg, "message",
"tag message", parse_msg_arg),
OPT_FILENAME('F', NULL, &msgfile, "read message from file"),
OPT_BOOLEAN('s', NULL, &sign, "annotated and GPG-signed tag"),
OPT_STRING('u', NULL, &keyid, "key-id",
"use another key to sign the tag"),
OPT__FORCE(&force, "replace the tag if exists"),
OPT_GROUP("Tag listing options"),
{
OPTION_CALLBACK, 0, "contains", &with_commit, "commit",
"print only tags that contain the commit",
PARSE_OPT_LASTARG_DEFAULT,
parse_opt_with_commit, (intptr_t)"HEAD",
},
OPT_END()
};
git_config(git_tag_config, NULL);
argc = parse_options(argc, argv, prefix, options, git_tag_usage, 0);
if (keyid) {
sign = 1;
set_signingkey(keyid);
}
if (sign)
annotate = 1;
if (argc == 0 && !(delete || verify))
list = 1;
if ((annotate || msg.given || msgfile || force) &&
(list || delete || verify))
usage_with_options(git_tag_usage, options);
if (list + delete + verify > 1)
usage_with_options(git_tag_usage, options);
if (list)
return list_tags(argv, lines == -1 ? 0 : lines,
with_commit);
if (lines != -1)
die(_("-n option is only allowed with -l."));
if (with_commit)
die(_("--contains option is only allowed with -l."));
if (delete)
return for_each_tag_name(argv, delete_tag);
if (verify)
return for_each_tag_name(argv, verify_tag);
if (msg.given || msgfile) {
if (msg.given && msgfile)
die(_("only one -F or -m option is allowed."));
annotate = 1;
if (msg.given)
strbuf_addbuf(&buf, &(msg.buf));
else {
if (!strcmp(msgfile, "-")) {
if (strbuf_read(&buf, 0, 1024) < 0)
die_errno(_("cannot read '%s'"), msgfile);
} else {
if (strbuf_read_file(&buf, msgfile, 1024) < 0)
die_errno(_("could not open or read '%s'"),
msgfile);
}
}
}
tag = argv[0];
object_ref = argc == 2 ? argv[1] : "HEAD";
if (argc > 2)
die(_("too many params"));
if (get_sha1(object_ref, object))
die(_("Failed to resolve '%s' as a valid ref."), object_ref);
if (strbuf_check_tag_ref(&ref, tag))
die(_("'%s' is not a valid tag name."), tag);
if (!resolve_ref(ref.buf, prev, 1, NULL))
hashclr(prev);
else if (!force)
die(_("tag '%s' already exists"), tag);
if (annotate)
create_tag(object, tag, &buf, msg.given || msgfile,
sign, prev, object);
lock = lock_any_ref_for_update(ref.buf, prev, 0);
if (!lock)
die(_("%s: cannot lock the ref"), ref.buf);
if (write_ref_sha1(lock, object, NULL) < 0)
die(_("%s: cannot update the ref"), ref.buf);
if (force && hashcmp(prev, object))
printf(_("Updated tag '%s' (was %s)\n"), tag, find_unique_abbrev(prev, DEFAULT_ABBREV));
strbuf_release(&buf);
strbuf_release(&ref);
return 0;
}