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git/branch.c
Jeff King f932729cc7 memoize common git-path "constant" files 
One of the most common uses of git_path() is to pass a
constant, like git_path("MERGE_MSG"). This has two
drawbacks:

  1. The return value is a static buffer, and the lifetime
     is dependent on other calls to git_path, etc.

  2. There's no compile-time checking of the pathname. This
     is OK for a one-off (after all, we have to spell it
     correctly at least once), but many of these constant
     strings appear throughout the code.

This patch introduces a series of functions to "memoize"
these strings, which are essentially globals for the
lifetime of the program. We compute the value once, take
ownership of the buffer, and return the cached value for
subsequent calls.  cache.h provides a helper macro for
defining these functions as one-liners, and defines a few
common ones for global use.

Using a macro is a little bit gross, but it does nicely
document the purpose of the functions. If we need to touch
them all later (e.g., because we learned how to change the
git_dir variable at runtime, and need to invalidate all of
the stored values), it will be much easier to have the
complete list.

Note that the shared-global functions have separate, manual
declarations. We could do something clever with the macros
(e.g., expand it to a declaration in some places, and a
declaration _and_ a definition in path.c). But there aren't
that many, and it's probably better to stay away from
too-magical macros.

Likewise, if we abandon the C preprocessor in favor of
generating these with a script, we could get much fancier.
E.g., normalizing "FOO/BAR-BAZ" into "git_path_foo_bar_baz".
But the small amount of saved typing is probably not worth
the resulting confusion to readers who want to grep for the
function's definition.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-10 15:37:14 -07:00

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#include "git-compat-util.h"
#include "cache.h"
#include "branch.h"
#include "refs.h"
#include "remote.h"
#include "commit.h"
struct tracking {
struct refspec spec;
char *src;
const char *remote;
int matches;
};
static int find_tracked_branch(struct remote *remote, void *priv)
{
struct tracking *tracking = priv;
if (!remote_find_tracking(remote, &tracking->spec)) {
if (++tracking->matches == 1) {
tracking->src = tracking->spec.src;
tracking->remote = remote->name;
} else {
free(tracking->spec.src);
if (tracking->src) {
free(tracking->src);
tracking->src = NULL;
}
}
tracking->spec.src = NULL;
}
return 0;
}
static int should_setup_rebase(const char *origin)
{
switch (autorebase) {
case AUTOREBASE_NEVER:
return 0;
case AUTOREBASE_LOCAL:
return origin == NULL;
case AUTOREBASE_REMOTE:
return origin != NULL;
case AUTOREBASE_ALWAYS:
return 1;
}
return 0;
}
void install_branch_config(int flag, const char *local, const char *origin, const char *remote)
{
const char *shortname = NULL;
struct strbuf key = STRBUF_INIT;
int rebasing = should_setup_rebase(origin);
if (skip_prefix(remote, "refs/heads/", &shortname)
&& !strcmp(local, shortname)
&& !origin) {
warning(_("Not setting branch %s as its own upstream."),
local);
return;
}
strbuf_addf(&key, "branch.%s.remote", local);
git_config_set(key.buf, origin ? origin : ".");
strbuf_reset(&key);
strbuf_addf(&key, "branch.%s.merge", local);
git_config_set(key.buf, remote);
if (rebasing) {
strbuf_reset(&key);
strbuf_addf(&key, "branch.%s.rebase", local);
git_config_set(key.buf, "true");
}
strbuf_release(&key);
if (flag & BRANCH_CONFIG_VERBOSE) {
if (shortname) {
if (origin)
printf_ln(rebasing ?
_("Branch %s set up to track remote branch %s from %s by rebasing.") :
_("Branch %s set up to track remote branch %s from %s."),
local, shortname, origin);
else
printf_ln(rebasing ?
_("Branch %s set up to track local branch %s by rebasing.") :
_("Branch %s set up to track local branch %s."),
local, shortname);
} else {
if (origin)
printf_ln(rebasing ?
_("Branch %s set up to track remote ref %s by rebasing.") :
_("Branch %s set up to track remote ref %s."),
local, remote);
else
printf_ln(rebasing ?
_("Branch %s set up to track local ref %s by rebasing.") :
_("Branch %s set up to track local ref %s."),
local, remote);
}
}
}
/*
* This is called when new_ref is branched off of orig_ref, and tries
* to infer the settings for branch.<new_ref>.{remote,merge} from the
* config.
*/
static int setup_tracking(const char *new_ref, const char *orig_ref,
enum branch_track track, int quiet)
{
struct tracking tracking;
int config_flags = quiet ? 0 : BRANCH_CONFIG_VERBOSE;
memset(&tracking, 0, sizeof(tracking));
tracking.spec.dst = (char *)orig_ref;
if (for_each_remote(find_tracked_branch, &tracking))
return 1;
if (!tracking.matches)
switch (track) {
case BRANCH_TRACK_ALWAYS:
case BRANCH_TRACK_EXPLICIT:
case BRANCH_TRACK_OVERRIDE:
break;
default:
return 1;
}
if (tracking.matches > 1)
return error(_("Not tracking: ambiguous information for ref %s"),
orig_ref);
install_branch_config(config_flags, new_ref, tracking.remote,
tracking.src ? tracking.src : orig_ref);
free(tracking.src);
return 0;
}
int read_branch_desc(struct strbuf *buf, const char *branch_name)
{
char *v = NULL;
struct strbuf name = STRBUF_INIT;
strbuf_addf(&name, "branch.%s.description", branch_name);
if (git_config_get_string(name.buf, &v)) {
strbuf_release(&name);
return -1;
}
strbuf_addstr(buf, v);
free(v);
strbuf_release(&name);
return 0;
}
int validate_new_branchname(const char *name, struct strbuf *ref,
int force, int attr_only)
{
if (strbuf_check_branch_ref(ref, name))
die(_("'%s' is not a valid branch name."), name);
if (!ref_exists(ref->buf))
return 0;
else if (!force && !attr_only)
die(_("A branch named '%s' already exists."), ref->buf + strlen("refs/heads/"));
if (!attr_only) {
const char *head;
unsigned char sha1[20];
head = resolve_ref_unsafe("HEAD", 0, sha1, NULL);
if (!is_bare_repository() && head && !strcmp(head, ref->buf))
die(_("Cannot force update the current branch."));
}
return 1;
}
static int check_tracking_branch(struct remote *remote, void *cb_data)
{
char *tracking_branch = cb_data;
struct refspec query;
memset(&query, 0, sizeof(struct refspec));
query.dst = tracking_branch;
return !remote_find_tracking(remote, &query);
}
static int validate_remote_tracking_branch(char *ref)
{
return !for_each_remote(check_tracking_branch, ref);
}
static const char upstream_not_branch[] =
N_("Cannot setup tracking information; starting point '%s' is not a branch.");
static const char upstream_missing[] =
N_("the requested upstream branch '%s' does not exist");
static const char upstream_advice[] =
N_("\n"
"If you are planning on basing your work on an upstream\n"
"branch that already exists at the remote, you may need to\n"
"run \"git fetch\" to retrieve it.\n"
"\n"
"If you are planning to push out a new local branch that\n"
"will track its remote counterpart, you may want to use\n"
"\"git push -u\" to set the upstream config as you push.");
void create_branch(const char *head,
const char *name, const char *start_name,
int force, int reflog, int clobber_head,
int quiet, enum branch_track track)
{
struct commit *commit;
unsigned char sha1[20];
char *real_ref, msg[PATH_MAX + 20];
struct strbuf ref = STRBUF_INIT;
int forcing = 0;
int dont_change_ref = 0;
int explicit_tracking = 0;
if (track == BRANCH_TRACK_EXPLICIT || track == BRANCH_TRACK_OVERRIDE)
explicit_tracking = 1;
if (validate_new_branchname(name, &ref, force,
track == BRANCH_TRACK_OVERRIDE ||
clobber_head)) {
if (!force)
dont_change_ref = 1;
else
forcing = 1;
}
real_ref = NULL;
if (get_sha1(start_name, sha1)) {
if (explicit_tracking) {
if (advice_set_upstream_failure) {
error(_(upstream_missing), start_name);
advise(_(upstream_advice));
exit(1);
}
die(_(upstream_missing), start_name);
}
die(_("Not a valid object name: '%s'."), start_name);
}
switch (dwim_ref(start_name, strlen(start_name), sha1, &real_ref)) {
case 0:
/* Not branching from any existing branch */
if (explicit_tracking)
die(_(upstream_not_branch), start_name);
break;
case 1:
/* Unique completion -- good, only if it is a real branch */
if (!starts_with(real_ref, "refs/heads/") &&
validate_remote_tracking_branch(real_ref)) {
if (explicit_tracking)
die(_(upstream_not_branch), start_name);
else
real_ref = NULL;
}
break;
default:
die(_("Ambiguous object name: '%s'."), start_name);
break;
}
if ((commit = lookup_commit_reference(sha1)) == NULL)
die(_("Not a valid branch point: '%s'."), start_name);
hashcpy(sha1, commit->object.sha1);
if (forcing)
snprintf(msg, sizeof msg, "branch: Reset to %s",
start_name);
else if (!dont_change_ref)
snprintf(msg, sizeof msg, "branch: Created from %s",
start_name);
if (reflog)
log_all_ref_updates = 1;
if (!dont_change_ref) {
struct ref_transaction *transaction;
struct strbuf err = STRBUF_INIT;
transaction = ref_transaction_begin(&err);
if (!transaction ||
ref_transaction_update(transaction, ref.buf,
sha1, forcing ? NULL : null_sha1,
0, msg, &err) ||
ref_transaction_commit(transaction, &err))
die("%s", err.buf);
ref_transaction_free(transaction);
strbuf_release(&err);
}
if (real_ref && track)
setup_tracking(ref.buf + 11, real_ref, track, quiet);
strbuf_release(&ref);
free(real_ref);
}
void remove_branch_state(void)
{
unlink(git_path_cherry_pick_head());
unlink(git_path_revert_head());
unlink(git_path_merge_head());
unlink(git_path_merge_rr());
unlink(git_path_merge_msg());
unlink(git_path_merge_mode());
unlink(git_path_squash_msg());
}
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