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lockfile: change lock_file::filename into a strbuf

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For now, we still make sure to allocate at least PATH_MAX characters
for the strbuf because resolve_symlink() doesn't know how to expand
the space for its return value.  (That will be fixed in a moment.)

Another alternative would be to just use a strbuf as scratch space in
lock_file() but then store a pointer to the naked string in struct
lock_file.  But lock_file objects are often reused.  By reusing the
same strbuf, we can avoid having to reallocate the string most times
when a lock_file object is reused.

Helped-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michael Haggerty
2014-10-01 12:28:32 +02:00
committed by Junio C Hamano
parent 3e88e8fc08
commit cf6950d3bf
8 changed files with 47 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
lockfile.c
View File

@ -47,9 +47,9 @@
* failed attempt to lock, or a failed close_lock_file()). In this
* state:
* - active is unset
* - filename[0] == '\0' (usually, though there are transitory states
* in which this condition doesn't hold). Client code should *not*
* rely on this fact!
* - filename is empty (usually, though there are transitory
* states in which this condition doesn't hold). Client code should
* *not* rely on the filename being empty in this state.
* - fd is -1
* - the object is left registered in the lock_file_list, and
* on_list is set.
@ -170,13 +170,6 @@ static char *resolve_symlink(char *p, size_t s)
/* Make sure errno contains a meaningful value on error */
static int lock_file(struct lock_file *lk, const char *path, int flags)
{
/*
* subtract LOCK_SUFFIX_LEN from size to make sure there's
* room for adding ".lock" for the lock file name:
*/
static const size_t max_path_len = sizeof(lk->filename) -
LOCK_SUFFIX_LEN;
if (!lock_file_list) {
/* One-time initialization */
sigchain_push_common(remove_lock_file_on_signal);
@ -191,30 +184,32 @@ static int lock_file(struct lock_file *lk, const char *path, int flags)
lk->fd = -1;
lk->active = 0;
lk->owner = 0;
lk->filename[0] = 0;
strbuf_init(&lk->filename, PATH_MAX);
lk->next = lock_file_list;
lock_file_list = lk;
lk->on_list = 1;
} else if (lk->filename.len) {
/* This shouldn't happen, but better safe than sorry. */
die("BUG: lock_file(\"%s\") called with improperly-reset lock_file object",
path);
}
if (strlen(path) >= max_path_len) {
errno = ENAMETOOLONG;
return -1;
strbuf_addstr(&lk->filename, path);
if (!(flags & LOCK_NODEREF)) {
resolve_symlink(lk->filename.buf, lk->filename.alloc);
strbuf_setlen(&lk->filename, strlen(lk->filename.buf));
}
strcpy(lk->filename, path);
if (!(flags & LOCK_NODEREF))
resolve_symlink(lk->filename, max_path_len);
strcat(lk->filename, LOCK_SUFFIX);
lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
strbuf_addstr(&lk->filename, LOCK_SUFFIX);
lk->fd = open(lk->filename.buf, O_RDWR | O_CREAT | O_EXCL, 0666);
if (lk->fd < 0) {
lk->filename[0] = 0;
strbuf_reset(&lk->filename);
return -1;
}
lk->owner = getpid();
lk->active = 1;
if (adjust_shared_perm(lk->filename)) {
if (adjust_shared_perm(lk->filename.buf)) {
int save_errno = errno;
error("cannot fix permission bits on %s", lk->filename);
error("cannot fix permission bits on %s", lk->filename.buf);
rollback_lock_file(lk);
errno = save_errno;
return -1;
@ -313,7 +308,7 @@ int reopen_lock_file(struct lock_file *lk)
die(_("BUG: reopen a lockfile that is still open"));
if (!lk->active)
die(_("BUG: reopen a lockfile that has been committed"));
lk->fd = open(lk->filename, O_WRONLY);
lk->fd = open(lk->filename.buf, O_WRONLY);
return lk->fd;
}
@ -329,9 +324,9 @@ int commit_lock_file(struct lock_file *lk)
return -1;
/* remove ".lock": */
strbuf_add(&result_file, lk->filename,
strlen(lk->filename) - LOCK_SUFFIX_LEN);
err = rename(lk->filename, result_file.buf);
strbuf_add(&result_file, lk->filename.buf,
lk->filename.len - LOCK_SUFFIX_LEN);
err = rename(lk->filename.buf, result_file.buf);
strbuf_reset(&result_file);
if (err) {
int save_errno = errno;
@ -341,7 +336,7 @@ int commit_lock_file(struct lock_file *lk)
}
lk->active = 0;
lk->filename[0] = 0;
strbuf_reset(&lk->filename);
return 0;
}
@ -359,8 +354,8 @@ void rollback_lock_file(struct lock_file *lk)
return;
if (!close_lock_file(lk)) {
unlink_or_warn(lk->filename);
unlink_or_warn(lk->filename.buf);
lk->active = 0;
lk->filename[0] = 0;
strbuf_reset(&lk->filename);
}
}