* Copyright (c) 2005, Junio C Hamano
*/
#include "cache.h"
+#include "lockfile.h"
#include "sigchain.h"
-/*
- * File write-locks as used by Git.
- *
- * For an overview of how to use the lockfile API, please see
- *
- * Documentation/technical/api-lockfile.txt
- *
- * This module keeps track of all locked files in lock_file_list for
- * use at cleanup. This list and the lock_file objects that comprise
- * it must be kept in self-consistent states at all time, because the
- * program can be interrupted any time by a signal, in which case the
- * signal handler will walk through the list attempting to clean up
- * any open lock files.
- *
- * A lockfile is owned by the process that created it. The lock_file
- * object has an "owner" field that records its owner. This field is
- * used to prevent a forked process from closing a lockfile created by
- * its parent.
- *
- * The possible states of a lock_file object are as follows:
- *
- * - Uninitialized. In this state the object's on_list field must be
- * zero but the rest of its contents need not be initialized. As
- * soon as the object is used in any way, it is irrevocably
- * registered in the lock_file_list, and on_list is set.
- *
- * - Locked, lockfile open (after hold_lock_file_for_update(),
- * hold_lock_file_for_append(), or reopen_lock_file()). In this
- * state:
- * - the lockfile exists
- * - active is set
- * - filename holds the filename of the lockfile
- * - fd holds a file descriptor open for writing to the lockfile
- * - owner holds the PID of the process that locked the file
- *
- * - Locked, lockfile closed (after successful close_lock_file()).
- * Same as the previous state, except that the lockfile is closed
- * and fd is -1.
- *
- * - Unlocked (after commit_lock_file(), rollback_lock_file(), a
- * failed attempt to lock, or a failed close_lock_file()). In this
- * state:
- * - active is unset
- * - 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.
- */
-
static struct lock_file *volatile lock_file_list;
-static void remove_lock_file(void)
+static void remove_lock_files(void)
{
pid_t me = getpid();
}
}
-static void remove_lock_file_on_signal(int signo)
+static void remove_lock_files_on_signal(int signo)
{
- remove_lock_file();
+ remove_lock_files();
sigchain_pop(signo);
raise(signo);
}
/*
- * p = absolute or relative path name
+ * path = absolute or relative path name
*
- * Return a pointer into p showing the beginning of the last path name
- * element. If p is empty or the root directory ("/"), just return p.
+ * Remove the last path name element from path (leaving the preceding
+ * "/", if any). If path is empty or the root directory ("/"), set
+ * path to the empty string.
*/
-static char *last_path_elm(char *p)
+static void trim_last_path_component(struct strbuf *path)
{
- /* r starts pointing to null at the end of the string */
- char *r = strchr(p, '\0');
-
- if (r == p)
- return p; /* just return empty string */
-
- r--; /* back up to last non-null character */
+ int i = path->len;
/* back up past trailing slashes, if any */
- while (r > p && *r == '/')
- r--;
+ while (i && path->buf[i - 1] == '/')
+ i--;
/*
- * then go backwards until I hit a slash, or the beginning of
- * the string
+ * then go backwards until a slash, or the beginning of the
+ * string
*/
- while (r > p && *(r-1) != '/')
- r--;
- return r;
+ while (i && path->buf[i - 1] != '/')
+ i--;
+
+ strbuf_setlen(path, i);
}
if (is_absolute_path(link.buf))
/* absolute path simply replaces p */
strbuf_reset(path);
- else {
+ else
/*
* link is a relative path, so replace the
* last element of p with it.
*/
- char *r = last_path_elm(path->buf);
- strbuf_setlen(path, r - path->buf);
- }
+ trim_last_path_component(path);
strbuf_addbuf(path, &link);
}
if (!lock_file_list) {
/* One-time initialization */
- sigchain_push_common(remove_lock_file_on_signal);
- atexit(remove_lock_file);
+ sigchain_push_common(remove_lock_files_on_signal);
+ atexit(remove_lock_files);
}
if (lk->active)
}
strbuf_add(&lk->filename, path, pathlen);
- if (!(flags & LOCK_NODEREF))
+ if (!(flags & LOCK_NO_DEREF))
resolve_symlink(&lk->filename);
strbuf_addstr(&lk->filename, LOCK_SUFFIX);
lk->fd = open(lk->filename.buf, O_RDWR | O_CREAT | O_EXCL, 0666);
orig_fd = open(path, O_RDONLY);
if (orig_fd < 0) {
if (errno != ENOENT) {
+ int save_errno = errno;
+
if (flags & LOCK_DIE_ON_ERROR)
die("cannot open '%s' for copying", path);
rollback_lock_file(lk);
- return error("cannot open '%s' for copying", path);
+ error("cannot open '%s' for copying", path);
+ errno = save_errno;
+ return -1;
}
} else if (copy_fd(orig_fd, fd)) {
+ int save_errno = errno;
+
if (flags & LOCK_DIE_ON_ERROR)
exit(128);
rollback_lock_file(lk);
+ errno = save_errno;
return -1;
}
return fd;
}
+char *get_locked_file_path(struct lock_file *lk)
+{
+ if (!lk->active)
+ die("BUG: get_locked_file_path() called for unlocked object");
+ if (lk->filename.len <= LOCK_SUFFIX_LEN)
+ die("BUG: get_locked_file_path() called for malformed lock object");
+ return xmemdupz(lk->filename.buf, lk->filename.len - LOCK_SUFFIX_LEN);
+}
+
int close_lock_file(struct lock_file *lk)
{
int fd = lk->fd;
return lk->fd;
}
-int commit_lock_file(struct lock_file *lk)
+int commit_lock_file_to(struct lock_file *lk, const char *path)
{
- static struct strbuf result_file = STRBUF_INIT;
- int err;
-
if (!lk->active)
- die("BUG: attempt to commit unlocked object");
+ die("BUG: attempt to commit unlocked object to \"%s\"", path);
if (close_lock_file(lk))
return -1;
- /* remove ".lock": */
- 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) {
+ if (rename(lk->filename.buf, path)) {
int save_errno = errno;
rollback_lock_file(lk);
errno = save_errno;
return 0;
}
-int hold_locked_index(struct lock_file *lk, int die_on_error)
+int commit_lock_file(struct lock_file *lk)
{
- return hold_lock_file_for_update(lk, get_index_file(),
- die_on_error
- ? LOCK_DIE_ON_ERROR
- : 0);
+ static struct strbuf result_file = STRBUF_INIT;
+ int err;
+
+ if (!lk->active)
+ die("BUG: attempt to commit unlocked object");
+
+ if (lk->filename.len <= LOCK_SUFFIX_LEN ||
+ strcmp(lk->filename.buf + lk->filename.len - LOCK_SUFFIX_LEN, LOCK_SUFFIX))
+ die("BUG: lockfile filename corrupt");
+
+ /* remove ".lock": */
+ strbuf_add(&result_file, lk->filename.buf,
+ lk->filename.len - LOCK_SUFFIX_LEN);
+ err = commit_lock_file_to(lk, result_file.buf);
+ strbuf_reset(&result_file);
+ return err;
}
void rollback_lock_file(struct lock_file *lk)
projects / thirdparty / git.git / blobdiff