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-rw-r--r--Documentation/technical/api-lockfile.txt34
-rw-r--r--lockfile.c46
-rw-r--r--lockfile.h4
3 files changed, 68 insertions, 16 deletions
diff --git a/Documentation/technical/api-lockfile.txt b/Documentation/technical/api-lockfile.txt
index d4484d154d..93b5f23e4c 100644
--- a/Documentation/technical/api-lockfile.txt
+++ b/Documentation/technical/api-lockfile.txt
@@ -42,9 +42,13 @@ The caller:
of the final destination (e.g. `$GIT_DIR/index`) to
`hold_lock_file_for_update` or `hold_lock_file_for_append`.
-* Writes new content for the destination file by writing to the file
- descriptor returned by those functions (also available via
- `lock->fd`).
+* Writes new content for the destination file by either:
+
+ * writing to the file descriptor returned by the `hold_lock_file_*`
+ functions (also available via `lock->fd`).
+
+ * calling `fdopen_lock_file` to get a `FILE` pointer for the open
+ file and writing to the file using stdio.
When finished writing, the caller can:
@@ -70,10 +74,10 @@ any uncommitted changes.
If you need to close the file descriptor you obtained from a
`hold_lock_file_*` function yourself, do so by calling
-`close_lock_file`. You should never call `close(2)` yourself!
-Otherwise the `struct lock_file` structure would still think that the
-file descriptor needs to be closed, and a commit or rollback would
-result in duplicate calls to `close(2)`. Worse yet, if you `close(2)`
+`close_lock_file`. You should never call `close(2)` or `fclose(3)`
+yourself! Otherwise the `struct lock_file` structure would still think
+that the file descriptor needs to be closed, and a commit or rollback
+would result in duplicate calls to `close(2)`. Worse yet, if you close
and then later open another file descriptor for a completely different
purpose, then a commit or rollback might close that unrelated file
descriptor.
@@ -143,6 +147,13 @@ hold_lock_file_for_append::
the existing contents of the file (if any) to the lockfile and
position its write pointer at the end of the file.
+fdopen_lock_file::
+
+ Associate a stdio stream with the lockfile. Return NULL
+ (*without* rolling back the lockfile) on error. The stream is
+ closed automatically when `close_lock_file` is called or when
+ the file is committed or rolled back.
+
get_locked_file_path::
Return the path of the file that is locked by the specified
@@ -179,10 +190,11 @@ close_lock_file::
Take a pointer to the `struct lock_file` initialized with an
earlier call to `hold_lock_file_for_update` or
- `hold_lock_file_for_append`, and close the file descriptor.
- Return 0 upon success. On failure to `close(2)`, return a
- negative value and roll back the lock file. Usually
- `commit_lock_file`, `commit_lock_file_to`, or
+ `hold_lock_file_for_append`. Close the file descriptor (and
+ the file pointer if it has been opened using
+ `fdopen_lock_file`). Return 0 upon success. On failure to
+ `close(2)`, return a negative value and roll back the lock
+ file. Usually `commit_lock_file`, `commit_lock_file_to`, or
`rollback_lock_file` should eventually be called if
`close_lock_file` succeeds.
diff --git a/lockfile.c b/lockfile.c
index d27e61cafc..e0460275e1 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -7,20 +7,29 @@
static struct lock_file *volatile lock_file_list;
-static void remove_lock_files(void)
+static void remove_lock_files(int skip_fclose)
{
pid_t me = getpid();
while (lock_file_list) {
- if (lock_file_list->owner == me)
+ if (lock_file_list->owner == me) {
+ /* fclose() is not safe to call in a signal handler */
+ if (skip_fclose)
+ lock_file_list->fp = NULL;
rollback_lock_file(lock_file_list);
+ }
lock_file_list = lock_file_list->next;
}
}
+static void remove_lock_files_on_exit(void)
+{
+ remove_lock_files(0);
+}
+
static void remove_lock_files_on_signal(int signo)
{
- remove_lock_files();
+ remove_lock_files(1);
sigchain_pop(signo);
raise(signo);
}
@@ -97,7 +106,7 @@ static int lock_file(struct lock_file *lk, const char *path, int flags)
if (!lock_file_list) {
/* One-time initialization */
sigchain_push_common(remove_lock_files_on_signal);
- atexit(remove_lock_files);
+ atexit(remove_lock_files_on_exit);
}
if (lk->active)
@@ -106,6 +115,7 @@ static int lock_file(struct lock_file *lk, const char *path, int flags)
if (!lk->on_list) {
/* Initialize *lk and add it to lock_file_list: */
lk->fd = -1;
+ lk->fp = NULL;
lk->active = 0;
lk->owner = 0;
strbuf_init(&lk->filename, pathlen + LOCK_SUFFIX_LEN);
@@ -214,6 +224,17 @@ int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags)
return fd;
}
+FILE *fdopen_lock_file(struct lock_file *lk, const char *mode)
+{
+ if (!lk->active)
+ die("BUG: fdopen_lock_file() called for unlocked object");
+ if (lk->fp)
+ die("BUG: fdopen_lock_file() called twice for file '%s'", lk->filename.buf);
+
+ lk->fp = fdopen(lk->fd, mode);
+ return lk->fp;
+}
+
char *get_locked_file_path(struct lock_file *lk)
{
if (!lk->active)
@@ -226,17 +247,32 @@ char *get_locked_file_path(struct lock_file *lk)
int close_lock_file(struct lock_file *lk)
{
int fd = lk->fd;
+ FILE *fp = lk->fp;
+ int err;
if (fd < 0)
return 0;
lk->fd = -1;
- if (close(fd)) {
+ if (fp) {
+ lk->fp = NULL;
+
+ /*
+ * Note: no short-circuiting here; we want to fclose()
+ * in any case!
+ */
+ err = ferror(fp) | fclose(fp);
+ } else {
+ err = close(fd);
+ }
+
+ if (err) {
int save_errno = errno;
rollback_lock_file(lk);
errno = save_errno;
return -1;
}
+
return 0;
}
diff --git a/lockfile.h b/lockfile.h
index 9059e8958f..dc066d1783 100644
--- a/lockfile.h
+++ b/lockfile.h
@@ -34,6 +34,8 @@
* - active is set
* - filename holds the filename of the lockfile
* - fd holds a file descriptor open for writing to the lockfile
+ * - fp holds a pointer to an open FILE object if and only if
+ * fdopen_lock_file() has been called on the object
* - owner holds the PID of the process that locked the file
*
* - Locked, lockfile closed (after successful close_lock_file()).
@@ -56,6 +58,7 @@ struct lock_file {
struct lock_file *volatile next;
volatile sig_atomic_t active;
volatile int fd;
+ FILE *volatile fp;
volatile pid_t owner;
char on_list;
struct strbuf filename;
@@ -74,6 +77,7 @@ extern void unable_to_lock_message(const char *path, int err,
extern NORETURN void unable_to_lock_die(const char *path, int err);
extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);
extern int hold_lock_file_for_append(struct lock_file *, const char *path, int);
+extern FILE *fdopen_lock_file(struct lock_file *, const char *mode);
extern char *get_locked_file_path(struct lock_file *);
extern int commit_lock_file_to(struct lock_file *, const char *path);
extern int commit_lock_file(struct lock_file *);