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authorMichael Haggerty <mhagger@alum.mit.edu>2014-10-01 10:28:36 (GMT)
committerJunio C Hamano <gitster@pobox.com>2014-10-01 20:52:06 (GMT)
commit751bacedaa507b7b6d10b2c1f48e019a01a8fa6e (patch)
treec93a688ada9b9139a4aa661273d5867eab6e74aa
parent0c0d6e8601a1cfb8ebbdadb6a25a9f6fadc91359 (diff)
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commit_lock_file_to(): refactor a helper out of commit_lock_file()
commit_locked_index(), when writing to an alternate index file, duplicates (poorly) the code in commit_lock_file(). And anyway, it shouldn't have to know so much about the internal workings of lockfile objects. So extract a new function commit_lock_file_to() that does the work common to the two functions, and call it from both commit_lock_file() and commit_locked_index(). Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--Documentation/technical/api-lockfile.txt34
-rw-r--r--cache.h1
-rw-r--r--lockfile.c40
-rw-r--r--read-cache.c13
4 files changed, 50 insertions, 38 deletions
diff --git a/Documentation/technical/api-lockfile.txt b/Documentation/technical/api-lockfile.txt
index 9805da0..aa7d822 100644
--- a/Documentation/technical/api-lockfile.txt
+++ b/Documentation/technical/api-lockfile.txt
@@ -49,14 +49,14 @@ The caller:
When finished writing, the caller can:
* Close the file descriptor and rename the lockfile to its final
- destination by calling `commit_lock_file`.
+ destination by calling `commit_lock_file` or `commit_lock_file_to`.
* Close the file descriptor and remove the lockfile by calling
`rollback_lock_file`.
* Close the file descriptor without removing or renaming the lockfile
by calling `close_lock_file`, and later call `commit_lock_file`,
- `rollback_lock_file`, or `reopen_lock_file`.
+ `commit_lock_file_to`, `rollback_lock_file`, or `reopen_lock_file`.
Even after the lockfile is committed or rolled back, the `lock_file`
object must not be freed or altered by the caller. However, it may be
@@ -64,20 +64,19 @@ reused; just pass it to another call of `hold_lock_file_for_update` or
`hold_lock_file_for_append`.
If the program exits before you have called one of `commit_lock_file`,
-`rollback_lock_file`, or `close_lock_file`, an `atexit(3)` handler
-will close and remove the lockfile, rolling back any uncommitted
-changes.
+`commit_lock_file_to`, `rollback_lock_file`, or `close_lock_file`, an
+`atexit(3)` handler will close and remove the lockfile, rolling back
+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 later call to
-`commit_lock_file` or `rollback_lock_file` or program exit would
+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)`
and then later open another file descriptor for a completely different
-purpose, then a call to `commit_lock_file` or `rollback_lock_file`
-might close that unrelated file descriptor.
+purpose, then a commit or rollback might close that unrelated file
+descriptor.
Error handling
@@ -100,9 +99,9 @@ unable_to_lock_die::
Emit an appropriate error message and `die()`.
-Similarly, `commit_lock_file` and `close_lock_file` return 0 on
-success. On failure they set `errno` appropriately, do their best to
-roll back the lockfile, and return -1.
+Similarly, `commit_lock_file`, `commit_lock_file_to`, and
+`close_lock_file` return 0 on success. On failure they set `errno`
+appropriately, do their best to roll back the lockfile, and return -1.
Flags
@@ -156,6 +155,12 @@ commit_lock_file::
`commit_lock_file` for a `lock_file` object that is not
currently locked.
+commit_lock_file_to::
+
+ Like `commit_lock_file()`, except that it takes an explicit
+ `path` argument to which the lockfile should be renamed. The
+ `path` must be on the same filesystem as the lock file.
+
rollback_lock_file::
Take a pointer to the `struct lock_file` initialized with an
@@ -172,8 +177,9 @@ close_lock_file::
`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` or `rollback_lock_file` should eventually
- be called if `close_lock_file` succeeds.
+ `commit_lock_file`, `commit_lock_file_to`, or
+ `rollback_lock_file` should eventually be called if
+ `close_lock_file` succeeds.
reopen_lock_file::
diff --git a/cache.h b/cache.h
index f81d95f..414e93c 100644
--- a/cache.h
+++ b/cache.h
@@ -590,6 +590,7 @@ 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 int commit_lock_file_to(struct lock_file *, const char *path);
extern int commit_lock_file(struct lock_file *);
extern int reopen_lock_file(struct lock_file *);
extern void update_index_if_able(struct index_state *, struct lock_file *);
diff --git a/lockfile.c b/lockfile.c
index 56ad7e8..cf7f4d0 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -43,9 +43,9 @@
* 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:
+ * - Unlocked (after commit_lock_file(), commit_lock_file_to(),
+ * 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
@@ -284,23 +284,15 @@ int reopen_lock_file(struct lock_file *lk)
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;
@@ -312,6 +304,26 @@ int commit_lock_file(struct lock_file *lk)
return 0;
}
+int commit_lock_file(struct lock_file *lk)
+{
+ 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;
+}
+
int hold_locked_index(struct lock_file *lk, int die_on_error)
{
return hold_lock_file_for_update(lk, get_index_file(),
diff --git a/read-cache.c b/read-cache.c
index 91bf876..e887e23 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2041,17 +2041,10 @@ void set_alternate_index_output(const char *name)
static int commit_locked_index(struct lock_file *lk)
{
- if (alternate_index_output) {
- if (close_lock_file(lk))
- return -1;
- if (rename(lk->filename.buf, alternate_index_output))
- return -1;
- lk->active = 0;
- strbuf_reset(&lk->filename);
- return 0;
- } else {
+ if (alternate_index_output)
+ return commit_lock_file_to(lk, alternate_index_output);
+ else
return commit_lock_file(lk);
- }
}
static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,