Better error message when we are unable to lock the index file

Most of the callers except the one in refs.c use the function to
update the index file.  Among the index writers, everybody
except write-tree dies if they cannot open it for writing.

This gives the function an extra argument, to tell it to die
when it cannot create a new file as the lockfile.

The only caller that does not have to die is write-tree, because
updating the index for the cache-tree part is optional and not
being able to do so does not affect the correctness.  I think we
do not have to be so careful and make the failure into die() the
same way as other callers, but that would be a different patch.

Signed-off-by: Junio C Hamano <junkio@cox.net>

11 files changed, 20 insertions, 32 deletions

diff --git a/builtin-add.c b/builtin-add.c
index 096b611b5..0cb9c8120 100644
--- a/builtin-add.c
+++ b/builtin-add.c
@@ -93,9 +93,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
-	if (newfd < 0)
-		die("unable to create new index file");
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
 
 	if (read_cache() < 0)
 		die("index file corrupt");
diff --git a/builtin-apply.c b/builtin-apply.c
index be2c7152c..9cf477c70 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -2234,12 +2234,9 @@ static int apply_patch(int fd, const char *filename,
 		apply = 0;
 
 	write_index = check_index && apply;
-	if (write_index && newfd < 0) {
+	if (write_index && newfd < 0)
 		newfd = hold_lock_file_for_update(&lock_file,
-						  get_index_file());
-		if (newfd < 0)
-			die("unable to create new index file");
-	}
+						  get_index_file(), 1);
 	if (check_index) {
 		if (read_cache() < 0)
 			die("unable to read index file");
diff --git a/builtin-mv.c b/builtin-mv.c
index ce8187c1e..a731f8d9c 100644
--- a/builtin-mv.c
+++ b/builtin-mv.c
@@ -72,10 +72,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
-	if (newfd < 0)
-		die("unable to create new index file");
-
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
 	if (read_cache() < 0)
 		die("index file corrupt");
 
diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index b30160a5b..71a7026df 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -884,9 +884,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
-	if (newfd < 0)
-		die("unable to create new index file");
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
 
 	git_config(git_default_config);
 
diff --git a/builtin-rm.c b/builtin-rm.c
index 8af3d7eb4..593d86744 100644
--- a/builtin-rm.c
+++ b/builtin-rm.c
@@ -52,9 +52,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
-	if (newfd < 0)
-		die("unable to create new index file");
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
 
 	if (read_cache() < 0)
 		die("index file corrupt");
diff --git a/builtin-update-index.c b/builtin-update-index.c
index 24dca47d8..d2556f376 100644
--- a/builtin-update-index.c
+++ b/builtin-update-index.c
@@ -491,9 +491,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	/* We can't free this memory, it becomes part of a linked list parsed atexit() */
 	lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_lock_file_for_update(lock_file, get_index_file());
-	if (newfd < 0)
-		die("unable to create new cachefile");
+	newfd = hold_lock_file_for_update(lock_file, get_index_file(), 1);
 
 	entries = read_cache();
 	if (entries < 0)
diff --git a/builtin-write-tree.c b/builtin-write-tree.c
index 6b62d7dc8..ca06149f1 100644
--- a/builtin-write-tree.c
+++ b/builtin-write-tree.c
@@ -18,7 +18,7 @@ int write_tree(unsigned char *sha1, int missing_ok, const char *prefix)
 	/* We can't free this memory, it becomes part of a linked list parsed atexit() */
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_lock_file_for_update(lock_file, get_index_file());
+	newfd = hold_lock_file_for_update(lock_file, get_index_file(), 0);
 
 	entries = read_cache();
 	if (entries < 0)
diff --git a/cache.h b/cache.h
index b8c21e07b..b2ab2088e 100644
--- a/cache.h
+++ b/cache.h
@@ -175,7 +175,7 @@ struct lock_file {
 	struct lock_file *next;
 	char filename[PATH_MAX];
 };
-extern int hold_lock_file_for_update(struct lock_file *, const char *path);
+extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);
 extern int commit_lock_file(struct lock_file *);
 extern void rollback_lock_file(struct lock_file *);
 
diff --git a/checkout-index.c b/checkout-index.c
index 61152f34b..dfb1c4441 100644
--- a/checkout-index.c
+++ b/checkout-index.c
@@ -206,7 +206,7 @@ int main(int argc, char **argv)
 			state.refresh_cache = 1;
 			if (newfd < 0)
 				newfd = hold_lock_file_for_update
-					(&lock_file, get_index_file());
+					(&lock_file, get_index_file(), 1);
 			if (newfd < 0)
 				die("cannot open index.lock file.");
 			continue;
diff --git a/lockfile.c b/lockfile.c
index 2346e0e9e..2a2fea3cb 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -22,7 +22,7 @@ static void remove_lock_file_on_signal(int signo)
 	raise(signo);
 }
 
-int hold_lock_file_for_update(struct lock_file *lk, const char *path)
+static int lock_file(struct lock_file *lk, const char *path)
 {
 	int fd;
 	sprintf(lk->filename, "%s.lock", path);
@@ -41,6 +41,14 @@ int hold_lock_file_for_update(struct lock_file *lk, const char *path)
 	return fd;
 }
 
+int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error)
+{
+	int fd = lock_file(lk, path);
+	if (fd < 0 && die_on_error)
+		die("unable to create '%s': %s", path, strerror(errno));
+	return fd;
+}
+
 int commit_lock_file(struct lock_file *lk)
 {
 	char result_file[PATH_MAX];
diff --git a/refs.c b/refs.c
index 28a939460..86ef91661 100644
--- a/refs.c
+++ b/refs.c
@@ -319,13 +319,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *path,
 
 	if (safe_create_leading_directories(lock->ref_file))
 		die("unable to create directory for %s", lock->ref_file);
-	lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file);
-	if (lock->lock_fd < 0) {
-		error("Couldn't open lock file %s: %s",
-		      lock->lk->filename, strerror(errno));
-		unlock_ref(lock);
-		return NULL;
-	}
+	lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
 
 	return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 }