1 files changed, 112 insertions, 0 deletions
diff --git a/lockfile.c b/lockfile.c
new file mode 100644
index 0000000000..9202472498
--- /dev/null
+++ b/lockfile.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2005, Junio C Hamano
+ */
+#include "cache.h"
+
+static struct lock_file *lock_file_list;
+static const char *alternate_index_output;
+
+static void remove_lock_file(void)
+{
+	pid_t me = getpid();
+
+	while (lock_file_list) {
+		if (lock_file_list->owner == me &&
+		    lock_file_list->filename[0])
+			unlink(lock_file_list->filename);
+		lock_file_list = lock_file_list->next;
+	}
+}
+
+static void remove_lock_file_on_signal(int signo)
+{
+	remove_lock_file();
+	signal(SIGINT, SIG_DFL);
+	raise(signo);
+}
+
+static int lock_file(struct lock_file *lk, const char *path)
+{
+	int fd;
+	struct stat st;
+
+	if ((!lstat(path, &st)) && S_ISLNK(st.st_mode)) {
+		ssize_t sz;
+		static char target[PATH_MAX];
+		sz = readlink(path, target, sizeof(target));
+		if (sz < 0)
+			warning("Cannot readlink %s", path);
+		else if (target[0] != '/')
+			warning("Cannot lock target of relative symlink %s", path);
+		else
+			path = target;
+	}
+	sprintf(lk->filename, "%s.lock", path);
+	fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
+	if (0 <= fd) {
+		if (!lock_file_list) {
+			signal(SIGINT, remove_lock_file_on_signal);
+			atexit(remove_lock_file);
+		}
+		lk->owner = getpid();
+		if (!lk->on_list) {
+			lk->next = lock_file_list;
+			lock_file_list = lk;
+			lk->on_list = 1;
+		}
+		if (adjust_shared_perm(lk->filename))
+			return error("cannot fix permission bits on %s",
+				     lk->filename);
+	}
+	else
+		lk->filename[0] = 0;
+	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.lock': %s", path, strerror(errno));
+	return fd;
+}
+
+int commit_lock_file(struct lock_file *lk)
+{
+	char result_file[PATH_MAX];
+	int i;
+	strcpy(result_file, lk->filename);
+	i = strlen(result_file) - 5; /* .lock */
+	result_file[i] = 0;
+	i = rename(lk->filename, result_file);
+	lk->filename[0] = 0;
+	return i;
+}
+
+int hold_locked_index(struct lock_file *lk, int die_on_error)
+{
+	return hold_lock_file_for_update(lk, get_index_file(), die_on_error);
+}
+
+void set_alternate_index_output(const char *name)
+{
+	alternate_index_output = name;
+}
+
+int commit_locked_index(struct lock_file *lk)
+{
+	if (alternate_index_output) {
+		int result = rename(lk->filename, alternate_index_output);
+		lk->filename[0] = 0;
+		return result;
+	}
+	else
+		return commit_lock_file(lk);
+}
+
+void rollback_lock_file(struct lock_file *lk)
+{
+	if (lk->filename[0])
+		unlink(lk->filename);
+	lk->filename[0] = 0;
+}