X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=lockfile.c;h=4023797b00fe21ecbabe3407ef8a12fca0690607;hb=4a09bc966449ca0a7e9a5bb70f91b47debdd7c4e;hp=920247249823b8f69524b845d6bdb0cb0b1b802b;hpb=11bb2d4fa9ebc7481828c25752d8c23233b24c76;p=git.git

diff --git a/lockfile.c b/lockfile.c
index 920247249..4023797b0 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -12,8 +12,11 @@ static void remove_lock_file(void)
 
 	while (lock_file_list) {
 		if (lock_file_list->owner == me &&
-		    lock_file_list->filename[0])
+		    lock_file_list->filename[0]) {
+			if (lock_file_list->fd >= 0)
+				close(lock_file_list->fd);
 			unlink(lock_file_list->filename);
+		}
 		lock_file_list = lock_file_list->next;
 	}
 }
@@ -21,31 +24,120 @@ static void remove_lock_file(void)
 static void remove_lock_file_on_signal(int signo)
 {
 	remove_lock_file();
-	signal(SIGINT, SIG_DFL);
+	signal(signo, SIG_DFL);
 	raise(signo);
 }
 
-static int lock_file(struct lock_file *lk, const char *path)
+/*
+ * p = 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.
+ */
+static char *last_path_elm(char *p)
+{
+	/* 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 */
+
+	/* back up past trailing slashes, if any */
+	while (r > p && *r == '/')
+		r--;
+
+	/*
+	 * then go backwards until I hit a slash, or the beginning of
+	 * the string
+	 */
+	while (r > p && *(r-1) != '/')
+		r--;
+	return r;
+}
+
+
+/* We allow "recursive" symbolic links. Only within reason, though */
+#define MAXDEPTH 5
+
+/*
+ * p = path that may be a symlink
+ * s = full size of p
+ *
+ * If p is a symlink, attempt to overwrite p with a path to the real
+ * file or directory (which may or may not exist), following a chain of
+ * symlinks if necessary.  Otherwise, leave p unmodified.
+ *
+ * This is a best-effort routine.  If an error occurs, p will either be
+ * left unmodified or will name a different symlink in a symlink chain
+ * that started with p's initial contents.
+ *
+ * Always returns p.
+ */
+
+static char *resolve_symlink(char *p, size_t s)
 {
-	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;
+	int depth = MAXDEPTH;
+
+	while (depth--) {
+		char link[PATH_MAX];
+		int link_len = readlink(p, link, sizeof(link));
+		if (link_len < 0) {
+			/* not a symlink anymore */
+			return p;
+		}
+		else if (link_len < sizeof(link))
+			/* readlink() never null-terminates */
+			link[link_len] = '\0';
+		else {
+			warning("%s: symlink too long", p);
+			return p;
+		}
+
+		if (is_absolute_path(link)) {
+			/* absolute path simply replaces p */
+			if (link_len < s)
+				strcpy(p, link);
+			else {
+				warning("%s: symlink too long", p);
+				return p;
+			}
+		} else {
+			/*
+			 * link is a relative path, so I must replace the
+			 * last element of p with it.
+			 */
+			char *r = (char*)last_path_elm(p);
+			if (r - p + link_len < s)
+				strcpy(r, link);
+			else {
+				warning("%s: symlink too long", p);
+				return p;
+			}
+		}
 	}
-	sprintf(lk->filename, "%s.lock", path);
-	fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
-	if (0 <= fd) {
+	return p;
+}
+
+
+static int lock_file(struct lock_file *lk, const char *path)
+{
+	if (strlen(path) >= sizeof(lk->filename)) return -1;
+	strcpy(lk->filename, path);
+	/*
+	 * subtract 5 from size to make sure there's room for adding
+	 * ".lock" for the lock file name
+	 */
+	resolve_symlink(lk->filename, sizeof(lk->filename)-5);
+	strcat(lk->filename, ".lock");
+	lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
+	if (0 <= lk->fd) {
 		if (!lock_file_list) {
 			signal(SIGINT, remove_lock_file_on_signal);
+			signal(SIGHUP, remove_lock_file_on_signal);
+			signal(SIGTERM, remove_lock_file_on_signal);
+			signal(SIGQUIT, remove_lock_file_on_signal);
 			atexit(remove_lock_file);
 		}
 		lk->owner = getpid();
@@ -60,7 +152,7 @@ static int lock_file(struct lock_file *lk, const char *path)
 	}
 	else
 		lk->filename[0] = 0;
-	return fd;
+	return lk->fd;
 }
 
 int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error)
@@ -71,16 +163,54 @@ int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on
 	return fd;
 }
 
+int hold_lock_file_for_append(struct lock_file *lk, const char *path, int die_on_error)
+{
+	int fd, orig_fd;
+
+	fd = lock_file(lk, path);
+	if (fd < 0) {
+		if (die_on_error)
+			die("unable to create '%s.lock': %s", path, strerror(errno));
+		return fd;
+	}
+
+	orig_fd = open(path, O_RDONLY);
+	if (orig_fd < 0) {
+		if (errno != ENOENT) {
+			if (die_on_error)
+				die("cannot open '%s' for copying", path);
+			close(fd);
+			return error("cannot open '%s' for copying", path);
+		}
+	} else if (copy_fd(orig_fd, fd)) {
+		if (die_on_error)
+			exit(128);
+		close(fd);
+		return -1;
+	}
+	return fd;
+}
+
+int close_lock_file(struct lock_file *lk)
+{
+	int fd = lk->fd;
+	lk->fd = -1;
+	return close(fd);
+}
+
 int commit_lock_file(struct lock_file *lk)
 {
 	char result_file[PATH_MAX];
-	int i;
+	size_t i;
+	if (lk->fd >= 0 && close_lock_file(lk))
+		return -1;
 	strcpy(result_file, lk->filename);
 	i = strlen(result_file) - 5; /* .lock */
 	result_file[i] = 0;
-	i = rename(lk->filename, result_file);
+	if (rename(lk->filename, result_file))
+		return -1;
 	lk->filename[0] = 0;
-	return i;
+	return 0;
 }
 
 int hold_locked_index(struct lock_file *lk, int die_on_error)
@@ -96,9 +226,12 @@ void set_alternate_index_output(const char *name)
 int commit_locked_index(struct lock_file *lk)
 {
 	if (alternate_index_output) {
-		int result = rename(lk->filename, alternate_index_output);
+		if (lk->fd >= 0 && close_lock_file(lk))
+			return -1;
+		if (rename(lk->filename, alternate_index_output))
+			return -1;
 		lk->filename[0] = 0;
-		return result;
+		return 0;
 	}
 	else
 		return commit_lock_file(lk);
@@ -106,7 +239,10 @@ int commit_locked_index(struct lock_file *lk)
 
 void rollback_lock_file(struct lock_file *lk)
 {
-	if (lk->filename[0])
+	if (lk->filename[0]) {
+		if (lk->fd >= 0)
+			close(lk->fd);
 		unlink(lk->filename);
+	}
 	lk->filename[0] = 0;
 }