1 files changed, 36 insertions, 19 deletions

diff --git a/lockfile.c b/lockfile.c
index 4023797b00..3dbb2d1ff9 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -2,6 +2,7 @@
  * Copyright (c) 2005, Junio C Hamano
  */
 #include "cache.h"
+#include "sigchain.h"
 
 static struct lock_file *lock_file_list;
 static const char *alternate_index_output;
@@ -24,7 +25,7 @@ static void remove_lock_file(void)
 static void remove_lock_file_on_signal(int signo)
 {
 	remove_lock_file();
-	signal(signo, SIG_DFL);
+	sigchain_pop(signo);
 	raise(signo);
 }
 
@@ -121,23 +122,22 @@ static char *resolve_symlink(char *p, size_t s)
 }
 
 
-static int lock_file(struct lock_file *lk, const char *path)
+static int lock_file(struct lock_file *lk, const char *path, int flags)
 {
-	if (strlen(path) >= sizeof(lk->filename)) return -1;
+	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);
+	if (!(flags & LOCK_NODEREF))
+		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);
+			sigchain_push_common(remove_lock_file_on_signal);
 			atexit(remove_lock_file);
 		}
 		lk->owner = getpid();
@@ -155,35 +155,49 @@ static int lock_file(struct lock_file *lk, const char *path)
 	return lk->fd;
 }
 
-int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error)
+
+NORETURN void unable_to_lock_index_die(const char *path, int err)
+{
+	if (err == EEXIST) {
+		die("Unable to create '%s.lock': %s.\n\n"
+		    "If no other git process is currently running, this probably means a\n"
+		    "git process crashed in this repository earlier. Make sure no other git\n"
+		    "process is running and remove the file manually to continue.",
+		    path, strerror(err));
+	} else {
+		die("Unable to create '%s.lock': %s", path, strerror(err));
+	}
+}
+
+int hold_lock_file_for_update(struct lock_file *lk, const char *path, int flags)
 {
-	int fd = lock_file(lk, path);
-	if (fd < 0 && die_on_error)
-		die("unable to create '%s.lock': %s", path, strerror(errno));
+	int fd = lock_file(lk, path, flags);
+	if (fd < 0 && (flags & LOCK_DIE_ON_ERROR))
+		unable_to_lock_index_die(path, errno);
 	return fd;
 }
 
-int hold_lock_file_for_append(struct lock_file *lk, const char *path, int die_on_error)
+int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags)
 {
 	int fd, orig_fd;
 
-	fd = lock_file(lk, path);
+	fd = lock_file(lk, path, flags);
 	if (fd < 0) {
-		if (die_on_error)
-			die("unable to create '%s.lock': %s", path, strerror(errno));
+		if (flags & LOCK_DIE_ON_ERROR)
+			unable_to_lock_index_die(path, errno);
 		return fd;
 	}
 
 	orig_fd = open(path, O_RDONLY);
 	if (orig_fd < 0) {
 		if (errno != ENOENT) {
-			if (die_on_error)
+			if (flags & LOCK_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)
+		if (flags & LOCK_DIE_ON_ERROR)
 			exit(128);
 		close(fd);
 		return -1;
@@ -215,7 +229,10 @@ int commit_lock_file(struct lock_file *lk)
 
 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);
+	return hold_lock_file_for_update(lk, get_index_file(),
+					 die_on_error
+					 ? LOCK_DIE_ON_ERROR
+					 : 0);
 }
 
 void set_alternate_index_output(const char *name)