img: Use errno when checking optional images open fail

There will be no int-fd soon, so one more preparation
to this fact.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-restore.c

@@ -2354,7 +2354,7 @@ static int prepare_rlimits_from_fd(int pid)
 	 */
 	fd = open_image(CR_FD_RLIMIT, O_RSTR | O_OPT, pid);
 	if (fd < 0) {
-		if (fd == -ENOENT) {
+		if (errno == ENOENT) {
 			pr_info("Skip rlimits for %d\n", pid);
 			return 0;
 		}
@@ -2445,7 +2445,7 @@ static int open_signal_image(int type, pid_t pid, unsigned int *nr)
 
 	fd = open_image(type, O_RSTR | O_OPT, pid);
 	if (fd < 0) {
-		if (fd == -ENOENT) /* backward compatibility */
+		if (errno == ENOENT) /* backward compatibility */
 			return 0;
 		else
 			return -1;

file-lock.c

@@ -343,7 +343,7 @@ static int restore_file_locks_legacy(int pid)
 
 	fd = open_image(CR_FD_FILE_LOCKS_PID, O_RSTR | O_OPT, pid);
 	if (fd < 0) {
-		if (fd == -ENOENT)
+		if (errno == ENOENT)
 			return 0;
 		else
 			return -1;

files.c

@@ -598,7 +598,7 @@ int prepare_fd_pid(struct pstree_item *item)
 	if (!fdinfo_per_id) {
 		fdinfo_fd = open_image(CR_FD_FDINFO, O_RSTR | O_OPT, pid);
 		if (fdinfo_fd < 0) {
-			if (fdinfo_fd == -ENOENT)
+			if (errno == ENOENT)
 				return 0;
 			return -1;
 		}
@@ -1088,7 +1088,7 @@ int prepare_fs_pid(struct pstree_item *item)
 
 	ifd = open_image(CR_FD_FS, O_RSTR | O_OPT, pid);
 	if (ifd < 0) {
-		if (ifd == -ENOENT)
+		if (errno == ENOENT)
 			goto ok;
 		else
 			goto out;

irmap.c

@@ -381,7 +381,7 @@ in:
 		return 1;
 	}
 
-	if (*fd == -ENOENT && dir == AT_FDCWD) {
+	if (errno == ENOENT && dir == AT_FDCWD) {
 		pr_info("Searching irmap cache in parent\n");
 		dir = openat(get_service_fd(IMG_FD_OFF), CR_PARENT_LINK, O_RDONLY);
 		if (dir >= 0)

mem.c

@@ -389,7 +389,7 @@ int prepare_mm_pid(struct pstree_item *i)
 
 	fd = open_image(CR_FD_MM, O_RSTR | O_OPT, pid);
 	if (fd < 0) {
-		if (fd == -ENOENT)
+		if (errno == ENOENT)
 			return 0;
 		return -1;
 	}

protobuf.c

@@ -642,7 +642,7 @@ int collect_image(struct collect_image_info *cinfo)
 
 	fd = open_image(cinfo->fd_type, O_RSTR | (optional ? O_OPT : 0));
 	if (fd < 0) {
-		if (optional && fd == -ENOENT)
+		if (optional && errno == ENOENT)
 			return 0;
 		else
 			return -1;