fix backwards posix_spawn file action order

src/process/fdop.h

@@ -3,7 +3,7 @@
 #define FDOP_OPEN 3
 
 struct fdop {
-	struct fdop *next;
+	struct fdop *next, *prev;
 	int cmd, fd, newfd, oflag;
 	mode_t mode;
 	char path[];

src/process/posix_spawn.c

@@ -51,10 +51,11 @@ int __posix_spawnx(pid_t *res, const char *path,
 		__syscall(SYS_setuid, __syscall(SYS_getuid)) ))
 		_exit(127);
 
-	if (fa) {
+	if (fa && fa->__actions) {
 		struct fdop *op;
 		int ret, fd;
-		for (op = fa->__actions; op; op = op->next) {
+		for (op = fa->__actions; op->next; op = op->next);
+		for (; op; op = op->prev) {
 			switch(op->cmd) {
 			case FDOP_CLOSE:
 				ret = __syscall(SYS_close, op->fd);

src/process/posix_spawn_file_actions_addclose.c

@@ -9,7 +9,8 @@ int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *fa, int fd)
 	if (!op) return ENOMEM;
 	op->cmd = FDOP_CLOSE;
 	op->fd = fd;
-	op->next = fa->__actions;
+	if ((op->next = fa->__actions)) op->next->prev = op;
+	op->prev = 0;
 	fa->__actions = op;
 	return 0;
 }

src/process/posix_spawn_file_actions_adddup2.c

@@ -10,7 +10,8 @@ int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t *fa, int fd, int
 	op->cmd = FDOP_DUP2;
 	op->fd = fd;
 	op->newfd = newfd;
-	op->next = fa->__actions;
+	if ((op->next = fa->__actions)) op->next->prev = op;
+	op->prev = 0;
 	fa->__actions = op;
 	return 0;
 }

src/process/posix_spawn_file_actions_addopen.c

@@ -13,7 +13,8 @@ int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *fa, int fd, con
 	op->oflag = flags;
 	op->mode = mode;
 	strcpy(op->path, path);
-	op->next = fa->__actions;
+	if ((op->next = fa->__actions)) op->next->prev = op;
+	op->prev = 0;
 	fa->__actions = op;
 	return 0;
 }