From 6fc6ca1a323bc0b6b9e9cdc8fa72221ae18fe206 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 5 Nov 2017 17:26:48 -0500 Subject: adjust posix_spawn dup2 action behavior to match future requirements the resolution to Austin Group issue #411 defined new semantics for the posix_spawn dup2 file action in the (previously useless) case where src and dest fd are equal. future issues will require the dup2 file action to remove the close-on-exec flag. without this change, passing fds to a child with posix_spawn while avoiding fd-leak races in a multithreaded parent required a complex dance with temporary fds. based on patch by Petr Skocik. changes were made to preserve the 80-column formatting of the function and to remove code that became unreachable as a result of the new functionality. --- src/process/posix_spawn.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'src') diff --git a/src/process/posix_spawn.c b/src/process/posix_spawn.c index 0849c71f..93fb1555 100644 --- a/src/process/posix_spawn.c +++ b/src/process/posix_spawn.c @@ -27,12 +27,7 @@ static int __sys_dup2(int old, int new) #ifdef SYS_dup2 return __syscall(SYS_dup2, old, new); #else - if (old==new) { - int r = __syscall(SYS_fcntl, old, F_GETFD); - return r<0 ? r : old; - } else { - return __syscall(SYS_dup3, old, new, 0); - } + return __syscall(SYS_dup3, old, new, 0); #endif } @@ -109,8 +104,17 @@ static int child(void *args_vp) __syscall(SYS_close, op->fd); break; case FDOP_DUP2: - if ((ret=__sys_dup2(op->srcfd, op->fd))<0) - goto fail; + fd = op->srcfd; + if (fd != op->fd) { + if ((ret=__sys_dup2(fd, op->fd))<0) + goto fail; + } else { + ret = __syscall(SYS_fcntl, fd, F_GETFD); + ret = __syscall(SYS_fcntl, fd, F_SETFD, + ret & ~FD_CLOEXEC); + if (ret<0) + goto fail; + } break; case FDOP_OPEN: fd = __sys_open(op->path, op->oflag, op->mode); -- cgit v1.2.1