From 44eb4d8b9b7b3b539bcd4e311e9d7c8e2acf8d80 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 18 Oct 2012 15:58:23 -0400 Subject: overhaul system() and popen() to use vfork; fix various related bugs since we target systems without overcommit, special care should be taken that system() and popen(), like posix_spawn(), do not fail in processes whose commit charges are too high to allow ordinary forking. this in turn requires special precautions to ensure that the parent process's signal handlers do not end up running in the shared-memory child, where they could corrupt the state of the parent process. popen has also been updated to use pipe2, so it does not have a fd-leak race in multi-threaded programs. since pipe2 is missing on older kernels, (non-atomic) emulation has been added. some silly bugs in the old code should be gone too. --- src/unistd/pipe2.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) (limited to 'src/unistd') diff --git a/src/unistd/pipe2.c b/src/unistd/pipe2.c index 83282bb9..04e0c128 100644 --- a/src/unistd/pipe2.c +++ b/src/unistd/pipe2.c @@ -1,8 +1,22 @@ -#define _GNU_SOURCE #include +#include +#include #include "syscall.h" -int pipe2(int fd[2], int flg) +int pipe2(int fd[2], int flag) { - return syscall(SYS_pipe2, fd, flg); + if (!flag) return syscall(SYS_pipe, fd); + int ret = __syscall(SYS_pipe2, fd, flag); + if (ret != -ENOSYS) return __syscall_ret(ret); + ret = syscall(SYS_pipe, fd); + if (ret) return __syscall_ret(ret); + if (flag & O_CLOEXEC) { + fcntl(fd[0], F_SETFD, FD_CLOEXEC); + fcntl(fd[1], F_SETFD, FD_CLOEXEC); + } + if (flag & O_NONBLOCK) { + fcntl(fd[0], F_SETFL, fcntl(fd[0], F_GETFL) | O_NONBLOCK); + fcntl(fd[1], F_SETFL, fcntl(fd[1], F_GETFL) | O_NONBLOCK); + } + return 0; } -- cgit v1.2.1