diff options
Diffstat (limited to 'libio/iopopen.c')
| -rw-r--r-- | libio/iopopen.c | 80 |
1 files changed, 19 insertions, 61 deletions
diff --git a/libio/iopopen.c b/libio/iopopen.c index 08e29b44b0..95a12c90b5 100644 --- a/libio/iopopen.c +++ b/libio/iopopen.c @@ -140,29 +140,17 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode) if (_IO_file_is_open (fp)) return NULL; -#ifdef O_CLOEXEC -# ifndef __ASSUME_PIPE2 - if (__have_pipe2 >= 0) -# endif - { - int r = __pipe2 (pipe_fds, O_CLOEXEC); -# ifndef __ASSUME_PIPE2 - if (__have_pipe2 == 0) - __have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1; - - if (__have_pipe2 > 0) -# endif - if (r < 0) - return NULL; - } -#endif -#ifndef __ASSUME_PIPE2 -# ifdef O_CLOEXEC - if (__have_pipe2 < 0) -# endif - if (__pipe (pipe_fds) < 0) - return NULL; -#endif + /* Atomically set the O_CLOEXEC flag for the pipe end used by the + child process (to avoid leaking the file descriptor in case of a + concurrent fork). This is later reverted in the child process. + When popen returns, the parent pipe end can be O_CLOEXEC or not, + depending on the 'e' open mode, but there is only one flag which + controls both descriptors. The parent end is adjusted below, + after creating the child process. (In the child process, the + parent end should be closed on execve, so O_CLOEXEC remains set + there.) */ + if (__pipe2 (pipe_fds, O_CLOEXEC) < 0) + return NULL; if (do_read) { @@ -183,27 +171,13 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode) int child_std_end = do_read ? 1 : 0; struct _IO_proc_file *p; -#ifndef __ASSUME_PIPE2 - /* If we have pipe2 the descriptor is marked for close-on-exec. */ - _IO_close (parent_end); -#endif if (child_end != child_std_end) - { - _IO_dup2 (child_end, child_std_end); -#ifndef __ASSUME_PIPE2 - _IO_close (child_end); -#endif - } + _IO_dup2 (child_end, child_std_end); #ifdef O_CLOEXEC else - { - /* The descriptor is already the one we will use. But it must - not be marked close-on-exec. Undo the effects. */ -# ifndef __ASSUME_PIPE2 - if (__have_pipe2 > 0) -# endif - __fcntl (child_end, F_SETFD, 0); - } + /* The descriptor is already the one we will use. But it must + not be marked close-on-exec. Undo the effects. */ + __fcntl (child_end, F_SETFD, 0); #endif /* POSIX.2: "popen() shall ensure that any streams from previous popen() calls that remain open in the parent process are closed @@ -229,26 +203,10 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode) return NULL; } - if (do_cloexec) - { -#ifndef __ASSUME_PIPE2 -# ifdef O_CLOEXEC - if (__have_pipe2 < 0) -# endif - __fcntl (parent_end, F_SETFD, FD_CLOEXEC); -#endif - } - else - { -#ifdef O_CLOEXEC - /* Undo the effects of the pipe2 call which set the - close-on-exec flag. */ -# ifndef __ASSUME_PIPE2 - if (__have_pipe2 > 0) -# endif - __fcntl (parent_end, F_SETFD, 0); -#endif - } + if (!do_cloexec) + /* Undo the effects of the pipe2 call which set the + close-on-exec flag. */ + __fcntl (parent_end, F_SETFD, 0); _IO_fileno (fp) = parent_end; |