From 892cafff665b44d238e3b664f61ca38dd965cba6 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 24 Oct 2012 21:16:06 -0400 Subject: greatly improve freopen behavior 1. don't open /dev/null just as a basis to copy flags; use shared __fmodeflags function to get the right file flags for the mode. 2. handle the case (probably invalid, but whatever) case where the original stream's file descriptor was closed; previously, the logic re-closed it. 3. accept the "e" mode flag for close-on-exec; update dup3 to fallback to using dup2 so we can simply call __dup3 instead of putting fallback logic in freopen itself. --- src/stdio/freopen.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) (limited to 'src/stdio/freopen.c') diff --git a/src/stdio/freopen.c b/src/stdio/freopen.c index 5b4f126d..c80ce3b4 100644 --- a/src/stdio/freopen.c +++ b/src/stdio/freopen.c @@ -7,24 +7,27 @@ /* Locking is not necessary because, in the event of failure, the stream * passed to freopen is invalid as soon as freopen is called. */ +int __dup3(int, int, int); + FILE *freopen(const char *restrict filename, const char *restrict mode, FILE *restrict f) { - int fl; + int fl = __fmodeflags(mode); FILE *f2; fflush(f); if (!filename) { - f2 = fopen("/dev/null", mode); - if (!f2) goto fail; - fl = __syscall(SYS_fcntl, f2->fd, F_GETFL, 0); + if (fl&O_CLOEXEC) + __syscall(SYS_fcntl, f->fd, F_SETFD, FD_CLOEXEC); + fl &= ~(O_CREAT|O_EXCL|O_CLOEXEC); if (syscall(SYS_fcntl, f->fd, F_SETFL, fl) < 0) - goto fail2; + goto fail; + return f; } else { f2 = fopen(filename, mode); if (!f2) goto fail; - if (syscall(SYS_dup2, f2->fd, f->fd) < 0) - goto fail2; + if (f2->fd == f->fd) f2->fd = -1; /* avoid closing in fclose */ + else if (__dup3(f2->fd, f->fd, fl&O_CLOEXEC)<0) goto fail2; } f->flags = (f->flags & F_PERM) | f2->flags; -- cgit v1.2.1