diff options
Diffstat (limited to 'sysdeps/generic/check_fds.c')
| -rw-r--r-- | sysdeps/generic/check_fds.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/sysdeps/generic/check_fds.c b/sysdeps/generic/check_fds.c index 083b72de16..ff9562de08 100644 --- a/sysdeps/generic/check_fds.c +++ b/sysdeps/generic/check_fds.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2000 Free Software Foundation, Inc. +/* Copyright (C) 2000, 2002 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -50,9 +50,13 @@ check_one_fd (int fd, int mode) int nullfd = __libc_open (_PATH_DEVNULL, mode); /* We are very paranoid here. With all means we try to ensure that we are actually opening the /dev/null device and nothing - else. */ - if (__builtin_expect (nullfd, 0) == -1 - || __builtin_expect (__fxstat64 (_STAT_VER, nullfd, &st), 0) != 0 + else. + + Note that the following code assumes that STDIN_FILENO, + STDOUT_FILENO, STDERR_FILENO are the three lowest file + decsriptor numbers, in this order. */ + if (__builtin_expect (nullfd != fd, 0) + || __builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) != 0 || __builtin_expect (S_ISCHR (st.st_mode), 1) == 0 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR || st.st_rdev != makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR) @@ -72,7 +76,7 @@ __libc_check_standard_fds (void) { /* This is really paranoid but some people actually are. If /dev/null should happen to be a symlink to somewhere else and not the device - commonly known as "/dev/null" be bail out. We can detect this with + commonly known as "/dev/null" we bail out. We can detect this with the O_NOFOLLOW flag for open() but only on some system. */ #ifndef O_NOFOLLOW # define O_NOFOLLOW 0 |