diff options
Diffstat (limited to '')
-rw-r--r-- | lib/fd-safer-flag.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/lib/fd-safer-flag.c b/lib/fd-safer-flag.c new file mode 100644 index 0000000..9aef271 --- /dev/null +++ b/lib/fd-safer-flag.c @@ -0,0 +1,52 @@ +/* Adjust a file descriptor result so that it avoids clobbering + STD{IN,OUT,ERR}_FILENO, with specific flags. + + Copyright (C) 2005-2006, 2009-2023 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert and Eric Blake. */ + +#include <config.h> + +/* Specification. */ +#include "unistd-safer.h" + +#include <errno.h> +#include <unistd.h> + +/* Return FD, unless FD would be a copy of standard input, output, or + error; in that case, return a duplicate of FD, closing FD. If FLAG + contains O_CLOEXEC, the returned FD will have close-on-exec + semantics. On failure to duplicate, close FD, set errno, and + return -1. Preserve errno if FD is negative, so that the caller + can always inspect errno when the returned value is negative. + + This function is usefully wrapped around functions that return file + descriptors, e.g., fd_safer_flag (open ("file", O_RDONLY | flag), flag). */ + +int +fd_safer_flag (int fd, int flag) +{ + if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) + { + int f = dup_safer_flag (fd, flag); + int e = errno; + close (fd); + errno = e; + fd = f; + } + + return fd; +} |