/* cloexec.c - set or clear the close-on-exec descriptor flag Copyright (C) 1991, 2004-2006, 2009-2020 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/>. The code is taken from glibc/manual/llio.texi */ #include <config.h> #include "cloexec.h" #include <errno.h> #include <fcntl.h> #include <unistd.h> /* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true, or clear the flag if VALUE is false. Return 0 on success, or -1 on error with 'errno' set. Note that on MingW, this function does NOT protect DESC from being inherited into spawned children. Instead, either use dup_cloexec followed by closing the original DESC, or use interfaces such as open or pipe2 that accept flags like O_CLOEXEC to create DESC non-inheritable in the first place. */ int set_cloexec_flag (int desc, bool value) { #ifdef F_SETFD int flags = fcntl (desc, F_GETFD, 0); if (0 <= flags) { int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC); if (flags == newflags || fcntl (desc, F_SETFD, newflags) != -1) return 0; } return -1; #else /* !F_SETFD */ /* Use dup2 to reject invalid file descriptors; the cloexec flag will be unaffected. */ if (desc < 0) { errno = EBADF; return -1; } if (dup2 (desc, desc) < 0) /* errno is EBADF here. */ return -1; /* There is nothing we can do on this kind of platform. Punt. */ return 0; #endif /* !F_SETFD */ } /* Duplicates a file handle FD, while marking the copy to be closed prior to exec or spawn. Returns -1 and sets errno if FD could not be duplicated. */ int dup_cloexec (int fd) { return fcntl (fd, F_DUPFD_CLOEXEC, 0); } |