1*09d4459fSDaniel Fojt /* cloexec.c - set or clear the close-on-exec descriptor flag 2cf28ed85SJohn Marino 3*09d4459fSDaniel Fojt Copyright (C) 1991, 2004-2006, 2009-2020 Free Software Foundation, Inc. 4cf28ed85SJohn Marino 5cf28ed85SJohn Marino This program is free software: you can redistribute it and/or modify 6cf28ed85SJohn Marino it under the terms of the GNU General Public License as published by 7cf28ed85SJohn Marino the Free Software Foundation; either version 3 of the License, or 8cf28ed85SJohn Marino (at your option) any later version. 9cf28ed85SJohn Marino 10cf28ed85SJohn Marino This program is distributed in the hope that it will be useful, 11cf28ed85SJohn Marino but WITHOUT ANY WARRANTY; without even the implied warranty of 12cf28ed85SJohn Marino MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13cf28ed85SJohn Marino GNU General Public License for more details. 14cf28ed85SJohn Marino 15cf28ed85SJohn Marino You should have received a copy of the GNU General Public License 16*09d4459fSDaniel Fojt along with this program. If not, see <https://www.gnu.org/licenses/>. 17cf28ed85SJohn Marino 18cf28ed85SJohn Marino The code is taken from glibc/manual/llio.texi */ 19cf28ed85SJohn Marino 20cf28ed85SJohn Marino #include <config.h> 21cf28ed85SJohn Marino 22cf28ed85SJohn Marino #include "cloexec.h" 23cf28ed85SJohn Marino 24cf28ed85SJohn Marino #include <errno.h> 25cf28ed85SJohn Marino #include <fcntl.h> 26cf28ed85SJohn Marino #include <unistd.h> 27cf28ed85SJohn Marino 28cf28ed85SJohn Marino /* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true, 29cf28ed85SJohn Marino or clear the flag if VALUE is false. 30cf28ed85SJohn Marino Return 0 on success, or -1 on error with 'errno' set. 31cf28ed85SJohn Marino 32cf28ed85SJohn Marino Note that on MingW, this function does NOT protect DESC from being 33cf28ed85SJohn Marino inherited into spawned children. Instead, either use dup_cloexec 34cf28ed85SJohn Marino followed by closing the original DESC, or use interfaces such as 35cf28ed85SJohn Marino open or pipe2 that accept flags like O_CLOEXEC to create DESC 36cf28ed85SJohn Marino non-inheritable in the first place. */ 37cf28ed85SJohn Marino 38cf28ed85SJohn Marino int 39cf28ed85SJohn Marino set_cloexec_flag (int desc, bool value) 40cf28ed85SJohn Marino { 41cf28ed85SJohn Marino #ifdef F_SETFD 42cf28ed85SJohn Marino 43cf28ed85SJohn Marino int flags = fcntl (desc, F_GETFD, 0); 44cf28ed85SJohn Marino 45cf28ed85SJohn Marino if (0 <= flags) 46cf28ed85SJohn Marino { 47cf28ed85SJohn Marino int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC); 48cf28ed85SJohn Marino 49cf28ed85SJohn Marino if (flags == newflags 50cf28ed85SJohn Marino || fcntl (desc, F_SETFD, newflags) != -1) 51cf28ed85SJohn Marino return 0; 52cf28ed85SJohn Marino } 53cf28ed85SJohn Marino 54cf28ed85SJohn Marino return -1; 55cf28ed85SJohn Marino 56cf28ed85SJohn Marino #else /* !F_SETFD */ 57cf28ed85SJohn Marino 58cf28ed85SJohn Marino /* Use dup2 to reject invalid file descriptors; the cloexec flag 59cf28ed85SJohn Marino will be unaffected. */ 60cf28ed85SJohn Marino if (desc < 0) 61cf28ed85SJohn Marino { 62cf28ed85SJohn Marino errno = EBADF; 63cf28ed85SJohn Marino return -1; 64cf28ed85SJohn Marino } 65cf28ed85SJohn Marino if (dup2 (desc, desc) < 0) 66cf28ed85SJohn Marino /* errno is EBADF here. */ 67cf28ed85SJohn Marino return -1; 68cf28ed85SJohn Marino 69cf28ed85SJohn Marino /* There is nothing we can do on this kind of platform. Punt. */ 70cf28ed85SJohn Marino return 0; 71cf28ed85SJohn Marino #endif /* !F_SETFD */ 72cf28ed85SJohn Marino } 73cf28ed85SJohn Marino 74cf28ed85SJohn Marino 75cf28ed85SJohn Marino /* Duplicates a file handle FD, while marking the copy to be closed 76cf28ed85SJohn Marino prior to exec or spawn. Returns -1 and sets errno if FD could not 77cf28ed85SJohn Marino be duplicated. */ 78cf28ed85SJohn Marino 79cf28ed85SJohn Marino int 80cf28ed85SJohn Marino dup_cloexec (int fd) 81cf28ed85SJohn Marino { 82cf28ed85SJohn Marino return fcntl (fd, F_DUPFD_CLOEXEC, 0); 83cf28ed85SJohn Marino } 84