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8ef9d46)
popen was special-casing the possibility (only possible when the
parent closed stdin and/or stdout) that the child's end of the pipe
was already on the final desired fd number, in which case there was no
way to get rid of its close-on-exec flag in the child. commit
6fc6ca1a323bc0b6b9e9cdc8fa72221ae18fe206 made this unnecessary by
implementing the POSIX-future requirement that dup2 file actions with
equal source and destination fd values remove the close-on-exec flag.
- /* If the child's end of the pipe happens to already be on the final
- * fd number to which it will be assigned (either 0 or 1), it must
- * be moved to a different fd. Otherwise, there is no safe way to
- * remove the close-on-exec flag in the child without also creating
- * a file descriptor leak race condition in the parent. */
- if (p[1-op] == 1-op) {
- int tmp = fcntl(1-op, F_DUPFD_CLOEXEC, 0);
- if (tmp < 0) {
- e = errno;
- goto fail;
- }
- __syscall(SYS_close, p[1-op]);
- p[1-op] = tmp;
- }
-
e = ENOMEM;
if (!posix_spawn_file_actions_init(&fa)) {
if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
e = ENOMEM;
if (!posix_spawn_file_actions_init(&fa)) {
if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
}
posix_spawn_file_actions_destroy(&fa);
}
}
posix_spawn_file_actions_destroy(&fa);
}
fclose(f);
__syscall(SYS_close, p[1-op]);
fclose(f);
__syscall(SYS_close, p[1-op]);