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// SPDX-License-Identifier: 0BSD
///////////////////////////////////////////////////////////////////////////////
//
/// \file tuklib_open_stdxxx.c
/// \brief Make sure that file descriptors 0, 1, and 2 are open
//
// Author: Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////
#include "tuklib_open_stdxxx.h"
#ifndef TUKLIB_DOSLIKE
# include <stdlib.h>
# include <errno.h>
# include <fcntl.h>
# include <unistd.h>
#endif
extern void
tuklib_open_stdxxx(int err_status)
{
#ifdef TUKLIB_DOSLIKE
// Do nothing, just silence warnings.
(void)err_status;
#else
for (int i = 0; i <= 2; ++i) {
// We use fcntl() to check if the file descriptor is open.
if (fcntl(i, F_GETFD) == -1 && errno == EBADF) {
// With stdin, we could use /dev/full so that
// writing to stdin would fail. However, /dev/full
// is Linux specific, and if the program tries to
// write to stdin, there's already a problem anyway.
const int fd = open("/dev/null", O_NOCTTY
| (i == 0 ? O_WRONLY : O_RDONLY));
if (fd != i) {
if (fd != -1)
(void)close(fd);
// Something went wrong. Exit with the
// exit status we were given. Don't try
// to print an error message, since stderr
// may very well be non-existent. This
// error should be extremely rare.
exit(err_status);
}
}
}
#endif
return;
}
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