cosmopolitan/libc/stdio/freopen.c

95 lines
4.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ 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; version 2 of the License. │
│ │
│ 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, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/fileflagandattributes.h"
#include "libc/nt/enum/filesharemode.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/fd.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/sysv/consts/o.h"
/**
* Overwrites existing stream.
*
* This function can be used in two ways. The first is sort of a
* mutating assignment. The second behavior, if pathname is NULL, is
* just changing the mode of an already open file descriptor.
*
* @param pathname is the file to open or NULL
* @param mode is the mode string flags, see fopenflags()
* @param stream is the existing allocated stream memory, which is
* flushed and closed if already open
* @return stream object if successful, or NULL w/ errno
*/
FILE *freopen(const char *pathname, const char *mode, FILE *stream) {
int fd;
unsigned flags;
flags = fopenflags(mode);
fflush(stream);
if (pathname) {
/* open new stream, overwriting existing alloc */
if ((fd = open(pathname, flags, 0666)) != -1) {
if (!IsWindows()) {
dup3(fd, stream->fd, (flags & O_CLOEXEC));
close(fd);
} else {
g_fds.p[stream->fd].handle = g_fds.p[fd].handle;
g_fds.p[fd].kind = kFdEmpty;
}
stream->iomode = flags;
return stream;
} else {
return NULL;
}
} else {
/* change mode of open file */
if (!IsWindows()) {
if (flags & O_CLOEXEC) {
if (fcntl$sysv(stream->fd, F_SETFD, FD_CLOEXEC) == -1) return NULL;
flags &= ~O_CLOEXEC;
}
if (flags) {
if (fcntl$sysv(stream->fd, F_SETFL, flags) == -1) return NULL;
}
return stream;
} else {
if (ReOpenFile(
stream->fd,
(flags & O_RDWR) == O_RDWR ? kNtGenericWrite : kNtGenericRead,
(flags & O_EXCL) == O_EXCL
? kNtFileShareExclusive
: kNtFileShareRead | kNtFileShareWrite | kNtFileShareDelete,
kNtFileAttributeNormal)) {
return stream;
} else {
__winerr();
return NULL;
}
}
}
}