minix/lib/stdio/freopen.c
2005-06-23 11:07:31 +00:00

99 lines
1.9 KiB
C
Executable file

/*
* freopen.c - open a file and associate a stream with it
*/
/* $Header$ */
#if defined(_POSIX_SOURCE)
#include <sys/types.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include "loc_incl.h"
#define PMODE 0666
/* Do not "optimize" this file to use the open with O_CREAT if the file
* does not exist. The reason is given in fopen.c.
*/
#define O_RDONLY 0
#define O_WRONLY 1
#define O_RDWR 2
#define O_CREAT 0x010
#define O_TRUNC 0x020
#define O_APPEND 0x040
int _open(const char *path, int flags);
int _creat(const char *path, _mnx_Mode_t mode);
int _close(int d);
FILE *
freopen(const char *name, const char *mode, FILE *stream)
{
register int i;
int rwmode = 0, rwflags = 0;
int fd, flags = stream->_flags & (_IONBF | _IOFBF | _IOLBF | _IOMYBUF);
(void) fflush(stream); /* ignore errors */
(void) _close(fileno(stream));
switch(*mode++) {
case 'r':
flags |= _IOREAD;
rwmode = O_RDONLY;
break;
case 'w':
flags |= _IOWRITE;
rwmode = O_WRONLY;
rwflags = O_CREAT | O_TRUNC;
break;
case 'a':
flags |= _IOWRITE | _IOAPPEND;
rwmode = O_WRONLY;
rwflags |= O_APPEND | O_CREAT;
break;
default:
return (FILE *)NULL;
}
while (*mode) {
switch(*mode++) {
case 'b':
continue;
case '+':
rwmode = O_RDWR;
flags |= _IOREAD | _IOWRITE;
continue;
/* The sequence may be followed by aditional characters */
default:
break;
}
break;
}
if ((rwflags & O_TRUNC)
|| (((fd = _open(name, rwmode)) < 0)
&& (rwflags & O_CREAT))) {
if (((fd = _creat(name, PMODE)) < 0) && flags | _IOREAD) {
(void) _close(fd);
fd = _open(name, rwmode);
}
}
if (fd < 0) {
for( i = 0; i < FOPEN_MAX; i++) {
if (stream == __iotab[i]) {
__iotab[i] = 0;
break;
}
}
if (stream != stdin && stream != stdout && stream != stderr)
free((void *)stream);
return (FILE *)NULL;
}
stream->_count = 0;
stream->_fd = fd;
stream->_flags = flags;
return stream;
}