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