122 lines
2.4 KiB
C
122 lines
2.4 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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#if defined(_POSIX_SOURCE)
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#include <sys/types.h>
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#endif
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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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#include <sys/stat.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, mode_t 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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struct stat st;
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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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/* Find the slot the stream had, if any. */
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for(i = 0; i < FOPEN_MAX; i++)
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if (stream == __iotab[i])
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break;
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/* If none, it might've been fclose()d; find a new slot for it. */
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if(i >= FOPEN_MAX) {
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for (i = 0; __iotab[i] != 0 ; i++) {
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if ( i >= FOPEN_MAX-1 )
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return (FILE *)NULL;
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}
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}
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/* If it was valid, it isn't any more until the freopen() succeeds. */
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__iotab[i] = 0;
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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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goto loser;
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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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continue;
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case '+':
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rwmode = O_RDWR;
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flags |= _IOREAD | _IOWRITE;
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continue;
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/* The sequence may be followed by aditional characters */
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default:
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break;
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}
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break;
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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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goto loser;
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}
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if ( fstat( fd, &st ) == 0 ) {
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if ( S_ISFIFO(st.st_mode) ) flags |= _IOFIFO;
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} else {
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goto loser;
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}
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stream->_count = 0;
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stream->_fd = fd;
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stream->_flags = flags;
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__iotab[i] = stream;
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return stream;
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loser:
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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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