usr/src/lib/libbc/libc/stdio/sys5/fopen.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*      Copyright (c) 1984 AT&T */
  23 /*        All Rights Reserved   */
  24
  25 #pragma ident   "%Z%%M% %I%     %E% SMI"
  26
  27 /*LINTLIBRARY*/
  28
  29 #include <stdio.h>
  30 #include <fcntl.h>
  31
  32 extern FILE     *_findiop();
  33 static FILE     *_endopen();
  34
  35 FILE *
  36 fopen(char *file, char *mode)
  37 {
  38         return (_endopen(file, mode, _findiop()));
  39 }
  40
  41 FILE *
  42 freopen(char *file, char *mode, FILE *iop)
  43 {
  44         (void) fclose(iop); /* doesn't matter if this fails */
  45         return (_endopen(file, mode, iop));
  46 }
  47
  48 static FILE *
  49 _endopen(char *file, char *mode, FILE *iop)
  50 {
  51         int     plus, oflag, fd;
  52
  53         if (iop == NULL || file == NULL || file[0] == '\0')
  54                 return (NULL);
  55         plus = (mode[1] == '+');
  56         switch (mode[0]) {
  57         case 'w':
  58                 oflag = (plus ? O_RDWR : O_WRONLY) | O_TRUNC | O_CREAT;
  59                 break;
  60         case 'a':
  61                 oflag = (plus ? O_RDWR : O_WRONLY) | O_APPEND | O_CREAT;
  62                 break;
  63         case 'r':
  64                 oflag = plus ? O_RDWR : O_RDONLY;
  65                 break;
  66         default:
  67                 return (NULL);
  68         }
  69         if ((fd = open(file, oflag, 0666)) < 0)
  70                 return (NULL);
  71         iop->_cnt = 0;
  72         iop->_file = fd;
  73         iop->_flag = plus ? _IORW : (mode[0] == 'r') ? _IOREAD : _IOWRT;
  74         if (mode[0] == 'a')   {
  75                 if (!plus)  {
  76                         /* if update only mode, move file pointer to the end
  77                            of the file */
  78                         if ((lseek(fd,0L,2)) < 0)  {
  79                                 (void) close(fd);
  80                                 return NULL;
  81                         }
  82                 }
  83         }
  84         iop->_base = iop->_ptr = NULL;
  85         iop->_bufsiz = 0;
  86         return (iop);
  87 }