usr/src/lib/libc/port/stdio/_filbuf.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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32
  33 #pragma weak __filbuf = _filbuf
  34
  35 #include "lint.h"
  36 #include "file64.h"
  37 #include <stdio.h>
  38 #include <errno.h>
  39 #include <sys/types.h>
  40 #include <unistd.h>
  41 #include "stdiom.h"
  42
  43
  44 static int
  45 _xpg4_check(void)
  46 {
  47         extern int      __xpg4;
  48
  49         return (__xpg4);
  50 }
  51
  52 /* fill buffer, return first character or EOF */
  53 int
  54 _filbuf(FILE *iop)
  55 {
  56         ssize_t res;
  57         size_t nbyte;
  58         Uchar *endbuf;
  59 #ifdef  _LP64
  60         unsigned int    flag;
  61 #else
  62         unsigned char   flag;
  63 #endif
  64
  65         if (!(iop->_flag & _IOREAD))    /* check, correct permissions */
  66         {
  67                 if (iop->_flag & _IORW)
  68                         iop->_flag |= _IOREAD; /* change direction */
  69                                                 /* to read - fseek */
  70                 else {
  71                         errno = EBADF;
  72                         return (EOF);
  73                 }
  74         }
  75
  76         if (iop->_base == 0) {
  77                 if ((endbuf = _findbuf(iop)) == 0) /* get buffer and */
  78                                                 /* end_of_buffer */
  79                         return (EOF);
  80         }
  81         else
  82                 endbuf = _bufend(iop);
  83
  84         /*
  85          * Flush all line-buffered streams before we
  86          * read no-buffered or line-buffered input.
  87          */
  88         if (iop->_flag & (_IONBF | _IOLBF))
  89                 _flushlbf();
  90         /*
  91          * Changed the get family fns in Solaris 10 to comply with the
  92          * 1990 C Standard and standards based upon it.  If the
  93          * end-of-file indicator for the stream is set, or if the stream
  94          * is at end-of-file, the function will return EOF, and the file
  95          * position indicator for the stream will not be advanced.
  96          * Additional bytes appended to the file do not clear the EOF
  97          * indicator.
  98          */
  99         if ((flag = iop->_flag) & _IOEOF) {
 100                 if (_xpg4_check()) {
 101                         /*
 102                          * A previous read() has returned 0 (below),
 103                          * therefore iop->_cnt was set to 0, and the EOF
 104                          * indicator was set before returning EOF.  Reset
 105                          * iop->_cnt to 0; it has likely been changed by
 106                          * a function such as getc().
 107                          */
 108                         iop->_cnt = 0;
 109                         return (EOF);
 110                 }
 111         }
 112         /*
 113          * Fill buffer or read 1 byte for unbuffered, handling any errors.
 114          */
 115         iop->_ptr = iop->_base;
 116         if (flag & _IONBF)
 117                 nbyte = 1;
 118         else
 119                 nbyte = endbuf - iop->_base;
 120         if ((res = read(GET_FD(iop), (char *)iop->_base, nbyte)) > 0) {
 121                 iop->_cnt = res - 1;
 122                 return (*iop->_ptr++);
 123         }
 124
 125         iop->_cnt = 0;
 126         if (res == 0)
 127                 iop->_flag |= _IOEOF;
 128         else if (!cancel_active())
 129                 iop->_flag |= _IOERR;
 130         return (EOF);
 131 }