stdio/refill.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Chris Torek.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61
  62 #include <errno.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include "local.h"
  66
  67 static int
  68 lflush(fp)
  69         FILE *fp;
  70 {
  71
  72         if ((fp->_flags & (__SLBF|__SWR)) == __SLBF|__SWR)
  73                 return (__sflush(fp));
  74         return (0);
  75 }
  76
  77 /*
  78  * Refill a stdio buffer.
  79  * Return EOF on eof or error, 0 otherwise.
  80  */
  81 int
  82 __srefill(fp)
  83         register FILE *fp;
  84 {
  85
  86         /* make sure stdio is set up */
  87         if (!__sdidinit)
  88                 __sinit();
  89
  90         fp->_r = 0;             /* largely a convenience for callers */
  91
  92         /* SysV does not make this test; take it out for compatibility */
  93         if (fp->_flags & __SEOF)
  94                 return (EOF);
  95
  96         /* if not already reading, have to be reading and writing */
  97         if ((fp->_flags & __SRD) == 0) {
  98                 if ((fp->_flags & __SRW) == 0) {
  99                         errno = EBADF;
 100                         return (EOF);
 101                 }
 102                 /* switch to reading */
 103                 if (fp->_flags & __SWR) {
 104                         if (__sflush(fp))
 105                                 return (EOF);
 106                         fp->_flags &= ~__SWR;
 107                         fp->_w = 0;
 108                         fp->_lbfsize = 0;
 109                 }
 110                 fp->_flags |= __SRD;
 111         } else {
 112                 /*
 113                  * We were reading.  If there is an ungetc buffer,
 114                  * we must have been reading from that.  Drop it,
 115                  * restoring the previous buffer (if any).  If there
 116                  * is anything in that buffer, return.
 117                  */
 118                 if (HASUB(fp)) {
 119                         FREEUB(fp);
 120                         if ((fp->_r = fp->_ur) != 0) {
 121                                 fp->_p = fp->_up;
 122                                 return (0);
 123                         }
 124                 }
 125         }
 126
 127         if (fp->_bf._base == NULL)
 128                 __smakebuf(fp);
 129
 130         /*
 131          * Before reading from a line buffered or unbuffered file,
 132          * flush all line buffered output files, per the ANSI C
 133          * standard.
 134          */
 135         if (fp->_flags & (__SLBF|__SNBF))
 136                 (void) _fwalk(lflush);
 137         fp->_p = fp->_bf._base;
 138         fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
 139         fp->_flags &= ~__SMOD;  /* buffer contents are again pristine */
 140         if (fp->_r <= 0) {
 141                 if (fp->_r == 0)
 142                         fp->_flags |= __SEOF;
 143                 else {
 144                         fp->_r = 0;
 145                         fp->_flags |= __SERR;
 146                 }
 147                 return (EOF);
 148         }
 149         return (0);
 150 }