stdio/refill.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * This code is derived from software contributed to Berkeley by
  27  * Chris Torek.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58
  59 #include <errno.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include "local.h"
  63
  64 static int
  65 lflush(fp)
  66         FILE *fp;
  67 {
  68
  69         if ((fp->_flags & (__SLBF|__SWR)) == __SLBF|__SWR)
  70                 return (__sflush(fp));
  71         return (0);
  72 }
  73
  74 /*
  75  * Refill a stdio buffer.
  76  * Return EOF on eof or error, 0 otherwise.
  77  */
  78 int
  79 __srefill(fp)
  80         register FILE *fp;
  81 {
  82
  83         /* make sure stdio is set up */
  84         if (!__sdidinit)
  85                 __sinit();
  86
  87         fp->_r = 0;             /* largely a convenience for callers */
  88
  89         /* SysV does not make this test; take it out for compatibility */
  90         if (fp->_flags & __SEOF)
  91                 return (EOF);
  92
  93         /* if not already reading, have to be reading and writing */
  94         if ((fp->_flags & __SRD) == 0) {
  95                 if ((fp->_flags & __SRW) == 0) {
  96                         errno = EBADF;
  97                         return (EOF);
  98                 }
  99                 /* switch to reading */
 100                 if (fp->_flags & __SWR) {
 101                         if (__sflush(fp))
 102                                 return (EOF);
 103                         fp->_flags &= ~__SWR;
 104                         fp->_w = 0;
 105                         fp->_lbfsize = 0;
 106                 }
 107                 fp->_flags |= __SRD;
 108         } else {
 109                 /*
 110                  * We were reading.  If there is an ungetc buffer,
 111                  * we must have been reading from that.  Drop it,
 112                  * restoring the previous buffer (if any).  If there
 113                  * is anything in that buffer, return.
 114                  */
 115                 if (HASUB(fp)) {
 116                         FREEUB(fp);
 117                         if ((fp->_r = fp->_ur) != 0) {
 118                                 fp->_p = fp->_up;
 119                                 return (0);
 120                         }
 121                 }
 122         }
 123
 124         if (fp->_bf._base == NULL)
 125                 __smakebuf(fp);
 126
 127         /*
 128          * Before reading from a line buffered or unbuffered file,
 129          * flush all line buffered output files, per the ANSI C
 130          * standard.
 131          */
 132         if (fp->_flags & (__SLBF|__SNBF))
 133                 (void) _fwalk(lflush);
 134         fp->_p = fp->_bf._base;
 135         fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
 136         fp->_flags &= ~__SMOD;  /* buffer contents are again pristine */
 137         if (fp->_r <= 0) {
 138                 if (fp->_r == 0)
 139                         fp->_flags |= __SEOF;
 140                 else {
 141                         fp->_r = 0;
 142                         fp->_flags |= __SERR;
 143                 }
 144                 return (EOF);
 145         }
 146         return (0);
 147 }