lib/libc/stdio/refill.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)refill.c 8.1 (Berkeley) 6/4/93
  37  * $FreeBSD: src/lib/libc/stdio/refill.c,v 1.8.2.1 2001/03/05 11:27:49 obrien Exp $
  38  * $DragonFly: src/lib/libc/stdio/refill.c,v 1.10 2005/11/20 11:07:30 swildner Exp $
  39  */
  40
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44
  45 #include "local.h"
  46 #include "priv_stdio.h"
  47
  48 static int lflush (FILE *);
  49
  50 static int
  51 lflush(FILE *fp)
  52 {
  53
  54         if ((fp->pub._flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
  55                 return (__sflush(fp));
  56         return (0);
  57 }
  58
  59 /*
  60  * Refill a stdio buffer.
  61  * Return EOF on eof or error, 0 otherwise.
  62  */
  63 int
  64 __srefill(FILE *fp)
  65 {
  66
  67         /* make sure stdio is set up */
  68         if (!__sdidinit)
  69                 __sinit();
  70
  71         fp->pub._r = 0;         /* largely a convenience for callers */
  72
  73         /* SysV does not make this test; take it out for compatibility */
  74         if (fp->pub._flags & __SEOF)
  75                 return (EOF);
  76
  77         /* if not already reading, have to be reading and writing */
  78         if ((fp->pub._flags & __SRD) == 0) {
  79                 if ((fp->pub._flags & __SRW) == 0) {
  80                         errno = EBADF;
  81                         fp->pub._flags |= __SERR;
  82                         return (EOF);
  83                 }
  84                 /* switch to reading */
  85                 if (fp->pub._flags & __SWR) {
  86                         if (__sflush(fp))
  87                                 return (EOF);
  88                         fp->pub._flags &= ~__SWR;
  89                         fp->pub._w = 0;
  90                         fp->pub._lbfsize = 0;
  91                 }
  92                 fp->pub._flags |= __SRD;
  93         } else {
  94                 /*
  95                  * We were reading.  If there is an ungetc buffer,
  96                  * we must have been reading from that.  Drop it,
  97                  * restoring the previous buffer (if any).  If there
  98                  * is anything in that buffer, return.
  99                  */
 100                 if (HASUB(fp)) {
 101                         FREEUB(fp);
 102                         if ((fp->pub._r = fp->_ur) != 0) {
 103                                 fp->pub._p = fp->_up;
 104                                 return (0);
 105                         }
 106                 }
 107         }
 108
 109         if (fp->_bf._base == NULL)
 110                 __smakebuf(fp);
 111
 112         /*
 113          * Before reading from a line buffered or unbuffered file,
 114          * flush all line buffered output files, per the ANSI C
 115          * standard.
 116          */
 117         if (fp->pub._flags & (__SLBF|__SNBF))
 118                 _fwalk(lflush);
 119         fp->pub._p = fp->_bf._base;
 120         fp->pub._r = (*fp->_read)(fp->_cookie, (char *)fp->pub._p, fp->_bf._size);
 121         fp->pub._flags &= ~__SMOD;      /* buffer contents are again pristine */
 122         if (fp->pub._r <= 0) {
 123                 if (fp->pub._r == 0)
 124                         fp->pub._flags |= __SEOF;
 125                 else {
 126                         fp->pub._r = 0;
 127                         fp->pub._flags |= __SERR;
 128                 }
 129                 return (EOF);
 130         }
 131         return (0);
 132 }