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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#)refill.c 8.1 (Berkeley) 6/4/93
  33  * $FreeBSD: src/lib/libc/stdio/refill.c,v 1.20 2008/04/17 22:17:54 jhb Exp $
  34  */
  35
  36 #include "namespace.h"
  37 #include <errno.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include "un-namespace.h"
  41
  42 #include "libc_private.h"
  43 #include "local.h"
  44
  45 static int lflush(FILE *);
  46
  47 static int
  48 lflush(FILE *fp)
  49 {
  50         int     ret = 0;
  51
  52         if ((fp->pub._flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
  53                 FLOCKFILE(fp);
  54                 ret = __sflush(fp);
  55                 FUNLOCKFILE(fp);
  56         }
  57         return (ret);
  58 }
  59
  60 /*
  61  * Refill a stdio buffer.
  62  * Return EOF on eof or error, 0 otherwise.
  63  */
  64 int
  65 __srefill(FILE *fp)
  66 {
  67
  68         /* make sure stdio is set up */
  69         if (!__sdidinit)
  70                 __sinit();
  71
  72         ORIENT(fp, -1);
  73
  74         fp->pub._r = 0;         /* largely a convenience for callers */
  75
  76         /* SysV does not make this test; take it out for compatibility */
  77         if (fp->pub._flags & __SEOF)
  78                 return (EOF);
  79
  80         /* if not already reading, have to be reading and writing */
  81         if ((fp->pub._flags & __SRD) == 0) {
  82                 if ((fp->pub._flags & __SRW) == 0) {
  83                         errno = EBADF;
  84                         fp->pub._flags |= __SERR;
  85                         return (EOF);
  86                 }
  87                 /* switch to reading */
  88                 if (fp->pub._flags & __SWR) {
  89                         if (__sflush(fp))
  90                                 return (EOF);
  91                         fp->pub._flags &= ~__SWR;
  92                         fp->pub._w = 0;
  93                         fp->pub._lbfsize = 0;
  94                 }
  95                 fp->pub._flags |= __SRD;
  96         } else {
  97                 /*
  98                  * We were reading.  If there is an ungetc buffer,
  99                  * we must have been reading from that.  Drop it,
 100                  * restoring the previous buffer (if any).  If there
 101                  * is anything in that buffer, return.
 102                  */
 103                 if (HASUB(fp)) {
 104                         FREEUB(fp);
 105                         if ((fp->pub._r = fp->_ur) != 0) {
 106                                 fp->pub._p = fp->_up;
 107                                 return (0);
 108                         }
 109                 }
 110         }
 111
 112         if (fp->_bf._base == NULL)
 113                 __smakebuf(fp);
 114
 115         /*
 116          * Before reading from a line buffered or unbuffered file,
 117          * flush all line buffered output files, per the ANSI C
 118          * standard.
 119          */
 120         if (fp->pub._flags & (__SLBF|__SNBF)) {
 121                 /* Ignore this file in _fwalk to avoid potential deadlock. */
 122                 fp->pub._flags |= __SIGN;
 123                 _fwalk(lflush);
 124                 fp->pub._flags &= ~__SIGN;
 125
 126                 /* Now flush this file without locking it. */
 127                 if ((fp->pub._flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
 128                         __sflush(fp);
 129         }
 130         fp->pub._p = fp->_bf._base;
 131         fp->pub._r = _sread(fp, (char *)fp->pub._p, fp->_bf._size);
 132         fp->pub._flags &= ~__SMOD;      /* buffer contents are again pristine */
 133         if (fp->pub._r <= 0) {
 134                 if (fp->pub._r == 0)
 135                         fp->pub._flags |= __SEOF;
 136                 else {
 137                         fp->pub._r = 0;
 138                         fp->pub._flags |= __SERR;
 139                 }
 140                 return (EOF);
 141         }
 142         return (0);
 143 }