stdio/FreeBSD/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  * 4. 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
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)refill.c    8.1 (Berkeley) 6/4/93";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/refill.c,v 1.20 2008/04/17 22:17:54 jhb Exp $");
  38
  39 #include "namespace.h"
  40 #include <errno.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include "un-namespace.h"
  44
  45 #include "libc_private.h"
  46 #include "local.h"
  47
  48 static int lflush(FILE *);
  49
  50 static int
  51 lflush(FILE *fp)
  52 {
  53         int     ret = 0;
  54
  55         if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
  56                 FLOCKFILE(fp);
  57                 ret = __sflush(fp);
  58                 FUNLOCKFILE(fp);
  59         }
  60         return (ret);
  61 }
  62
  63 /*
  64  * Refill a stdio buffer.
  65  * Return EOF on eof or error, 0 otherwise.
  66  */
  67 int
  68 __srefill(FILE *fp)
  69 {
  70
  71         /* make sure stdio is set up */
  72         if (!__sdidinit)
  73                 __sinit();
  74
  75         ORIENT(fp, -1);
  76
  77         fp->_r = 0;             /* largely a convenience for callers */
  78
  79         /* SysV does not make this test; take it out for compatibility */
  80         if (fp->_flags & __SEOF)
  81                 return (EOF);
  82
  83         /* if not already reading, have to be reading and writing */
  84         if ((fp->_flags & __SRD) == 0) {
  85                 if ((fp->_flags & __SRW) == 0) {
  86                         errno = EBADF;
  87                         fp->_flags |= __SERR;
  88                         return (EOF);
  89                 }
  90                 /* switch to reading */
  91                 if (fp->_flags & __SWR) {
  92                         if (__sflush(fp))
  93                                 return (EOF);
  94                         fp->_flags &= ~__SWR;
  95                         fp->_w = 0;
  96                         fp->_lbfsize = 0;
  97                 }
  98                 fp->_flags |= __SRD;
  99         } else {
 100                 /*
 101                  * We were reading.  If there is an ungetc buffer,
 102                  * we must have been reading from that.  Drop it,
 103                  * restoring the previous buffer (if any).  If there
 104                  * is anything in that buffer, return.
 105                  */
 106                 if (HASUB(fp)) {
 107                         FREEUB(fp);
 108                         if ((fp->_r = fp->_ur) != 0) {
 109                                 fp->_p = fp->_up;
 110                                 return (0);
 111                         }
 112                 }
 113         }
 114
 115         if (fp->_bf._base == NULL)
 116                 __smakebuf(fp);
 117
 118         /*
 119          * Before reading from a line buffered or unbuffered file,
 120          * flush all line buffered output files, per the ANSI C
 121          * standard.
 122          */
 123         if (fp->_flags & (__SLBF|__SNBF)) {
 124                 /* Ignore this file in _fwalk to avoid potential deadlock. */
 125                 fp->_flags |= __SIGN;
 126                 (void) _fwalk(lflush);
 127                 fp->_flags &= ~__SIGN;
 128
 129                 /* Now flush this file without locking it. */
 130                 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
 131                         __sflush(fp);
 132         }
 133         fp->_p = fp->_bf._base;
 134         fp->_r = _sread(fp, (char *)fp->_p, fp->_bf._size);
 135         fp->_flags &= ~__SMOD;  /* buffer contents are again pristine */
 136         if (fp->_r <= 0) {
 137                 if (fp->_r == 0)
 138                         fp->_flags |= __SEOF;
 139                 else {
 140                         fp->_r = 0;
 141                         fp->_flags |= __SERR;
 142                 }
 143                 return (EOF);
 144         }
 145         return (0);
 146 }