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  * 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
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)refill.c    8.1 (Berkeley) 6/4/93";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdio/refill.c,v 1.18 2002/08/13 09:30:41 tjr Exp $");
  42
  43 #include "namespace.h"
  44 #include <errno.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include "un-namespace.h"
  48
  49 #include "libc_private.h"
  50 #include "local.h"
  51
  52 static int lflush(FILE *);
  53
  54 static int
  55 lflush(FILE *fp)
  56 {
  57         int     ret = 0;
  58
  59         if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) {
  60                 FLOCKFILE(fp);
  61                 ret = __sflush(fp);
  62                 FUNLOCKFILE(fp);
  63         }
  64         return (ret);
  65 }
  66
  67 /*
  68  * Refill a stdio buffer.
  69  * Return EOF on eof or error, 0 otherwise.
  70  */
  71 int
  72 __srefill(FILE *fp)
  73 {
  74
  75         /* make sure stdio is set up */
  76         if (!__sdidinit)
  77                 __sinit();
  78
  79         ORIENT(fp, -1);
  80
  81         fp->_r = 0;             /* largely a convenience for callers */
  82
  83         /* SysV does not make this test; take it out for compatibility */
  84         if (fp->_flags & __SEOF)
  85                 return (EOF);
  86
  87         /* if not already reading, have to be reading and writing */
  88         if ((fp->_flags & __SRD) == 0) {
  89                 if ((fp->_flags & __SRW) == 0) {
  90                         errno = EBADF;
  91                         fp->_flags |= __SERR;
  92                         return (EOF);
  93                 }
  94                 /* switch to reading */
  95                 if (fp->_flags & __SWR) {
  96                         if (__sflush(fp))
  97                                 return (EOF);
  98                         fp->_flags &= ~__SWR;
  99                         fp->_w = 0;
 100                         fp->_lbfsize = 0;
 101                 }
 102                 fp->_flags |= __SRD;
 103         } else {
 104                 /*
 105                  * We were reading.  If there is an ungetc buffer,
 106                  * we must have been reading from that.  Drop it,
 107                  * restoring the previous buffer (if any).  If there
 108                  * is anything in that buffer, return.
 109                  */
 110                 if (HASUB(fp)) {
 111                         FREEUB(fp);
 112                         if ((fp->_r = fp->_ur) != 0) {
 113                                 fp->_p = fp->_extra->_up;
 114                                 return (0);
 115                         }
 116                 }
 117         }
 118
 119         if (fp->_bf._base == NULL)
 120                 __smakebuf(fp);
 121
 122         /*
 123          * Before reading from a line buffered or unbuffered file,
 124          * flush all line buffered output files, per the ANSI C
 125          * standard.
 126          */
 127         if (fp->_flags & (__SLBF|__SNBF)) {
 128                 /* Ignore this file in _fwalk to avoid potential deadlock. */
 129                 fp->_flags |= __SIGN;
 130                 (void) _fwalk(lflush);
 131                 fp->_flags &= ~__SIGN;
 132
 133                 /* Now flush this file without locking it. */
 134                 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
 135                         __sflush(fp);
 136         }
 137         fp->_p = fp->_bf._base;
 138         fp->_r = _sread(fp, (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 }