gonzui

    1: /*      $OpenBSD: refill.c,v 1.11 2009/11/09 00:18:27 kurt Exp $ */
    2: /*-
    3:  * Copyright (c) 1990, 1993
    4:  *      The Regents of the University of California.  All rights reserved.
    5:  *
    6:  * This code is derived from software contributed to Berkeley by
    7:  * Chris Torek.
    8:  *
    9:  * Redistribution and use in source and binary forms, with or without
   10:  * modification, are permitted provided that the following conditions
   11:  * are met:
   12:  * 1. Redistributions of source code must retain the above copyright
   13:  *    notice, this list of conditions and the following disclaimer.
   14:  * 2. Redistributions in binary form must reproduce the above copyright
   15:  *    notice, this list of conditions and the following disclaimer in the
   16:  *    documentation and/or other materials provided with the distribution.
   17:  * 3. Neither the name of the University nor the names of its contributors
   18:  *    may be used to endorse or promote products derived from this software
   19:  *    without specific prior written permission.
   20:  *
   21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31:  * SUCH DAMAGE.
   32:  */
   33: 
   34: #include <errno.h>
   35: #include <stdio.h>
   36: #include <stdlib.h>
   37: #include "local.h"
   38: 
   39: static int
   40: lflush(FILE *fp)
   41: {
   42:         if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
   43:                 return (__sflush_locked(fp)); /* ignored... */
   44:         return (0);
   45: }
   46: 
   47: /*
   48:  * Refill a stdio buffer.
   49:  * Return EOF on eof or error, 0 otherwise.
   50:  */
   51: int
   52: __srefill(FILE *fp)
   53: {
   54: 
   55:         /* make sure stdio is set up */
   56:         if (!__sdidinit)
   57:                 __sinit();
   58: 
   59:         fp->_r = 0;            /* largely a convenience for callers */
   60: 
   61:         /* SysV does not make this test; take it out for compatibility */
   62:         if (fp->_flags & __SEOF)
   63:                 return (EOF);
   64: 
   65:         /* if not already reading, have to be reading and writing */
   66:         if ((fp->_flags & __SRD) == 0) {
   67:                 if ((fp->_flags & __SRW) == 0) {
   68:                         __sseterr(fp, EBADF);
   69:                         fp->_flags |= __SERR;
   70:                         return (EOF);
   71:                 }
   72:                 /* switch to reading */
   73:                 if (fp->_flags & __SWR) {
   74:                         if (__sflush(fp))
   75:                                 return (EOF);
   76:                         fp->_flags &= ~__SWR;
   77:                         fp->_w = 0;
   78:                         fp->_lbfsize = 0;
   79:                 }
   80:                 fp->_flags |= __SRD;
   81:         } else {
   82:                 /*
   83:                  * We were reading.  If there is an ungetc buffer,
   84:                  * we must have been reading from that.  Drop it,
   85:                  * restoring the previous buffer (if any).  If there
   86:                  * is anything in that buffer, return.
   87:                  */
   88:                 if (HASUB(fp)) {
   89:                         FREEUB(fp);
   90:                         if ((fp->_r = fp->_ur) != 0) {
   91:                                 fp->_p = fp->_up;
   92:                                 return (0);
   93:                         }
   94:                 }
   95:         }
   96: 
   97:         if (fp->_bf._base == NULL)
   98:                 __smakebuf(fp);
   99: 
  100:         /*
  101:          * Before reading from a line buffered or unbuffered file,
  102:          * flush all line buffered output files, per the ANSI C
  103:          * standard.
  104:          */
  105:         if (fp->_flags & (__SLBF|__SNBF)) {
  106:                 /* Ignore this file in _fwalk to avoid potential deadlock. */
  107:                 fp->_flags |= __SIGN;
  108:                 (void) _fwalk(lflush);
  109:                 fp->_flags &= ~__SIGN;
  110: 
  111:                 /* Now flush this file without locking it. */
  112:                 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
  113:                         __sflush(fp);
  114:         }
  115:         fp->_p = fp->_bf._base;
  116:         fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
  117:         fp->_flags &= ~__SMOD; /* buffer contents are again pristine */
  118:         if (fp->_r <= 0) {
  119:                 if (fp->_r == 0)
  120:                         fp->_flags |= __SEOF;
  121:                 else {
  122:                         fp->_r = 0;
  123:                         fp->_flags |= __SERR;
  124:                 }
  125:                 return (EOF);
  126:         }
  127:         return (0);
  128: }