StdLib/LibC/Stdio/fgetstr.c

   1 /*  $NetBSD: fgetstr.c,v 1.4 2006/11/24 19:46:58 christos Exp $ */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *  The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34 #include  <LibConfig.h>
  35 #include <sys/EfiCdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)fgetline.c  8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: fgetstr.c,v 1.4 2006/11/24 19:46:58 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45
  46 #include <assert.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include "reentrant.h"
  51 #include "local.h"
  52
  53 /*
  54  * Expand the line buffer.  Return -1 on error.
  55 #ifdef notdef
  56  * The `new size' does not account for a terminating '\0',
  57  * so we add 1 here.
  58 #endif
  59  */
  60 int
  61 __slbexpand(FILE *fp, size_t newsize)
  62 {
  63   void *p;
  64
  65 #ifdef notdef
  66   ++newsize;
  67 #endif
  68   _DIAGASSERT(fp != NULL);
  69
  70   if ((size_t)fp->_lb._size >= newsize)
  71     return (0);
  72   if ((p = realloc(fp->_lb._base, newsize)) == NULL)
  73     return (-1);
  74   fp->_lb._base = p;
  75   fp->_lb._size = (int)newsize;
  76   return (0);
  77 }
  78
  79 /*
  80  * Get an input line.  The returned pointer often (but not always)
  81  * points into a stdio buffer.  Fgetline does not alter the text of
  82  * the returned line (which is thus not a C string because it will
  83  * not necessarily end with '\0'), but does allow callers to modify
  84  * it if they wish.  Thus, we set __SMOD in case the caller does.
  85  */
  86 char *
  87 __fgetstr(FILE *fp, size_t *lenp, int sep)
  88 {
  89   unsigned char *p;
  90   size_t len;
  91   size_t off;
  92
  93   _DIAGASSERT(fp != NULL);
  94   _DIAGASSERT(lenp != NULL);
  95
  96   /* make sure there is input */
  97   if (fp->_r <= 0 && __srefill(fp)) {
  98     *lenp = 0;
  99     return (NULL);
 100   }
 101
 102   /* look for a newline in the input */
 103   if ((p = memchr((void *)fp->_p, sep, (size_t)fp->_r)) != NULL) {
 104     char *ret;
 105
 106     /*
 107      * Found one.  Flag buffer as modified to keep fseek from
 108      * `optimising' a backward seek, in case the user stomps on
 109      * the text.
 110      */
 111     p++;    /* advance over it */
 112     ret = (char *)fp->_p;
 113     *lenp = len = p - fp->_p;
 114     fp->_flags |= __SMOD;
 115     fp->_r -= (int)len;
 116     fp->_p = p;
 117     return (ret);
 118   }
 119
 120   /*
 121    * We have to copy the current buffered data to the line buffer.
 122    * As a bonus, though, we can leave off the __SMOD.
 123    *
 124    * OPTIMISTIC is length that we (optimistically) expect will
 125    * accommodate the `rest' of the string, on each trip through the
 126    * loop below.
 127    */
 128 #define OPTIMISTIC 80
 129
 130   for (len = fp->_r, off = 0;; len += fp->_r) {
 131     size_t diff;
 132
 133     /*
 134      * Make sure there is room for more bytes.  Copy data from
 135      * file buffer to line buffer, refill file and look for
 136      * newline.  The loop stops only when we find a newline.
 137      */
 138     if (__slbexpand(fp, len + OPTIMISTIC))
 139       goto error;
 140     (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
 141         len - off);
 142     off = len;
 143     if (__srefill(fp))
 144       break;  /* EOF or error: return partial line */
 145     if ((p = memchr((void *)fp->_p, sep, (size_t)fp->_r)) == NULL)
 146       continue;
 147
 148     /* got it: finish up the line (like code above) */
 149     p++;
 150     diff = p - fp->_p;
 151     len += diff;
 152     if (__slbexpand(fp, len))
 153       goto error;
 154     (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
 155         diff);
 156     fp->_r -= (int)diff;
 157     fp->_p = p;
 158     break;
 159   }
 160   *lenp = len;
 161 #ifdef notdef
 162   fp->_lb._base[len] = 0;
 163 #endif
 164   return ((char *)fp->_lb._base);
 165
 166 error:
 167   *lenp = 0;    /* ??? */
 168   return (NULL);    /* ??? */
 169 }