lib/libc/stdio/fparseln.c

   1 /*      $NetBSD: fparseln.c,v 1.10 2009/10/21 01:07:45 snj Exp $        */
   2
   3 /*
   4  * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 #if defined(LIBC_SCCS) && !defined(lint)
  29 __RCSID("$NetBSD: fparseln.c,v 1.10 2009/10/21 01:07:45 snj Exp $");
  30 #endif /* LIBC_SCCS and not lint */
  31
  32 #include "namespace.h"
  33
  34 #include <assert.h>
  35 #include <errno.h>
  36 #include <stdio.h>
  37 #include <string.h>
  38 #include <stdlib.h>
  39
  40 #ifdef __weak_alias
  41 __weak_alias(fparseln,_fparseln)
  42 #endif
  43
  44 #if ! HAVE_FPARSELN || BROKEN_FPARSELN
  45
  46 #ifndef HAVE_NBTOOL_CONFIG_H
  47 #include "reentrant.h"
  48 #include "local.h"
  49 #else
  50 #define FLOCKFILE(fp)
  51 #define FUNLOCKFILE(fp)
  52 #endif
  53
  54 #if defined(_REENTRANT) && !HAVE_NBTOOL_CONFIG_H
  55 #define __fgetln(f, l) __fgetstr(f, l, '\n')
  56 #else
  57 #define __fgetln(f, l) fgetln(f, l)
  58 #endif
  59
  60 static int isescaped(const char *, const char *, int);
  61
  62 /* isescaped():
  63  *      Return true if the character in *p that belongs to a string
  64  *      that starts in *sp, is escaped by the escape character esc.
  65  */
  66 static int
  67 isescaped(const char *sp, const char *p, int esc)
  68 {
  69         const char     *cp;
  70         size_t          ne;
  71
  72         _DIAGASSERT(sp != NULL);
  73         _DIAGASSERT(p != NULL);
  74
  75         /* No escape character */
  76         if (esc == '\0')
  77                 return 0;
  78
  79         /* Count the number of escape characters that precede ours */
  80         for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
  81                 continue;
  82
  83         /* Return true if odd number of escape characters */
  84         return (ne & 1) != 0;
  85 }
  86
  87
  88 /* fparseln():
  89  *      Read a line from a file parsing continuations ending in \
  90  *      and eliminating trailing newlines, or comments starting with
  91  *      the comment char.
  92  */
  93 char *
  94 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
  95 {
  96         static const char dstr[3] = { '\\', '\\', '#' };
  97
  98         size_t  s, len;
  99         char   *buf;
 100         char   *ptr, *cp;
 101         int     cnt;
 102         char    esc, con, nl, com;
 103
 104         _DIAGASSERT(fp != NULL);
 105
 106         len = 0;
 107         buf = NULL;
 108         cnt = 1;
 109
 110         if (str == NULL)
 111                 str = dstr;
 112
 113         esc = str[0];
 114         con = str[1];
 115         com = str[2];
 116         /*
 117          * XXX: it would be cool to be able to specify the newline character,
 118          * but unfortunately, fgetln does not let us
 119          */
 120         nl  = '\n';
 121
 122         FLOCKFILE(fp);
 123
 124         while (cnt) {
 125                 cnt = 0;
 126
 127                 if (lineno)
 128                         (*lineno)++;
 129
 130                 if ((ptr = __fgetln(fp, &s)) == NULL)
 131                         break;
 132
 133                 if (s && com) {         /* Check and eliminate comments */
 134                         for (cp = ptr; cp < ptr + s; cp++)
 135                                 if (*cp == com && !isescaped(ptr, cp, esc)) {
 136                                         s = cp - ptr;
 137                                         cnt = s == 0 && buf == NULL;
 138                                         break;
 139                                 }
 140                 }
 141
 142                 if (s && nl) {          /* Check and eliminate newlines */
 143                         cp = &ptr[s - 1];
 144
 145                         if (*cp == nl)
 146                                 s--;    /* forget newline */
 147                 }
 148
 149                 if (s && con) {         /* Check and eliminate continuations */
 150                         cp = &ptr[s - 1];
 151
 152                         if (*cp == con && !isescaped(ptr, cp, esc)) {
 153                                 s--;    /* forget continuation char */
 154                                 cnt = 1;
 155                         }
 156                 }
 157
 158                 if (s == 0) {
 159                         /*
 160                          * nothing to add, skip realloc except in case
 161                          * we need a minimal buf to return an empty line
 162                          */
 163                         if (cnt || buf != NULL)
 164                                 continue;
 165                 }
 166
 167                 if ((cp = realloc(buf, len + s + 1)) == NULL) {
 168                         FUNLOCKFILE(fp);
 169                         free(buf);
 170                         return NULL;
 171                 }
 172                 buf = cp;
 173
 174                 (void) memcpy(buf + len, ptr, s);
 175                 len += s;
 176                 buf[len] = '\0';
 177         }
 178
 179         FUNLOCKFILE(fp);
 180
 181         if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
 182             strchr(buf, esc) != NULL) {
 183                 ptr = cp = buf;
 184                 while (cp[0] != '\0') {
 185                         int skipesc;
 186
 187                         while (cp[0] != '\0' && cp[0] != esc)
 188                                 *ptr++ = *cp++;
 189                         if (cp[0] == '\0' || cp[1] == '\0')
 190                                 break;
 191
 192                         skipesc = 0;
 193                         if (cp[1] == com)
 194                                 skipesc += (flags & FPARSELN_UNESCCOMM);
 195                         if (cp[1] == con)
 196                                 skipesc += (flags & FPARSELN_UNESCCONT);
 197                         if (cp[1] == esc)
 198                                 skipesc += (flags & FPARSELN_UNESCESC);
 199                         if (cp[1] != com && cp[1] != con && cp[1] != esc)
 200                                 skipesc = (flags & FPARSELN_UNESCREST);
 201
 202                         if (skipesc)
 203                                 cp++;
 204                         else
 205                                 *ptr++ = *cp++;
 206                         *ptr++ = *cp++;
 207                 }
 208                 *ptr = '\0';
 209                 len = strlen(buf);
 210         }
 211
 212         if (size)
 213                 *size = len;
 214         return buf;
 215 }
 216
 217 #ifdef TEST
 218
 219 int main(int, char **);
 220
 221 int
 222 main(int argc, char **argv)
 223 {
 224         char   *ptr;
 225         size_t  size, line;
 226
 227         line = 0;
 228         while ((ptr = fparseln(stdin, &size, &line, NULL,
 229             FPARSELN_UNESCALL)) != NULL)
 230                 printf("line %d (%d) |%s|\n", line, size, ptr);
 231         return 0;
 232 }
 233
 234 /*
 235
 236 # This is a test
 237 line 1
 238 line 2 \
 239 line 3 # Comment
 240 line 4 \# Not comment \\\\
 241
 242 # And a comment \
 243 line 5 \\\
 244 line 6
 245
 246 */
 247
 248 #endif /* TEST */
 249 #endif  /* ! HAVE_FPARSELN || BROKEN_FPARSELN */