lib/libutil/fparseln.c

   1 /*      $NetBSD: fparseln.c,v 1.9 1999/09/20 04:48:06 lukem 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  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by Christos Zoulas.
  17  * 4. The name of the author may not be used to endorse or promote products
  18  *    derived from this software without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include <sys/types.h>
  36 #include <assert.h>
  37 #include <errno.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <stdlib.h>
  41 #include <libutil.h>
  42
  43 static int isescaped(const char *, const char *, int);
  44
  45 /* isescaped():
  46  *      Return true if the character in *p that belongs to a string
  47  *      that starts in *sp, is escaped by the escape character esc.
  48  */
  49 static int
  50 isescaped(const char *sp, const char *p, int esc)
  51 {
  52         const char     *cp;
  53         size_t          ne;
  54
  55 #if 0
  56         _DIAGASSERT(sp != NULL);
  57         _DIAGASSERT(p != NULL);
  58 #endif
  59
  60         /* No escape character */
  61         if (esc == '\0')
  62                 return 1;
  63
  64         /* Count the number of escape characters that precede ours */
  65         for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
  66                 continue;
  67
  68         /* Return true if odd number of escape characters */
  69         return (ne & 1) != 0;
  70 }
  71
  72
  73 /* fparseln():
  74  *      Read a line from a file parsing continuations ending in \
  75  *      and eliminating trailing newlines, or comments starting with
  76  *      the comment char.
  77  */
  78 char *
  79 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
  80 {
  81         static const char dstr[3] = { '\\', '\\', '#' };
  82
  83         size_t  s, len;
  84         char   *buf;
  85         char   *ptr, *cp;
  86         int     cnt;
  87         char    esc, con, nl, com;
  88
  89 #if 0
  90         _DIAGASSERT(fp != NULL);
  91 #endif
  92
  93         len = 0;
  94         buf = NULL;
  95         cnt = 1;
  96
  97         if (str == NULL)
  98                 str = dstr;
  99
 100         esc = str[0];
 101         con = str[1];
 102         com = str[2];
 103         /*
 104          * XXX: it would be cool to be able to specify the newline character,
 105          * but unfortunately, fgetln does not let us
 106          */
 107         nl  = '\n';
 108
 109         while (cnt) {
 110                 cnt = 0;
 111
 112                 if (lineno)
 113                         (*lineno)++;
 114
 115                 if ((ptr = fgetln(fp, &s)) == NULL)
 116                         break;
 117
 118                 if (s && com) {         /* Check and eliminate comments */
 119                         for (cp = ptr; cp < ptr + s; cp++)
 120                                 if (*cp == com && !isescaped(ptr, cp, esc)) {
 121                                         s = cp - ptr;
 122                                         cnt = s == 0 && buf == NULL;
 123                                         break;
 124                                 }
 125                 }
 126
 127                 if (s && nl) {          /* Check and eliminate newlines */
 128                         cp = &ptr[s - 1];
 129
 130                         if (*cp == nl)
 131                                 s--;    /* forget newline */
 132                 }
 133
 134                 if (s && con) {         /* Check and eliminate continuations */
 135                         cp = &ptr[s - 1];
 136
 137                         if (*cp == con && !isescaped(ptr, cp, esc)) {
 138                                 s--;    /* forget escape */
 139                                 cnt = 1;
 140                         }
 141                 }
 142
 143                 if (s == 0 && buf != NULL)
 144                         continue;
 145
 146                 if ((cp = realloc(buf, len + s + 1)) == NULL) {
 147                         free(buf);
 148                         return NULL;
 149                 }
 150                 buf = cp;
 151
 152                 (void) memcpy(buf + len, ptr, s);
 153                 len += s;
 154                 buf[len] = '\0';
 155         }
 156
 157         if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
 158             strchr(buf, esc) != NULL) {
 159                 ptr = cp = buf;
 160                 while (cp[0] != '\0') {
 161                         int skipesc;
 162
 163                         while (cp[0] != '\0' && cp[0] != esc)
 164                                 *ptr++ = *cp++;
 165                         if (cp[0] == '\0' || cp[1] == '\0')
 166                                 break;
 167
 168                         skipesc = 0;
 169                         if (cp[1] == com)
 170                                 skipesc += (flags & FPARSELN_UNESCCOMM);
 171                         if (cp[1] == con)
 172                                 skipesc += (flags & FPARSELN_UNESCCONT);
 173                         if (cp[1] == esc)
 174                                 skipesc += (flags & FPARSELN_UNESCESC);
 175                         if (cp[1] != com && cp[1] != con && cp[1] != esc)
 176                                 skipesc = (flags & FPARSELN_UNESCREST);
 177
 178                         if (skipesc)
 179                                 cp++;
 180                         else
 181                                 *ptr++ = *cp++;
 182                         *ptr++ = *cp++;
 183                 }
 184                 *ptr = '\0';
 185                 len = strlen(buf);
 186         }
 187
 188         if (size)
 189                 *size = len;
 190         return buf;
 191 }
 192
 193 #ifdef TEST
 194
 195 int
 196 main(int argc, char *argv[])
 197 {
 198         char   *ptr;
 199         size_t  size, line;
 200
 201         line = 0;
 202         while ((ptr = fparseln(stdin, &size, &line, NULL,
 203             FPARSELN_UNESCALL)) != NULL)
 204                 printf("line %d (%d) |%s|\n", line, size, ptr);
 205         return 0;
 206 }
 207
 208 /*
 209
 210 # This is a test
 211 line 1
 212 line 2 \
 213 line 3 # Comment
 214 line 4 \# Not comment \\\\
 215
 216 # And a comment \
 217 line 5 \\\
 218 line 6
 219
 220 */
 221
 222 #endif /* TEST */