1 /* $NetBSD: fparseln.c,v 1.7 2007/03/08 19:57:53 drochner Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-4-Clause 5 * 6 * Copyright (c) 1997 Christos Zoulas. All rights reserved. 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 Christos Zoulas. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include <sys/types.h> 38 #include <assert.h> 39 #include <errno.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdlib.h> 43 #include <libutil.h> 44 45 static int isescaped(const char *, const char *, int); 46 47 /* isescaped(): 48 * Return true if the character in *p that belongs to a string 49 * that starts in *sp, is escaped by the escape character esc. 50 */ 51 static int 52 isescaped(const char *sp, const char *p, int esc) 53 { 54 const char *cp; 55 size_t ne; 56 57 #if 0 58 _DIAGASSERT(sp != NULL); 59 _DIAGASSERT(p != NULL); 60 #endif 61 62 /* No escape character */ 63 if (esc == '\0') 64 return 0; 65 66 /* Count the number of escape characters that precede ours */ 67 for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++) 68 continue; 69 70 /* Return true if odd number of escape characters */ 71 return (ne & 1) != 0; 72 } 73 74 75 /* fparseln(): 76 * Read a line from a file parsing continuations ending in \ 77 * and eliminating trailing newlines, or comments starting with 78 * the comment char. 79 */ 80 char * 81 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags) 82 { 83 static const char dstr[3] = { '\\', '\\', '#' }; 84 85 size_t s, len; 86 char *buf; 87 char *ptr, *cp; 88 int cnt; 89 char esc, con, nl, com; 90 91 #if 0 92 _DIAGASSERT(fp != NULL); 93 #endif 94 95 len = 0; 96 buf = NULL; 97 cnt = 1; 98 99 if (str == NULL) 100 str = dstr; 101 102 esc = str[0]; 103 con = str[1]; 104 com = str[2]; 105 /* 106 * XXX: it would be cool to be able to specify the newline character, 107 * but unfortunately, fgetln does not let us 108 */ 109 nl = '\n'; 110 111 while (cnt) { 112 cnt = 0; 113 114 if (lineno) 115 (*lineno)++; 116 117 if ((ptr = fgetln(fp, &s)) == NULL) 118 break; 119 120 if (s && com) { /* Check and eliminate comments */ 121 for (cp = ptr; cp < ptr + s; cp++) 122 if (*cp == com && !isescaped(ptr, cp, esc)) { 123 s = cp - ptr; 124 cnt = s == 0 && buf == NULL; 125 break; 126 } 127 } 128 129 if (s && nl) { /* Check and eliminate newlines */ 130 cp = &ptr[s - 1]; 131 132 if (*cp == nl) 133 s--; /* forget newline */ 134 } 135 136 if (s && con) { /* Check and eliminate continuations */ 137 cp = &ptr[s - 1]; 138 139 if (*cp == con && !isescaped(ptr, cp, esc)) { 140 s--; /* forget continuation char */ 141 cnt = 1; 142 } 143 } 144 145 if (s == 0) { 146 /* 147 * nothing to add, skip realloc except in case 148 * we need a minimal buf to return an empty line 149 */ 150 if (cnt || buf != NULL) 151 continue; 152 } 153 154 if ((cp = realloc(buf, len + s + 1)) == NULL) { 155 free(buf); 156 return NULL; 157 } 158 buf = cp; 159 160 (void) memcpy(buf + len, ptr, s); 161 len += s; 162 buf[len] = '\0'; 163 } 164 165 if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL && 166 strchr(buf, esc) != NULL) { 167 ptr = cp = buf; 168 while (cp[0] != '\0') { 169 int skipesc; 170 171 while (cp[0] != '\0' && cp[0] != esc) 172 *ptr++ = *cp++; 173 if (cp[0] == '\0' || cp[1] == '\0') 174 break; 175 176 skipesc = 0; 177 if (cp[1] == com) 178 skipesc += (flags & FPARSELN_UNESCCOMM); 179 if (cp[1] == con) 180 skipesc += (flags & FPARSELN_UNESCCONT); 181 if (cp[1] == esc) 182 skipesc += (flags & FPARSELN_UNESCESC); 183 if (cp[1] != com && cp[1] != con && cp[1] != esc) 184 skipesc = (flags & FPARSELN_UNESCREST); 185 186 if (skipesc) 187 cp++; 188 else 189 *ptr++ = *cp++; 190 *ptr++ = *cp++; 191 } 192 *ptr = '\0'; 193 len = strlen(buf); 194 } 195 196 if (size) 197 *size = len; 198 return buf; 199 } 200 201 #ifdef TEST 202 203 int 204 main(int argc, char *argv[]) 205 { 206 char *ptr; 207 size_t size, line; 208 209 line = 0; 210 while ((ptr = fparseln(stdin, &size, &line, NULL, 211 FPARSELN_UNESCALL)) != NULL) 212 printf("line %d (%d) |%s|\n", line, size, ptr); 213 return 0; 214 } 215 216 /* 217 218 # This is a test 219 line 1 220 line 2 \ 221 line 3 # Comment 222 line 4 \# Not comment \\\\ 223 224 # And a comment \ 225 line 5 \\\ 226 line 6 227 228 */ 229 230 #endif /* TEST */ 231