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/types.h> 35 #include <assert.h> 36 #include <errno.h> 37 #include <stdio.h> 38 #include <string.h> 39 #include <stdlib.h> 40 #include <libutil.h> 41 42 static int isescaped(const char *, const char *, int); 43 44 /* isescaped(): 45 * Return true if the character in *p that belongs to a string 46 * that starts in *sp, is escaped by the escape character esc. 47 */ 48 static int 49 isescaped(const char *sp, const char *p, int esc) 50 { 51 const char *cp; 52 size_t ne; 53 54 #if 0 55 _DIAGASSERT(sp != NULL); 56 _DIAGASSERT(p != NULL); 57 #endif 58 59 /* No escape character */ 60 if (esc == '\0') 61 return 0; 62 63 /* Count the number of escape characters that precede ours */ 64 for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++) 65 continue; 66 67 /* Return true if odd number of escape characters */ 68 return (ne & 1) != 0; 69 } 70 71 72 /* fparseln(): 73 * Read a line from a file parsing continuations ending in \ 74 * and eliminating trailing newlines, or comments starting with 75 * the comment char. 76 */ 77 char * 78 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags) 79 { 80 static const char dstr[3] = { '\\', '\\', '#' }; 81 82 size_t s, len; 83 char *buf; 84 char *ptr, *cp; 85 int cnt; 86 char esc, con, nl, com; 87 88 #if 0 89 _DIAGASSERT(fp != NULL); 90 #endif 91 92 len = 0; 93 buf = NULL; 94 cnt = 1; 95 96 if (str == NULL) 97 str = dstr; 98 99 esc = str[0]; 100 con = str[1]; 101 com = str[2]; 102 /* 103 * XXX: it would be cool to be able to specify the newline character, 104 * but unfortunately, fgetln does not let us 105 */ 106 nl = '\n'; 107 108 while (cnt) { 109 cnt = 0; 110 111 if (lineno) 112 (*lineno)++; 113 114 if ((ptr = fgetln(fp, &s)) == NULL) 115 break; 116 117 if (s && com) { /* Check and eliminate comments */ 118 for (cp = ptr; cp < ptr + s; cp++) 119 if (*cp == com && !isescaped(ptr, cp, esc)) { 120 s = cp - ptr; 121 cnt = s == 0 && buf == NULL; 122 break; 123 } 124 } 125 126 if (s && nl) { /* Check and eliminate newlines */ 127 cp = &ptr[s - 1]; 128 129 if (*cp == nl) 130 s--; /* forget newline */ 131 } 132 133 if (s && con) { /* Check and eliminate continuations */ 134 cp = &ptr[s - 1]; 135 136 if (*cp == con && !isescaped(ptr, cp, esc)) { 137 s--; /* forget continuation char */ 138 cnt = 1; 139 } 140 } 141 142 if (s == 0) { 143 /* 144 * nothing to add, skip realloc except in case 145 * we need a minimal buf to return an empty line 146 */ 147 if (cnt || buf != NULL) 148 continue; 149 } 150 151 if ((cp = realloc(buf, len + s + 1)) == NULL) { 152 free(buf); 153 return NULL; 154 } 155 buf = cp; 156 157 (void) memcpy(buf + len, ptr, s); 158 len += s; 159 buf[len] = '\0'; 160 } 161 162 if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL && 163 strchr(buf, esc) != NULL) { 164 ptr = cp = buf; 165 while (cp[0] != '\0') { 166 int skipesc; 167 168 while (cp[0] != '\0' && cp[0] != esc) 169 *ptr++ = *cp++; 170 if (cp[0] == '\0' || cp[1] == '\0') 171 break; 172 173 skipesc = 0; 174 if (cp[1] == com) 175 skipesc += (flags & FPARSELN_UNESCCOMM); 176 if (cp[1] == con) 177 skipesc += (flags & FPARSELN_UNESCCONT); 178 if (cp[1] == esc) 179 skipesc += (flags & FPARSELN_UNESCESC); 180 if (cp[1] != com && cp[1] != con && cp[1] != esc) 181 skipesc = (flags & FPARSELN_UNESCREST); 182 183 if (skipesc) 184 cp++; 185 else 186 *ptr++ = *cp++; 187 *ptr++ = *cp++; 188 } 189 *ptr = '\0'; 190 len = strlen(buf); 191 } 192 193 if (size) 194 *size = len; 195 return buf; 196 } 197 198 #ifdef TEST 199 200 int 201 main(int argc, char *argv[]) 202 { 203 char *ptr; 204 size_t size, line; 205 206 line = 0; 207 while ((ptr = fparseln(stdin, &size, &line, NULL, 208 FPARSELN_UNESCALL)) != NULL) 209 printf("line %d (%d) |%s|\n", line, size, ptr); 210 return 0; 211 } 212 213 /* 214 215 # This is a test 216 line 1 217 line 2 \ 218 line 3 # Comment 219 line 4 \# Not comment \\\\ 220 221 # And a comment \ 222 line 5 \\\ 223 line 6 224 225 */ 226 227 #endif /* TEST */ 228