1 /* $NetBSD: fparseln.c,v 1.10 2009/10/21 01:07:45 snj Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-2-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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/types.h> 30 #include <assert.h> 31 #include <errno.h> 32 #include <stdio.h> 33 #include <string.h> 34 #include <stdlib.h> 35 #include <libutil.h> 36 37 static int isescaped(const char *, const char *, int); 38 39 /* isescaped(): 40 * Return true if the character in *p that belongs to a string 41 * that starts in *sp, is escaped by the escape character esc. 42 */ 43 static int 44 isescaped(const char *sp, const char *p, int esc) 45 { 46 const char *cp; 47 size_t ne; 48 49 #if 0 50 _DIAGASSERT(sp != NULL); 51 _DIAGASSERT(p != NULL); 52 #endif 53 54 /* No escape character */ 55 if (esc == '\0') 56 return 0; 57 58 /* Count the number of escape characters that precede ours */ 59 for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++) 60 continue; 61 62 /* Return true if odd number of escape characters */ 63 return (ne & 1) != 0; 64 } 65 66 67 /* fparseln(): 68 * Read a line from a file parsing continuations ending in \ 69 * and eliminating trailing newlines, or comments starting with 70 * the comment char. 71 */ 72 char * 73 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags) 74 { 75 static const char dstr[3] = { '\\', '\\', '#' }; 76 77 size_t s, len; 78 char *buf; 79 char *ptr, *cp; 80 int cnt; 81 char esc, con, nl, com; 82 83 #if 0 84 _DIAGASSERT(fp != NULL); 85 #endif 86 87 len = 0; 88 buf = NULL; 89 cnt = 1; 90 91 if (str == NULL) 92 str = dstr; 93 94 esc = str[0]; 95 con = str[1]; 96 com = str[2]; 97 /* 98 * XXX: it would be cool to be able to specify the newline character, 99 * but unfortunately, fgetln does not let us 100 */ 101 nl = '\n'; 102 103 while (cnt) { 104 cnt = 0; 105 106 if (lineno) 107 (*lineno)++; 108 109 if ((ptr = fgetln(fp, &s)) == NULL) 110 break; 111 112 if (s && com) { /* Check and eliminate comments */ 113 for (cp = ptr; cp < ptr + s; cp++) 114 if (*cp == com && !isescaped(ptr, cp, esc)) { 115 s = cp - ptr; 116 cnt = s == 0 && buf == NULL; 117 break; 118 } 119 } 120 121 if (s && nl) { /* Check and eliminate newlines */ 122 cp = &ptr[s - 1]; 123 124 if (*cp == nl) 125 s--; /* forget newline */ 126 } 127 128 if (s && con) { /* Check and eliminate continuations */ 129 cp = &ptr[s - 1]; 130 131 if (*cp == con && !isescaped(ptr, cp, esc)) { 132 s--; /* forget continuation char */ 133 cnt = 1; 134 } 135 } 136 137 if (s == 0) { 138 /* 139 * nothing to add, skip realloc except in case 140 * we need a minimal buf to return an empty line 141 */ 142 if (cnt || buf != NULL) 143 continue; 144 } 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 */ 223