1 /*- 2 * Copyright (c) 2019 Christos Zoulas 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 15 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 16 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 18 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 19 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 20 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 21 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 22 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 23 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 24 * POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * Parse CSV object serialization format (RFC-4180, RFC-7111) 29 */ 30 31 #ifndef TEST 32 #include "file.h" 33 34 #ifndef lint 35 FILE_RCSID("@(#)$File: is_csv.c,v 1.6 2020/08/09 16:43:36 christos Exp $") 36 #endif 37 38 #include <string.h> 39 #include "magic.h" 40 #else 41 #include <sys/types.h> 42 #endif 43 44 45 #ifdef DEBUG 46 #include <stdio.h> 47 #define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__) 48 #else 49 #define DPRINTF(fmt, ...) 50 #endif 51 52 /* 53 * if CSV_LINES == 0: 54 * check all the lines in the buffer 55 * otherwise: 56 * check only up-to the number of lines specified 57 * 58 * the last line count is always ignored if it does not end in CRLF 59 */ 60 #ifndef CSV_LINES 61 #define CSV_LINES 10 62 #endif 63 64 static int csv_parse(const unsigned char *, const unsigned char *); 65 66 static const unsigned char * 67 eatquote(const unsigned char *uc, const unsigned char *ue) 68 { 69 int quote = 0; 70 71 while (uc < ue) { 72 unsigned char c = *uc++; 73 if (c != '"') { 74 // We already got one, done. 75 if (quote) { 76 return --uc; 77 } 78 continue; 79 } 80 if (quote) { 81 // quote-quote escapes 82 quote = 0; 83 continue; 84 } 85 // first quote 86 quote = 1; 87 } 88 return ue; 89 } 90 91 static int 92 csv_parse(const unsigned char *uc, const unsigned char *ue) 93 { 94 size_t nf = 0, tf = 0, nl = 0; 95 96 while (uc < ue) { 97 switch (*uc++) { 98 case '"': 99 // Eat until the matching quote 100 uc = eatquote(uc, ue); 101 break; 102 case ',': 103 nf++; 104 break; 105 case '\n': 106 DPRINTF("%zu %zu %zu\n", nl, nf, tf); 107 nl++; 108 #if CSV_LINES 109 if (nl == CSV_LINES) 110 return tf != 0 && tf == nf; 111 #endif 112 if (tf == 0) { 113 // First time and no fields, give up 114 if (nf == 0) 115 return 0; 116 // First time, set the number of fields 117 tf = nf; 118 } else if (tf != nf) { 119 // Field number mismatch, we are done. 120 return 0; 121 } 122 nf = 0; 123 break; 124 default: 125 break; 126 } 127 } 128 return tf && nl > 2; 129 } 130 131 #ifndef TEST 132 int 133 file_is_csv(struct magic_set *ms, const struct buffer *b, int looks_text) 134 { 135 const unsigned char *uc = CAST(const unsigned char *, b->fbuf); 136 const unsigned char *ue = uc + b->flen; 137 int mime = ms->flags & MAGIC_MIME; 138 139 if (!looks_text) 140 return 0; 141 142 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0) 143 return 0; 144 145 if (!csv_parse(uc, ue)) 146 return 0; 147 148 if (mime == MAGIC_MIME_ENCODING) 149 return 1; 150 151 if (mime) { 152 if (file_printf(ms, "text/csv") == -1) 153 return -1; 154 return 1; 155 } 156 157 if (file_printf(ms, "CSV text") == -1) 158 return -1; 159 160 return 1; 161 } 162 163 #else 164 165 #include <sys/types.h> 166 #include <sys/stat.h> 167 #include <stdio.h> 168 #include <fcntl.h> 169 #include <unistd.h> 170 #include <stdlib.h> 171 #include <stdint.h> 172 #include <err.h> 173 174 int 175 main(int argc, char *argv[]) 176 { 177 int fd, rv; 178 struct stat st; 179 unsigned char *p; 180 181 if ((fd = open(argv[1], O_RDONLY)) == -1) 182 err(EXIT_FAILURE, "Can't open `%s'", argv[1]); 183 184 if (fstat(fd, &st) == -1) 185 err(EXIT_FAILURE, "Can't stat `%s'", argv[1]); 186 187 if ((p = malloc(st.st_size)) == NULL) 188 err(EXIT_FAILURE, "Can't allocate %jd bytes", 189 (intmax_t)st.st_size); 190 if (read(fd, p, st.st_size) != st.st_size) 191 err(EXIT_FAILURE, "Can't read %jd bytes", 192 (intmax_t)st.st_size); 193 printf("is csv %d\n", csv_parse(p, p + st.st_size)); 194 return 0; 195 } 196 #endif 197