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 1.7 2022/05/28 00:44:22 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 *
eatquote(const unsigned char * uc,const unsigned char * ue)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
csv_parse(const unsigned char * uc,const unsigned char * ue)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
file_is_csv(struct magic_set * ms,const struct buffer * b,int looks_text)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
main(int argc,char * argv[])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 = CAST(char *, 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