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 1.4 2019/06/26 20:31:31 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 unsigned char c;
98 switch (c = *uc++) {
99 case '"':
100 // Eat until the matching quote
101 uc = eatquote(uc, ue);
102 break;
103 case ',':
104 nf++;
105 break;
106 case '\n':
107 DPRINTF("%zu %zu %zu\n", nl, nf, tf);
108 nl++;
109 #if CSV_LINES
110 if (nl == CSV_LINES)
111 return tf != 0 && tf == nf;
112 #endif
113 if (tf == 0) {
114 // First time and no fields, give up
115 if (nf == 0)
116 return 0;
117 // First time, set the number of fields
118 tf = nf;
119 } else if (tf != nf) {
120 // Field number mismatch, we are done.
121 return 0;
122 }
123 nf = 0;
124 break;
125 default:
126 break;
127 }
128 }
129 return tf && nl > 2;
130 }
131
132 #ifndef TEST
133 int
file_is_csv(struct magic_set * ms,const struct buffer * b,int looks_text)134 file_is_csv(struct magic_set *ms, const struct buffer *b, int looks_text)
135 {
136 const unsigned char *uc = CAST(const unsigned char *, b->fbuf);
137 const unsigned char *ue = uc + b->flen;
138 int mime = ms->flags & MAGIC_MIME;
139
140 if (!looks_text)
141 return 0;
142
143 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0)
144 return 0;
145
146 if (!csv_parse(uc, ue))
147 return 0;
148
149 if (mime == MAGIC_MIME_ENCODING)
150 return 1;
151
152 if (mime) {
153 if (file_printf(ms, "application/csv") == -1)
154 return -1;
155 return 1;
156 }
157
158 if (file_printf(ms, "CSV text") == -1)
159 return -1;
160
161 return 1;
162 }
163
164 #else
165
166 #include <sys/types.h>
167 #include <sys/stat.h>
168 #include <stdio.h>
169 #include <fcntl.h>
170 #include <unistd.h>
171 #include <stdlib.h>
172 #include <stdint.h>
173 #include <err.h>
174
175 int
main(int argc,char * argv[])176 main(int argc, char *argv[])
177 {
178 int fd, rv;
179 struct stat st;
180 unsigned char *p;
181
182 if ((fd = open(argv[1], O_RDONLY)) == -1)
183 err(EXIT_FAILURE, "Can't open `%s'", argv[1]);
184
185 if (fstat(fd, &st) == -1)
186 err(EXIT_FAILURE, "Can't stat `%s'", argv[1]);
187
188 if ((p = malloc(st.st_size)) == NULL)
189 err(EXIT_FAILURE, "Can't allocate %jd bytes",
190 (intmax_t)st.st_size);
191 if (read(fd, p, st.st_size) != st.st_size)
192 err(EXIT_FAILURE, "Can't read %jd bytes",
193 (intmax_t)st.st_size);
194 printf("is csv %d\n", csv_parse(p, p + st.st_size));
195 return 0;
196 }
197 #endif
198
