xref: /freebsd/contrib/file/src/is_csv.c (revision f7c32ed617858bcd22f8d1b03199099d50125721)
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 *
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 		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
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
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