xref: /PHP-8.1/ext/fileinfo/libmagic/is_csv.c (revision 3b9173dc)
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 *
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 = 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