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Diffstat (limited to 'src/is_csv.c')
| -rw-r--r-- | src/is_csv.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/src/is_csv.c b/src/is_csv.c new file mode 100644 index 0000000..597d775 --- /dev/null +++ b/src/is_csv.c @@ -0,0 +1,196 @@ +/*- + * Copyright (c) 2019 Christos Zoulas + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +/* + * Parse CSV object serialization format (RFC-4180, RFC-7111) + */ + +#ifndef TEST +#include "file.h" + +#ifndef lint +FILE_RCSID("@(#)$File: is_csv.c,v 1.10 2022/09/24 20:30:13 christos Exp $") +#endif + +#include <string.h> +#include "magic.h" +#else +#include <sys/types.h> +#endif + + +#ifdef DEBUG +#include <stdio.h> +#define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__) +#else +#define DPRINTF(fmt, ...) +#endif + +/* + * if CSV_LINES == 0: + * check all the lines in the buffer + * otherwise: + * check only up-to the number of lines specified + * + * the last line count is always ignored if it does not end in CRLF + */ +#ifndef CSV_LINES +#define CSV_LINES 10 +#endif + +static int csv_parse(const unsigned char *, const unsigned char *); + +static const unsigned char * +eatquote(const unsigned char *uc, const unsigned char *ue) +{ + int quote = 0; + + while (uc < ue) { + unsigned char c = *uc++; + if (c != '"') { + // We already got one, done. + if (quote) { + return --uc; + } + continue; + } + if (quote) { + // quote-quote escapes + quote = 0; + continue; + } + // first quote + quote = 1; + } + return ue; +} + +static int +csv_parse(const unsigned char *uc, const unsigned char *ue) +{ + size_t nf = 0, tf = 0, nl = 0; + + while (uc < ue) { + switch (*uc++) { + case '"': + // Eat until the matching quote + uc = eatquote(uc, ue); + break; + case ',': + nf++; + break; + case '\n': + DPRINTF("%zu %zu %zu\n", nl, nf, tf); + nl++; +#if CSV_LINES + if (nl == CSV_LINES) + return tf != 0 && tf == nf; +#endif + if (tf == 0) { + // First time and no fields, give up + if (nf == 0) + return 0; + // First time, set the number of fields + tf = nf; + } else if (tf != nf) { + // Field number mismatch, we are done. + return 0; + } + nf = 0; + break; + default: + break; + } + } + return tf && nl > 2; +} + +#ifndef TEST +int +file_is_csv(struct magic_set *ms, const struct buffer *b, int looks_text) +{ + const unsigned char *uc = CAST(const unsigned char *, b->fbuf); + const unsigned char *ue = uc + b->flen; + int mime = ms->flags & MAGIC_MIME; + + if (!looks_text) + return 0; + + if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0) + return 0; + + if (!csv_parse(uc, ue)) + return 0; + + if (mime == MAGIC_MIME_ENCODING) + return 1; + + if (mime) { + if (file_printf(ms, "text/csv") == -1) + return -1; + return 1; + } + + if (file_printf(ms, "CSV text") == -1) + return -1; + + return 1; +} + +#else + +#include <sys/types.h> +#include <sys/stat.h> +#include <stdio.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdint.h> +#include <err.h> + +int +main(int argc, char *argv[]) +{ + int fd; + struct stat st; + unsigned char *p; + + if ((fd = open(argv[1], O_RDONLY)) == -1) + err(EXIT_FAILURE, "Can't open `%s'", argv[1]); + + if (fstat(fd, &st) == -1) + err(EXIT_FAILURE, "Can't stat `%s'", argv[1]); + + if ((p = CAST(char *, malloc(st.st_size))) == NULL) + err(EXIT_FAILURE, "Can't allocate %jd bytes", + (intmax_t)st.st_size); + if (read(fd, p, st.st_size) != st.st_size) + err(EXIT_FAILURE, "Can't read %jd bytes", + (intmax_t)st.st_size); + printf("is csv %d\n", csv_parse(p, p + st.st_size)); + return 0; +} +#endif |