Edit File: is_csv.c
/*- * 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 1.6 2020/08/09 16:43:36 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, rv; 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 = 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