390 lines
10 KiB
C
390 lines
10 KiB
C
/*
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* Copyright (c) Ian F. Darwin 1986-1995.
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* Software written by Ian F. Darwin and others;
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* maintained 1995-present by Christos Zoulas and others.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* ASCII magic -- file types that we know based on keywords
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* that can appear anywhere in the file.
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*
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* Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000,
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* to handle character codes other than ASCII on a unified basis.
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*/
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#include "file.h"
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#ifndef lint
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FILE_RCSID("@(#)$File: ascmagic.c,v 1.75 2009/02/03 20:27:51 christos Exp $")
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#endif /* lint */
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#include "magic.h"
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#include <string.h>
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#include <memory.h>
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#include <ctype.h>
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#include <stdlib.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "names.h"
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#define MAXLINELEN 300 /* longest sane line length */
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#define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
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|| (x) == 0x85 || (x) == '\f')
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private int ascmatch(const unsigned char *, const unichar *, size_t);
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private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t);
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private size_t trim_nuls(const unsigned char *, size_t);
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/*
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* Undo the NUL-termination kindly provided by process()
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* but leave at least one byte to look at
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*/
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private size_t
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trim_nuls(const unsigned char *buf, size_t nbytes)
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{
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while (nbytes > 1 && buf[nbytes - 1] == '\0')
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nbytes--;
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return nbytes;
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}
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protected int
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file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes)
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{
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unichar *ubuf = NULL;
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size_t ulen;
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int rv = 1;
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const char *code = NULL;
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const char *code_mime = NULL;
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const char *type = NULL;
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if (ms->flags & MAGIC_APPLE)
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return 0;
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nbytes = trim_nuls(buf, nbytes);
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/* If file doesn't look like any sort of text, give up. */
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if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime,
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&type) == 0) {
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rv = 0;
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goto done;
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}
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rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code,
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type);
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done:
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if (ubuf)
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free(ubuf);
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return rv;
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}
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protected int
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file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf,
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size_t nbytes, unichar *ubuf, size_t ulen, const char *code,
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const char *type)
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{
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unsigned char *utf8_buf = NULL, *utf8_end;
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size_t mlen, i;
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const struct names *p;
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int rv = -1;
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int mime = ms->flags & MAGIC_MIME;
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const char *subtype = NULL;
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const char *subtype_mime = NULL;
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int has_escapes = 0;
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int has_backspace = 0;
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int seen_cr = 0;
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int n_crlf = 0;
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int n_lf = 0;
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int n_cr = 0;
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int n_nel = 0;
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size_t last_line_end = (size_t)-1;
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int has_long_lines = 0;
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if (ms->flags & MAGIC_APPLE)
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return 0;
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nbytes = trim_nuls(buf, nbytes);
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/* If we have fewer than 2 bytes, give up. */
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if (nbytes <= 1) {
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rv = 0;
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goto done;
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}
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/* Convert ubuf to UTF-8 and try text soft magic */
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/* malloc size is a conservative overestimate; could be
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improved, or at least realloced after conversion. */
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mlen = ulen * 6;
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if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) {
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file_oomem(ms, mlen);
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goto done;
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}
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if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) == NULL)
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goto done;
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if ((rv = file_softmagic(ms, utf8_buf, (size_t)(utf8_end - utf8_buf),
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TEXTTEST)) != 0)
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goto done;
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else
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rv = -1;
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/* look for tokens from names.h - this is expensive! */
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if ((ms->flags & MAGIC_NO_CHECK_TOKENS) != 0)
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goto subtype_identified;
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i = 0;
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while (i < ulen) {
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size_t end;
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/* skip past any leading space */
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while (i < ulen && ISSPC(ubuf[i]))
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i++;
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if (i >= ulen)
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break;
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/* find the next whitespace */
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for (end = i + 1; end < nbytes; end++)
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if (ISSPC(ubuf[end]))
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break;
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/* compare the word thus isolated against the token list */
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for (p = names; p < names + NNAMES; p++) {
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if (ascmatch((const unsigned char *)p->name, ubuf + i,
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end - i)) {
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subtype = types[p->type].human;
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subtype_mime = types[p->type].mime;
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goto subtype_identified;
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}
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}
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i = end;
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}
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subtype_identified:
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/* Now try to discover other details about the file. */
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for (i = 0; i < ulen; i++) {
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if (ubuf[i] == '\n') {
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if (seen_cr)
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n_crlf++;
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else
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n_lf++;
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last_line_end = i;
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} else if (seen_cr)
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n_cr++;
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seen_cr = (ubuf[i] == '\r');
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if (seen_cr)
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last_line_end = i;
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if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
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n_nel++;
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last_line_end = i;
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}
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/* If this line is _longer_ than MAXLINELEN, remember it. */
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if (i > last_line_end + MAXLINELEN)
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has_long_lines = 1;
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if (ubuf[i] == '\033')
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has_escapes = 1;
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if (ubuf[i] == '\b')
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has_backspace = 1;
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}
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/* Beware, if the data has been truncated, the final CR could have
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been followed by a LF. If we have HOWMANY bytes, it indicates
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that the data might have been truncated, probably even before
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this function was called. */
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if (seen_cr && nbytes < HOWMANY)
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n_cr++;
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if (strcmp(type, "binary") == 0) {
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rv = 0;
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goto done;
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}
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if (mime) {
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if ((mime & MAGIC_MIME_TYPE) != 0) {
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if (subtype_mime) {
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if (file_printf(ms, "%s", subtype_mime) == -1)
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goto done;
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} else {
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if (file_printf(ms, "text/plain") == -1)
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goto done;
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}
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}
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} else {
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if (file_printf(ms, "%s", code) == -1)
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goto done;
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if (subtype) {
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if (file_printf(ms, " %s", subtype) == -1)
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goto done;
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}
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if (file_printf(ms, " %s", type) == -1)
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goto done;
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if (has_long_lines)
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if (file_printf(ms, ", with very long lines") == -1)
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goto done;
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/*
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* Only report line terminators if we find one other than LF,
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* or if we find none at all.
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*/
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if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
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(n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
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if (file_printf(ms, ", with") == -1)
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goto done;
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if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
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if (file_printf(ms, " no") == -1)
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goto done;
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} else {
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if (n_crlf) {
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if (file_printf(ms, " CRLF") == -1)
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goto done;
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if (n_cr || n_lf || n_nel)
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if (file_printf(ms, ",") == -1)
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goto done;
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}
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if (n_cr) {
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if (file_printf(ms, " CR") == -1)
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goto done;
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if (n_lf || n_nel)
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if (file_printf(ms, ",") == -1)
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goto done;
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}
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if (n_lf) {
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if (file_printf(ms, " LF") == -1)
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goto done;
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if (n_nel)
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if (file_printf(ms, ",") == -1)
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goto done;
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}
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if (n_nel)
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if (file_printf(ms, " NEL") == -1)
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goto done;
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}
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if (file_printf(ms, " line terminators") == -1)
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goto done;
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}
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if (has_escapes)
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if (file_printf(ms, ", with escape sequences") == -1)
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goto done;
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if (has_backspace)
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if (file_printf(ms, ", with overstriking") == -1)
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goto done;
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}
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rv = 1;
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done:
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if (utf8_buf)
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free(utf8_buf);
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return rv;
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}
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private int
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ascmatch(const unsigned char *s, const unichar *us, size_t ulen)
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{
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size_t i;
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for (i = 0; i < ulen; i++) {
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if (s[i] != us[i])
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return 0;
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}
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if (s[i])
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return 0;
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else
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return 1;
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}
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/*
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* Encode Unicode string as UTF-8, returning pointer to character
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* after end of string, or NULL if an invalid character is found.
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*/
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private unsigned char *
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encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
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{
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size_t i;
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unsigned char *end = buf + len;
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for (i = 0; i < ulen; i++) {
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if (ubuf[i] <= 0x7f) {
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if (end - buf < 1)
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return NULL;
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*buf++ = (unsigned char)ubuf[i];
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} else if (ubuf[i] <= 0x7ff) {
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if (end - buf < 2)
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return NULL;
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*buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
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*buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
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} else if (ubuf[i] <= 0xffff) {
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if (end - buf < 3)
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return NULL;
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*buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
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*buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
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*buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
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} else if (ubuf[i] <= 0x1fffff) {
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if (end - buf < 4)
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return NULL;
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*buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
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*buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
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*buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
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} else if (ubuf[i] <= 0x3ffffff) {
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if (end - buf < 5)
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return NULL;
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*buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
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*buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
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*buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
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} else if (ubuf[i] <= 0x7fffffff) {
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if (end - buf < 6)
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return NULL;
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*buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
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*buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
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*buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
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*buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
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} else /* Invalid character */
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return NULL;
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}
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return buf;
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}
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