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Diffstat (limited to 'src/ascmagic.c')
| -rw-r--r-- | src/ascmagic.c | 395 |
1 files changed, 395 insertions, 0 deletions
diff --git a/src/ascmagic.c b/src/ascmagic.c new file mode 100644 index 0000000..487f55d --- /dev/null +++ b/src/ascmagic.c @@ -0,0 +1,395 @@ +/* + * Copyright (c) Ian F. Darwin 1986-1995. + * Software written by Ian F. Darwin and others; + * maintained 1995-present by Christos Zoulas and others. + * + * 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 immediately at the beginning of the file, without modification, + * 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 AUTHOR 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 AUTHOR 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. + */ +/* + * ASCII magic -- try to detect text encoding. + * + * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000, + * to handle character codes other than ASCII on a unified basis. + */ + +#include "file.h" + +#ifndef lint +FILE_RCSID("@(#)$File: ascmagic.c,v 1.113 2022/12/26 17:31:14 christos Exp $") +#endif /* lint */ + +#include "magic.h" +#include <string.h> +#include <ctype.h> +#include <stdlib.h> +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif + +#define MAXLINELEN 300 /* longest sane line length */ +#define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \ + || (x) == 0x85 || (x) == '\f') + +file_private unsigned char *encode_utf8(unsigned char *, size_t, file_unichar_t *, + size_t); +file_private size_t trim_nuls(const unsigned char *, size_t); + +/* + * Undo the NUL-termination kindly provided by process() + * but leave at least one byte to look at + */ +file_private size_t +trim_nuls(const unsigned char *buf, size_t nbytes) +{ + while (nbytes > 1 && buf[nbytes - 1] == '\0') + nbytes--; + + return nbytes; +} + +file_protected int +file_ascmagic(struct magic_set *ms, const struct buffer *b, int text) +{ + file_unichar_t *ubuf = NULL; + size_t ulen = 0; + int rv = 1; + struct buffer bb; + + const char *code = NULL; + const char *code_mime = NULL; + const char *type = NULL; + + bb = *b; + bb.flen = trim_nuls(CAST(const unsigned char *, b->fbuf), b->flen); + /* + * Avoid trimming at an odd byte if the original buffer was evenly + * sized; this avoids losing the last character on UTF-16 LE text + */ + if ((bb.flen & 1) && !(b->flen & 1)) + bb.flen++; + + /* If file doesn't look like any sort of text, give up. */ + if (file_encoding(ms, &bb, &ubuf, &ulen, &code, &code_mime, + &type) == 0) + rv = 0; + else + rv = file_ascmagic_with_encoding(ms, &bb, + ubuf, ulen, code, type, text); + + free(ubuf); + + return rv; +} + +file_protected int +file_ascmagic_with_encoding(struct magic_set *ms, const struct buffer *b, + file_unichar_t *ubuf, size_t ulen, const char *code, const char *type, + int text) +{ + struct buffer bb; + const unsigned char *buf = CAST(const unsigned char *, b->fbuf); + size_t nbytes = b->flen; + unsigned char *utf8_buf = NULL, *utf8_end; + size_t mlen, i, len; + int rv = -1; + int mime = ms->flags & MAGIC_MIME; + int need_separator = 0; + + const char *subtype = NULL; + + int has_escapes = 0; + int has_backspace = 0; + int seen_cr = 0; + + int n_crlf = 0; + int n_lf = 0; + int n_cr = 0; + int n_nel = 0; + int executable = 0; + + size_t last_line_end = CAST(size_t, -1); + size_t has_long_lines = 0; + + nbytes = trim_nuls(buf, nbytes); + + /* If we have fewer than 2 bytes, give up. */ + if (nbytes <= 1) { + rv = 0; + goto done; + } + + if (ulen > 0 && (ms->flags & MAGIC_NO_CHECK_SOFT) == 0) { + /* Convert ubuf to UTF-8 and try text soft magic */ + /* malloc size is a conservative overestimate; could be + improved, or at least realloced after conversion. */ + mlen = ulen * 6; + if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) { + file_oomem(ms, mlen); + goto done; + } + if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen)) + == NULL) + goto done; + buffer_init(&bb, b->fd, &b->st, utf8_buf, + CAST(size_t, utf8_end - utf8_buf)); + + if ((rv = file_softmagic(ms, &bb, NULL, NULL, + TEXTTEST, text)) == 0) + rv = -1; + else + need_separator = 1; + buffer_fini(&bb); + if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { + rv = rv == -1 ? 0 : 1; + goto done; + } + } + + if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION))) { + rv = 0; + goto done; + } + + /* Now try to discover other details about the file. */ + for (i = 0; i < ulen; i++) { + if (ubuf[i] == '\n') { + if (seen_cr) + n_crlf++; + else + n_lf++; + last_line_end = i; + } else if (seen_cr) + n_cr++; + + seen_cr = (ubuf[i] == '\r'); + if (seen_cr) + last_line_end = i; + + if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */ + n_nel++; + last_line_end = i; + } + + /* If this line is _longer_ than MAXLINELEN, remember it. */ + if (i > last_line_end + MAXLINELEN) { + size_t ll = i - last_line_end; + if (ll > has_long_lines) + has_long_lines = ll; + } + + if (ubuf[i] == '\033') + has_escapes = 1; + if (ubuf[i] == '\b') + has_backspace = 1; + } + + /* Beware, if the data has been truncated, the final CR could have + been followed by a LF. If we have ms->bytes_max bytes, it indicates + that the data might have been truncated, probably even before + this function was called. */ + if (seen_cr && nbytes < ms->bytes_max) + n_cr++; + + if (strcmp(type, "binary") == 0) { + rv = 0; + goto done; + } + len = file_printedlen(ms); + if (mime) { + if ((mime & MAGIC_MIME_TYPE) != 0) { + if (len) { + /* + * Softmagic printed something, we + * are either done, or we need a separator + */ + if ((ms->flags & MAGIC_CONTINUE) == 0) { + rv = 1; + goto done; + } + if (need_separator && file_separator(ms) == -1) + goto done; + } else { + if (file_printf(ms, "text/plain") == -1) + goto done; + } + } + } else { + if (len) { + switch (file_replace(ms, " text$", ", ")) { + case 0: + switch (file_replace(ms, " text executable$", + ", ")) { + case 0: + if (file_printf(ms, ", ") == -1) + goto done; + break; + case -1: + goto done; + default: + executable = 1; + break; + } + break; + case -1: + goto done; + default: + break; + } + } + + if (file_printf(ms, "%s", code) == -1) + goto done; + + if (subtype) { + if (file_printf(ms, " %s", subtype) == -1) + goto done; + } + + if (file_printf(ms, " %s", type) == -1) + goto done; + + if (executable) + if (file_printf(ms, " executable") == -1) + goto done; + + if (has_long_lines) + if (file_printf(ms, ", with very long lines (%" + SIZE_T_FORMAT "u)", has_long_lines) == -1) + goto done; + + /* + * Only report line terminators if we find one other than LF, + * or if we find none at all. + */ + if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) || + (n_crlf != 0 || n_cr != 0 || n_nel != 0)) { + if (file_printf(ms, ", with") == -1) + goto done; + + if (n_crlf == 0 && n_cr == 0 && + n_nel == 0 && n_lf == 0) { + if (file_printf(ms, " no") == -1) + goto done; + } else { + if (n_crlf) { + if (file_printf(ms, " CRLF") == -1) + goto done; + if (n_cr || n_lf || n_nel) + if (file_printf(ms, ",") == -1) + goto done; + } + if (n_cr) { + if (file_printf(ms, " CR") == -1) + goto done; + if (n_lf || n_nel) + if (file_printf(ms, ",") == -1) + goto done; + } + if (n_lf) { + if (file_printf(ms, " LF") == -1) + goto done; + if (n_nel) + if (file_printf(ms, ",") == -1) + goto done; + } + if (n_nel) + if (file_printf(ms, " NEL") == -1) + goto done; + } + + if (file_printf(ms, " line terminators") == -1) + goto done; + } + + if (has_escapes) + if (file_printf(ms, ", with escape sequences") == -1) + goto done; + if (has_backspace) + if (file_printf(ms, ", with overstriking") == -1) + goto done; + } + rv = 1; +done: + free(utf8_buf); + + return rv; +} + +/* + * Encode Unicode string as UTF-8, returning pointer to character + * after end of string, or NULL if an invalid character is found. + */ +file_private unsigned char * +encode_utf8(unsigned char *buf, size_t len, file_unichar_t *ubuf, size_t ulen) +{ + size_t i; + unsigned char *end = buf + len; + + for (i = 0; i < ulen; i++) { + if (ubuf[i] <= 0x7f) { + if (end - buf < 1) + return NULL; + *buf++ = CAST(unsigned char, ubuf[i]); + continue; + } + if (ubuf[i] <= 0x7ff) { + if (end - buf < 2) + return NULL; + *buf++ = CAST(unsigned char, (ubuf[i] >> 6) + 0xc0); + goto out1; + } + if (ubuf[i] <= 0xffff) { + if (end - buf < 3) + return NULL; + *buf++ = CAST(unsigned char, (ubuf[i] >> 12) + 0xe0); + goto out2; + } + if (ubuf[i] <= 0x1fffff) { + if (end - buf < 4) + return NULL; + *buf++ = CAST(unsigned char, (ubuf[i] >> 18) + 0xf0); + goto out3; + } + if (ubuf[i] <= 0x3ffffff) { + if (end - buf < 5) + return NULL; + *buf++ = CAST(unsigned char, (ubuf[i] >> 24) + 0xf8); + goto out4; + } + if (ubuf[i] <= 0x7fffffff) { + if (end - buf < 6) + return NULL; + *buf++ = CAST(unsigned char, (ubuf[i] >> 30) + 0xfc); + goto out5; + } + /* Invalid character */ + return NULL; + out5: *buf++ = CAST(unsigned char, ((ubuf[i] >> 24) & 0x3f) + 0x80); + out4: *buf++ = CAST(unsigned char, ((ubuf[i] >> 18) & 0x3f) + 0x80); + out3: *buf++ = CAST(unsigned char, ((ubuf[i] >> 12) & 0x3f) + 0x80); + out2: *buf++ = CAST(unsigned char, ((ubuf[i] >> 6) & 0x3f) + 0x80); + out1: *buf++ = CAST(unsigned char, ((ubuf[i] >> 0) & 0x3f) + 0x80); + } + + return buf; +} |