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DEFINITIONS
This source file includes following definitions.
- FILE_RCSID
- looks_ascii
- looks_latin1
- looks_extended
- file_looks_utf8
- looks_utf8_with_BOM
- looks_ucs16
- from_ebcdic
/*
* 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.
*/
/*
* Encoding -- determine the character encoding of a text file.
*
* Joerg Wunsch <joerg@freebsd.org> wrote the original support for 8-bit
* international characters.
*/
#include "file.h"
#ifndef lint
FILE_RCSID("@(#)$File: encoding.c,v 1.7 2012/01/24 19:02:02 christos Exp $")
#endif /* lint */
#include "magic.h"
#include <string.h>
#include <memory.h>
#include <stdlib.h>
private int looks_ascii(const unsigned char *, size_t, unichar *, size_t *);
private int looks_utf8_with_BOM(const unsigned char *, size_t, unichar *,
size_t *);
private int looks_ucs16(const unsigned char *, size_t, unichar *, size_t *);
private int looks_latin1(const unsigned char *, size_t, unichar *, size_t *);
private int looks_extended(const unsigned char *, size_t, unichar *, size_t *);
private void from_ebcdic(const unsigned char *, size_t, unsigned char *);
#ifdef DEBUG_ENCODING
#define DPRINTF(a) printf a
#else
#define DPRINTF(a)
#endif
/*
* Try to determine whether text is in some character code we can
* identify. Each of these tests, if it succeeds, will leave
* the text converted into one-unichar-per-character Unicode in
* ubuf, and the number of characters converted in ulen.
*/
protected int
file_encoding(struct magic_set *ms, const unsigned char *buf, size_t nbytes, unichar **ubuf, size_t *ulen, const char **code, const char **code_mime, const char **type)
{
size_t mlen;
int rv = 1, ucs_type;
unsigned char *nbuf = NULL;
*type = "text";
mlen = (nbytes + 1) * sizeof(nbuf[0]);
if ((nbuf = CAST(unsigned char *, calloc((size_t)1, mlen))) == NULL) {
file_oomem(ms, mlen);
goto done;
}
mlen = (nbytes + 1) * sizeof((*ubuf)[0]);
if ((*ubuf = CAST(unichar *, calloc((size_t)1, mlen))) == NULL) {
file_oomem(ms, mlen);
goto done;
}
if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
DPRINTF(("ascii %" SIZE_T_FORMAT "u\n", *ulen));
*code = "ASCII";
*code_mime = "us-ascii";
} else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
DPRINTF(("utf8/bom %" SIZE_T_FORMAT "u\n", *ulen));
*code = "UTF-8 Unicode (with BOM)";
*code_mime = "utf-8";
} else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
DPRINTF(("utf8 %" SIZE_T_FORMAT "u\n", *ulen));
*code = "UTF-8 Unicode (with BOM)";
*code = "UTF-8 Unicode";
*code_mime = "utf-8";
} else if ((ucs_type = looks_ucs16(buf, nbytes, *ubuf, ulen)) != 0) {
if (ucs_type == 1) {
*code = "Little-endian UTF-16 Unicode";
*code_mime = "utf-16le";
} else {
*code = "Big-endian UTF-16 Unicode";
*code_mime = "utf-16be";
}
DPRINTF(("ucs16 %" SIZE_T_FORMAT "u\n", *ulen));
} else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
DPRINTF(("latin1 %" SIZE_T_FORMAT "u\n", *ulen));
*code = "ISO-8859";
*code_mime = "iso-8859-1";
} else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
DPRINTF(("extended %" SIZE_T_FORMAT "u\n", *ulen));
*code = "Non-ISO extended-ASCII";
*code_mime = "unknown-8bit";
} else {
from_ebcdic(buf, nbytes, nbuf);
if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
DPRINTF(("ebcdic %" SIZE_T_FORMAT "u\n", *ulen));
*code = "EBCDIC";
*code_mime = "ebcdic";
} else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
DPRINTF(("ebcdic/international %" SIZE_T_FORMAT "u\n",
*ulen));
*code = "International EBCDIC";
*code_mime = "ebcdic";
} else { /* Doesn't look like text at all */
DPRINTF(("binary\n"));
rv = 0;
*type = "binary";
}
}
done:
free(nbuf);
return rv;
}
/*
* This table reflects a particular philosophy about what constitutes
* "text," and there is room for disagreement about it.
*
* Version 3.31 of the file command considered a file to be ASCII if
* each of its characters was approved by either the isascii() or
* isalpha() function. On most systems, this would mean that any
* file consisting only of characters in the range 0x00 ... 0x7F
* would be called ASCII text, but many systems might reasonably
* consider some characters outside this range to be alphabetic,
* so the file command would call such characters ASCII. It might
* have been more accurate to call this "considered textual on the
* local system" than "ASCII."
*
* It considered a file to be "International language text" if each
* of its characters was either an ASCII printing character (according
* to the real ASCII standard, not the above test), a character in
* the range 0x80 ... 0xFF, or one of the following control characters:
* backspace, tab, line feed, vertical tab, form feed, carriage return,
* escape. No attempt was made to determine the language in which files
* of this type were written.
*
*
* The table below considers a file to be ASCII if all of its characters
* are either ASCII printing characters (again, according to the X3.4
* standard, not isascii()) or any of the following controls: bell,
* backspace, tab, line feed, form feed, carriage return, esc, nextline.
*
* I include bell because some programs (particularly shell scripts)
* use it literally, even though it is rare in normal text. I exclude
* vertical tab because it never seems to be used in real text. I also
* include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
* because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
* character to. It might be more appropriate to include it in the 8859
* set instead of the ASCII set, but it's got to be included in *something*
* we recognize or EBCDIC files aren't going to be considered textual.
* Some old Unix source files use SO/SI (^N/^O) to shift between Greek
* and Latin characters, so these should possibly be allowed. But they
* make a real mess on VT100-style displays if they're not paired properly,
* so we are probably better off not calling them text.
*
* A file is considered to be ISO-8859 text if its characters are all
* either ASCII, according to the above definition, or printing characters
* from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
*
* Finally, a file is considered to be international text from some other
* character code if its characters are all either ISO-8859 (according to
* the above definition) or characters in the range 0x80 ... 0x9F, which
* ISO-8859 considers to be control characters but the IBM PC and Macintosh
* consider to be printing characters.
*/
#define F 0 /* character never appears in text */
#define T 1 /* character appears in plain ASCII text */
#define I 2 /* character appears in ISO-8859 text */
#define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
private char text_chars[256] = {
/* BEL BS HT LF FF CR */
F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
/* ESC */
F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
/* NEL */
X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
};
private int
looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
size_t *ulen)
{
size_t i;
*ulen = 0;
for (i = 0; i < nbytes; i++) {
int t = text_chars[buf[i]];
if (t != T)
return 0;
ubuf[(*ulen)++] = buf[i];
}
return 1;
}
private int
looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
{
size_t i;
*ulen = 0;
for (i = 0; i < nbytes; i++) {
int t = text_chars[buf[i]];
if (t != T && t != I)
return 0;
ubuf[(*ulen)++] = buf[i];
}
return 1;
}
private int
looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
size_t *ulen)
{
size_t i;
*ulen = 0;
for (i = 0; i < nbytes; i++) {
int t = text_chars[buf[i]];
if (t != T && t != I && t != X)
return 0;
ubuf[(*ulen)++] = buf[i];
}
return 1;
}
/*
* Decide whether some text looks like UTF-8. Returns:
*
* -1: invalid UTF-8
* 0: uses odd control characters, so doesn't look like text
* 1: 7-bit text
* 2: definitely UTF-8 text (valid high-bit set bytes)
*
* If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
* ubuf must be big enough!
*/
protected int
file_looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
{
size_t i;
int n;
unichar c;
int gotone = 0, ctrl = 0;
if (ubuf)
*ulen = 0;
for (i = 0; i < nbytes; i++) {
if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
/*
* Even if the whole file is valid UTF-8 sequences,
* still reject it if it uses weird control characters.
*/
if (text_chars[buf[i]] != T)
ctrl = 1;
if (ubuf)
ubuf[(*ulen)++] = buf[i];
} else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
return -1;
} else { /* 11xxxxxx begins UTF-8 */
int following;
if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
c = buf[i] & 0x1f;
following = 1;
} else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
c = buf[i] & 0x0f;
following = 2;
} else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
c = buf[i] & 0x07;
following = 3;
} else if ((buf[i] & 0x04) == 0) { /* 111110xx */
c = buf[i] & 0x03;
following = 4;
} else if ((buf[i] & 0x02) == 0) { /* 1111110x */
c = buf[i] & 0x01;
following = 5;
} else
return -1;
for (n = 0; n < following; n++) {
i++;
if (i >= nbytes)
goto done;
if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
return -1;
c = (c << 6) + (buf[i] & 0x3f);
}
if (ubuf)
ubuf[(*ulen)++] = c;
gotone = 1;
}
}
done:
return ctrl ? 0 : (gotone ? 2 : 1);
}
/*
* Decide whether some text looks like UTF-8 with BOM. If there is no
* BOM, return -1; otherwise return the result of looks_utf8 on the
* rest of the text.
*/
private int
looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes, unichar *ubuf,
size_t *ulen)
{
if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
else
return -1;
}
private int
looks_ucs16(const unsigned char *buf, size_t nbytes, unichar *ubuf,
size_t *ulen)
{
int bigend;
size_t i;
if (nbytes < 2)
return 0;
if (buf[0] == 0xff && buf[1] == 0xfe)
bigend = 0;
else if (buf[0] == 0xfe && buf[1] == 0xff)
bigend = 1;
else
return 0;
*ulen = 0;
for (i = 2; i + 1 < nbytes; i += 2) {
/* XXX fix to properly handle chars > 65536 */
if (bigend)
ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
else
ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
if (ubuf[*ulen - 1] == 0xfffe)
return 0;
if (ubuf[*ulen - 1] < 128 &&
text_chars[(size_t)ubuf[*ulen - 1]] != T)
return 0;
}
return 1 + bigend;
}
#undef F
#undef T
#undef I
#undef X
/*
* This table maps each EBCDIC character to an (8-bit extended) ASCII
* character, as specified in the rationale for the dd(1) command in
* draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
*
* Unfortunately it does not seem to correspond exactly to any of the
* five variants of EBCDIC documented in IBM's _Enterprise Systems
* Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
* Edition, July, 1999, pp. I-1 - I-4.
*
* Fortunately, though, all versions of EBCDIC, including this one, agree
* on most of the printing characters that also appear in (7-bit) ASCII.
* Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
*
* Fortunately too, there is general agreement that codes 0x00 through
* 0x3F represent control characters, 0x41 a nonbreaking space, and the
* remainder printing characters.
*
* This is sufficient to allow us to identify EBCDIC text and to distinguish
* between old-style and internationalized examples of text.
*/
private unsigned char ebcdic_to_ascii[] = {
0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
'&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
'-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
'{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
'}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
'\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
};
#ifdef notdef
/*
* The following EBCDIC-to-ASCII table may relate more closely to reality,
* or at least to modern reality. It comes from
*
* http://ftp.s390.ibm.com/products/oe/bpxqp9.html
*
* and maps the characters of EBCDIC code page 1047 (the code used for
* Unix-derived software on IBM's 390 systems) to the corresponding
* characters from ISO 8859-1.
*
* If this table is used instead of the above one, some of the special
* cases for the NEL character can be taken out of the code.
*/
private unsigned char ebcdic_1047_to_8859[] = {
0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
};
#endif
/*
* Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
*/
private void
from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
{
size_t i;
for (i = 0; i < nbytes; i++) {
out[i] = ebcdic_to_ascii[buf[i]];
}
}