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-rw-r--r--encoding.c484
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diff --git a/encoding.c b/encoding.c
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+/*
+ * 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 1.3 2009/02/03 20:27:51 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 *);
+
+/*
+ * 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;
+
+ 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;
+ }
+
+ *type = "text";
+ if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
+ *code = "ASCII";
+ *code_mime = "us-ascii";
+ } else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
+ *code = "UTF-8 Unicode (with BOM)";
+ *code_mime = "utf-8";
+ } else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
+ *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";
+ }
+ } else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
+ *code = "ISO-8859";
+ *code_mime = "iso-8859-1";
+ } else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
+ *code = "Non-ISO extended-ASCII";
+ *code_mime = "unknown-8bit";
+ } else {
+ from_ebcdic(buf, nbytes, nbuf);
+
+ if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
+ *code = "EBCDIC";
+ *code_mime = "ebcdic";
+ } else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
+ *code = "International EBCDIC";
+ *code_mime = "ebcdic";
+ } else { /* Doesn't look like text at all */
+ rv = 0;
+ *type = "binary";
+ }
+ }
+
+ done:
+ if (nbuf)
+ 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]];
+ }
+}