git/utf8.c
brian m. carlson 79444c9294 utf8: handle systems that don't write BOM for UTF-16
When serializing UTF-16 (and UTF-32), there are three possible ways to
write the stream. One can write the data with a BOM in either big-endian
or little-endian format, or one can write the data without a BOM in
big-endian format.

Most systems' iconv implementations choose to write it with a BOM in
some endianness, since this is the most foolproof, and it is resistant
to misinterpretation on Windows, where UTF-16 and the little-endian
serialization are very common. For compatibility with Windows and to
avoid accidental misuse there, Git always wants to write UTF-16 with a
BOM, and will refuse to read UTF-16 without it.

However, musl's iconv implementation writes UTF-16 without a BOM,
relying on the user to interpret it as big-endian. This causes t0028 and
the related functionality to fail, since Git won't read the file without
a BOM.

Add a Makefile and #define knob, ICONV_OMITS_BOM, that can be set if the
iconv implementation has this behavior. When set, Git will write a BOM
manually for UTF-16 and UTF-32 and then force the data to be written in
UTF-16BE or UTF-32BE. We choose big-endian behavior here because the
tests use the raw "UTF-16" encoding, which will be big-endian when the
implementation requires this knob to be set.

Update the tests to detect this case and write test data with an added
BOM if necessary. Always write the BOM in the tests in big-endian
format, since all iconv implementations that omit a BOM must use
big-endian serialization according to the Unicode standard.

Preserve the existing behavior for systems which do not have this knob
enabled, since they may use optimized implementations, including
defaulting to the native endianness, which may improve performance.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-02-11 18:20:07 -08:00

814 lines
20 KiB
C

#include "git-compat-util.h"
#include "strbuf.h"
#include "utf8.h"
/* This code is originally from http://www.cl.cam.ac.uk/~mgk25/ucs/ */
static const char utf16_be_bom[] = {'\xFE', '\xFF'};
static const char utf16_le_bom[] = {'\xFF', '\xFE'};
static const char utf32_be_bom[] = {'\0', '\0', '\xFE', '\xFF'};
static const char utf32_le_bom[] = {'\xFF', '\xFE', '\0', '\0'};
struct interval {
ucs_char_t first;
ucs_char_t last;
};
size_t display_mode_esc_sequence_len(const char *s)
{
const char *p = s;
if (*p++ != '\033')
return 0;
if (*p++ != '[')
return 0;
while (isdigit(*p) || *p == ';')
p++;
if (*p++ != 'm')
return 0;
return p - s;
}
/* auxiliary function for binary search in interval table */
static int bisearch(ucs_char_t ucs, const struct interval *table, int max)
{
int min = 0;
int mid;
if (ucs < table[0].first || ucs > table[max].last)
return 0;
while (max >= min) {
mid = min + (max - min) / 2;
if (ucs > table[mid].last)
min = mid + 1;
else if (ucs < table[mid].first)
max = mid - 1;
else
return 1;
}
return 0;
}
/* The following two functions define the column width of an ISO 10646
* character as follows:
*
* - The null character (U+0000) has a column width of 0.
*
* - Other C0/C1 control characters and DEL will lead to a return
* value of -1.
*
* - Non-spacing and enclosing combining characters (general
* category code Mn or Me in the Unicode database) have a
* column width of 0.
*
* - SOFT HYPHEN (U+00AD) has a column width of 1.
*
* - Other format characters (general category code Cf in the Unicode
* database) and ZERO WIDTH SPACE (U+200B) have a column width of 0.
*
* - Hangul Jamo medial vowels and final consonants (U+1160-U+11FF)
* have a column width of 0.
*
* - Spacing characters in the East Asian Wide (W) or East Asian
* Full-width (F) category as defined in Unicode Technical
* Report #11 have a column width of 2.
*
* - All remaining characters (including all printable
* ISO 8859-1 and WGL4 characters, Unicode control characters,
* etc.) have a column width of 1.
*
* This implementation assumes that ucs_char_t characters are encoded
* in ISO 10646.
*/
static int git_wcwidth(ucs_char_t ch)
{
/*
* Sorted list of non-overlapping intervals of non-spacing characters,
*/
#include "unicode-width.h"
/* test for 8-bit control characters */
if (ch == 0)
return 0;
if (ch < 32 || (ch >= 0x7f && ch < 0xa0))
return -1;
/* binary search in table of non-spacing characters */
if (bisearch(ch, zero_width, sizeof(zero_width)
/ sizeof(struct interval) - 1))
return 0;
/* binary search in table of double width characters */
if (bisearch(ch, double_width, sizeof(double_width)
/ sizeof(struct interval) - 1))
return 2;
return 1;
}
/*
* Pick one ucs character starting from the location *start points at,
* and return it, while updating the *start pointer to point at the
* end of that character. When remainder_p is not NULL, the location
* holds the number of bytes remaining in the string that we are allowed
* to pick from. Otherwise we are allowed to pick up to the NUL that
* would eventually appear in the string. *remainder_p is also reduced
* by the number of bytes we have consumed.
*
* If the string was not a valid UTF-8, *start pointer is set to NULL
* and the return value is undefined.
*/
static ucs_char_t pick_one_utf8_char(const char **start, size_t *remainder_p)
{
unsigned char *s = (unsigned char *)*start;
ucs_char_t ch;
size_t remainder, incr;
/*
* A caller that assumes NUL terminated text can choose
* not to bother with the remainder length. We will
* stop at the first NUL.
*/
remainder = (remainder_p ? *remainder_p : 999);
if (remainder < 1) {
goto invalid;
} else if (*s < 0x80) {
/* 0xxxxxxx */
ch = *s;
incr = 1;
} else if ((s[0] & 0xe0) == 0xc0) {
/* 110XXXXx 10xxxxxx */
if (remainder < 2 ||
(s[1] & 0xc0) != 0x80 ||
(s[0] & 0xfe) == 0xc0)
goto invalid;
ch = ((s[0] & 0x1f) << 6) | (s[1] & 0x3f);
incr = 2;
} else if ((s[0] & 0xf0) == 0xe0) {
/* 1110XXXX 10Xxxxxx 10xxxxxx */
if (remainder < 3 ||
(s[1] & 0xc0) != 0x80 ||
(s[2] & 0xc0) != 0x80 ||
/* overlong? */
(s[0] == 0xe0 && (s[1] & 0xe0) == 0x80) ||
/* surrogate? */
(s[0] == 0xed && (s[1] & 0xe0) == 0xa0) ||
/* U+FFFE or U+FFFF? */
(s[0] == 0xef && s[1] == 0xbf &&
(s[2] & 0xfe) == 0xbe))
goto invalid;
ch = ((s[0] & 0x0f) << 12) |
((s[1] & 0x3f) << 6) | (s[2] & 0x3f);
incr = 3;
} else if ((s[0] & 0xf8) == 0xf0) {
/* 11110XXX 10XXxxxx 10xxxxxx 10xxxxxx */
if (remainder < 4 ||
(s[1] & 0xc0) != 0x80 ||
(s[2] & 0xc0) != 0x80 ||
(s[3] & 0xc0) != 0x80 ||
/* overlong? */
(s[0] == 0xf0 && (s[1] & 0xf0) == 0x80) ||
/* > U+10FFFF? */
(s[0] == 0xf4 && s[1] > 0x8f) || s[0] > 0xf4)
goto invalid;
ch = ((s[0] & 0x07) << 18) | ((s[1] & 0x3f) << 12) |
((s[2] & 0x3f) << 6) | (s[3] & 0x3f);
incr = 4;
} else {
invalid:
*start = NULL;
return 0;
}
*start += incr;
if (remainder_p)
*remainder_p = remainder - incr;
return ch;
}
/*
* This function returns the number of columns occupied by the character
* pointed to by the variable start. The pointer is updated to point at
* the next character. When remainder_p is not NULL, it points at the
* location that stores the number of remaining bytes we can use to pick
* a character (see pick_one_utf8_char() above).
*/
int utf8_width(const char **start, size_t *remainder_p)
{
ucs_char_t ch = pick_one_utf8_char(start, remainder_p);
if (!*start)
return 0;
return git_wcwidth(ch);
}
/*
* Returns the total number of columns required by a null-terminated
* string, assuming that the string is utf8. Returns strlen() instead
* if the string does not look like a valid utf8 string.
*/
int utf8_strnwidth(const char *string, int len, int skip_ansi)
{
int width = 0;
const char *orig = string;
if (len == -1)
len = strlen(string);
while (string && string < orig + len) {
int skip;
while (skip_ansi &&
(skip = display_mode_esc_sequence_len(string)) != 0)
string += skip;
width += utf8_width(&string, NULL);
}
return string ? width : len;
}
int utf8_strwidth(const char *string)
{
return utf8_strnwidth(string, -1, 0);
}
int is_utf8(const char *text)
{
while (*text) {
if (*text == '\n' || *text == '\t' || *text == '\r') {
text++;
continue;
}
utf8_width(&text, NULL);
if (!text)
return 0;
}
return 1;
}
static void strbuf_add_indented_text(struct strbuf *buf, const char *text,
int indent, int indent2)
{
if (indent < 0)
indent = 0;
while (*text) {
const char *eol = strchrnul(text, '\n');
if (*eol == '\n')
eol++;
strbuf_addchars(buf, ' ', indent);
strbuf_add(buf, text, eol - text);
text = eol;
indent = indent2;
}
}
/*
* Wrap the text, if necessary. The variable indent is the indent for the
* first line, indent2 is the indent for all other lines.
* If indent is negative, assume that already -indent columns have been
* consumed (and no extra indent is necessary for the first line).
*/
void strbuf_add_wrapped_text(struct strbuf *buf,
const char *text, int indent1, int indent2, int width)
{
int indent, w, assume_utf8 = 1;
const char *bol, *space, *start = text;
size_t orig_len = buf->len;
if (width <= 0) {
strbuf_add_indented_text(buf, text, indent1, indent2);
return;
}
retry:
bol = text;
w = indent = indent1;
space = NULL;
if (indent < 0) {
w = -indent;
space = text;
}
for (;;) {
char c;
size_t skip;
while ((skip = display_mode_esc_sequence_len(text)))
text += skip;
c = *text;
if (!c || isspace(c)) {
if (w <= width || !space) {
const char *start = bol;
if (!c && text == start)
return;
if (space)
start = space;
else
strbuf_addchars(buf, ' ', indent);
strbuf_add(buf, start, text - start);
if (!c)
return;
space = text;
if (c == '\t')
w |= 0x07;
else if (c == '\n') {
space++;
if (*space == '\n') {
strbuf_addch(buf, '\n');
goto new_line;
}
else if (!isalnum(*space))
goto new_line;
else
strbuf_addch(buf, ' ');
}
w++;
text++;
}
else {
new_line:
strbuf_addch(buf, '\n');
text = bol = space + isspace(*space);
space = NULL;
w = indent = indent2;
}
continue;
}
if (assume_utf8) {
w += utf8_width(&text, NULL);
if (!text) {
assume_utf8 = 0;
text = start;
strbuf_setlen(buf, orig_len);
goto retry;
}
} else {
w++;
text++;
}
}
}
void strbuf_add_wrapped_bytes(struct strbuf *buf, const char *data, int len,
int indent, int indent2, int width)
{
char *tmp = xstrndup(data, len);
strbuf_add_wrapped_text(buf, tmp, indent, indent2, width);
free(tmp);
}
void strbuf_utf8_replace(struct strbuf *sb_src, int pos, int width,
const char *subst)
{
struct strbuf sb_dst = STRBUF_INIT;
char *src = sb_src->buf;
char *end = src + sb_src->len;
char *dst;
int w = 0, subst_len = 0;
if (subst)
subst_len = strlen(subst);
strbuf_grow(&sb_dst, sb_src->len + subst_len);
dst = sb_dst.buf;
while (src < end) {
char *old;
size_t n;
while ((n = display_mode_esc_sequence_len(src))) {
memcpy(dst, src, n);
src += n;
dst += n;
}
if (src >= end)
break;
old = src;
n = utf8_width((const char**)&src, NULL);
if (!src) /* broken utf-8, do nothing */
goto out;
if (n && w >= pos && w < pos + width) {
if (subst) {
memcpy(dst, subst, subst_len);
dst += subst_len;
subst = NULL;
}
w += n;
continue;
}
memcpy(dst, old, src - old);
dst += src - old;
w += n;
}
strbuf_setlen(&sb_dst, dst - sb_dst.buf);
strbuf_swap(sb_src, &sb_dst);
out:
strbuf_release(&sb_dst);
}
/*
* Returns true (1) if the src encoding name matches the dst encoding
* name directly or one of its alternative names. E.g. UTF-16BE is the
* same as UTF16BE.
*/
static int same_utf_encoding(const char *src, const char *dst)
{
if (istarts_with(src, "utf") && istarts_with(dst, "utf")) {
/* src[3] or dst[3] might be '\0' */
int i = (src[3] == '-' ? 4 : 3);
int j = (dst[3] == '-' ? 4 : 3);
return !strcasecmp(src+i, dst+j);
}
return 0;
}
int is_encoding_utf8(const char *name)
{
if (!name)
return 1;
if (same_utf_encoding("utf-8", name))
return 1;
return 0;
}
int same_encoding(const char *src, const char *dst)
{
static const char utf8[] = "UTF-8";
if (!src)
src = utf8;
if (!dst)
dst = utf8;
if (same_utf_encoding(src, dst))
return 1;
return !strcasecmp(src, dst);
}
/*
* Wrapper for fprintf and returns the total number of columns required
* for the printed string, assuming that the string is utf8.
*/
int utf8_fprintf(FILE *stream, const char *format, ...)
{
struct strbuf buf = STRBUF_INIT;
va_list arg;
int columns;
va_start(arg, format);
strbuf_vaddf(&buf, format, arg);
va_end(arg);
columns = fputs(buf.buf, stream);
if (0 <= columns) /* keep the error from the I/O */
columns = utf8_strwidth(buf.buf);
strbuf_release(&buf);
return columns;
}
/*
* Given a buffer and its encoding, return it re-encoded
* with iconv. If the conversion fails, returns NULL.
*/
#ifndef NO_ICONV
#if defined(OLD_ICONV) || (defined(__sun__) && !defined(_XPG6))
typedef const char * iconv_ibp;
#else
typedef char * iconv_ibp;
#endif
char *reencode_string_iconv(const char *in, size_t insz, iconv_t conv,
size_t bom_len, size_t *outsz_p)
{
size_t outsz, outalloc;
char *out, *outpos;
iconv_ibp cp;
outsz = insz;
outalloc = st_add(outsz, 1 + bom_len); /* for terminating NUL */
out = xmalloc(outalloc);
outpos = out + bom_len;
cp = (iconv_ibp)in;
while (1) {
size_t cnt = iconv(conv, &cp, &insz, &outpos, &outsz);
if (cnt == (size_t) -1) {
size_t sofar;
if (errno != E2BIG) {
free(out);
return NULL;
}
/* insz has remaining number of bytes.
* since we started outsz the same as insz,
* it is likely that insz is not enough for
* converting the rest.
*/
sofar = outpos - out;
outalloc = st_add3(sofar, st_mult(insz, 2), 32);
out = xrealloc(out, outalloc);
outpos = out + sofar;
outsz = outalloc - sofar - 1;
}
else {
*outpos = '\0';
if (outsz_p)
*outsz_p = outpos - out;
break;
}
}
return out;
}
static const char *fallback_encoding(const char *name)
{
/*
* Some platforms do not have the variously spelled variants of
* UTF-8, so let's fall back to trying the most official
* spelling. We do so only as a fallback in case the platform
* does understand the user's spelling, but not our official
* one.
*/
if (is_encoding_utf8(name))
return "UTF-8";
/*
* Even though latin-1 is still seen in e-mail
* headers, some platforms only install ISO-8859-1.
*/
if (!strcasecmp(name, "latin-1"))
return "ISO-8859-1";
return name;
}
char *reencode_string_len(const char *in, size_t insz,
const char *out_encoding, const char *in_encoding,
size_t *outsz)
{
iconv_t conv;
char *out;
const char *bom_str = NULL;
size_t bom_len = 0;
if (!in_encoding)
return NULL;
/* UTF-16LE-BOM is the same as UTF-16 for reading */
if (same_utf_encoding("UTF-16LE-BOM", in_encoding))
in_encoding = "UTF-16";
/*
* For writing, UTF-16 iconv typically creates "UTF-16BE-BOM"
* Some users under Windows want the little endian version
*
* We handle UTF-16 and UTF-32 ourselves only if the platform does not
* provide a BOM (which we require), since we want to match the behavior
* of the system tools and libc as much as possible.
*/
if (same_utf_encoding("UTF-16LE-BOM", out_encoding)) {
bom_str = utf16_le_bom;
bom_len = sizeof(utf16_le_bom);
out_encoding = "UTF-16LE";
} else if (same_utf_encoding("UTF-16BE-BOM", out_encoding)) {
bom_str = utf16_be_bom;
bom_len = sizeof(utf16_be_bom);
out_encoding = "UTF-16BE";
#ifdef ICONV_OMITS_BOM
} else if (same_utf_encoding("UTF-16", out_encoding)) {
bom_str = utf16_be_bom;
bom_len = sizeof(utf16_be_bom);
out_encoding = "UTF-16BE";
} else if (same_utf_encoding("UTF-32", out_encoding)) {
bom_str = utf32_be_bom;
bom_len = sizeof(utf32_be_bom);
out_encoding = "UTF-32BE";
#endif
}
conv = iconv_open(out_encoding, in_encoding);
if (conv == (iconv_t) -1) {
in_encoding = fallback_encoding(in_encoding);
out_encoding = fallback_encoding(out_encoding);
conv = iconv_open(out_encoding, in_encoding);
if (conv == (iconv_t) -1)
return NULL;
}
out = reencode_string_iconv(in, insz, conv, bom_len, outsz);
iconv_close(conv);
if (out && bom_str && bom_len)
memcpy(out, bom_str, bom_len);
return out;
}
#endif
static int has_bom_prefix(const char *data, size_t len,
const char *bom, size_t bom_len)
{
return data && bom && (len >= bom_len) && !memcmp(data, bom, bom_len);
}
int has_prohibited_utf_bom(const char *enc, const char *data, size_t len)
{
return (
(same_utf_encoding("UTF-16BE", enc) ||
same_utf_encoding("UTF-16LE", enc)) &&
(has_bom_prefix(data, len, utf16_be_bom, sizeof(utf16_be_bom)) ||
has_bom_prefix(data, len, utf16_le_bom, sizeof(utf16_le_bom)))
) || (
(same_utf_encoding("UTF-32BE", enc) ||
same_utf_encoding("UTF-32LE", enc)) &&
(has_bom_prefix(data, len, utf32_be_bom, sizeof(utf32_be_bom)) ||
has_bom_prefix(data, len, utf32_le_bom, sizeof(utf32_le_bom)))
);
}
int is_missing_required_utf_bom(const char *enc, const char *data, size_t len)
{
return (
(same_utf_encoding(enc, "UTF-16")) &&
!(has_bom_prefix(data, len, utf16_be_bom, sizeof(utf16_be_bom)) ||
has_bom_prefix(data, len, utf16_le_bom, sizeof(utf16_le_bom)))
) || (
(same_utf_encoding(enc, "UTF-32")) &&
!(has_bom_prefix(data, len, utf32_be_bom, sizeof(utf32_be_bom)) ||
has_bom_prefix(data, len, utf32_le_bom, sizeof(utf32_le_bom)))
);
}
/*
* Returns first character length in bytes for multi-byte `text` according to
* `encoding`.
*
* - The `text` pointer is updated to point at the next character.
* - When `remainder_p` is not NULL, on entry `*remainder_p` is how much bytes
* we can consume from text, and on exit `*remainder_p` is reduced by returned
* character length. Otherwise `text` is treated as limited by NUL.
*/
int mbs_chrlen(const char **text, size_t *remainder_p, const char *encoding)
{
int chrlen;
const char *p = *text;
size_t r = (remainder_p ? *remainder_p : SIZE_MAX);
if (r < 1)
return 0;
if (is_encoding_utf8(encoding)) {
pick_one_utf8_char(&p, &r);
chrlen = p ? (p - *text)
: 1 /* not valid UTF-8 -> raw byte sequence */;
}
else {
/*
* TODO use iconv to decode one char and obtain its chrlen
* for now, let's treat encodings != UTF-8 as one-byte
*/
chrlen = 1;
}
*text += chrlen;
if (remainder_p)
*remainder_p -= chrlen;
return chrlen;
}
/*
* Pick the next char from the stream, ignoring codepoints an HFS+ would.
* Note that this is _not_ complete by any means. It's just enough
* to make is_hfs_dotgit() work, and should not be used otherwise.
*/
static ucs_char_t next_hfs_char(const char **in)
{
while (1) {
ucs_char_t out = pick_one_utf8_char(in, NULL);
/*
* check for malformed utf8. Technically this
* gets converted to a percent-sequence, but
* returning 0 is good enough for is_hfs_dotgit
* to realize it cannot be .git
*/
if (!*in)
return 0;
/* these code points are ignored completely */
switch (out) {
case 0x200c: /* ZERO WIDTH NON-JOINER */
case 0x200d: /* ZERO WIDTH JOINER */
case 0x200e: /* LEFT-TO-RIGHT MARK */
case 0x200f: /* RIGHT-TO-LEFT MARK */
case 0x202a: /* LEFT-TO-RIGHT EMBEDDING */
case 0x202b: /* RIGHT-TO-LEFT EMBEDDING */
case 0x202c: /* POP DIRECTIONAL FORMATTING */
case 0x202d: /* LEFT-TO-RIGHT OVERRIDE */
case 0x202e: /* RIGHT-TO-LEFT OVERRIDE */
case 0x206a: /* INHIBIT SYMMETRIC SWAPPING */
case 0x206b: /* ACTIVATE SYMMETRIC SWAPPING */
case 0x206c: /* INHIBIT ARABIC FORM SHAPING */
case 0x206d: /* ACTIVATE ARABIC FORM SHAPING */
case 0x206e: /* NATIONAL DIGIT SHAPES */
case 0x206f: /* NOMINAL DIGIT SHAPES */
case 0xfeff: /* ZERO WIDTH NO-BREAK SPACE */
continue;
}
return out;
}
}
static int is_hfs_dot_generic(const char *path,
const char *needle, size_t needle_len)
{
ucs_char_t c;
c = next_hfs_char(&path);
if (c != '.')
return 0;
/*
* there's a great deal of other case-folding that occurs
* in HFS+, but this is enough to catch our fairly vanilla
* hard-coded needles.
*/
for (; needle_len > 0; needle++, needle_len--) {
c = next_hfs_char(&path);
/*
* We know our needles contain only ASCII, so we clamp here to
* make the results of tolower() sane.
*/
if (c > 127)
return 0;
if (tolower(c) != *needle)
return 0;
}
c = next_hfs_char(&path);
if (c && !is_dir_sep(c))
return 0;
return 1;
}
/*
* Inline wrapper to make sure the compiler resolves strlen() on literals at
* compile time.
*/
static inline int is_hfs_dot_str(const char *path, const char *needle)
{
return is_hfs_dot_generic(path, needle, strlen(needle));
}
int is_hfs_dotgit(const char *path)
{
return is_hfs_dot_str(path, "git");
}
int is_hfs_dotgitmodules(const char *path)
{
return is_hfs_dot_str(path, "gitmodules");
}
int is_hfs_dotgitignore(const char *path)
{
return is_hfs_dot_str(path, "gitignore");
}
int is_hfs_dotgitattributes(const char *path)
{
return is_hfs_dot_str(path, "gitattributes");
}
const char utf8_bom[] = "\357\273\277";
int skip_utf8_bom(char **text, size_t len)
{
if (len < strlen(utf8_bom) ||
memcmp(*text, utf8_bom, strlen(utf8_bom)))
return 0;
*text += strlen(utf8_bom);
return 1;
}
void strbuf_utf8_align(struct strbuf *buf, align_type position, unsigned int width,
const char *s)
{
int slen = strlen(s);
int display_len = utf8_strnwidth(s, slen, 0);
int utf8_compensation = slen - display_len;
if (display_len >= width) {
strbuf_addstr(buf, s);
return;
}
if (position == ALIGN_LEFT)
strbuf_addf(buf, "%-*s", width + utf8_compensation, s);
else if (position == ALIGN_MIDDLE) {
int left = (width - display_len) / 2;
strbuf_addf(buf, "%*s%-*s", left, "", width - left + utf8_compensation, s);
} else if (position == ALIGN_RIGHT)
strbuf_addf(buf, "%*s", width + utf8_compensation, s);
}