diff options
Diffstat (limited to 'util')
| -rw-r--r-- | util/Makefile.objs | 2 | ||||
| -rw-r--r-- | util/unicode.c | 100 |
2 files changed, 101 insertions, 1 deletions
diff --git a/util/Makefile.objs b/util/Makefile.objs index 557bda7a15..c5652f5260 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -1,4 +1,4 @@ -util-obj-y = osdep.o cutils.o qemu-timer-common.o +util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o util-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o event_notifier-win32.o util-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o event_notifier-posix.o util-obj-y += envlist.o path.o host-utils.o cache-utils.o module.o diff --git a/util/unicode.c b/util/unicode.c new file mode 100644 index 0000000000..d1c8658850 --- /dev/null +++ b/util/unicode.c @@ -0,0 +1,100 @@ +/* + * Dealing with Unicode + * + * Copyright (C) 2013 Red Hat, Inc. + * + * Authors: + * Markus Armbruster <armbru@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + */ + +#include "qemu-common.h" + +/** + * mod_utf8_codepoint: + * @s: string encoded in modified UTF-8 + * @n: maximum number of bytes to read from @s, if less than 6 + * @end: set to end of sequence on return + * + * Convert the modified UTF-8 sequence at the start of @s. Modified + * UTF-8 is exactly like UTF-8, except U+0000 is encoded as + * "\xC0\x80". + * + * If @n is zero or @s points to a zero byte, the sequence is invalid, + * and @end is set to @s. + * + * If @s points to an impossible byte (0xFE or 0xFF) or a continuation + * byte, the sequence is invalid, and @end is set to @s + 1 + * + * Else, the first byte determines how many continuation bytes are + * expected. If there are fewer, the sequence is invalid, and @end is + * set to @s + 1 + actual number of continuation bytes. Else, the + * sequence is well-formed, and @end is set to @s + 1 + expected + * number of continuation bytes. + * + * A well-formed sequence is valid unless it encodes a codepoint + * outside the Unicode range U+0000..U+10FFFF, one of Unicode's 66 + * noncharacters, a surrogate codepoint, or is overlong. Except the + * overlong sequence "\xC0\x80" is valid. + * + * Conversion succeeds if and only if the sequence is valid. + * + * Returns: the Unicode codepoint on success, -1 on failure. + */ +int mod_utf8_codepoint(const char *s, size_t n, char **end) +{ + static int min_cp[5] = { 0x80, 0x800, 0x10000, 0x200000, 0x4000000 }; + const unsigned char *p; + unsigned byte, mask, len, i; + int cp; + + if (n == 0 || *s == 0) { + /* empty sequence */ + *end = (char *)s; + return -1; + } + + p = (const unsigned char *)s; + byte = *p++; + if (byte < 0x80) { + cp = byte; /* one byte sequence */ + } else if (byte >= 0xFE) { + cp = -1; /* impossible bytes 0xFE, 0xFF */ + } else if ((byte & 0x40) == 0) { + cp = -1; /* unexpected continuation byte */ + } else { + /* multi-byte sequence */ + len = 0; + for (mask = 0x80; byte & mask; mask >>= 1) { + len++; + } + assert(len > 1 && len < 7); + cp = byte & (mask - 1); + for (i = 1; i < len; i++) { + byte = i < n ? *p : 0; + if ((byte & 0xC0) != 0x80) { + cp = -1; /* continuation byte missing */ + goto out; + } + p++; + cp <<= 6; + cp |= byte & 0x3F; + } + if (cp > 0x10FFFF) { + cp = -1; /* beyond Unicode range */ + } else if ((cp >= 0xFDD0 && cp <= 0xFDEF) + || (cp & 0xFFFE) == 0xFFFE) { + cp = -1; /* noncharacter */ + } else if (cp >= 0xD800 && cp <= 0xDFFF) { + cp = -1; /* surrogate code point */ + } else if (cp < min_cp[len - 2] && !(cp == 0 && len == 2)) { + cp = -1; /* overlong, not \xC0\x80 */ + } + } + +out: + *end = (char *)p; + return cp; +} |