181 lines
6.7 KiB
C++
181 lines
6.7 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_LIBDEXFILE_DEX_UTF_H_
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#define ART_LIBDEXFILE_DEX_UTF_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <string>
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#include <string_view>
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#include <type_traits>
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#include "base/macros.h"
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/*
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* All UTF-8 in art is actually modified UTF-8. Mostly, this distinction
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* doesn't matter.
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*
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* See http://en.wikipedia.org/wiki/UTF-8#Modified_UTF-8 for the details.
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*/
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namespace art {
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/*
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* Returns the number of UTF-16 characters in the given modified UTF-8 string.
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*/
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size_t CountModifiedUtf8Chars(const char* utf8);
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size_t CountModifiedUtf8Chars(const char* utf8, size_t byte_count);
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/*
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* Returns the number of modified UTF-8 bytes needed to represent the given
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* UTF-16 string.
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*/
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size_t CountUtf8Bytes(const uint16_t* chars, size_t char_count);
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/*
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* Convert from Modified UTF-8 to UTF-16.
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*/
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void ConvertModifiedUtf8ToUtf16(uint16_t* utf16_out, const char* utf8_in);
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void ConvertModifiedUtf8ToUtf16(uint16_t* utf16_out, size_t out_chars,
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const char* utf8_in, size_t in_bytes);
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/*
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* Compare two modified UTF-8 strings as UTF-16 code point values in a non-locale sensitive manner
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*/
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ALWAYS_INLINE int CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues(const char* utf8_1,
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const char* utf8_2);
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/*
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* Compare a null-terminated modified UTF-8 string with a UTF-16 string (not null-terminated)
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* as code point values in a non-locale sensitive manner.
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*/
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int CompareModifiedUtf8ToUtf16AsCodePointValues(const char* utf8, const uint16_t* utf16,
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size_t utf16_length);
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/*
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* Helper template for converting UTF-16 to UTF-8 and similar encodings.
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*
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* Template arguments:
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* kUseShortZero: Encode U+0000 as a single byte with value 0 (otherwise emit 0xc0 0x80).
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* kUse4ByteSequence: Encode valid surrogate pairs as a 4-byte sequence.
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* kReplaceBadSurrogates: Replace unmatched surrogates with '?' (otherwise use 3-byte sequence).
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* Must be false if kUse4ByteSequence is false.
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* Append: The type of the `append` functor. Should be deduced automatically.
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*
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* Encoding kUseShortZero kUse4ByteSequence kReplaceBadSurrogates
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* UTF-8 true true true
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* Modified UTF8 false false n/a
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* JNI GetStringUTFChars false true false
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*/
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template <bool kUseShortZero, bool kUse4ByteSequence, bool kReplaceBadSurrogates, typename Append>
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void ConvertUtf16ToUtf8(const uint16_t* utf16, size_t char_count, Append&& append);
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/*
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* Convert from UTF-16 to Modified UTF-8. Note that the output is _not_
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* NUL-terminated. You probably need to call CountUtf8Bytes before calling
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* this anyway, so if you want a NUL-terminated string, you know where to
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* put the NUL byte.
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*/
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void ConvertUtf16ToModifiedUtf8(char* utf8_out, size_t byte_count,
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const uint16_t* utf16_in, size_t char_count);
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/*
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* The java.lang.String hashCode() algorithm.
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*/
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template<typename MemoryType>
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int32_t ComputeUtf16Hash(const MemoryType* chars, size_t char_count) {
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static_assert(std::is_same_v<MemoryType, char> ||
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std::is_same_v<MemoryType, uint8_t> ||
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std::is_same_v<MemoryType, uint16_t>);
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using UnsignedMemoryType = std::make_unsigned_t<MemoryType>;
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uint32_t hash = 0;
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while (char_count--) {
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hash = hash * 31 + static_cast<UnsignedMemoryType>(*chars++);
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}
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return static_cast<int32_t>(hash);
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}
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int32_t ComputeUtf16HashFromModifiedUtf8(const char* utf8, size_t utf16_length);
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// Compute a hash code of a modified UTF-8 string. Not the standard java hash since it returns a
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// uint32_t and hashes individual chars instead of codepoint words.
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uint32_t ComputeModifiedUtf8Hash(const char* chars);
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uint32_t ComputeModifiedUtf8Hash(std::string_view chars);
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// The starting value of a modified UTF-8 hash.
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constexpr uint32_t StartModifiedUtf8Hash() {
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return 0u;
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}
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// Update a modified UTF-8 hash with one character.
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ALWAYS_INLINE
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inline uint32_t UpdateModifiedUtf8Hash(uint32_t hash, char c) {
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return hash * 31u + static_cast<uint8_t>(c);
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}
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// Update a modified UTF-8 hash with characters of a `std::string_view`.
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ALWAYS_INLINE
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inline uint32_t UpdateModifiedUtf8Hash(uint32_t hash, std::string_view chars) {
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for (char c : chars) {
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hash = UpdateModifiedUtf8Hash(hash, c);
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}
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return hash;
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}
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/*
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* Retrieve the next UTF-16 character or surrogate pair from a UTF-8 string.
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* single byte, 2-byte and 3-byte UTF-8 sequences result in a single UTF-16
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* character (possibly one half of a surrogate) whereas 4-byte UTF-8 sequences
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* result in a surrogate pair. Use GetLeadingUtf16Char and GetTrailingUtf16Char
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* to process the return value of this function.
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*
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* Advances "*utf8_data_in" to the start of the next character.
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*
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* WARNING: If a string is corrupted by dropping a '\0' in the middle
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* of a multi byte sequence, you can end up overrunning the buffer with
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* reads (and possibly with the writes if the length was computed and
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* cached before the damage). For performance reasons, this function
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* assumes that the string being parsed is known to be valid (e.g., by
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* already being verified). Most strings we process here are coming
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* out of dex files or other internal translations, so the only real
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* risk comes from the JNI NewStringUTF call.
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*/
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uint32_t GetUtf16FromUtf8(const char** utf8_data_in);
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/**
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* Gets the leading UTF-16 character from a surrogate pair, or the sole
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* UTF-16 character from the return value of GetUtf16FromUtf8.
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*/
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ALWAYS_INLINE uint16_t GetLeadingUtf16Char(uint32_t maybe_pair);
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/**
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* Gets the trailing UTF-16 character from a surrogate pair, or 0 otherwise
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* from the return value of GetUtf16FromUtf8.
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*/
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ALWAYS_INLINE uint16_t GetTrailingUtf16Char(uint32_t maybe_pair);
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// Returns a printable (escaped) version of a character.
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std::string PrintableChar(uint16_t ch);
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// Returns an ASCII string corresponding to the given UTF-8 string.
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// Java escapes are used for non-ASCII characters.
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std::string PrintableString(const char* utf8);
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} // namespace art
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#endif // ART_LIBDEXFILE_DEX_UTF_H_
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