165 lines
4.3 KiB
C++
165 lines
4.3 KiB
C++
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/json/string_escape.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <limits>
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#include <string>
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#include "base/strings/string_util.h"
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#include "base/strings/stringprintf.h"
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#include "base/strings/utf_string_conversion_utils.h"
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#include "base/strings/utf_string_conversions.h"
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#include "base/third_party/icu/icu_utf.h"
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namespace base {
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namespace {
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// Format string for printing a \uXXXX escape sequence.
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const char kU16EscapeFormat[] = "\\u%04X";
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// The code point to output for an invalid input code unit.
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const uint32_t kReplacementCodePoint = 0xFFFD;
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// Used below in EscapeSpecialCodePoint().
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static_assert('<' == 0x3C, "less than sign must be 0x3c");
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// Try to escape the |code_point| if it is a known special character. If
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// successful, returns true and appends the escape sequence to |dest|. This
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// isn't required by the spec, but it's more readable by humans.
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bool EscapeSpecialCodePoint(uint32_t code_point, std::string* dest) {
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// WARNING: if you add a new case here, you need to update the reader as well.
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// Note: \v is in the reader, but not here since the JSON spec doesn't
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// allow it.
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switch (code_point) {
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case '\b':
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dest->append("\\b");
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break;
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case '\f':
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dest->append("\\f");
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break;
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case '\n':
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dest->append("\\n");
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break;
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case '\r':
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dest->append("\\r");
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break;
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case '\t':
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dest->append("\\t");
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break;
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case '\\':
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dest->append("\\\\");
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break;
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case '"':
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dest->append("\\\"");
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break;
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// Escape < to prevent script execution; escaping > is not necessary and
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// not doing so save a few bytes.
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case '<':
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dest->append("\\u003C");
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break;
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// Escape the "Line Separator" and "Paragraph Separator" characters, since
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// they should be treated like a new line \r or \n.
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case 0x2028:
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dest->append("\\u2028");
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break;
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case 0x2029:
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dest->append("\\u2029");
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break;
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default:
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return false;
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}
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return true;
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}
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template <typename S>
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bool EscapeJSONStringImpl(const S& str, bool put_in_quotes, std::string* dest) {
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bool did_replacement = false;
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if (put_in_quotes)
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dest->push_back('"');
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// Casting is necessary because ICU uses int32_t. Try and do so safely.
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CHECK_LE(str.length(),
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static_cast<size_t>(std::numeric_limits<int32_t>::max()));
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const int32_t length = static_cast<int32_t>(str.length());
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for (int32_t i = 0; i < length; ++i) {
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uint32_t code_point;
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if (!ReadUnicodeCharacter(str.data(), length, &i, &code_point) ||
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code_point == static_cast<decltype(code_point)>(CBU_SENTINEL) ||
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!IsValidCodepoint(code_point)) {
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code_point = kReplacementCodePoint;
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did_replacement = true;
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}
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if (EscapeSpecialCodePoint(code_point, dest))
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continue;
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// Escape non-printing characters.
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if (code_point < 32)
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base::StringAppendF(dest, kU16EscapeFormat, code_point);
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else
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WriteUnicodeCharacter(code_point, dest);
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}
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if (put_in_quotes)
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dest->push_back('"');
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return !did_replacement;
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}
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} // namespace
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bool EscapeJSONString(StringPiece str, bool put_in_quotes, std::string* dest) {
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return EscapeJSONStringImpl(str, put_in_quotes, dest);
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}
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bool EscapeJSONString(StringPiece16 str,
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bool put_in_quotes,
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std::string* dest) {
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return EscapeJSONStringImpl(str, put_in_quotes, dest);
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}
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std::string GetQuotedJSONString(StringPiece str) {
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std::string dest;
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EscapeJSONStringImpl(str, true, &dest);
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return dest;
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}
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std::string GetQuotedJSONString(StringPiece16 str) {
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std::string dest;
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EscapeJSONStringImpl(str, true, &dest);
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return dest;
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}
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std::string EscapeBytesAsInvalidJSONString(StringPiece str,
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bool put_in_quotes) {
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std::string dest;
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if (put_in_quotes)
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dest.push_back('"');
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for (unsigned char c : str) {
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if (EscapeSpecialCodePoint(c, &dest))
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continue;
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if (c < 32 || c > 126)
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base::StringAppendF(&dest, kU16EscapeFormat, c);
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else
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dest.push_back(c);
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}
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if (put_in_quotes)
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dest.push_back('"');
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return dest;
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}
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} // namespace base
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