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Fix sign-extension issue in absl::HexStringToBytes()

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Fixes #2006

PiperOrigin-RevId: 867661246
Change-Id: Ia4ad66620e0298287993b228bf604b8b75302c7d
This commit is contained in:
Derek Mauro
2026-02-09 10:14:52 -08:00
committed by Copybara-Service
parent b1b9c189ae
commit 7313246786
2 changed files with 11 additions and 5 deletions
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12
absl/strings/escaping.cc
View File

@@ -827,7 +827,7 @@ bool Base64UnescapeInternal(const char* absl_nullable src, size_t slen,
}
/* clang-format off */
constexpr std::array<char, 256> kHexValueLenient = {
constexpr std::array<uint8_t, 256> kHexValueLenient = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -846,7 +846,7 @@ constexpr std::array<char, 256> kHexValueLenient = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};
constexpr std::array<signed char, 256> kHexValueStrict = {
constexpr std::array<int8_t, 256> kHexValueStrict = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
@@ -874,7 +874,7 @@ void HexStringToBytesInternal(const char* absl_nullable from, T to,
size_t num) {
for (size_t i = 0; i < num; i++) {
to[i] = static_cast<char>(kHexValueLenient[from[i * 2] & 0xFF] << 4) +
(kHexValueLenient[from[i * 2 + 1] & 0xFF]);
static_cast<char>(kHexValueLenient[from[i * 2 + 1] & 0xFF]);
}
}
@@ -992,8 +992,10 @@ bool HexStringToBytes(absl::string_view hex, std::string* absl_nonnull bytes) {
output, num_bytes, [hex](char* buf, size_t buf_size) {
auto hex_p = hex.cbegin();
for (size_t i = 0; i < buf_size; ++i) {
int h1 = absl::kHexValueStrict[static_cast<size_t>(*hex_p++)];
int h2 = absl::kHexValueStrict[static_cast<size_t>(*hex_p++)];
int h1 = absl::kHexValueStrict[static_cast<size_t>(
static_cast<uint8_t>(*hex_p++))];
int h2 = absl::kHexValueStrict[static_cast<size_t>(
static_cast<uint8_t>(*hex_p++))];
if (h1 == -1 || h2 == -1) {
return size_t{0};
}

4
absl/strings/escaping_test.cc
View File

@@ -733,6 +733,10 @@ TEST(Escaping, HexStringToBytesBackToHex) {
bytes = "abc";
EXPECT_TRUE(absl::HexStringToBytes("", &bytes));
EXPECT_EQ("", bytes); // Results in empty output.
// Ensure there is no sign extension bug on a signed char.
hex.assign("\xC8" "b", 2);
EXPECT_FALSE(absl::HexStringToBytes(hex, &bytes));
}
TEST(HexAndBack, HexStringToBytes_and_BytesToHexString) {