From c7cf999bda8390d2dd294ef903716a80135e6f4c Mon Sep 17 00:00:00 2001
From: Derek Mauro <dmauro@google.com>
Date: Tue, 26 Nov 2024 10:29:23 -0800
Subject: [PATCH] Change some C-arrays to std::array as this enables bounds
 checking in some hardened standard library builds

For example https://libcxx.llvm.org/Hardening.html

PiperOrigin-RevId: 700386333
Change-Id: Id839ab6b1daa74d7f80c3309dfa9a21076450cea
---
 absl/strings/escaping.cc                           | 14 +++++++-------
 .../internal/str_format/float_conversion.cc        |  5 +++--
 absl/strings/numbers.cc                            |  3 ++-
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/absl/strings/escaping.cc b/absl/strings/escaping.cc
index 8f5dbcf59e6..b70c5041ae9 100644
--- a/absl/strings/escaping.cc
+++ b/absl/strings/escaping.cc
@@ -370,7 +370,7 @@ std::string CEscapeInternal(absl::string_view src, bool use_hex,
 }
 
 /* clang-format off */
-constexpr unsigned char kCEscapedLen[256] = {
+constexpr std::array<unsigned char, 256> kCEscapedLen = {
     4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 4, 4, 2, 4, 4,  // \t, \n, \r
     4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
     1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1,  // ", '
@@ -481,7 +481,7 @@ void CEscapeAndAppendInternal(absl::string_view src,
 // documentation for details of the mapping.
 bool Base64UnescapeInternal(absl::Nullable<const char*> src_param, size_t szsrc,
                             absl::Nullable<char*> dest, size_t szdest,
-                            absl::Nonnull<const signed char*> unbase64,
+                            const std::array<signed char, 256>& unbase64,
                             absl::Nonnull<size_t*> len) {
   static const char kPad64Equals = '=';
   static const char kPad64Dot = '.';
@@ -746,7 +746,7 @@ bool Base64UnescapeInternal(absl::Nullable<const char*> src_param, size_t szsrc,
 // where the value of "Base64[]" was replaced by one of k(WebSafe)Base64Chars
 // in the internal escaping.cc.
 /* clang-format off */
-constexpr signed char kUnBase64[] = {
+constexpr std::array<signed char, 256> kUnBase64 = {
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
@@ -781,7 +781,7 @@ constexpr signed char kUnBase64[] = {
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1
 };
 
-constexpr signed char kUnWebSafeBase64[] = {
+constexpr std::array<signed char, 256> kUnWebSafeBase64 = {
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
     -1,      -1,      -1,      -1,      -1,      -1,      -1,      -1,
@@ -820,7 +820,7 @@ constexpr signed char kUnWebSafeBase64[] = {
 template <typename String>
 bool Base64UnescapeInternal(absl::Nullable<const char*> src, size_t slen,
                             absl::Nonnull<String*> dest,
-                            absl::Nonnull<const signed char*> unbase64) {
+                            const std::array<signed char, 256>& unbase64) {
   // Determine the size of the output string.  Base64 encodes every 3 bytes into
   // 4 characters.  Any leftover chars are added directly for good measure.
   const size_t dest_len = 3 * (slen / 4) + (slen % 4);
@@ -845,7 +845,7 @@ bool Base64UnescapeInternal(absl::Nullable<const char*> src, size_t slen,
 }
 
 /* clang-format off */
-constexpr char kHexValueLenient[256] = {
+constexpr std::array<char, 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,
@@ -864,7 +864,7 @@ constexpr char kHexValueLenient[256] = {
     0,  0,  0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 };
 
-constexpr signed char kHexValueStrict[256] = {
+constexpr std::array<signed char, 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,
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc
index 8edf520dcd6..aa319980884 100644
--- a/absl/strings/internal/str_format/float_conversion.cc
+++ b/absl/strings/internal/str_format/float_conversion.cc
@@ -17,6 +17,7 @@
 #include <string.h>
 
 #include <algorithm>
+#include <array>
 #include <cassert>
 #include <cmath>
 #include <limits>
@@ -159,7 +160,7 @@ class BinaryToDecimal {
 
   // See the current block of digits.
   absl::string_view CurrentDigits() const {
-    return absl::string_view(digits_ + kDigitsPerChunk - size_, size_);
+    return absl::string_view(&digits_[kDigitsPerChunk - size_], size_);
   }
 
   // Advance the current view of digits.
@@ -234,7 +235,7 @@ class BinaryToDecimal {
   size_t decimal_start_;
   size_t decimal_end_;
 
-  char digits_[kDigitsPerChunk];
+  std::array<char, kDigitsPerChunk> digits_;
   size_t size_ = 0;
 
   absl::Span<uint32_t> data_;
diff --git a/absl/strings/numbers.cc b/absl/strings/numbers.cc
index b57d9e82e5b..83ea80b474b 100644
--- a/absl/strings/numbers.cc
+++ b/absl/strings/numbers.cc
@@ -18,6 +18,7 @@
 #include "absl/strings/numbers.h"
 
 #include <algorithm>
+#include <array>
 #include <cassert>
 #include <cfloat>  // for DBL_DIG and FLT_DIG
 #include <cmath>   // for HUGE_VAL
@@ -674,7 +675,7 @@ namespace {
 // Represents integer values of digits.
 // Uses 36 to indicate an invalid character since we support
 // bases up to 36.
-static const int8_t kAsciiToInt[256] = {
+static constexpr std::array<int8_t, 256> kAsciiToInt = {
     36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36,  // 16 36s.
     36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36,
     36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 0,  1,  2,  3,  4,  5,