Use absl::byteswap in minielf

Abseil's `internal/endian.h` will become private with abseil-cpp LTS 202507.

PiperOrigin-RevId: 764221623
Change-Id: Id12e24a115d15a3d93722358bc81d1bdaaad2c09

Author: cblichmann

sandboxed_api/sandbox2/util/BUILD

@@ -52,7 +52,8 @@ cc_library(
         "//sandboxed_api/sandbox2:util",
         "//sandboxed_api/util:raw_logging",
         "//sandboxed_api/util:status",
-        "@abseil-cpp//absl/base:endian",
+        "@abseil-cpp//absl/base:nullability",
+        "@abseil-cpp//absl/numeric:bits",
         "@abseil-cpp//absl/status",
         "@abseil-cpp//absl/status:statusor",
         "@abseil-cpp//absl/strings",

sandboxed_api/sandbox2/util/CMakeLists.txt

@@ -29,6 +29,7 @@ add_library(sandbox2_util_minielf ${SAPI_LIB_TYPE}
 )
 add_library(sandbox2::minielf ALIAS sandbox2_util_minielf)
 target_link_libraries(sandbox2_util_minielf PRIVATE
+  absl::bits
   absl::status
   absl::strings
   sandbox2::util

sandboxed_api/sandbox2/util/minielf.cc

@@ -27,9 +27,8 @@
 #include <utility>
 #include <vector>
 
-// TODO: internal/endian.h will become private with abseil-cpp LTS 202507.
-// Switch to absl::byteswap.
-#include "absl/base/internal/endian.h"
+#include "absl/base/nullability.h"
+#include "absl/numeric/bits.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "absl/strings/match.h"
@@ -123,18 +122,32 @@ class ElfParser {
  private:
   ElfParser() = default;
 
-  // Endianess support functions
-  uint16_t Load16(const void* src) {
-    return elf_little_ ? absl::little_endian::Load16(src)
-                       : absl::big_endian::Load16(src);
+  // Endianness support functions
+  uint16_t Load16(const void* absl_nonnull src) {
+    uint16_t v;
+    memcpy(&v, src, sizeof(v));
+    if constexpr (absl::endian::native == absl::endian::little) {
+      return elf_little_ ? v : absl::byteswap(v);
+    }
+    return elf_little_ ? absl::byteswap(v) : v;
   }
-  uint32_t Load32(const void* src) {
-    return elf_little_ ? absl::little_endian::Load32(src)
-                       : absl::big_endian::Load32(src);
+
+  uint32_t Load32(const void* absl_nonnull src) {
+    uint32_t v;
+    memcpy(&v, src, sizeof(v));
+    if constexpr (absl::endian::native == absl::endian::little) {
+      return elf_little_ ? v : absl::byteswap(v);
+    }
+    return elf_little_ ? absl::byteswap(v) : v;
   }
-  uint64_t Load64(const void* src) {
-    return elf_little_ ? absl::little_endian::Load64(src)
-                       : absl::big_endian::Load64(src);
+
+  uint64_t Load64(const void* absl_nonnull src) {
+    uint64_t v;
+    memcpy(&v, src, sizeof(v));
+    if constexpr (absl::endian::native == absl::endian::little) {
+      return elf_little_ ? v : absl::byteswap(v);
+    }
+    return elf_little_ ? absl::byteswap(v) : v;
   }
 
   template <size_t N>