Check compiler for 'linux/random.h' (#2716)

### Description of changes:
Detect the availability of the "linux/random.h" header in build logic.

### Call-outs:
* Alternative (or complementary) fix for the same issue as  #2712

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license and the ISC license.

Author: justsmth

.github/workflows/actions-ci.yml

@@ -277,6 +277,37 @@ jobs:
       - name: Run tests
         run: cmake --build ./build --target run_tests
 
+  musl-tests:
+    name: musl - ${{ matrix.config.arch }}
+    needs: [sanity-test-run]
+    env:
+      DEBIAN_FRONTEND: noninteractive
+      GOFLAGS: "-buildvcs=false"
+      CC: musl-gcc
+    strategy:
+      fail-fast: false
+      matrix:
+        config:
+          - { host: 'ubuntu-latest', arch: 'x86_64' }
+          - { host: 'ubuntu-24.04-arm', arch: 'aarch64' }
+    runs-on: ${{ matrix.config.host }}
+    container:
+      image: rust:latest
+      options: "--platform linux/${{ (matrix.config.arch == 'aarch64' && 'arm64/v8') || 'amd64'}}"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v4
+        with:
+          go-version: ">=1.18"
+      - run: |
+          set -x
+          apt-get update
+          apt-get install -y cmake musl-tools musl-dev ninja-build
+      - name: Setup Build
+        run: cmake -GNinja -B ./build -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=ON -DBUILD_TESTING=OFF -DBUILD_LIBSSL=OFF
+      - name: Build Project
+        run: cmake --build ./build --target crypto
+
   arm-gcc-tests:
     if: github.repository_owner == 'aws'
     needs: [sanity-test-run]

CMakeLists.txt

@@ -569,11 +569,16 @@ if(GCC OR CLANG)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-array-bounds")
   endif()
 
+  check_compiler("linux_random_h.c" HAVE_LINUX_RANDOM_H)
+  if(NOT HAVE_LINUX_RANDOM_H)
+    check_compiler("linux_random_h.c" AWS_LC_URANDOM_NEEDS_U32 "-DDEFINE_U32")
+    if(AWS_LC_URANDOM_NEEDS_U32)
+      add_definitions("-DHAVE_LINUX_RANDOM_H")
+    endif()
+  endif()
+
   check_compiler("stdalign_check.c" AWS_LC_STDALIGN_AVAILABLE)
   check_compiler("builtin_swap_check.c" AWS_LC_BUILTIN_SWAP_SUPPORTED)
-  if(FIPS AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
-    check_compiler("linux_u32.c" AWS_LC_URANDOM_U32)
-  endif()
 
 elseif(MSVC)
   set(MSVC_DISABLED_WARNINGS_LIST

crypto/rand_extra/internal.h

@@ -10,7 +10,9 @@
 #define OPENSSL_RAND_DETERMINISTIC
 #elif defined(OPENSSL_WINDOWS)
 #define OPENSSL_RAND_WINDOWS
-#elif defined(OPENSSL_MACOS) || defined(OPENSSL_OPENBSD) || defined(OPENSSL_FREEBSD) || defined(OPENSSL_SOLARIS)
+#elif defined(OPENSSL_MACOS) || defined(OPENSSL_OPENBSD) || \
+    defined(OPENSSL_FREEBSD) || defined(OPENSSL_SOLARIS) || \
+    (defined(OPENSSL_LINUX) && !defined(HAVE_LINUX_RANDOM_H))
 #define OPENSSL_RAND_GETENTROPY
 #elif defined(OPENSSL_IOS)
 #define OPENSSL_RAND_CCRANDOMGENERATEBYTES
@@ -51,10 +53,11 @@ OPENSSL_INLINE int CRYPTO_sysrand_if_available(uint8_t *buf, size_t len) {
 // spinning loops.
 #define MAX_BACKOFF_RETRIES 9
 
-OPENSSL_EXPORT int snapsafe_fallback_get_seed(uint8_t seed[CTR_DRBG_ENTROPY_LEN]);
+OPENSSL_EXPORT int snapsafe_fallback_get_seed(
+    uint8_t seed[CTR_DRBG_ENTROPY_LEN]);
 
 #if defined(__cplusplus)
 }  // extern C
 #endif
 
-#endif // AWSLC_HEADER_CRYPTO_RAND_EXTRA_RAND_INTERNAL_H
+#endif  // AWSLC_HEADER_CRYPTO_RAND_EXTRA_RAND_INTERNAL_H

crypto/rand_extra/urandom.c

@@ -31,7 +31,7 @@
 #include <unistd.h>
 
 #if defined(OPENSSL_LINUX)
-#if !defined(AWS_LC_URANDOM_U32)
+#if defined(AWS_LC_URANDOM_NEEDS_U32)
   // On old Linux OS: unknown type name '__u32' when include <linux/random.h>.
   // If '__u32' is predefined, redefine will cause compiler error.
   typedef unsigned int __u32;

tests/compiler_features_tests/linux_u32.c …compiler_features_tests/linux_random_h.ctests/compiler_features_tests/linux_u32.c renamed to tests/compiler_features_tests/linux_random_h.c tests/compiler_features_tests/linux_u32.c renamed to tests/compiler_features_tests/linux_random_h.c

@@ -9,6 +9,9 @@
 // /usr/include/linux/random.h:38:2: error: unknown type name '__u32'
 // __u32 buf[0];
 // ^
+#if defined(DEFINE_U32)
+typedef unsigned int __u32;
+#endif
 #include <linux/random.h>
 #include <stdlib.h>