build: add s2n_prelude.h to consolidate defines

CMakeLists.txt

@@ -192,11 +192,12 @@ if(S2N_BLOCK_NONPORTABLE_OPTIMIZATIONS)
     target_compile_options(${PROJECT_NAME} PUBLIC -DS2N_BLOCK_NONPORTABLE_OPTIMIZATIONS=1)
 endif()
 
-target_compile_options(${PROJECT_NAME} PUBLIC -fPIC)
+target_compile_options(${PROJECT_NAME} PUBLIC -fPIC -include "${CMAKE_CURRENT_LIST_DIR}/utils/s2n_prelude.h")
 
-add_definitions(-D_POSIX_C_SOURCE=200809L)
-if(CMAKE_BUILD_TYPE MATCHES Release)
-    add_definitions(-D_FORTIFY_SOURCE=2)
+# Match on Release, RelWithDebInfo and MinSizeRel
+# See: https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html#variable:CMAKE_BUILD_TYPE
+if(CMAKE_BUILD_TYPE MATCHES Rel)
+    add_definitions(-DS2N_BUILD_RELEASE)
 endif()
 
 if(NO_STACK_PROTECTOR)
@@ -331,7 +332,7 @@ function(feature_probe PROBE_NAME)
         SOURCES "${CMAKE_CURRENT_LIST_DIR}/tests/features/${PROBE_NAME}.c"
         LINK_LIBRARIES ${LINK_LIB} ${OS_LIBS}
         CMAKE_FLAGS ${ADDITIONAL_FLAGS}
-        COMPILE_DEFINITIONS -c ${GLOBAL_FLAGS} ${PROBE_FLAGS}
+        COMPILE_DEFINITIONS -I "${CMAKE_CURRENT_LIST_DIR}" -include "${CMAKE_CURRENT_LIST_DIR}/utils/s2n_prelude.h" -c ${GLOBAL_FLAGS} ${PROBE_FLAGS}
         ${ARGN}
         OUTPUT_VARIABLE TRY_COMPILE_OUTPUT
     )

api/s2n.h

@@ -22,17 +22,12 @@
 
 #pragma once
 
-#if ((__GNUC__ >= 4) || defined(__clang__)) && defined(S2N_EXPORTS)
-    /**
-     * Marks a function as belonging to the public s2n API.
-     */
-    #define S2N_API __attribute__((visibility("default")))
-#else
+#ifndef S2N_API
     /**
      * Marks a function as belonging to the public s2n API.
      */
     #define S2N_API
-#endif /* __GNUC__ >= 4 || defined(__clang__) */
+#endif
 
 #ifdef __cplusplus
 extern "C" {

bindings/rust/s2n-tls-sys/build.rs

@@ -85,9 +85,14 @@ fn build_vendored() {
 
     build.files(include!("./files.rs"));
 
-    if env("PROFILE") == "release" {
-        // fortify source is only available in release mode
-        build.define("_FORTIFY_SOURCE", "2");
+    // https://doc.rust-lang.org/cargo/reference/environment-variables.html
+    // * OPT_LEVEL, DEBUG — values of the corresponding variables for the profile currently being built.
+    // * PROFILE — release for release builds, debug for other builds. This is determined based on if
+    //   the profile inherits from the dev or release profile. Using this environment variable is not
+    //   recommended. Using other environment variables like OPT_LEVEL provide a more correct view of
+    //   the actual settings being used.
+    if env("OPT_LEVEL") != "0" {
+        build.define("S2N_BUILD_RELEASE", "1");
         build.define("NDEBUG", "1");
 
         // build s2n-tls with LTO if supported
@@ -166,15 +171,16 @@ fn builder(libcrypto: &Libcrypto) -> cc::Build {
     };
 
     build
+        .flag("-include")
+        .flag("lib/utils/s2n_prelude.h")
         .flag("-std=c11")
         .flag("-fgnu89-inline")
         // make sure the stack is non-executable
         .flag_if_supported("-z relro")
         .flag_if_supported("-z now")
         .flag_if_supported("-z noexecstack")
         // we use some deprecated libcrypto features so don't warn here
-        .flag_if_supported("-Wno-deprecated-declarations")
-        .define("_POSIX_C_SOURCE", "200112L");
+        .flag_if_supported("-Wno-deprecated-declarations");
 
     build
 }

s2n.mk

@@ -49,9 +49,10 @@ endif
 
 DEFAULT_CFLAGS += -pedantic -Wall -Werror -Wimplicit -Wunused -Wcomment -Wchar-subscripts -Wuninitialized \
                  -Wshadow  -Wcast-align -Wwrite-strings -fPIC -Wno-missing-braces\
-                 -D_POSIX_C_SOURCE=200809L -O2 -I$(LIBCRYPTO_ROOT)/include/ \
+                 -O2 -I$(LIBCRYPTO_ROOT)/include/ \
+                 -DS2N_BUILD_RELEASE -include utils/s2n_prelude.h \
                  -I$(S2N_ROOT)/api/ -I$(S2N_ROOT) -Wno-deprecated-declarations -Wno-unknown-pragmas -Wformat-security \
-                 -D_FORTIFY_SOURCE=2 -fgnu89-inline -fvisibility=hidden -DS2N_EXPORTS
+                 -fgnu89-inline -fvisibility=hidden -DS2N_EXPORTS
 
 COVERAGE_CFLAGS = -fprofile-arcs -ftest-coverage
 COVERAGE_LDFLAGS = --coverage

tests/features/S2N_MADVISE_SUPPORTED.c

@@ -13,17 +13,7 @@
  * permissions and limitations under the License.
  */
 
-/* Keep in sync with utils/s2n_fork_detection.c */
-#if defined(__FreeBSD__)
-    /* FreeBSD requires POSIX compatibility off for its syscalls (enables __BSD_VISIBLE)
-     * Without the below line, <sys/mman.h> cannot be imported (it requires __BSD_VISIBLE) */
-    #undef _POSIX_C_SOURCE
-#elif !defined(__APPLE__) && !defined(_GNU_SOURCE)
-    #define _GNU_SOURCE
-#endif
-
-#include <stddef.h>
-#include <sys/mman.h>
+#include "utils/s2n_fork_detection_features.h"
 
 int main() {
     madvise(NULL, 0, 0);

tests/features/S2N_MINHERIT_SUPPORTED.c

@@ -13,15 +13,7 @@
  * permissions and limitations under the License.
  */
 
-/* Keep in sync with utils/s2n_fork_detection.c */
-#if defined(__FreeBSD__)
-    /* FreeBSD requires POSIX compatibility off for its syscalls (enables __BSD_VISIBLE)
-     * Without the below line, <sys/mman.h> cannot be imported (it requires __BSD_VISIBLE) */
-    #undef _POSIX_C_SOURCE
-#endif
-
-#include <stddef.h>
-#include <sys/mman.h>
+#include "utils/s2n_fork_detection_features.h"
 
 int main() {
     minherit(NULL, 0, 0);

tests/unit/s2n_build_test.c

@@ -12,6 +12,12 @@
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */
+
+#ifndef _S2N_PRELUDE_INCLUDED
+    /* make sure s2n_prelude.h is includes as part of the compiler flags, if not then fail the build */
+    #error "Expected s2n_prelude.h to be included as part of the compiler flags"
+#endif
+
 #define _GNU_SOURCE
 #include <ctype.h>
 #include <openssl/crypto.h>

tls/s2n_config.c

@@ -13,6 +13,11 @@
  * permissions and limitations under the License.
  */
 
+#ifndef _S2N_PRELUDE_INCLUDED
+    /* make sure s2n_prelude.h is includes as part of the compiler flags, if not then fail the build */
+    #error "Expected s2n_prelude.h to be included as part of the compiler flags"
+#endif
+
 #include <strings.h>
 #include <time.h>
 

utils/s2n_fork_detection.c

@@ -13,36 +13,14 @@
  * permissions and limitations under the License.
  */
 
-/* This captures Darwin specialities. This is the only APPLE flavor we care about.
- * Here we also capture varius required feature test macros.
- */
-#if defined(__APPLE__)
-typedef struct _opaque_pthread_once_t __darwin_pthread_once_t;
-typedef __darwin_pthread_once_t pthread_once_t;
-    #define _DARWIN_C_SOURCE
-#elif defined(__FreeBSD__) || defined(__OpenBSD__)
-    /* FreeBSD requires POSIX compatibility off for its syscalls (enables __BSD_VISIBLE)
-     * Without the below line, <sys/mman.h> cannot be imported (it requires __BSD_VISIBLE) */
-    #undef _POSIX_C_SOURCE
-#elif !defined(_GNU_SOURCE)
-    /* Keep in sync with feature probe tests/features/madvise.c */
-    #define _GNU_SOURCE
-#endif
+/* force the internal header to be included first, since it modifies _GNU_SOURCE/_POSIX_C_SOURCE */
+/* clang-format off */
+#include "utils/s2n_fork_detection_features.h"
+/* clang-format on */
 
-#include <sys/mman.h>
-
-/* Not always defined for Darwin */
-#if !defined(MAP_ANONYMOUS)
-    #define MAP_ANONYMOUS MAP_ANON
-#endif
-
-#include <pthread.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <unistd.h>
+#include "utils/s2n_fork_detection.h"
 
 #include "error/s2n_errno.h"
-#include "utils/s2n_fork_detection.h"
 #include "utils/s2n_safety.h"
 
 #if defined(S2N_MADVISE_SUPPORTED) && defined(MADV_WIPEONFORK)

utils/s2n_fork_detection_features.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#pragma once
+
+/* This captures Darwin specialities. This is the only APPLE flavor we care about.
+ * Here we also capture various required feature test macros.
+ */
+#if defined(__APPLE__)
+typedef struct _opaque_pthread_once_t __darwin_pthread_once_t;
+typedef __darwin_pthread_once_t pthread_once_t;
+    #define _DARWIN_C_SOURCE
+#elif defined(__FreeBSD__) || defined(__OpenBSD__)
+    /* FreeBSD requires POSIX compatibility off for its syscalls (enables __BSD_VISIBLE)
+     * Without the below line, <sys/mman.h> cannot be imported (it requires __BSD_VISIBLE) */
+    #undef _POSIX_C_SOURCE
+#elif !defined(_GNU_SOURCE)
+    #define _GNU_SOURCE
+#endif
+
+#include <sys/mman.h>
+
+/* Not always defined for Darwin */
+#if !defined(MAP_ANONYMOUS)
+    #define MAP_ANONYMOUS MAP_ANON
+#endif
+
+#include <pthread.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>

utils/s2n_prelude.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#pragma once
+
+/* Let modules know that the prelude was included */
+#define _S2N_PRELUDE_INCLUDED
+
+/* Define the POSIX API we are targeting */
+#ifndef _POSIX_C_SOURCE
+    #define _POSIX_C_SOURCE 200809L
+#endif
+
+/**
+ * If we're building in release mode make sure _FORTIFY_SOURCE is set
+ * See: https://www.gnu.org/software/libc/manual/html_node/Source-Fortification.html
+ *      https://man7.org/linux/man-pages/man7/feature_test_macros.7.html
+ *
+ * NOTE: _FORTIFY_SOURCE can only be set when optimizations are enabled.
+ *       https://sourceware.org/git/?p=glibc.git;a=commit;f=include/features.h;h=05c2c9618f583ea4acd69b3fe5ae2a2922dd2ddc
+ */
+#if !defined(_FORTIFY_SOURCE) && defined(S2N_BUILD_RELEASE)
+    #define _FORTIFY_SOURCE 2
+#endif
+
+#if ((__GNUC__ >= 4) || defined(__clang__)) && defined(S2N_EXPORTS)
+    /**
+     * Marks a function as belonging to the public s2n API.
+     *
+     * See: https://gcc.gnu.org/wiki/Visibility
+     */
+    #define S2N_API __attribute__((visibility("default")))
+#endif