From c57d0e5ed5a5560bcee2775d03ce855f6abf7e7c Mon Sep 17 00:00:00 2001
From: Azim Khan <Azim.Khan@arm.com>
Date: Wed, 23 May 2018 16:55:16 +0100
Subject: [PATCH] Treat warnings as errors for IAR

Fix IAR compiler warnings

Two warnings have been fixed:
1. code 'if( len <= 0xFFFFFFFF )' gave warning 'pointless integer comparison'.
   This was fixed by wraping the condition in '#if SIZE_MAX > 0xFFFFFFFF'.
2. code 'diff |= A[i] ^ B[i];' gave warning 'the order of volatile accesses is undefined in'.
   This was fixed by read the volatile data in temporary variables before the computation.

Explain IAR warning on volatile access

Consistent use of CMAKE_C_COMPILER_ID
---
 CMakeLists.txt                 | 23 ++++++++++++++++-------
 include/mbedtls/ssl_internal.h |  8 +++++++-
 library/pkcs5.c                |  2 ++
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ecacc7ade..b61350eca 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,8 +7,13 @@ option(ENABLE_ZLIB_SUPPORT "Build mbed TLS with zlib library." OFF)
 option(ENABLE_PROGRAMS "Build mbed TLS programs." ON)
 
 
+string(REGEX MATCH "Clang" CMAKE_COMPILER_IS_CLANG "${CMAKE_C_COMPILER_ID}")
+string(REGEX MATCH "GNU" CMAKE_COMPILER_IS_GNU "${CMAKE_C_COMPILER_ID}")
+string(REGEX MATCH "IAR" CMAKE_COMPILER_IS_IAR "${CMAKE_C_COMPILER_ID}")
+string(REGEX MATCH "MSVC" CMAKE_COMPILER_IS_MSVC "${CMAKE_C_COMPILER_ID}")
+
 # the test suites currently have compile errors with MSVC
-if(MSVC)
+if(CMAKE_COMPILER_IS_MSVC)
     option(ENABLE_TESTING "Build mbed TLS tests." OFF)
 else()
     option(ENABLE_TESTING "Build mbed TLS tests." ON)
@@ -48,7 +53,7 @@ endfunction(link_to_source)
 
 string(REGEX MATCH "Clang" CMAKE_COMPILER_IS_CLANG "${CMAKE_C_COMPILER_ID}")
 
-if(CMAKE_COMPILER_IS_GNUCC)
+if(CMAKE_COMPILER_IS_GNU)
     # some warnings we want are not available with old GCC versions
     # note: starting with CMake 2.8 we could use CMAKE_C_COMPILER_VERSION
     execute_process(COMMAND ${CMAKE_C_COMPILER} -dumpversion
@@ -67,7 +72,7 @@ if(CMAKE_COMPILER_IS_GNUCC)
     set(CMAKE_C_FLAGS_ASANDBG     "-Werror -fsanitize=address -fno-common -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls ")
     set(CMAKE_C_FLAGS_CHECK       "-Werror -Os")
     set(CMAKE_C_FLAGS_CHECKFULL   "${CMAKE_C_FLAGS_CHECK} -Wcast-qual")
-endif(CMAKE_COMPILER_IS_GNUCC)
+endif(CMAKE_COMPILER_IS_GNU)
 
 if(CMAKE_COMPILER_IS_CLANG)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -W -Wdeclaration-after-statement -Wwrite-strings -Wpointer-arith -Wimplicit-fallthrough -Wshadow")
@@ -81,16 +86,20 @@ if(CMAKE_COMPILER_IS_CLANG)
     set(CMAKE_C_FLAGS_CHECK       "-Werror -Os")
 endif(CMAKE_COMPILER_IS_CLANG)
 
-if(MSVC)
+if(CMAKE_COMPILER_IS_IAR)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --warn_about_c_style_casts --warnings_are_errors -Ohz")
+endif(CMAKE_COMPILER_IS_IAR)
+
+if(CMAKE_COMPILER_IS_MSVC)
     # Strictest warnings, and treat as errors
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
-endif(MSVC)
+endif(CMAKE_COMPILER_IS_MSVC)
 
 if(CMAKE_BUILD_TYPE STREQUAL "Coverage")
-    if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
+    if(CMAKE_COMPILER_IS_GNU OR CMAKE_COMPILER_IS_CLANG)
         set(CMAKE_SHARED_LINKER_FLAGS "--coverage")
-    endif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
+    endif(CMAKE_COMPILER_IS_GNU OR CMAKE_COMPILER_IS_CLANG)
 endif(CMAKE_BUILD_TYPE STREQUAL "Coverage")
 
 if(LIB_INSTALL_DIR)
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index cc0e7865c..e4b609c9a 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -613,7 +613,13 @@ static inline int mbedtls_ssl_safer_memcmp( const void *a, const void *b, size_t
     volatile unsigned char diff = 0;
 
     for( i = 0; i < n; i++ )
-        diff |= A[i] ^ B[i];
+    {
+        /* Read volatile data in order before computing diff.
+         * This avoids IAR compiler warning:
+         * 'the order of volatile accesses is undefined ..' */
+        unsigned char x = A[i], y = B[i];
+        diff |= x ^ y;
+    }
 
     return( diff );
 }
diff --git a/library/pkcs5.c b/library/pkcs5.c
index 35146b74b..a20471084 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -249,8 +249,10 @@ int mbedtls_pkcs5_pbkdf2_hmac( mbedtls_md_context_t *ctx, const unsigned char *p
     memset( counter, 0, 4 );
     counter[3] = 1;
 
+#if UINT_MAX > 0xFFFFFFFF
     if( iteration_count > 0xFFFFFFFF )
         return( MBEDTLS_ERR_PKCS5_BAD_INPUT_DATA );
+#endif
 
     while( key_length )
     {