Work on CMake build system - several cleanups

ports/CMakeCommon.cmake

@@ -1,7 +1,31 @@
-set(LWIP_GNU_CLANG_COMMON_FLAGS "-Wall -pedantic -Werror -Wparentheses -Wsequence-point -Wswitch-default -Wextra -Wundef -Wshadow -Wpointer-arith -Wcast-qual -Wc++-compat -Wwrite-strings -Wold-style-definition -Wcast-align -Wmissing-prototypes -Wredundant-decls -Wnested-externs -Wunreachable-code -Wuninitialized -Wmissing-prototypes -Wredundant-decls -Waggregate-return -Wlogical-not-parentheses")
+# ARM mbedtls support https://tls.mbed.org/
+# Build mbedtls BEFORE adding our own compile flags -
+# mbedtls produces errors with them
+set(MBEDTLSDIR ${LWIP_CONTRIB_DIR}/../mbedtls)
+if(EXISTS ${MBEDTLSDIR}/include/mbedtls/ssl.h)
+    set(LWIP_HAVE_MBEDTLS ON BOOL)
+
+    # Prevent building MBEDTLS programs and tests
+    set(ENABLE_PROGRAMS OFF CACHE BOOL "")
+    set(ENABLE_TESTING  OFF CACHE BOOL "")
+    
+    # mbedtls uses cmake. Sweet!
+    add_subdirectory(${LWIP_CONTRIB_DIR}/../mbedtls mbedtls)
+    add_definitions(-DLWIP_HAVE_MBEDTLS=1)
+    include_directories(${MBEDTLSDIR}/include)
+    link_libraries(mbedtls mbedcrypto mbedx509)
+endif()
+
+set(LWIP_GNU_CLANG_COMMON_FLAGS "-Wall -pedantic -Werror -Wparentheses -Wsequence-point -Wswitch-default -Wextra -Wundef -Wshadow -Wpointer-arith -Wcast-qual -Wc++-compat -Wwrite-strings -Wold-style-definition -Wcast-align -Wmissing-prototypes -Wnested-externs -Wunreachable-code -Wuninitialized -Wmissing-prototypes -Waggregate-return -Wlogical-not-parentheses")
+if (NOT LWIP_HAVE_MBEDTLS)
+    set(LWIP_GNU_CLANG_COMMON_FLAGS "${LWIP_GNU_CLANG_COMMON_FLAGS} -Wredundant-decls")
+endif()
 
 if(CMAKE_C_COMPILER_ID STREQUAL GNU)
-    set(CMAKE_C_FLAGS "${LWIP_GNU_CLANG_COMMON_FLAGS} -Wlogical-op -Wc90-c99-compat -Wtrampolines")
+    set(CMAKE_C_FLAGS "${LWIP_GNU_CLANG_COMMON_FLAGS} -Wlogical-op -Wtrampolines")
+    if (NOT LWIP_HAVE_MBEDTLS)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wc90-c99-compat")
+    endif()
 
     if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.9)
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fstack-protector -fstack-check -fsanitize=undefined -fno-sanitize=alignment")
@@ -15,14 +39,3 @@ endif()
 if(CMAKE_C_COMPILER_ID STREQUAL MSVC)
     # TODO
 endif()
-
-# ARM mbedtls support https://tls.mbed.org/
-set(MBEDTLSDIR ${LWIP_CONTRIB_DIR}/../mbedtls)
-if(EXISTS ${MBEDTLSDIR}/include/mbedtls/ssl.h)
-    set(ENABLE_PROGRAMS OFF CACHE BOOL "Prevent building MBEDTLS programs")
-
-    add_subdirectory(${LWIP_CONTRIB_DIR}/../mbedtls mbedtls)
-    add_definitions(-DLWIP_HAVE_MBEDTLS=1)
-    include_directories(${MBEDTLSDIR}/include)
-    link_libraries(mbedtls mbedcrypto mbedx509)
-endif()

ports/unix/CMakeLists.txt

@@ -12,14 +12,20 @@ set(lwipcontribportunix_SRCS
 )
 
 if (CMAKE_SYSTEM_NAME STREQUAL Linux)
-    link_libraries(util)
-    link_libraries(pthread)
-    link_libraries(rt)
+    find_library(LIBUTIL util)
+    link_libraries(${LIBUTIL})
+    
+    find_library(LIBPTHREAD pthread)
+    link_libraries(${LIBPTHREAD})
+    
+    find_library(LIBRT rt)
+    link_libraries(${LIBRT})
 endif()
 
 if (CMAKE_SYSTEM_NAME STREQUAL Darwin)
     # Darwin doesn't have pthreads or POSIX real-time extensions libs
-    link_libraries(util)
+    find_library(LIBUTIL util)
+    link_libraries(${LIBUTIL})
 endif()
 
 add_library(lwipcontribportunix EXCLUDE_FROM_ALL ${lwipcontribportunix_SRCS})

ports/unix/unixsim/CMakeLists.txt

@@ -10,15 +10,15 @@ include(${LWIP_CONTRIB_DIR}/ports/CMakeCommon.cmake)
 add_definitions(-DLWIP_DEBUG)
 
 include_directories(
-    "${LWIP_CONTRIB_DIR}/../lwip/src/include"
+    "${LWIP_DIR}/src/include"
     "${LWIP_CONTRIB_DIR}/"
     "${LWIP_CONTRIB_DIR}/ports/unix/port/include"
-    "${CMAKE_CURRENT_SOURCE_DIR}/./"
+    "${CMAKE_CURRENT_SOURCE_DIR}/"
 )
 
-add_subdirectory(../../../../lwip/src lwip)
-add_subdirectory(../../../ contrib)
-add_subdirectory(../ unixport)
+add_subdirectory(${LWIP_DIR}/src lwip)
+add_subdirectory(${LWIP_CONTRIB_DIR} contrib)
+add_subdirectory(${LWIP_CONTRIB_DIR}/ports/unix unixport)
 
 # lwipcontribaddons is specified multiple times in target_link_libraries because of cyclic dependency
 # lwipcontribaddons call various functions in lwipcore