Merge pull request #112 from ermo/cmake-fpie-off-by-default

Set -fno-PIE by default as a Ubuntu/Mint workaround

README.md

@@ -251,7 +251,7 @@ sudo apt-get -y install git cmake python-dev build-essential automake autoconf l
    ccmake ../engine
    # (configure/edit options to taste in ccmake, press 'c' to save the selected options
    # and press 'g' to update the build configuration files used by the make build tool)
-   make -jN # (where N is the number of available CPU threads/cores on your system)
+   cmake --build . -j $(nproc) # (where $(nproc) returns the number of available CPU threads/cores on the system)
    mkdir ../bin && cp vegastrike ../bin/ && cp setup/vssetup ../bin/ && cd ..
    ```
 
@@ -260,15 +260,45 @@ sudo apt-get -y install git cmake python-dev build-essential automake autoconf l
    ```bash
    mkdir build & cd build
    cmake ../engine
-   make -jN # (where N is the number of available CPU threads/cores on your system)
+   cmake --build . -j $(nproc) # (where $(nproc) returns the number of available CPU threads/cores on the system)
    mkdir ../bin && cp vegastrike ../bin/ && cp setup/vssetup ../bin/ && cd ..
    ```
-   To enable/disable compile-time options with cmake, use `cmake -D<option>`. Example:
+
+   __TIPS__:
+
+   To enable verbose output for debugging purposes (will show compilation commands), pass the `-- VERBOSE=1` argument:
+
+   ```bash
+   cmake --build . -- VERBOSE=1
+   ```
+
+   To enable/disable compile-time options with cmake, use `cmake -D<option>=<value>`. Example:
 
    ```bash
-   cmake ../engine -DUSE_PYTHON_3=ON -DCPU_SMP=2 -DCPUINTEL_native=ON -CMAKE_BUILD_TYPE=Debug
+   cmake ../engine -DENABLE_PIE=ON -DUSE_PYTHON_3=ON -DCPU_SMP=2 -DCPUINTEL_native=ON -CMAKE_BUILD_TYPE=Debug
    ```
 
+   __NOTE__:
+
+   On some Ubuntu versions and derivatives, a bug exists whereby enabling
+   PIE compilation (Position Independent Executables) results in the
+   `file` utility incorrectly recognising the compiled vegastrike binary
+   as a shared library instead of a position independent shared executable
+   object.
+
+   The effect of the bug is that vegastrike can still be started from the
+   command line but that it will not be recognised as an executable by GUI
+   file managers such as Nautilus and Dolphin.
+
+   To avoid this scenario, turn off this flag by default and let packagers
+   on other distributions turn this on if their OS is able to correctly deal
+   with Position Independent Executables.
+
+   For more info, see:
+
+   - https://bugs.launchpad.net/ubuntu/+source/file/+bug/1747711
+   - https://github.com/vegastrike/Vega-Strike-Engine-Source/issues/94
+
 [Link to list of dependencies in wiki](http://vegastrike.sourceforge.net/wiki/HowTo:Compile_from_CVS)
 
 If there are any problems with this installation method,

engine/CMakeLists.txt

@@ -580,6 +580,40 @@ IF(DATADIR)
 ENDIF(DATADIR)
 
 
+# On some Ubuntu versions and derivatives, a bug exists whereby enabling
+# PIE compilation (Position Independent Executables) results in the
+# `file` utility incorrectly recognising the compiled vegastrike binary
+# as a shared library instead of a position independent shared executable
+# object.
+#
+# The effect of the bug is that vegastrike can still be started from the
+# command line but that it will not be recognised as an executable by GUI
+# file managers such as Nautilus and Dolphin.
+#
+# To avoid this scenario, turn off this flag by default and let packagers
+# on other distributions turn this on if their OS is able to correctly deal
+# with Position Independent Executables.
+
+# For more info, see:
+# - https://bugs.launchpad.net/ubuntu/+source/file/+bug/1747711
+# - https://github.com/vegastrike/Vega-Strike-Engine-Source/issues/94
+#
+#UNSET(CMAKE_POSITION_INDEPENDENT_CODE)
+OPTION(ENABLE_PIE
+  "Enable Position Independent Executables/Shared Libraries (NOT RECOMMENDED on Ubuntu/Mint)"
+  OFF)
+IF(ENABLE_PIE)
+  message("!! Enabling Position Independent Executables/Shared Libraries (NOT RECOMMENDED on Ubuntu/Mint) !!")
+  #SET(CMAKE_POSITION_INDEPENDENT_CODE ON)
+  add_compile_options("-pie")
+  link_libraries("-pie")
+ELSE(ENABLE_PIE)
+  message("++ Disabling Position Independent Executables/Shared Libraries (Recommended on Ubuntu/Mint)")
+  add_compile_options("-no-pie")
+  link_libraries("-no-pie")
+ENDIF(ENABLE_PIE)
+
+
 # Debug target block. 
 SET(CMAKE_CXX_FLAGS_DEBUG " ${BUILD_OPT} ${CPU_OPTS} ${DEFINES} -include config.h -pipe -g2 -std=c++11 -Wall -fvisibility=hidden" CACHE STRING
     "Flags used by the C++ compiler during debug builds."
@@ -1000,13 +1034,11 @@ add_subdirectory(setup)
 add_subdirectory(objconv)
 
 
-
-
 # show debug output 
 get_directory_property(TEMP_DIRECTORY INCLUDE_DIRECTORIES)
-message("Default build type is Release, no cpu opts enabled. ")
-message("Building with BUILD_OPT: ${BUILD_OPT}")
-#message("Building with CFLAGS: ${CMAKE_CXX_FLAGS}")
+message("-- Default build type is Release, no cpu opts enabled. ")
+message("++ Building with BUILD_OPT: ${BUILD_OPT}")
+#message("++ Building with CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")
 #message("Linking with : ${TST_LIBS}")
 #message("including : ${TEMP_DIRECTORY}")
 # end debug output 

sh/vsbuild.sh

@@ -19,7 +19,7 @@
 
 
 echo "-------------------------------"
-echo "--- vsbuild.sh | 2020-02-09 ---"
+echo "--- vsbuild.sh | 2020-05-13 ---"
 echo "-------------------------------"
 
 #----------------------------------
@@ -32,26 +32,23 @@ BIN_DIR=$ROOT_DIR/bin
 SRC_DIR=$ROOT_DIR/engine
 COMMAND=""
 
-if [ ! -d "$BUILD_DIR" ]; then
-    mkdir $BUILD_DIR
-fi
+# -p creates if the target doesn't exist, noop otherwise
+mkdir -pv $BUILD_DIR && cd $BUILD_DIR
 
-cd $BUILD_DIR
-
-# configure libraries
-cmake -DCMAKE_BUILD_TYPE=Release $@ $SRC_DIR
+# configure libraries and prepare for the Debug build having -Werror set,
+# thus gating VS commits on being warning-free at some point in the near
+# future -- see https://github.com/vegastrike/Vega-Strike-Engine-Source/issues/50
+cmake -DCMAKE_BUILD_TYPE=Debug $@ $SRC_DIR
 
 # for a clean build only
 # mut we can do it manually
 #make clean
 
-# compile now using all cpus
-make -j$(nproc)
+# compile now using all cpus and show compilation commands
+cmake --build . -j $(nproc) -- VERBOSE=1
 
 cd $ROOT_DIR
 
-if [ ! -d "$BIN_DIR" ]; then
-    mkdir $BIN_DIR
-fi
+mkdir -pv $BIN_DIR
 
-cp $BUILD_DIR/{vegastrike,setup/vssetup,objconv/mesh_tool} $BIN_DIR
+cp -v $BUILD_DIR/{vegastrike,setup/vssetup,objconv/mesh_tool} $BIN_DIR