Goal: embed an external file inside a binary.

Method 1: Use Python script to dump file bytes as a C-string into .cpp file
Method 2: Use .incbin technique shown here

Caveat:

• The external file should be embedded in lib.so
• main should be able to access the external file from lib.so through a global variable

Method 1 (GENERATE_RESOURCES) always works.

Method 2 works depending on:

• The compiler/linker (I tested g++-10 and clang++-10)

• Whether the global variable has __attribute__((weak)) (ATTRIBUTE_WEAK)

  • This seems to fix the issue for g++-10, but not for clang++-10

• Whether the global variable is const (CONST)

  • If const is used, there will be a big unintialized "placeholder" for the external file in main, inflating the executable size

• Whether the global variable is used in lib.cpp (LIB_PASSTHROUGH)

The ./build_all.py script tries all possibilities. My output on Ubuntu 20.04 is in output.log:

...
Successful cmds:
./build.py g++-10 GENERATE_RESOURCES
./build.py g++-10 ATTRIBUTE_WEAK
./build.py g++-10 GENERATE_RESOURCES LIB_PASSTHROUGH
./build.py g++-10 GENERATE_RESOURCES ATTRIBUTE_WEAK
./build.py g++-10 LIB_PASSTHROUGH ATTRIBUTE_WEAK
./build.py g++-10 ATTRIBUTE_WEAK CONST
./build.py g++-10 GENERATE_RESOURCES LIB_PASSTHROUGH ATTRIBUTE_WEAK
./build.py g++-10 GENERATE_RESOURCES ATTRIBUTE_WEAK CONST
./build.py g++-10 LIB_PASSTHROUGH ATTRIBUTE_WEAK CONST
./build.py g++-10 GENERATE_RESOURCES LIB_PASSTHROUGH ATTRIBUTE_WEAK CONST
./build.py clang++-10 GENERATE_RESOURCES
./build.py clang++-10 GENERATE_RESOURCES LIB_PASSTHROUGH
./build.py clang++-10 GENERATE_RESOURCES ATTRIBUTE_WEAK
./build.py clang++-10 GENERATE_RESOURCES LIB_PASSTHROUGH ATTRIBUTE_WEAK