CMakeLists.txt

cmake_minimum_required(VERSION 3.16)

project(toy_dynamic_linker)

# Set clang as the default compiler
set(CMAKE_C_COMPILER clang)
set(CMAKE_CXX_COMPILER clang++)

# Set output directories
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

# Create the toy_linker shared library
add_library(toy_linker SHARED src/toy_linker.c src/auxv.h src/util.h src/program_header.h src/dynamic_section.h src/library_types.h src/loader.h src/symbol.h src/relocation.h src/hash_table.h src/init_libs.h)

# Set include directories
target_include_directories(toy_linker PRIVATE src)

# Set the output name to toy_linker.so
set_target_properties(toy_linker PROPERTIES OUTPUT_NAME "toy_linker")

# Set compilation flags
target_compile_options(toy_linker PRIVATE
    -nostdlib
    -fPIC
    -g
)

# Set linker flags
target_link_options(toy_linker PRIVATE
    -nostdlib
    -shared
    -Wl,-e,_start,--no-undefined
)



# Create a simple shared library with no external dependencies
add_library(simple_lib SHARED example/simple_lib.c)
target_compile_options(simple_lib PRIVATE
    -g
    -fPIC
    -fno-builtin
    -nostdlib
    -fno-stack-protector
)
target_link_options(simple_lib PRIVATE
    -nostdlib
    -shared
)

# Create a simpler C program that uses our simple_lib
add_executable(simple_program example/simple_program.c)

# Add debug information to simple_program and disable standard library
target_compile_options(simple_program PRIVATE
    -g
    -fno-builtin
    -nostdlib
    -fno-stack-protector
)

# Link against our simple_lib
target_link_libraries(simple_program PRIVATE simple_lib)

# Use our toy_linker as the dynamic linker
target_link_options(simple_program PRIVATE
    -Wl,--dynamic-linker=${CMAKE_BINARY_DIR}/lib/libtoy_linker.so
    -nostdlib
    -nostartfiles
    -nodefaultlibs
)

# Make sure simple_program depends on toy_linker and simple_lib so they're built first
add_dependencies(simple_program toy_linker simple_lib)