Add cmake support

This change will allow us to remove the libc.py script and
build the wasm targets using cmake+ninja instead.

CMakeLists.txt

@@ -0,0 +1,148 @@
+# We require 3.9 because of the use of $<TARGET_OBJECTS:crt1>
+cmake_minimum_required(VERSION 3.9)
+project(MUSL)
+enable_language(C ASM)
+include(CheckCCompilerFlag)
+
+if(WASM)
+  set(ARCH "wasm32")
+elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64")
+  set(ARCH "x86_64")
+else()
+  error("Could not detect ARCH")
+endif(WASM)
+
+set(EMPTY_LIB_NAMES m rt pthread crypt util xnet resolv dl)
+
+include_directories(
+  ${MUSL_SOURCE_DIR}/arch/${ARCH}
+  ${MUSL_SOURCE_DIR}/arch/generic
+  ${MUSL_BINARY_DIR}/src/internal
+  ${MUSL_SOURCE_DIR}/src/internal
+  ${MUSL_BINARY_DIR}/include
+  ${MUSL_SOURCE_DIR}/include
+)
+
+add_definitions(
+ -D_XOPEN_SOURCE=700
+ -std=c99
+ -ffreestanding
+ -nostdinc
+)
+
+set(OPTIONAL_FLAGS
+ -fomit-frame-pointer
+ -fno-unwind-tables
+ -fno-asynchronous-unwind-tables
+ -ffunction-sections
+ -fdata-sections
+ -fexcess-precision=standard
+ -frounding-math
+ -Wa,--noexecstack
+)
+
+set(WARNING_FLAGS
+ -Werror
+ -Wno-empty-body
+ -Wno-incompatible-library-redeclaration
+ -Wno-shift-op-parentheses
+ -Wno-tautological-unsigned-zero-compare
+ -Wno-tautological-constant-out-of-range-compare
+ -Wno-tautological-unsigned-enum-zero-compare
+ -Wno-ignored-attributes
+ -Wno-format
+ -Wno-bitwise-op-parentheses
+ -Wno-logical-op-paretheses
+ -Wno-string-plus-int
+ -Wno-pointer-sign
+ -Wno-dangling-else
+ -Wno-absolute-value
+ -Wno-parentheses
+ -Wno-unknown-pragmas
+)
+
+foreach(flag IN LISTS OPTIONAL_FLAGS WARNING_FLAGS)
+  check_c_compiler_flag(${flag} FLAG_${flag})
+  if(FLAG_${flag})
+    add_definitions(${flag})
+  endif(FLAG_${flag})
+endforeach(flag)
+
+set(CMAKE_SHARED_LINKER_FLAGS "-nostdlib -Wl,-e,_dlstart")
+
+add_custom_command(
+  OUTPUT ${MUSL_BINARY_DIR}/src/internal/version.h
+  COMMAND
+  echo '\#define VERSION \"1\"' > ${MUSL_BINARY_DIR}/src/internal/version.h
+  DEPENDS
+  ${MUSL_SOURCE_DIR}/VERSION
+)
+
+add_custom_command(
+  OUTPUT ${MUSL_BINARY_DIR}/include/bits/syscall.h
+  COMMAND
+  cp ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits/syscall.h.in ${MUSL_BINARY_DIR}/include/bits/syscall.h &&
+  sed -n -e s/__NR_/SYS_/p < ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits/syscall.h.in >> ${MUSL_BINARY_DIR}/include/bits/syscall.h
+  DEPENDS ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits/syscall.h.in
+)
+
+add_custom_command(
+  OUTPUT ${MUSL_BINARY_DIR}/include/bits/alltypes.h
+  COMMAND
+  sed -f ${MUSL_SOURCE_DIR}/tools/mkalltypes.sed ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits/alltypes.h.in ${MUSL_SOURCE_DIR}/include/alltypes.h.in >${MUSL_BINARY_DIR}/include/bits/alltypes.h
+  DEPENDS
+  ${MUSL_SOURCE_DIR}/tools/mkalltypes.sed
+  ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits/alltypes.h.in
+  ${MUSL_SOURCE_DIR}/include/alltypes.h.in
+)
+
+file(GLOB SOURCES "src/*/*.c")
+file(GLOB LDSO_SOURCES "ldso/*.c")
+file(GLOB ASM_SOURCES "src/*/${ARCH}/*.s")
+
+# Filter out (replace) any sources that are provided in asm form
+foreach(src IN LISTS ASM_SOURCES)
+  string(REPLACE "/${ARCH}/" "/" src ${src})
+  string(REPLACE ".s" ".c" src ${src})
+  list(REMOVE_ITEM SOURCES ${src})
+endforeach(src)
+
+set(ALL_SOURCES
+  ${SOURCES}
+  ${ASM_SOURCES}
+  ${MUSL_BINARY_DIR}/src/internal/version.h
+  ${MUSL_BINARY_DIR}/include/bits/alltypes.h
+  ${MUSL_BINARY_DIR}/include/bits/syscall.h
+)
+
+foreach(lib IN LISTS EMPTY_LIB_NAMES)
+  # Include a random header here to avoid CMake warning about creating
+  # a library with no sources.
+  add_library(${lib} STATIC ${MUSL_SOURCE_DIR}/include/stdio.h)
+  # Also to avoid a cmake warning
+  set_property(TARGET ${lib} PROPERTY LINKER_LANGUAGE C)
+endforeach(lib)
+
+add_library(c-static STATIC ${ALL_SOURCES})
+set_target_properties(c-static PROPERTIES OUTPUT_NAME c CLEAN_DIRECT_OUTPUT 1)
+
+add_library(crt1 OBJECT crt/crt1.c)
+set_target_properties(crt1 PROPERTIES OUTPUT_NAME crt1 CLEAN_DIRECT_OUTPUT 1)
+
+add_custom_target(
+  crt1.o ALL
+  COMMAND cp $<TARGET_OBJECTS:crt1> crt1.o
+  DEPENDS crt1
+)
+
+if(!WASM)
+  add_library(c SHARED ${ALL_SOURCES} ${LDSO_SOURCES})
+  install(TARGETS c DESTINATION lib)
+endif(!WASM)
+
+install(TARGETS c-static ${EMPTY_LIB_NAMES} DESTINATION lib)
+install(FILES ${MUSL_BINARY_DIR}/crt1.o DESTINATION lib)
+install(DIRECTORY ${MUSL_SOURCE_DIR}/include DESTINATION include)
+install(DIRECTORY ${MUSL_SOURCE_DIR}/arch/generic/bits DESTINATION include/bits)
+install(DIRECTORY ${MUSL_SOURCE_DIR}/arch/${ARCH}/bits DESTINATION include/bits)
+install(DIRECTORY ${MUSL_BINARY_DIR}/include/bits DESTINATION include/bits)