helloworld/shadowsocksr-libev/src/cmake/CheckSTDC.cmake

message(STATUS "Checking whether system has ANSI C header files")
include(CheckPrototypeExists)
include(CheckIncludeFiles)

check_include_files("dlfcn.h;stdint.h;stddef.h;inttypes.h;stdlib.h;strings.h;string.h;float.h" StandardHeadersExist)
if(StandardHeadersExist)
    check_prototype_exists(memchr string.h memchrExists)
    if(memchrExists)
        check_prototype_exists(free stdlib.h freeExists)
        if(freeExists)
            message(STATUS "ANSI C header files - found")
            set(STDC_HEADERS 1 CACHE INTERNAL "System has ANSI C header files")
            set(HAVE_STRINGS_H 1)
            set(HAVE_STRING_H 1)
            set(HAVE_FLOAT_H 1)
            set(HAVE_STDLIB_H 1)
            set(HAVE_STDDEF_H 1)
            set(HAVE_STDINT_H 1)
            set(HAVE_INTTYPES_H 1)
            set(HAVE_DLFCN_H 1)
        endif(freeExists)
    endif(memchrExists)
endif(StandardHeadersExist)

if(NOT STDC_HEADERS)
    message(STATUS "ANSI C header files - not found")
    set(STDC_HEADERS 0 CACHE INTERNAL "System has ANSI C header files")
endif(NOT STDC_HEADERS)

check_include_files(unistd.h HAVE_UNISTD_H)

include(CheckDIRSymbolExists)
check_dirsymbol_exists("sys/stat.h;sys/types.h;dirent.h" HAVE_DIRENT_H)
if (HAVE_DIRENT_H)
    set(HAVE_SYS_STAT_H 1)
    set(HAVE_SYS_TYPES_H 1)
endif (HAVE_DIRENT_H)