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xmake高级特性之批量检测库函数

有时候可能用到某个库的某些函数接口，但是这个库有可能在某个平台上被裁减过了，接口支持不全，如果你想跨平台使用，就会出问题

因此在使用之前进行检测是否存在这个函数，还是很有必要的，xmake提供了方便的api，可以批量检测某个库的一些函数：

例如：

 add_target("test")      -- 检测libc库中，对宽字符操作的接口是否存在，检测条件：检查wchar.h、stdlib.h中是否有函数声明     add_cfuncs("libc", nil,         {"wchar.h", "stdlib.h"},            "wcscat",                                                                         "wcsncat",                                                                         "wcscpy",                                                                         "wcsncpy",                                                                         "wcslcpy",                                                                         "wcslen",                                                                         "wcsnlen",                                                                         "wcsstr",                                                                         "wcscasestr",                                                                         "wcscmp",                                                                         "wcscasecmp",                                                                         "wcsncmp",                                                                         "wcsncasecmp",                                                                         "wcstombs",                                                                         "mbstowcs")      -- 检测pthread库中，是否存在pthread_mutex_init, pthread_create接口，相当于检测了pthread是否存在     -- 第一个参数是库类型、别名，可以随便写     add_cfuncs("posix", nil,        "pthread.h",                        "pthread_mutex_init", "pthread_create")      -- 检测pthread库中，是否存在pthread_mutex_init, pthread_create接口，相当于检测了pthread是否存在     -- 这个检测更加严格，同时检测了libpthread.a静态库是否存在这个接口的定义，如果链接不通过，就检测失败     -- xmake会在检测时，尝试链接-lpthread     add_cfuncs("posix", "pthread",  "pthread.h",                        "pthread_mutex_init", "pthread_create")

可以执行： xmake f -v 看到实际的检测信息，这里随便摘取了一段tbox中检测信息：

checking for the c include string.h ... ok checking for the c include stdlib.h ... ok checking for the c function strlen ... ok checking for the c function sincosf ... no checking for the c include wchar.h ... ok checking for the c function wcscmp ... ok checking for the c function wcsncat ... ok checking for the c include dlfcn.h ... ok checking for the c function dlopen ... ok checking for the links polarssl ... ok checking for the c include polarssl/polarssl.h ... ok checking for the c function strcat ... ok checking for the c function wcsstr ... ok checking for the c function wcscat ... ok checking for the c function sincos ... no checking for the c function memcpy ... ok checking for the c function sqrtf ... ok checking for the c function wcsnlen ... ok checking for the c function acosf ... ok checking for the links pthread, dl, m, c ... ok checking for the c include sys/stat.h ... ok checking for the c function open ... ok checking for the c function strnlen ... ok checking for the c function system ... ok checking for the links z ... ok checking for the c include zlib/zlib.h ... ok checking for the c function strncat ... ok checking for the c function wcsncpy ... ok checking for the c function gmtime ... ok checking for the c include signal.h ... ok checking for the c include setjmp.h ... ok checking for the c function sigsetjmp ... ok checking for the c function sinf ... ok checking for the c function strncmp ... ok checking for the c function memmove ... ok checking for the c function strncasecmp ... ok checking for the c function strlcpy ... ok checking for the links sqlite3 ... ok checking for the c include sqlite3/sqlite3.h ... ok checking for the c include sys/sem.h ... ok checking for the c include sys/ipc.h ... ok checking for the c function semtimedop ... no checking for the c function wcscpy ... ok checking for the c function sqrt ... ok checking for the c function strcmp ... ok checking for the c function strcasecmp ... ok checking for the c function semget ... ok checking for the c include unistd.h ... ok checking for the c function sysconf ... ok checking for the c function memset ... ok checking for the c function getpagesize ... ok checking for the c include semaphore.h ... ok checking for the c function sem_init ... ok checking for the c function strncpy ... ok checking for the c function localtime ... ok checking for the c include ifaddrs.h ... ok checking for the c function getifaddrs ... ok checking for the c function strcpy ... ok checking for the c function gethostname ... ok checking for the c function wcslcpy ... ok checking for the c include dirent.h ... ok checking for the c function opendir ... ok checking for the c function wcslen ... ok checking for the c function cos ... ok checking for the c include sys/time.h ... ok checking for the c function gettimeofday ... ok checking for the c function signal ... ok checking for the c function strstr ... ok checking for the c function exp ... ok checking for the c function log2f ... ok checking for the c function sin ... ok checking for the c function log2 ... ok checking for the c function cosf ... ok checking for the c include pthread.h ... ok checking for the c function pthread_mutex_init ... ok checking for the c function fmodf ... ok checking for the c function wcstombs ... ok checking for the c function fmod ... ok checking for the c function memcmp ... ok checking for the c function atan2f ... ok checking for the c function atan2 ... ok checking for the c function atanf ... ok checking for the c function atan ... ok checking for the c function powf ... ok checking for the c function pow ... ok checking for the c function asinf ... ok checking for the c function asin ... ok checking for the c function pthread_create ... ok

最后的检测结果会自动输出到config.h中（如果有启用的话）：

#define TB_CONFIG_LIBC_HAVE_MEMCPY #define TB_CONFIG_LIBC_HAVE_MEMSET #define TB_CONFIG_LIBC_HAVE_MEMMOVE #define TB_CONFIG_LIBC_HAVE_MEMCMP #define TB_CONFIG_LIBC_HAVE_MEMMEM #define TB_CONFIG_LIBC_HAVE_STRCAT #define TB_CONFIG_LIBC_HAVE_STRNCAT #define TB_CONFIG_LIBC_HAVE_STRCPY #define TB_CONFIG_LIBC_HAVE_STRNCPY #define TB_CONFIG_LIBC_HAVE_STRLCPY #define TB_CONFIG_LIBC_HAVE_STRLEN #define TB_CONFIG_LIBC_HAVE_STRNLEN #define TB_CONFIG_LIBC_HAVE_STRSTR #define TB_CONFIG_LIBC_HAVE_STRCASESTR #define TB_CONFIG_LIBC_HAVE_STRCMP #define TB_CONFIG_LIBC_HAVE_STRCASECMP #define TB_CONFIG_LIBC_HAVE_STRNCMP #define TB_CONFIG_LIBC_HAVE_STRNCASECMP #define TB_CONFIG_LIBC_HAVE_WCSCAT #define TB_CONFIG_LIBC_HAVE_WCSNCAT #define TB_CONFIG_LIBC_HAVE_WCSCPY #define TB_CONFIG_LIBC_HAVE_WCSNCPY #define TB_CONFIG_LIBC_HAVE_WCSLCPY #define TB_CONFIG_LIBC_HAVE_WCSLEN #define TB_CONFIG_LIBC_HAVE_WCSNLEN #define TB_CONFIG_LIBC_HAVE_WCSSTR #define TB_CONFIG_LIBC_HAVE_WCSCMP #define TB_CONFIG_LIBC_HAVE_WCSCASECMP #define TB_CONFIG_LIBC_HAVE_WCSNCMP #define TB_CONFIG_LIBC_HAVE_WCSNCASECMP #define TB_CONFIG_LIBC_HAVE_WCSTOMBS #define TB_CONFIG_LIBC_HAVE_MBSTOWCS #define TB_CONFIG_LIBC_HAVE_GMTIME #define TB_CONFIG_LIBC_HAVE_MKTIME #define TB_CONFIG_LIBC_HAVE_LOCALTIME #define TB_CONFIG_LIBC_HAVE_GETTIMEOFDAY #define TB_CONFIG_LIBC_HAVE_SIGNAL #define TB_CONFIG_LIBC_HAVE_SETJMP #define TB_CONFIG_LIBC_HAVE_SIGSETJMP #define TB_CONFIG_LIBC_HAVE_BACKTRACE #define TB_CONFIG_LIBC_HAVE_SYSTEM #define TB_CONFIG_LIBM_HAVE_LOG2 #define TB_CONFIG_LIBM_HAVE_LOG2F #define TB_CONFIG_LIBM_HAVE_SQRT #define TB_CONFIG_LIBM_HAVE_SQRTF #define TB_CONFIG_LIBM_HAVE_ACOS #define TB_CONFIG_LIBM_HAVE_ACOSF #define TB_CONFIG_LIBM_HAVE_ASIN #define TB_CONFIG_LIBM_HAVE_ASINF #define TB_CONFIG_LIBM_HAVE_POW #define TB_CONFIG_LIBM_HAVE_POWF #define TB_CONFIG_LIBM_HAVE_FMOD #define TB_CONFIG_LIBM_HAVE_FMODF #define TB_CONFIG_LIBM_HAVE_ATAN #define TB_CONFIG_LIBM_HAVE_ATANF #define TB_CONFIG_LIBM_HAVE_ATAN2 #define TB_CONFIG_LIBM_HAVE_ATAN2F #define TB_CONFIG_LIBM_HAVE_COS #define TB_CONFIG_LIBM_HAVE_COSF #define TB_CONFIG_LIBM_HAVE_SIN #define TB_CONFIG_LIBM_HAVE_SINF #define TB_CONFIG_LIBM_HAVE_EXP #define TB_CONFIG_LIBM_HAVE_EXPF #define TB_CONFIG_POSIX_HAVE_POLL #define TB_CONFIG_POSIX_HAVE_PTHREAD_MUTEX_INIT #define TB_CONFIG_POSIX_HAVE_PTHREAD_CREATE #define TB_CONFIG_POSIX_HAVE_SOCKET #define TB_CONFIG_POSIX_HAVE_OPENDIR #define TB_CONFIG_POSIX_HAVE_DLOPEN #define TB_CONFIG_POSIX_HAVE_OPEN #define TB_CONFIG_POSIX_HAVE_GETHOSTNAME #define TB_CONFIG_POSIX_HAVE_GETIFADDRS #define TB_CONFIG_POSIX_HAVE_SEM_INIT #define TB_CONFIG_POSIX_HAVE_GETPAGESIZE #define TB_CONFIG_POSIX_HAVE_SYSCONF #define TB_CONFIG_POSIX_HAVE_SCHED_YIELD #define TB_CONFIG_SYSTEMV_HAVE_SEMGET

之后就可以在代码中，包含这个config.h来判断是否需要实际调用这个接口了，如果要多c++代码的接口进行检测，只需把名字改成：