configure.ac 宏解释

configure.ac (configure.in)
		configure.ac (sometimes also named: configure.in) is an input file for . It contains tests that check for conditions that are likely to differ on different platforms. The tests are made by actually invoke macros. configure.ac is processed by which produces . Basically, configure.ac is copied, but macros found within configure.ac are expanded. A configure.ac should contain the following macros: AC_DEFINE (???) helps create a configure.ac file by examining source files. It creates a configure.scan file which can then be changed for a configure.ac file. Typical layout AC_INIT(package, version, bug-report-address) package information program checks library checks header file checks type checks structure checks compiler characteristics checks library functions check system service checks AC_CONFIG_FILES([...]) AC_OUTPUT Macros AC_INIT AC_INIT(package, version, [bug-report], [tar-name]) AC_INIT and are the two only required macros by the configure script. program_file is used to check wheter autoconf finds it. If it doesn't find it, it is somehow screwed up. AC_INIT generates the following m4 macros, output variables and preprocessor symbols: [AC_]PACKAGE_NAME [AC_]PACKAGE_TARNAME [AC_]PACKAGE_VERSION [AC_]PACKAGE_STRING [AC_]PACKAGE_BUGREPORT AC_PREREQ AC_PREREQ(version) Indicates the version of that is used. AM_INIT_AUTOMAKE AM_INIT_AUTOMAKE([options]) The following form obsolete: the package and the version can be optained by AM_INIT_AUTOMAKE(package, version [, no-define]) This macro is always needed for AC_DEFINE Defines a c preprocessor macro For example AC_DEFINE(DEBUG) or AC_DEFINE(VERSION, "2.3") AC_DEFINE_UNQUOTED Defines a preprocessor macro with shell expansion AC_DEFINE_UNQUOTED(FOO, "${some_variable}") AC_CHECK_LIB Checks for a symbol within a library AC_ARG_ENABLE AC_OUTPUT AC_OUTPUT(Makefile foo_config) There should be an AC_OUTPUT for each in the project. and AC_OUTPUT are the two only required macros by the configure script. AC_OUTPUT generates the files that are required for the building process. Lists the names of the files that will be output by the script. AC_CHECK_FUNCS(func-name-1 func-name-2) Checks if a functions exist (within the c library ???). If they exist, it defines HAVE_func-name-n AC_HEADERS Defines STDC_HEADER if Ansi C header files are present. It actually assumes that the header files are present if it finds stdlib.h stdarg.h string.h and float.h. AC_HEADERS Checks if a header file is present. ??? If so, defines HAVE_header. AC_EGREP_HEADER AC_FUNC_xxx AC_FUNC_STRFTIME Checks if strftime exists. Includes libintl in LIBS if needed (eg for SCO). AC_FUNC_MEMCMP Checks if memcmp exists and is 8-bit clean. AC_FUNC_UTIME_NULL Checks whether utime accepts a NULL second argument to set the file change time to the current time. See also AC_PROG_INSTALL Generates an install target, so that it is possible to install the program with make install Sets INSTALL to a BSD compatible install programm, if possible. If not possible, sets it to some-dir/install-sh. In order to determine some-dir, it checkes the directories specified with . Also sets variable INSTALL_PROGRAM to ${INSTALL} and INSTALL_DATA to ${INSTALL} -m 644. If AC_PROG_INSTALL is used but configure cannot find an install-sh, configure will report an error. AC_CONFIG_AUX_DIR AC_CONFIG_HEADER AC_CONFIG_SRCDIR AC_CONFIG_FILES AC_PROG_CC Checks for a working C compiler and discovers its characteristics. AC_PROG_CXX Like AC_PROG_CC, but for C++ compilers. AM_DISABLE_SHARED See . AM_PROG_LIBTOOL Used if building libraries. By default, libraries are built as shared libraries. In order to build static libraries, needs to be defined before AM_PROG_LIBTOOL. This behaviour can be overriden with the and configure options. AM_CONFIG_HEADER AM_CONFIG_HEADER(config.h) AM_CONFIG_HEADER(config.h:config.in) It may optionally name the input file for the output file, by default this is config.h.in, however, this works poorly on dos. Names the header file which will hold the preprocessor macro definitions for compile time. Normally, this is config.h. The source files will then #include "config.h". Generates a portability header file, requires a file. ???? Use AC_CONFIG_HEADER instead of AM_CONFIG_HEADER if you're not using . ???? ??? In order to use AM_CONFIG_HEADER, a stamp-h file is needed ???. AM_MAINTAINER_MODE AC_EXEEXT Always present in Cygnus configure scripts, finds the executable suffix on the system (.exe for windows, empty for unix). AC_STRUCT_TM Defines TM_IN_SYS_TIME if does not define struct tm.