CMake使用介绍
最近，公司的代码编译从直接使用 GNU make 转向了 cmake.
下面介绍一下cmake 的使用
1) cmake 的基本语法
cmake 可以看作一种脚本语言，它的一些语法和其他一下脚本语言（bash, python等）是相似的。
1.1 命令：
基本格式为
command(param)
命令可大写或者小写 (case-insensitive)
1.1 变量
引用变量 var的值： ${var}
给变量赋值：
set(Foo a b c)
或者
set(Foo a;b;c)
Foo 的值为 a b c (一个 list)
$ENV{name} --》得到环境变量的值
2. 流程控制：
2.1 if 语句
# some_command will be called if the variable's value is not:
# empty, 0, N, NO, OFF, FALSE, NOTFOUND, or -NOTFOUND.
if(var)
some_command(...)
endif(var) 2. loop:
set(VAR a b c)
# loop over a, b,c with the variable f
foreach(f ${VAR})
message(${f})
endforeach(f) # define a macro hello
macro(hello MESSAGE)
message(${MESSAGE})
endmacro(hello)
# call the macro with the string "hello world"
hello("hello world")
# define a function hello
function(hello MESSAGE)
message(${MESSAGE})
endfunction(hello) 下面举个例子来说明如何使用 cmake.
下面的例子中, 我们用 cmake 来生成静态库,动态库, 并使用生成的库文件.
代码树如下:
.
├── CMakeLists.txt
├── FooFunctions
│ ├── CMakeLists.txt
│ ├── inc
│ │ └── foo.h
│ └── src
│ └── foo.c
├── MathFunctions
│ ├── CMakeLists.txt
│ ├── inc
│ │ └── mysqrt.h
│ └── src
│ └── mysqrt.c
└── tutorial.c
top-level CMakeList.txt 如下:
cmake_minimum_required (VERSION 2.6)
2 project (Tutorial)
3
4 set(CMAKE_BUILD_TYPE Debug)
5
6 #message(status "PROJECT_SOURCE_DIR = ${PROJECT_SOURCE_DIR}")
7 #message(status "PROJECT_BINARY_DIR = ${PROJECT_BINARY_DIR}")
8 #message(status "CMAKE_SOURCE_DIR = ${CMAKE_SOURCE_DIR}")
9 #message(status "CMAKE_BINARY_DIR = ${CMAKE_BINARY_DIR}")
10
11 include_directories ("${PROJECT_SOURCE_DIR}/MathFunctions/inc")
12 include_directories("${PROJECT_SOURCE_DIR}/FooFunctions/inc")
13 add_subdirectory (MathFunctions)
14 add_subdirectory(FooFunctions)
15
16 add_executable(Tutorial tutorial.c)
17 target_link_libraries (Tutorial MathFunctions m FooFunctions)
18 set_target_properties(Tutorial PROPERTIES RUNTIME_OUTPUT_DIRECTORY ../BIN)
解释如下:
1) set(CMAKE_BUILD_TYPE Debug)
设置debug模式,也就是 gcc 加上 -g 选项
也可以用
set(CMAKE_C_FLAGS ${CMAKE_C_FLAGS} "-g -Wall")
或者命令行设置：
cmake -DCMAKE_BUILD_TYPE=Debug/Release dir
2) include_directories
设置头文件的搜索路径. 相当于 C_FLAGS 加上 "-I"
3)add_executable
设置生成的可执行文件
4) add_subdirectory
设置包含 其它 CMakeLists.txt的目录.
一般,需要单独变成一个库的代码,都要有一个 CMakeLists.txt
5)target_link_libraries
设置要 link到可执行文件的库
6)set_target_properties
这里是设置可执行文件的位置
然后再看一下 FooFunctions 下的 CMakeLists.txt:
set(shared_src src/foo.c)
2 add_library(FooFunctions SHARED ${shared_src})
3 include_directories("${PROJECT_SOURCE_DIR}/FooFunctions/inc")
4 set_target_properties(FooFunctions PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/LIB)
5 set_target_properties(FooFunctions PROPERTIES VERSION 1.1 SOVERSION 1)比如，最后生成的共享库如下:
$ ls LIB/ -l
total 12
lrwxrwxrwx 1 charles charles 20 Feb 20 01:38 libFooFunctions.so -> libFooFunctions.so.1
lrwxrwxrwx 1 charles charles 22 Feb 20 01:38 libFooFunctions.so.1 -> libFooFunctions.so.1.1
-rwxrwxr-x 1 charles charles 7726 Feb 20 01:38 libFooFunctions.so.1.1
MathFunctions 下的 CMakeLists.txt如下:
1 add_library(MathFunctions src/mysqrt.c)
2 set_target_properties(MathFunctions PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${CM AKE_BINARY_DIR}/LIB)
每一个 CMakeLists.txt 都会生成一组 Makefile文件.
其中主要的是 Makefile, link.txt 和 flags.make
link.txt 是用来生成可执行文件或者库的命令. flags.make 则是命令选项.
比如, top-level CMakeLists.txt 的 link.txt 为:
charles@mikiehara:~/Code/cmake_tutorial/cmake/CMakeFiles/Tutorial.dir$ cat link.txt
/usr/bin/gcc -g CMakeFiles/Tutorial.dir/tutorial.c.o -o ../BIN/Tutorial -rdynamic LIB/libMathFunctions.a -lm LIB/libFooFunctions.so.1.1 -Wl,-rpath,/home/charles/Code/cmake_tutorial/cmake/LIB
charles@mikiehara:~/Code/cmake_tutorial/cmake/CMakeFiles/Tutorial.dir$ cat flags.make
# CMAKE generated file: DO NOT EDIT!
# Generated by "Unix Makefiles" Generator, CMake Version 2.8
# compile C with /usr/bin/gcc
C_FLAGS = -g -I/home/charles/Code/cmake_tutorial/MathFunctions/inc -I/home/charles/Code/cmake_tutorial/FooFunctions/inc
C_DEFINES =