cmake

project()

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
# zh @ li in ~/tmp/hello [22:45:26]
$ tree
.
├── CMakeLists.txt
└── subhello
    └── CMakeLists.txt

1 directory, 2 files

# zh @ li in ~/tmp/hello [22:45:27]
$ cat CMakeLists.txt
cmake_minimum_required(VERSION 3.9)
project(hello VERSION 0.1.2.3 DESCRIPTION "an hello program" LANGUAGES C HOMEPAGE_URL “https://www.hello.com”)

add_subdirectory(subhello)

# zh @ li in ~/tmp/hello [22:45:34]
$ cat subhello/CMakeLists.txt
cmake_minimum_required(VERSION 3.9)
project(subhello VERSION 3.2.1.0 DESCRIPTION "an subhello program" LANGUAGES C HOMEPAGE_URL “https://www.subhello.com”)

function(print)
    foreach(var ${ARGN})
        message("${var} = ${${var}}")
    endforeach()
endfunction()


print(
    PROJECT_NAME       # PROJECT_NAME = subhello    # 当前
    CMAKE_PROJECT_NAME # CMAKE_PROJECT_NAME = hello # 顶层

    hello_SOURCE_DIR    # hello_SOURCE_DIR = /home/zh/tmp/hello             # hello项目
    subhello_SOURCE_DIR # subhello_SOURCE_DIR = /home/zh/tmp/hello/subhello # subhello项目
    PROJECT_SOURCE_DIR  # PROJECT_SOURCE_DIR = /home/zh/tmp/hello/subhello  # 当前
    CMAKE_SOURCE_DIR    # CMAKE_SOURCE_DIR = /home/zh/tmp/hello             # 顶层

    hello_BINARY_DIR    # hello_BINARY_DIR = /home/zh/tmp/hello/build             # hello项目
    subhello_BINARY_DIR # subhello_BINARY_DIR = /home/zh/tmp/hello/build/subhello # subhello项目
    PROJECT_BINARY_DIR  # PROJECT_BINARY_DIR = /home/zh/tmp/hello/build/subhello  # 当前
    CMAKE_BINARY_DIR    # CMAKE_BINARY_DIR = /home/zh/tmp/hello/build             # 顶层

    hello_VERSION         # hello_VERSION = 0.1.2.3
    subhello_VERSION      # subhello_VERSION = 3.2.1.0
    PROJECT_VERSION       # PROJECT_VERSION = 3.2.1.0
    CMAKE_PROJECT_VERSION # CMAKE_PROJECT_VERSION = 0.1.2.3 #顶层

    hello_VERSION_MAJOR         # hello_VERSION_MAJOR = 0
    subhello_VERSION_MAJOR      # subhello_VERSION_MAJOR = 3
    PROJECT_VERSION_MAJOR       # PROJECT_VERSION_MAJOR = 3
    CMAKE_PROJECT_VERSION_MAJOR # PROJECT_VERSION_MAJOR = 0 #顶层

    hello_VERSION_MINOR         # hello_VERSION_MINOR = 1
    subhello_VERSION_MINOR      # subhello_VERSION_MINOR = 2
    PROJECT_VERSION_MINOR       # PROJECT_VERSION_MINOR = 2
    CMAKE_PROJECT_VERSION_MINOR # PROJECT_VERSION_MINOR = 1 #顶层

    hello_VERSION_PATCH         # hello_VERSION_PATCH = 2
    subhello_VERSION_PATCH      # subhello_VERSION_PATCH = 1
    PROJECT_VERSION_PATCH       # PROJECT_VERSION_PATCH = 1
    CMAKE_PROJECT_VERSION_PATCH # PROJECT_VERSION_PATCH = 2 #顶层

    hello_VERSION_TWEAK         # hello_VERSION_TWEAK = 3
    subhello_VERSION_TWEAK      # subhello_VERSION_TWEAK = 0
    PROJECT_VERSION_TWEAK       # PROJECT_VERSION_TWEAK = 0
    CMAKE_PROJECT_VERSION_TWEAK # PROJECT_VERSION_TWEAK = 3 #顶层

    hello_DESCRIPTION         # PROJECT_DESCRIPTION = an hello program
    subhello_DESCRIPTION      # PROJECT_DESCRIPTION = an subhello program
    PROJECT_DESCRIPTION       # PROJECT_DESCRIPTION = an subhello program
    CMAKE_PROJECT_DESCRIPTION # CMAKE_PROJECT_DESCRIPTION = an hello program # 顶层

    hello_HOMEPAGE_URL         # hello_HOMEPAGE_URL = “https://www.hello.com”
    subhello_HOMEPAGE_URL      # subhello_HOMEPAGE_URL = “https://www.subhello.com”
    PROJECT_HOMEPAGE_URL       # subhello_HOMEPAGE_URL = “https://www.subhello.com”
    CMAKE_PROJECT_HOMEPAGE_URL # hello_HOMEPAGE_URL = “https://www.hello.com” # 顶层
    )

GNUInstallDirs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
# zh @ li in ~/li/tmp/hello [11:19:03]
$ tree
.
└── CMakeLists.txt

0 directories, 1 file

# zh @ li in ~/li/tmp/hello [11:19:04]
$ cat CMakeLists.txt
cmake_minimum_required(VERSION 3.9)
project(hello VERSION 0.1.2.3 DESCRIPTION "an hello program" LANGUAGES C)

function(print)
    foreach(var ${ARGN})
        message("${var} # ${var} = ${${var}}")
    endforeach()
endfunction()

set(CMAKE_INSTALL_PREFIX "/usr") # 在include(GNUInstallDirs)前设置，否则就是默认/usr/local
include(GNUInstallDirs)
print(
    CMAKE_INSTALL_PREFIX # CMAKE_INSTALL_PREFIX = /

    CMAKE_INSTALL_BINDIR      # CMAKE_INSTALL_BINDIR = usr/bin
    CMAKE_INSTALL_FULL_BINDIR # CMAKE_INSTALL_FULL_BINDIR = /usr/bin

    CMAKE_INSTALL_SBINDIR      # CMAKE_INSTALL_SBINDIR = usr/sbin
    CMAKE_INSTALL_FULL_SBINDIR # CMAKE_INSTALL_FULL_SBINDIR = /usr/sbin

    CMAKE_INSTALL_LIBEXECDIR      # CMAKE_INSTALL_LIBEXECDIR = usr/libexec
    CMAKE_INSTALL_FULL_LIBEXECDIR # CMAKE_INSTALL_FULL_LIBEXECDIR = /usr/libexec

    CMAKE_INSTALL_SYSCONFDIR      # CMAKE_INSTALL_SYSCONFDIR = etc
    CMAKE_INSTALL_FULL_SYSCONFDIR # CMAKE_INSTALL_FULL_SYSCONFDIR = /etc

    CMAKE_INSTALL_SHAREDSTATEDIR      # CMAKE_INSTALL_SHAREDSTATEDIR = usr/com
    CMAKE_INSTALL_FULL_SHAREDSTATEDIR # CMAKE_INSTALL_FULL_SHAREDSTATEDIR = /usr/com

    CMAKE_INSTALL_LOCALSTATEDIR      # CMAKE_INSTALL_LOCALSTATEDIR = var
    CMAKE_INSTALL_FULL_LOCALSTATEDIR # CMAKE_INSTALL_FULL_LOCALSTATEDIR = /var

    CMAKE_INSTALL_RUNSTATEDIR      # CMAKE_INSTALL_RUNSTATEDIR = var/run
    CMAKE_INSTALL_FULL_RUNSTATEDIR # CMAKE_INSTALL_FULL_RUNSTATEDIR = /var/run

    CMAKE_INSTALL_LIBDIR      # CMAKE_INSTALL_LIBDIR = usr/lib
    CMAKE_INSTALL_FULL_LIBDIR # CMAKE_INSTALL_FULL_LIBDIR = /usr/lib

    CMAKE_INSTALL_INCLUDEDIR      # CMAKE_INSTALL_INCLUDEDIR = usr/include
    CMAKE_INSTALL_FULL_INCLUDEDIR # CMAKE_INSTALL_FULL_INCLUDEDIR = /usr/include

    CMAKE_INSTALL_OLDINCLUDEDIR      # CMAKE_INSTALL_OLDINCLUDEDIR = /usr/include
    CMAKE_INSTALL_FULL_OLDINCLUDEDIR # CMAKE_INSTALL_FULL_OLDINCLUDEDIR = /usr/include

    CMAKE_INSTALL_DATAROOTDIR      # CMAKE_INSTALL_DATAROOTDIR = usr/share
    CMAKE_INSTALL_FULL_DATAROOTDIR # CMAKE_INSTALL_FULL_DATAROOTDIR = /usr/share

    CMAKE_INSTALL_DATADIR      # CMAKE_INSTALL_DATADIR = usr/share
    CMAKE_INSTALL_FULL_DATADIR # CMAKE_INSTALL_FULL_DATADIR = /usr/share

    CMAKE_INSTALL_INFODIR      # CMAKE_INSTALL_INFODIR = usr/share/info
    CMAKE_INSTALL_FULL_INFODIR # CMAKE_INSTALL_FULL_INFODIR = /usr/share/info

    CMAKE_INSTALL_LOCALEDIR      # CMAKE_INSTALL_LOCALEDIR = usr/share/locale
    CMAKE_INSTALL_FULL_LOCALEDIR # CMAKE_INSTALL_FULL_LOCALEDIR = /usr/share/locale

    CMAKE_INSTALL_MANDIR      # CMAKE_INSTALL_MANDIR = usr/share/man
    CMAKE_INSTALL_FULL_MANDIR # CMAKE_INSTALL_FULL_MANDIR = /usr/share/man

    CMAKE_INSTALL_DOCDIR      # CMAKE_INSTALL_DOCDIR = usr/share/doc/hello
    CMAKE_INSTALL_FULL_DOCDIR # CMAKE_INSTALL_FULL_DOCDIR = /usr/share/doc/hello
    )

交叉编译

1
2
3
4
set(CMAKE_SYSTEM_NAME Linux)
set(TOOLCHAIN_PATH /OPT/gcc-arm-linux-gnueabi)
set(CMAKE_C_COMPILER ${tools}/bin/arm-linux-gnueabi-gcc)
set(CMAKE_CXX_COMPILER ${tools}/bin/arm-linux-gnueabi-g++)

set(CMAKE_SYSTEM_NAME Linux)该指令必须存在，其目的是设置目标机使用的操作系统名称，支持Linux，QNX，WindowsCE，Android等。如果没有操作系统，那么就写 Generic。执行该指令后，cmake 变量——CMAKE_CROSSCOMPILING 会自动被设置为 TRUE，此时 cmake 就会“知道“现在执行的是交叉编译；

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
# zh @ li in ~/li/tmp/hello [19:44:35]
$ tree
.
├── cmake
│   └── toolchain_x86.cmake
├── CMakeLists.txt
└── src
    └── main.c

2 directories, 3 files

# zh @ li in ~/li/tmp/hello [19:44:38]
$ cat cmake/toolchain_x86.cmake
set(CMAKE_SYSTEM_NAME Linux)

set(TOOLCHAIN_PATH /usr/bin)
set(CMAKE_C_COMPILER gcc)
set(CMAKE_CXX_COMPILER g++)

# zh @ li in ~/li/tmp/hello [19:44:41]
$ cat CMakeLists.txt
cmake_minimum_required(VERSION 3.9)
project(hello VERSION 0.1.2.3 DESCRIPTION "an hello program" LANGUAGES C)

FILE(GLOB SRC_FILES "src/*.c")

add_executable(${PROJECT_NAME} ${SRC_FILES})

# zh @ li in ~/li/tmp/hello [19:44:43]
$ cat src/main.c
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv) { printf("hello world\n"); return 0; }

# zh @ li in ~/li/tmp/hello [19:44:46]
$ mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchain_x86.cmake ..
-- The C compiler identification is GNU 11.2.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/gcc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/zh/li/tmp/hello/build

# zh @ li in ~/li/tmp/hello/build [19:44:53]
$ make
[ 50%] Building C object CMakeFiles/hello.dir/src/main.c.o
[100%] Linking C executable hello
[100%] Built target hello

注意：-DCMAKE_TOOLCHAIN_FILE=../cmake/toolchain_x86.cmake 不能直接写入CMakeLists.txt或include(toolchain_x86.cmake)

需要链接系统库或第三方库时，cmake 提供了FIND_PROGRAM()，FIND_LIBRARY()， FIND_FILE()， FIND_PATH() 和 FIND_PACKAGE() 来查找库路径或包。默认情况下，上述指令查找的是主机上的文件，其并不适用于目标机器。为此cmake提供了相应的变量：

set(CMAKE_FIND_ROOT_PATH path1 path2 path3 ...)：设置其值为多个目录，这样 FIND_XXX() 就会从这些目录中查找。

跟随该变量的有下述 3 个变量，它们的值为 NEVER 、 ONLY 或 BOTH：

CMAKE_FIND_ROOT_PATH_MODE_PROGRAM若设为

  • NEVER，则FIND_PROGRAM() 不会在 CMAKE_FIND_ROOT_PATH 指定的目录中寻找
  • ONLY，则FIND_PROGRAM() 只会从 CMAKE_FIND_ROOT_PATH 指定的目录中寻找
  • BOTH，则FIND_PROGRAM() 会优先从 CMAKE_FIND_ROOT_PATH 指定的目录中寻找，再从默认的目录中寻找

FIND_PROGRAM() 通常用于寻找可执行程序，给后续的 EXECUTE_PROCESS() 或 ADD_CUSTOM_COMMAND() 指令使用。并且，只有主机在生成编译文件时使用该可执行程序。因此通常设置 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

CMAKE_FIND_ROOT_PATH_MODE_LIBRARY：交叉编译只能使用 FIND_LIBRARY() 查找符合目标机器的库文件，因此设置set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)

CMAKE_FIND_ROOT_PATH_MODE_INCLUDE：同上，设为 ONLY。

编译选项

1
2
3
add_definitions(-std=c++11)
SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -ggdb -Wl,-rpath=./:./lib") #-Wl,-rpath=./
SET(CMAKE_CXX_FLAGS_RELEASE "$ENV{CXXFLAGS} -O3 -Wl,-rpath=./:./lib") #-Wall
1
cmake -DCMAKE_PREFIX_PATH=/path/to -DCMAKE_LIBRARY_PATH=/path/to -DCMAKE_CXX_FLAGS=-m32 -DCMAKE_C_FLAGS=-m32

find_xxx()

  1. set(CMAKE_PREFIX_PATH "/path/libs/xxx-install")之后，pkg_search_module()就能去/path/libs/xxx-install找到库的libxxx.pc文件
  2. set(ENV{PKG_CONFIG_PATH} "$ENV{PKG_CONFIG_PATH}:/my/path/to/pkgconfig")之后，也能找找到libxxx.pc

pkg_search_module()

旧版本: pkg_search_module(PKG_XXX REQUIRED xxx)生成3个变量

  • PKG_XXX_INCLUDE_DIRS:编译时xxx库提供的头文件目录
  • PKG_XXX_LIBRARIES:只提供xxx库的名字，不提供路径
  • PKG_XXX_LDFLAGS:包含xxx的路径和库

你可以：target_link_libraries(my_proj ${PKG_XXX_LDFLAGS})

新版本: pkg_search_module(PKG_XXX REQUIRED IMPORTED_TARGET opencv)里面的IMPORTED_TARGET会创建一个供你直接在项目中使用的目标
你可以: target_link_libraries(my_proj PRIVATE PkgConfig::PKG_XXX)