注意
本文最后更新于 2024-01-31，文中内容可能已过时。
一、导言
导言
代码生成在配置时发生，如 CMake可以检测操作系统和可用库；基于这些信息，可以定制构建的源代码。本篇我们将探索如何生成一个简单源文件，该文件定义了一个函数，用于报告构建系统配置。
二、项目结构
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| .
├── CMakeLists.txt
└── print_info.c.in
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项目地址：
https://gitee.com/jiangli01/tutorials/tree/master/cmake-tutorial/chapter6/01
CMakeLists.txt
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| cmake_minimum_required(VERSION 3.10 FATAL_ERROR)
project(config_generator LANGUAGES C)
execute_process(
COMMAND
whoami
TIMEOUT
1
OUTPUT_VARIABLE
_user_name
OUTPUT_STRIP_TRAILING_WHITESPACE
)
# host name information
cmake_host_system_information(RESULT _host_name QUERY HOSTNAME)
cmake_host_system_information(RESULT _fqdn QUERY FQDN)
# processor information
cmake_host_system_information(RESULT _processor_name QUERY PROCESSOR_NAME)
cmake_host_system_information(RESULT _processor_description QUERY PROCESSOR_DESCRIPTION)
# os information
cmake_host_system_information(RESULT _os_name QUERY OS_NAME)
cmake_host_system_information(RESULT _os_release QUERY OS_RELEASE)
cmake_host_system_information(RESULT _os_version QUERY OS_VERSION)
cmake_host_system_information(RESULT _os_platform QUERY OS_PLATFORM)
string(TIMESTAMP _configuration_time "%Y-%m-%d %H:%M:%S [UTC]" UTC)
configure_file(print_info.c.in print_info.c @ONLY)
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tips
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| execute_process(
COMMAND
whoami
TIMEOUT
1
OUTPUT_VARIABLE
_user_name
OUTPUT_STRIP_TRAILING_WHITESPACE
)
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使用 execute_process为项目获取当前使用者的信息。
tips
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| # host name information
cmake_host_system_information(RESULT _host_name QUERY HOSTNAME)
cmake_host_system_information(RESULT _fqdn QUERY FQDN)
# processor information
cmake_host_system_information(RESULT _processor_name QUERY PROCESSOR_NAME)
cmake_host_system_information(RESULT _processor_description QUERY PROCESSOR_DESCRIPTION)
# os information
cmake_host_system_information(RESULT _os_name QUERY OS_NAME)
cmake_host_system_information(RESULT _os_release QUERY OS_RELEASE)
cmake_host_system_information(RESULT _os_version QUERY OS_VERSION)
cmake_host_system_information(RESULT _os_platform QUERY OS_PLATFORM)
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使用cmake_host_system_information()函数查询系统信息。
tips
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| string(TIMESTAMP _configuration_time "%Y-%m-%d %H:%M:%S [UTC]" UTC)
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捕获配置时的时间戳，并通过使用字符串操作函数。
tips
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| configure_file(print_info.c.in print_info.c @ONLY)
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通过configure_file函数生成代码。注意，这里只要求以@开头和结尾的字符串被替换。
print_info.c.in
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| #include <stdio.h>
#include <unistd.h>
void print_info(void) {
printf("\n");
printf("Configuration and build information\n");
printf("-----------------------------------\n");
printf("\n");
printf("Who compiled | %s\n", "@_user_name@");
printf("Compilation hostname | %s\n", "@_host_name@");
printf("Fully qualified domain name | %s\n", "@_fqdn@");
printf("Operating system | %s\n",
"@_os_name@, @_os_release@, @_os_version@");
printf("Platform | %s\n", "@_os_platform@");
printf("Processor info | %s\n",
"@_processor_name@, @_processor_description@");
printf("CMake version | %s\n", "@CMAKE_VERSION@");
printf("CMake generator | %s\n", "@CMAKE_GENERATOR@");
printf("Configuration time | %s\n", "@_configuration_time@");
printf("Fortran compiler | %s\n", "@CMAKE_Fortran_COMPILER@");
printf("C compiler | %s\n", "@CMAKE_C_COMPILER@");
printf("\n");
fflush(stdout);
}
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生成print_info.c
print_info.c
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| #include <stdio.h>
#include <unistd.h>
void print_info(void) {
printf("\n");
printf("Configuration and build information\n");
printf("-----------------------------------\n");
printf("\n");
printf("Who compiled | %s\n", "jiangli");
printf("Compilation hostname | %s\n", "jiangli-virtual-machine");
printf("Fully qualified domain name | %s\n", "jiangli-virtual-machine.lan");
printf("Operating system | %s\n",
"Linux, 5.15.0-89-generic, #99~20.04.1-Ubuntu SMP Thu Nov 2 15:16:47 UTC 2023");
printf("Platform | %s\n", "x86_64");
printf("Processor info | %s\n",
"Unknown AMD family, 16 core AMD Ryzen 7 4800H with Radeon Graphics");
printf("CMake version | %s\n", "3.16.3");
printf("CMake generator | %s\n", "Unix Makefiles");
printf("Configuration time | %s\n", "2023-11-24 01:01:31 [UTC]");
printf("Fortran compiler | %s\n", "");
printf("C compiler | %s\n", "/usr/bin/gcc");
printf("\n");
fflush(stdout);
}
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补充
用值替换占位符时，CMake中的变量名应该与将要配置的文件中使用的变量名完全相同，并放在@之间。可以在调用configure_file时定义的任何CMake变量。
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