musl-libc 安装与调试

musl-libc 官网：http://musl.libc.org
1、下载与安装

下载源码并解压

编译参数

./configure [option]... [VAR=VALUE]...

option	说明
--help	帮助
--prefix=DIR	指定安装目录。默认为`/usr/local/musl`
--host=HOST	设置目标程序运行的CPU平台一般不需要设置，除非你想要`交叉编译` 默认与宿主机一样
--enable-FEATURE[=yes\|no]	`yes：`开启`FEATURE` `no：` 关闭`FEATURE`
--enable-static[=yes\|no]	是否生成`静态库`
--enable-shared[=yes\|no]	是否生成`动态库`
--enable-warnings[=yes\|no]	是否开启编译器警告
--enable-debug[=yes\|no]	是否带上`debug`符号

与enable-FEATURE对应的选项，还有disable-FEATURE，disable-FEATURE相当于enable-FEATURE=no

VAR	VALUE示例	说明
`CC`	gcc \| clang	指定C编译器
`CFLAGS`	`-O2 -v`	指定C编译器的参数

`CPP`	cpp	指定C预处理器
`CPPFLAGS`	`-I<includeDIR>`	指定C预处理器的参数

`LDFLAGS`	`-L<libDIR>`	指定C链接器的参数
`LIBS`	`-l<libName>`	指定C链接器要链接的库的名称

示例：将musl 安装到/usr/local/musl 下，添加调试符号

./configure --prefix=/usr/local/musl CFLAGS='-O2 -v' --enable-debug && make && make install

2、查看musl-gcc 编译器

root@test:/data/musl-1.2.5# ls -al /usr/bin/gcc-musl 
lrwxrwxrwx 1 root root 28  5月  7 23:36 /usr/bin/gcc-musl -> /usr/local/musl/bin/musl-gcc
root@test:/data/musl-1.2.5# cat /usr/bin/gcc-musl 
#!/bin/sh
exec "${REALGCC:-gcc}" -static -g3 "$@" -specs "/usr/local/musl/lib/musl-gcc.specs"

本质上使用的还是gcc，添加了编译参数变成musl-gcc 想了解可以查看 /usr/local/musl/lib/musl-gcc.specs

3、编写第一个程序并调试

root@test:/data/musl_test# cat main.c 


int main()
{
    return 1;
}
root@test:/data/musl_test# gcc-musl main.c -g -o test
root@test:/data/musl_test# ls -al
总用量 64
drwxr-xr-x 2 root root  4096  5月 10 00:00 .
drwxr-xr-x 5 root root  4096  5月  7 23:35 ..
-rw-r--r-- 1 root root    31  5月  7 23:35 main.c
-rwxr-xr-x 1 root root 50208  5月 10 00:00 test

gdb 调试

root@test:/data/musl_test# gdb ./test 
GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./test...
(gdb) starti
Starting program: /data/shiqi/musl_test/test 

Program stopped.
0x000000000040102f in _start ()
(gdb) layout asm