我试图捕获libc检测到错误条件时生成的错误消息.例如,我的测试代码：
#include <stdlib.h>
int main()
{
char* p = (char*)malloc(10);
free(p);
free(p);
}
$./main *** Error in `./main': double free or corruption (fasttop): 0x000000000124b010 *** ======= Backtrace: ========= /lib64/libc.so.6(+0x7d1fd)[0x7f8c121291fd] ./main[0x400b86] /lib64/libc.so.6(__libc_start_main+0xf5)[0x7f8c120cdaf5] ./main[0x400a79] ... <snip>
但是,它不是写入stderr或stdout,而是/ dev / tty(我发现使用strace)
open("/dev/tty",O_RDWR|O_NOCTTY|O_NONBLOCK) = 3
writev(3,[{"*** Error in `",14},{"./main",6},{"': ",3},{"double free or corruption (fastt"...,35},{": 0x",4},{"00000000011bf010",16},{" ***\n",5}],7*** Error in `./main': double free or corruption (fasttop): 0x00000000011bf010 ***
) = 83
mmap(NULL,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0) = 0x7f0f2f7ac000
write(3,"======= Backtrace: =========\n",29======= Backtrace: =========
) = 29
writev(3,[{"/lib64/libc.so.6",{"(",1},{"+0x",{"7d1fd",5},{")",{"[0x",{"7f0f2ea2a1fd",12},{"]\n",2}],8/lib64/libc.so.6(+0x7d1fd)[0x7f0f2ea2a1fd]
) = 43
writev(3,[{"./main",{"400b86",4./main[0x400b86]
) = 17
writev(3,{"__libc_start_main",17},{"f5",2},{"7f0f2e9ceaf5",9/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f0f2e9ceaf5]
) = 57
writev(3,{"400a79",4./main[0x400a79]
) = 17
如何将其重定向到文件？标准的stdout和stderr重定向不起作用.我需要捕获这个系统服务,现在,输出消失在以太网中.
解决方法
我通过检查
libc source code,libc_fatal.c找到了一份UNDOCUMENTED(不在glibc文档中！)的答案.
将以下环境变量设置为任何内容
LIBC_FATAL_STDERR_=1
使libc写入stderr而不是/ dev / tty.
