2015-08-17 30 views
5

我試圖捕獲libc在檢測到錯誤條件時生成的錯誤消息。例如,我的測試代碼:捕獲libc錯誤消息,從/ dev/tty重定向

#include <stdlib.h> 

int main() 
{ 
    char* p = (char*)malloc(10); 
    free(p); 
    free(p); 
} 

生成的輸出

$ ./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,它沒有被寫入stderr或標準輸出,但的/ dev/tty的(這我發現使用strace的)

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", 16}, {"(", 1}, {"+0x", 3}, {"7d1fd", 5}, {")", 1}, {"[0x", 3}, {"7f0f2ea2a1fd", 12}, {"]\n", 2}], 8/lib64/libc.so.6(+0x7d1fd)[0x7f0f2ea2a1fd] 
) = 43 
writev(3, [{"./main", 6}, {"[0x", 3}, {"400b86", 6}, {"]\n", 2}], 4./main[0x400b86] 
) = 17 
writev(3, [{"/lib64/libc.so.6", 16}, {"(", 1}, {"__libc_start_main", 17}, {"+0x", 3}, {"f5", 2}, {")", 1}, {"[0x", 3}, {"7f0f2e9ceaf5", 12}, {"]\n", 2}], 9/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f0f2e9ceaf5] 
) = 57 
writev(3, [{"./main", 6}, {"[0x", 3}, {"400a79", 6}, {"]\n", 2}], 4./main[0x400a79] 
) = 17 

如何將其重定向到文件?標準stdout和stderr重定向不起作用。我需要趕上systemd服務,現在,輸出消失在以太網中。

+0

Duplicate:[如何將RUNTIME ERRORS重定向到STDERR?](http://stackoverflow.com/questions/4290336/how-to-redirect-runtime-errors-to-stderr) –

回答

7

我通過檢查libc source code, libc_fatal.c發現了一個UNDOCUMENTED(不在glibc文檔!)答案。

設置以下環境變量來什麼

LIBC_FATAL_STDERR_=1 

造成的libc寫stderr,而不是/dev/tty