c - TCP 代码中出现未初始化值错误

Question

我有一个 TCP 代码，但它一直在服务器代码中给出错误。

当我使用 valgrind 运行它时，我在服务器终端中收到以下内容:

    ==12370== Use of uninitialised value of size 8
==12370==    at 0x4E6B506: ____strtol_l_internal (in /lib64/libc-2.18.so)
==12370==    by 0x4E687DF: atoi (in /lib64/libc-2.18.so)
==12370==    by 0x400F1D: main (in /mnt/castor/seas_home/x/xyz/TCP/serv)
==12370== 
==12370== Invalid read of size 1
==12370==    at 0x4E6B506: ____strtol_l_internal (in /lib64/libc-2.18.so)
==12370==    by 0x4E687DF: atoi (in /lib64/libc-2.18.so)
==12370==    by 0x400F1D: main (in /mnt/castor/seas_home/a/xyz/TCP/serv)
==12370==  Address 0xffdfffac00000 is not stack'd, malloc'd or (recently) free'd
==12370== 
==12370== 
==12370== Process terminating with default action of signal 11 (SIGSEGV)
==12370==  General Protection Fault
==12370==    at 0x4E6B506: ____strtol_l_internal (in /lib64/libc-2.18.so)
==12370==    by 0x4E687DF: atoi (in /lib64/libc-2.18.so)
==12370==    by 0x400F1D: main (in /mnt/castor/seas_home/a/xyz/TCP/serv)
==12370== 
==12370== HEAP SUMMARY:
==12370==     in use at exit: 0 bytes in 0 blocks
==12370==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==12370== 
==12370== All heap blocks were freed -- no leaks are possible
==12370== 
==12370== For counts of detected and suppressed errors, rerun with: -v
==12370== Use --track-origins=yes to see where uninitialised values come from
==12370== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 2 from 2)

但我不知道如何解决它。谁能告诉我如何解决这个问题？

Answer 1

这是代码的重要部分:

char *words[10];
char buffer[1024];
memset(buffer, 0, sizeof buffer);
nwords = getwords(buffer, words, 10);
option = atoi(words[0]);

因为您使用空缓冲区调用 getwords，它将返回 0 并且不会在 words 中设置任何内容，因此 words[0] 为也未初始化。 您不会检查 getwords 的返回值，但您应该检查。如果nwords==0，则不应使用words[0]。