为什么下面 code 会 crash ?

w_anthony

回复 9# hellioncu


编辑掉，不好意思，是我看漏了

linux_c_py_php

strncpy经常有人用错, 因为有一种情况是不会\0结尾的, 解释如下:

1.        The strcpy() function copies the string pointed to by src, including the terminating null byte ('\0'), to the buffer pointed to by dest.  The
   
2.        strings may not overlap, and the destination string dest must be large enough to receive the copy.  Beware of buffer overruns!  (See BUGS.)
   
3. 
   
4.        The strncpy() function is similar, except that at most n bytes of src are copied.  Warning: If there is no null byte among the first n  bytes
   
5.        of src, the string placed in dest will not be null-terminated.
   
6. 
   
7.        If the length of src is less than n, strncpy() writes additional null bytes to dest to ensure that a total of n bytes are written.
   
8. 
   
9.        A simple implementation of strncpy() might be:
   
10. 
    
11.            char *
    
12.            strncpy(char *dest, const char *src, size_t n)
    
13.            {
    
14.                size_t i;
    
15. 
    
16.                for (i = 0; i < n && src[i] != '\0'; i++)
    
17.                    dest[i] = src[i];
    
18.                for ( ; i < n; i++)
    
19.                    dest[i] = '\0';
    
20. 
    
21.                return dest;
    
22.            }

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蹩脚的梦

strncpy在拷贝结束后，还要把dst剩余的空间都清零导致

为什么清零就到这了Segmental fault