信号11（SIGSEGV）

我写以下代码：信号11（SIGSEGV）

FILE *book; 
wchar_t bufferln[FILE_READ_BUFFER]; 
wchar_t buffer[FILE_READ_BUFFER]; 
book = fopen(file, "r"); 
if(book == NULL){ 
    perror("Es ist ein Fehler beim lesen des Buches aufgetreten"); 
    return EXIT_FAILURE; 
} 
while(fgetws(buffer, FILE_READ_BUFFER, book) != NULL){ 
    if(wcscmp(buffer, L"\n") == 0){ 
     bufferln[0] = L'\0'; 
     continue; 
    } 
    buffer[wcsnlen(buffer, FILE_READ_BUFFER)-1] = L' '; 
    wcsncat(bufferln, buffer, FILE_READ_BUFFER); 
} 
return EXIT_SUCCESS;

它崩溃与SIGSEGV。我跑Valgrind的，显示如下：

==11251== Conditional jump or move depends on uninitialised value(s) 
==11251== at 0x40BD5CF: wcsncat (wcsncat.c:36) 
==11251== by 0x804865D: read_book (book.c:18) 
==11251== by 0x804872B: main (main.c:19) 
==11251== Uninitialised value was created by a stack allocation 
==11251== at 0x80485B7: read_book (book.c:3) 
==11251== 
==11251== Invalid read of size 4 
==11251== at 0x40A58E2: fgetws (iofgetws.c:52) 
==11251== by 0x804867D: read_book (book.c:12) 
==11251== by 0x6D: ??? 
==11251== Address 0x65 is not stack'd, malloc'd or (recently) free'd 
==11251== 
==11251== 
==11251== Process terminating with default action of signal 11 (SIGSEGV) 
==11251== Access not within mapped region at address 0x65 
==11251== at 0x40A58E2: fgetws (iofgetws.c:52) 
==11251== by 0x804867D: read_book (book.c:12) 
==11251== by 0x6D: ??? 
==11251== If you believe this happened as a result of a stack 
==11251== overflow in your program's main thread (unlikely but 
==11251== possible), you can try to increase the size of the 
==11251== main thread stack using the --main-stacksize= flag. 
==11251== The main thread stack size used in this run was 8388608.

我认为这个问题以某种方式与我wcsncat的使用（写入*本书内存也许？），但为什么呢？我想逐段阅读文档（UTF-8），然后执行不在此代码中的内容。

来源

2011-09-16 Jonas Schwabe