C语言编程 - 免费的方法给我一个无效的下一个尺寸（快）错误

我有一个问题释放正由getLine函数分配一个字符指针。C语言编程 - 免费的方法给我一个无效的下一个尺寸（快）错误

的应用程序的目的是读取/ PROC /净/ dev文件，并显示关于由用户通过接口信息。

每当自由方法执行我有一个无效的下一个大小（快速）错误。

我从杂志上复制了代码，但正如文章作者所说，它应该按原样工作。

给我的问题的功能是本

int ParseDevFile(const char * Interface, ull *bRx, ull *pRx, ull *bTx, ull *pTx) 
{ 
FILE *FilePointer = NULL; 

char *ReadLine = NULL; 

unsigned int Length = 0; 

FilePointer = fopen("/proc/net/dev", "r"); 

if (FilePointer == NULL) 
{ 
    perror("Error"); 
    return -1; 
} 

while (getline(&ReadLine, &Length, FilePointer) != -1) 
{ 
    if (strstr(ReadLine, Interface) != NULL) 
    { 
     sscanf(strstr(ReadLine, ":") + 1, "%llu%llu%*u%*u%*u%*u%*u%*u%llu%llu", bRx, bRx, bTx, pTx); 
    } 
} 

free(ReadLine); 

fclose(FilePointer); 

return 0; 
}

我是新来的C语言的，但是，如果我阅读，则对getline手册页正确它增加根据行的大小readline的缓冲区大小。

此外，当在Valgrind的运行应用程序工作正常（除了一些无效的写在应用程序的开始）。

下面是Valgrind错误。请注意，在这些错误之后，应用程序将继续正常运行。

==31361== Command: ./ifstat wlan0 
==31361== 
==31361== Invalid write of size 8 
==31361== at 0x4EC63FA: __GI_memcpy (memcpy.S:125) 
==31361== by 0x4EA40BF: getdelim (iogetdelim.c:116) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== Address 0x51fc333 is 115 bytes inside a block of size 120 alloc'd 
==31361== at 0x4C2CD7B: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x4EA404D: getdelim (iogetdelim.c:67) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== 
==31361== Invalid write of size 1 
==31361== at 0x4EA41B4: getdelim (iogetdelim.c:123) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== Address 0x51fc33b is 3 bytes after a block of size 120 alloc'd 
==31361== at 0x4C2CD7B: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x4EA404D: getdelim (iogetdelim.c:67) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== 
==31361== Invalid read of size 1 
==31361== at 0x4C302E4: strstr (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x40089F: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== Address 0x51fc338 is 0 bytes after a block of size 120 alloc'd 
==31361== at 0x4C2CD7B: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x4EA404D: getdelim (iogetdelim.c:67) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== 
==31361== Invalid read of size 1 
==31361== at 0x4C2FF14: __GI___rawmemchr (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x4EB237F: _IO_str_init_static_internal (strops.c:44) 
==31361== by 0x4E9306F: __isoc99_vsscanf (isoc99_vsscanf.c:41) 
==31361== by 0x4E93006: __isoc99_sscanf (isoc99_sscanf.c:32) 
==31361== by 0x4008E4: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== Address 0x51fc338 is 0 bytes after a block of size 120 alloc'd 
==31361== at 0x4C2CD7B: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==31361== by 0x4EA404D: getdelim (iogetdelim.c:67) 
==31361== by 0x4008FE: ParseDevFile (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400996: DumpInterfaceUsage (in /home/andrew/C Programming/Magazine Tutorials/ifstat) 
==31361== by 0x400B4F: main (in /home/andrew/C Programming/Magazine Tutorials/ifstat)

谢谢你，安德鲁·博格

来源

2013-07-13 Andrew

从'ReadLine'未分配的内存，'Length'是垃圾。 –

你是什么意思？我从杂志中复制了这个内容，并且我教导了getline的长度为零方法来扩展缓冲区 – Andrew

@GrijeshChauhan ['man 3 getline']（http://man7.org/linux/man-pages/man3/getline .3.html） - 如果你仔细观察：它会为你分配内存。指针指针传递的原因有很多，而不仅仅是指向某个缓冲区的第一个元素的指针。 – 2013-07-13 08:46:05

我设法通过改变无符号整数长度是可变的，以size_t类型来解决这个问题。

unsigned int Length = 0;

到

size_t Length = 0;

来源

2013-07-13 09:03:47 Andrew

C语言编程 - 免费的方法给我一个无效的下一个尺寸（快）错误

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