分配字符串内存的valgrind memcheck错误答案

【问题标题】：valgrind memcheck error allocating a string memory分配字符串内存的valgrind memcheck错误
【发布时间】：2016-08-19 19:07:45
【问题描述】：

运行我的程序，我得到这个错误：

==3205== Invalid write of size 8
==3205==    at 0x40167C: push (load.c:75)
==3205==    by 0x401725: load_tetrimino (load.c:112)
==3205==    by 0x40112F: main (main.c:130)
==3205==  Address 0x544e718 is 24 bytes after a block of size 16 in arena "client"
==3205== 

valgrind: m_mallocfree.c:303 (get_bszB_as_is): Assertion 'bszB_lo == bszB_hi' failed. valgrind: Heap block lo/hi size mismatch: lo = 80, hi
= 88401728. This is probably caused by your program erroneously writing past the end of a heap block and corrupting heap metadata.  If you fix any invalid writes reported by Memcheck, this assertion failure will probably go away.  Please try that before reporting this as a bug.


host stacktrace:
==3205==    at 0x38082F78: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x38083094: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x38083221: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x380909D4: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x3807C683: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x3807AF03: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x3807F13A: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x3807A49A: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x38057FEE: ??? (in /usr/lib/valgrind/memcheck-amd64-linux)
==3205==    by 0x802C8C764: ???
==3205==    by 0x802BA9F2F: ???
==3205==    by 0x8020082CF: ???
==3205==    by 0x401674: push (load.c:75)
==3205==    by 0x8020082CF: ???
==3205==    by 0x1BFF: ???
==3205==    by 0x38C4F9FF: ???
==3205==    by 0x804C2BFFF: ???
==3205==    by 0x12C05: ???

sched status:   running_tid=1

Thread 1: status = VgTs_Runnable (lwpid 3205)
==3205==    at 0x401684: push (load.c:75)
==3205==    by 0x401725: load_tetrimino (load.c:112)
==3205==    by 0x40112F: main (main.c:130)

这段代码：

int                             push(t_node **head, t_node **tail,                                       
                                     struct dirent *file)                                                
{                                                                                                        
  t_node                        *new;                                                       
  if ((new = malloc(sizeof(t_node *))) == NULL)                                                          
    return (1);                                                                                          
  if ((new->tetrimino.name = malloc(12 + my_strlen(file->d_name))) == NULL)                              
    return (1);                                                                                          
  exit(0);

打印 my_strlen(d_name) 没有错误，所以它不是来自那个

结构：

typedef struct          s_tetrimino 
{                                                                                                        
  int                   id;                                                                              
  int                   sundial;                                                                         
  int                   color;                                                                           
  int                   height;                                                                          
  int                   width;                                                                           
  int                   end;                                                                             
  char                  **shape;                                                                         
  t_coord               coord;                                                                           
  char                  *name;                                                                           
}                       t_tetrimino;

谢谢

【问题讨论】：

malloc(12 + strlen(file->d_name) 看起来很可疑 - 12 来自哪里，它们是否包括尾随的 0？此外，自 ANSI C 时代以来，人们不赞成调用 new。

标签： c string memory

【解决方案1】：

分配

new = malloc(sizeof(t_node *))

为节点指针分配内存，但这

new = malloc(sizeof(*new))

为一个节点struct分配内存。

编辑：正如这段代码所示：

#include <stdio.h>

typedef struct {
    double a;
    double b;
    double c;
} t_node;

int main(void)
{
    t_node *new;
    printf("%zu\n", sizeof(t_node *));
    printf("%zu\n", sizeof(*new));
    return 0;
}

程序输出（32位编译器）

4
24

【讨论】：

非常感谢，我犯了一个愚蠢的错误但找不到它