C错误-free（）：下一个尺寸无效（快速） [英] C error - free(): invalid next size (fast)
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问题描述
我不确定为什么会出现以下错误。奇怪的是，当我使用Mac OS X时不会发生此错误，但是当我使用Linux（Debian）分区时会发生此错误。
I am not sure why I am getting the below error. Strangely enough, this error doesn't occur when I use Mac OS X, but it does when I use my Linux (Debian) partition.
-----------
Empty Queue: 0 0 0 0 0 0 0 0 0 0
---------------
Populated Queue: 5 3 1 7 6 3 2 1 4 4
-------------
After Dequeue: 3 1 7 6 3 2 1 4 4 0
Datum: 5
*** glibc detected *** ./queue_demo: free(): invalid next size (fast): 0x0000000000c73010 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x75b76)[0x7fde5c98db76]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x6c)[0x7fde5c9928ac]
./queue_demo[0x40098d]
./queue_demo[0x4008d8]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xfd)[0x7fde5c936ead]
./queue_demo[0x4006d9]
======= Memory map: ========
00400000-00401000 r-xp 00000000 08:01 940937 /home/dylan/Desktop/CST352_Gleason_Lab2/solution_1/queue_demo
00601000-00602000 rw-p 00001000 08:01 940937 /home/dylan/Desktop/CST352_Gleason_Lab2/solution_1/queue_demo
00c73000-00c94000 rw-p 00000000 00:00 0 [heap]
7fde58000000-7fde58021000 rw-p 00000000 00:00 0
7fde58021000-7fde5c000000 ---p 00000000 00:00 0
7fde5c702000-7fde5c717000 r-xp 00000000 08:01 1079347 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fde5c717000-7fde5c917000 ---p 00015000 08:01 1079347 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fde5c917000-7fde5c918000 rw-p 00015000 08:01 1079347 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fde5c918000-7fde5ca95000 r-xp 00000000 08:01 1079316 /lib/x86_64-linux-gnu/libc-2.13.so
7fde5ca95000-7fde5cc95000 ---p 0017d000 08:01 1079316 /lib/x86_64-linux-gnu/libc-2.13.so
7fde5cc95000-7fde5cc99000 r--p 0017d000 08:01 1079316 /lib/x86_64-linux-gnu/libc-2.13.so
7fde5cc99000-7fde5cc9a000 rw-p 00181000 08:01 1079316 /lib/x86_64-linux-gnu/libc-2.13.so
7fde5cc9a000-7fde5cc9f000 rw-p 00000000 00:00 0
7fde5cc9f000-7fde5ccbf000 r-xp 00000000 08:01 1079447 /lib/x86_64-linux-gnu/ld-2.13.so
7fde5cea3000-7fde5cea6000 rw-p 00000000 00:00 0
7fde5cebb000-7fde5cebe000 rw-p 00000000 00:00 0
7fde5cebe000-7fde5cebf000 r--p 0001f000 08:01 1079447 /lib/x86_64-linux-gnu/ld-2.13.so
7fde5cebf000-7fde5cec0000 rw-p 00020000 08:01 1079447 /lib/x86_64-linux-gnu/ld-2.13.so
7fde5cec0000-7fde5cec1000 rw-p 00000000 00:00 0
7fff13797000-7fff137b8000 rw-p 00000000 00:00 0 [stack]
7fff137ff000-7fff13800000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Aborted
当我调用 destruct 函数时，会发生此错误
This error happens when I call the destruct function in my Queue structure, in a test program written below.
#include <time.h>
#include <stdio.h>
#include "Queue.h"
int main(int argc, char* argv[])
{
// create a "queue" data structure
Queue_t* my_queue = construct(10);
// generate a random seed
srand( (unsigned)time(NULL) );
// display the empty queue
printf("-----------\n");
printf("Empty Queue: ");
display(my_queue);
printf("\n");
// populate the queue with random numbers
int i = 0;
for(; i < my_queue->maximum_count; ++i)
enqueue(my_queue, rand() % 10);
printf("---------------\n");
printf("Populated Queue: ");
display(my_queue);
printf("\n");
// dequeue, print the current queue and the datum
int datum = dequeue(my_queue);
printf("-------------\n");
printf("After Dequeue: ");
display(my_queue);
printf("\tDatum: %d\n\n", datum);
// clean up memory
destruct(my_queue);
return 0;
}
这是我的数据结构：
#ifndef QUEUE_H
#define QUEUE_H
typedef struct Queue
{
int current_count;
int maximum_count;
int buffer[]; // queue uses an array
} Queue_t;
// routines to implement Queue-like functionality (FIFO)
// TODO: somehow encapsulate all these features in the struct itself.
//
Queue_t* construct(int buff_size);
void destruct (Queue_t* queue);
void display (Queue_t* queue);
int dequeue (Queue_t* queue);
void enqueue (Queue_t* queue, const int datum);
#endif
实施：
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "Queue.h"
Queue_t* construct(int buff_size)
{
Queue_t* queue = malloc(
sizeof(Queue_t) + sizeof(int) * sizeof(Queue_t));
assert(queue != NULL);
queue->maximum_count = buff_size;
queue->current_count = 0;
memset(queue->buffer, 0, sizeof(int)*buff_size);
return queue;
}
void destruct(Queue_t* queue)
{
assert(queue != NULL);
free(queue); // error at this statement
printf("Queue destroyed!\n");
}
void display(Queue_t* queue)
{
int i = 0;
for(; i < queue->maximum_count; ++i)
printf("%d ", queue->buffer[i]);
printf("\n");
}
void enqueue(Queue_t* queue, const int datum)
{
assert(queue->current_count < queue->maximum_count);
queue->buffer[queue->current_count] = datum;
++queue->current_count;
}
int dequeue(Queue_t* queue)
{
int i = 1;
int datum = queue->buffer[0];
assert(queue->current_count > 0);
for(; i < queue->maximum_count; ++i)
{
queue->buffer[i-1] = queue->buffer[i];
queue->buffer[i] = 0;
}
--queue->current_count;
return datum;
}
推荐答案
这似乎已损坏libc内存分配功能使用的一些数据。在您的构造函数中，我们不应该更改
This looks like you have corrupted some data used by libc memory allocation functions. In your construct function shouldn't we change
Queue_t* queue = malloc(
sizeof(Queue_t) + sizeof(int) * sizeof(Queue_t));
至
Queue_t* queue = malloc(
sizeof(Queue_t) + sizeof(int) * buff_size);
construct 中的以下行似乎会导致
The following line in construct seems to cause the corruption now due to incorrect amount of memory being allocated for queue.
memset(queue->buffer, 0, sizeof(int)*buff_size);
将 sizeof 运算符应用于具有灵活数组成员的结构，只有灵活数组以外的其他字段构成了结构的总大小，即其大小为0。为此类结构分配内存时，需要明确指定所需的额外字节数。结构。
When you apply the sizeof operator to a structure with a flexible array member, only fields other than the flexible array comprise the total structure size i.e. its size is 0. When you are allocating memory for such structures, you need to specify explicitly how many extra bytes you want at the end of the structure.
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