我已经花了数小时试图弄清楚为什么我的程序在此输入上失败，但是对我来说仍然是一个谜。首先，这里是重现此错误的相关详细信息。
使用下面同一目录中列出的文件，使用gcc -O0 -g main.c ArrayList.c进行编译（注意：gcc --version输出7.3.0）。然后，运行./a.out $((10**9))。您应该收到以下错误：
a.out: malloc.c:2868: mremap_chunk: Assertion `((size + offset) & (GLRO (dl_pagesize) - 1)) == 0' failed.
Aborted (core dumped)
我已经尝试通过此方法进行调试，但问题似乎不是我的代码，即错误似乎是在realloc的代码中引发的，但老实说我不知道。如果我使用./a.out $((10**10))，则程序不会失败，这对我来说是个谜。问题似乎是这一行：
arraylist->data = realloc(arraylist->data, sizeof(uint64_t) * (arraylist->capacity));
我已经通读了手册页，以获取有关我是否错误地调用realloc的线索，但没有任何提示。程序要尝试做的所有事情就是使用修改过的eratosthenes筛子筛除小于sqrt（n）的非素数。有人可以帮我吗？谢谢！
main.c：
// main.c
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#include "ArrayList.h"
// Segment addressing.
#define BYTE_IDX(i) i >> 4
#define BIT_IDX(i) (i >> 1) % 8
// Bit manipulation.
#define IS_PRIME(i) ~(S[BYTE_IDX(i)] >> BIT_IDX(i)) & 1U
#define SET_BIT(i) S[BYTE_IDX(i)] |= (1U << BIT_IDX(i))
uint64_t primepi(uint64_t n)
{
uint64_t sqrtn = (uint64_t)sqrt((double)n);
uint8_t *S = calloc((sqrtn + 1) / 16, sizeof(uint8_t));
ArrayList arraylist;
arraylist_init(&arraylist);
for (uint64_t i = 3; i * i <= n; i += 2)
if (IS_PRIME(i))
{
arraylist_append(&arraylist, i);
for (uint64_t j = i * i; j * j <= n; j += 2 * i)
SET_BIT(j);
}
free(S);
arraylist_free(&arraylist);
return (uint64_t)0;
}
int main(int argc, char **argv)
{
uint64_t n = primepi(atoll(argv[1]));
printf("n = %lu\n", n);
return 0;
}
ArrayList.h：
/**
* ArrayList.h
*
* Summary:
* Provides a specification of the ArrayList data structure.
*/
#define ARRAYLIST_INITIAL_CAPACITY 128
typedef struct {
uint64_t size;
uint64_t capacity;
uint64_t *data;
} ArrayList;
void arraylist_init(ArrayList *arraylist);
void arraylist_append(ArrayList *arraylist, uint64_t value);
uint64_t arraylist_get(ArrayList *arraylist, uint64_t index);
void arraylist_double_capacity_if_full(ArrayList *arraylist);
void arraylist_free(ArrayList *arraylist);
ArrayList.c：
/**
* ArrayList.c
*
* Summary:
* Provides an implementation of the ArrayList data structure.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "ArrayList.h"
void arraylist_init(ArrayList *arraylist)
{
// Initialize size and capacity.
arraylist->size = (uint64_t)0;
arraylist->capacity = ARRAYLIST_INITIAL_CAPACITY;
// Allocate memory of the arraylist->data.
arraylist->data = calloc(arraylist->capacity, sizeof(uint64_t));
}
void arraylist_append(ArrayList *arraylist, uint64_t value)
{
// Double ArrayList if it is full.
arraylist_double_capacity_if_full(arraylist);
// Append the value and increment the size.
arraylist->data[arraylist->size++] = value;
}
uint64_t arraylist_get(ArrayList *arraylist, uint64_t index)
{
if (index >= arraylist->size || index < (uint64_t)0)
{
printf("Index %lu out of bounds for ArrayList of size %lu\n", index, arraylist->size);
exit(1);
}
return arraylist->data[index];
}
void arraylist_double_capacity_if_full(ArrayList *arraylist)
{
if (arraylist->size >= arraylist->capacity)
{
arraylist->capacity *= (uint64_t)2;
arraylist->data = realloc(arraylist->data, sizeof(uint64_t) * (arraylist->capacity));
}
}
void arraylist_free(ArrayList *arraylist)
{
free(arraylist->data);
}
编辑：
运行valgrind --tool=memcheck ./a.out $((10**9))的输出：
==31666== Memcheck, a memory error detector
==31666== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==31666== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==31666== Command: ./a.out 1000000000
==31666==
==31666== Invalid read of size 1
==31666== at 0x1089E7: primepi (main.c:29)
==31666== by 0x108AA7: main (main.c:40)
==31666== Address 0x55cb7f8 is 0 bytes after a block of size 1,976 alloc'd
==31666== at 0x4C31B25: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31666== by 0x108952: primepi (main.c:19)
==31666== by 0x108AA7: main (main.c:40)
==31666==
==31666== Invalid write of size 1
==31666== at 0x108A17: primepi (main.c:29)
==31666== by 0x108AA7: main (main.c:40)
==31666== Address 0x55cb7f8 is 0 bytes after a block of size 1,976 alloc'd
==31666== at 0x4C31B25: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31666== by 0x108952: primepi (main.c:19)
==31666== by 0x108AA7: main (main.c:40)
==31666==
==31666== Invalid read of size 1
==31666== at 0x108982: primepi (main.c:25)
==31666== by 0x108AA7: main (main.c:40)
==31666== Address 0x55cb7f8 is 0 bytes after a block of size 1,976 alloc'd
==31666== at 0x4C31B25: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31666== by 0x108952: primepi (main.c:19)
==31666== by 0x108AA7: main (main.c:40)
==31666==
n = 0
==31666==
==31666== HEAP SUMMARY:
==31666== in use at exit: 0 bytes in 0 blocks
==31666== total heap usage: 8 allocs, 8 frees, 70,584 bytes allocated
==31666==
==31666== All heap blocks were freed -- no leaks are possible
==31666==
==31666== For counts of detected and suppressed errors, rerun with: -v
==31666== ERROR SUMMARY: 9 errors from 3 contexts (suppressed: 0 from 0)
答案 0 :(得分：4)
问题出在您的SET_BIT宏上：
#define SET_BIT(i) S[BYTE_IDX(i)] |= (1U << BIT_IDX(i))
或者在您的BYTE_IDX宏中：
#define BYTE_IDX(i) i >> 4
或者可能在此循环中：
for (uint64_t j = i * i; j * j <= n; j += 2 * i)
SET_BIT(j);
它访问S数组的边界。
何时：
S的最大索引为1975。将SET_BIT宏设置为：
#define SET_BIT(i) do{ \
size_t _a = BYTE_IDX(i); \
if (_a > 1975) \
fprintf(stderr, "Setting byte %ld\n", _a); \
S[_a] |= (1U << BIT_IDX(i)); \
}while(0)
我们可以在输出中看到：
Setting byte 1976
您正在为S数组写越界，该数组将覆盖* alloc数据-它会引发一个断言。
可通过onlinedbg获得实时代码。
输入您的代码：
S，则可以将其作为参数（可能带有size参数）传递，这样您可以编写断言。您刚刚发现了IS_PRIME和SET_BIT宏为什么不好的原因。我非常喜欢您的size_t是用于存储大小的类型。对ArrayList.size和ArrayList.capacity使用size_t。使用uint64_t arraylist_get(ArrayList *arraylist, size_t index);。当您处理大数时，检查乘法是否溢出也可能很好，表达式arraylist->capacity *= (uint64_t)2;和sizeof(uint64_t) * (arraylist->capacity)可能会溢出。