我如何解决由 "Invalid write" 和 "Invalid read" 引起的 sysmalloc 断言（根据 Valgrind）？
How can I resolve a sysmalloc assertion caused by an "Invalid write" and an "Invalid read" (according to Valgrind)?
如何解决此 sysmalloc 断言：
main: malloc.c:2542: sysmalloc: Assertion `(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize - 1)) == 0)' failed.
我是否在 Valgrind 引用的两个函数（即 set_slice_array() 和 print_int()）中犯了一些明显的内存相关错误？
经过一些研究，我看到的错误似乎可能是由于我在其过去分配的堆上覆盖了一些记录（malloc 需要）造成的。但我仍在学习 C 中的动态内存分配，所以我不确定如何解决问题。
运行 我通过 Valgrind 编写的程序提供了以下信息（以及关于“无效写入”和“无效读取”的两个提示）：
==2328== **Invalid write of size 2**
==2328== at 0x48452E3: memmove (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x4019FB: set_slice_array (main.c:44)
==2328== by 0x4019FB: extend_slice (main.c:97)
==2328== by 0x4019FB: join_slices (main.c:107)
==2328== by 0x4019FB: main (main.c:124)
==2328== Address 0x4a14698 is 0 bytes after a block of size 40 alloc'd
==2328== at 0x4840B68: realloc (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x40189D: grow_dynamic_array (main.c:29)
==2328== by 0x40189D: set_slice_array (main.c:41)
==2328== by 0x40189D: new_slice_from_array (main.c:59)
==2328== by 0x40189D: main (main.c:118)
==2328==
==2328== **Invalid read of size 4**
==2328== at 0x401B59: print_int (main.c:65)
==2328== by 0x401B59: print_slice (main.c:71)
==2328== by 0x401B59: debug_slice (main.c:86)
==2328== by 0x401B59: main (main.c:125)
==2328== Address 0x4a14698 is 0 bytes after a block of size 40 alloc'd
==2328== at 0x4840B68: realloc (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x40189D: grow_dynamic_array (main.c:29)
==2328== by 0x40189D: set_slice_array (main.c:41)
==2328== by 0x40189D: new_slice_from_array (main.c:59)
==2328== by 0x40189D: main (main.c:118)
==2328==
==2328==
==2328== HEAP SUMMARY:
==2328== in use at exit: 168 bytes in 5 blocks
==2328== total heap usage: 9 allocs, 4 frees, 1,252 bytes allocated
==2328==
==2328== LEAK SUMMARY:
==2328== definitely lost: 88 bytes in 3 blocks
==2328== indirectly lost: 80 bytes in 2 blocks
==2328== possibly lost: 0 bytes in 0 blocks
==2328== still reachable: 0 bytes in 0 blocks
==2328== suppressed: 0 bytes in 0 blocks
参考下面的代码（在 main.c 中）我试图在 C:
中实现 Go 的“切片”数据结构
#include <stdio.h>
#include <stdlib.h>
typedef char byte;
typedef struct dynamic_array {
size_t capacity;
size_t item_size;
byte *data;
} dynamic_array;
typedef struct slice {
size_t start;
size_t length;
void (*print_func)(void *);
dynamic_array *array;
} slice;
dynamic_array *new_dynamic_array(capacity, item_size) {
dynamic_array *this = malloc(sizeof(dynamic_array));
this->capacity = capacity;
this->item_size = item_size;
this->data = malloc(capacity * item_size * sizeof(byte));
return this;
}
void grow_dynamic_array(dynamic_array *da, size_t length_needed) {
da->capacity = length_needed;
da->data = realloc(da->data, length_needed * sizeof(byte) * da->item_size);
}
void *get_slice_ptr(slice this) {
return (this.array->data + (this.start * this.array->item_size));
}
slice set_slice_array(slice this, void *array, size_t capacity) {
dynamic_array *da = this.array;
size_t capacity_required = capacity;
while (capacity_required >= da->capacity) {
grow_dynamic_array(da, 2 * capacity_required);
}
memcpy(get_slice_ptr(this), array, da->item_size * capacity); // Culprit?
this.length += capacity;
return this;
}
slice new_slice(size_t capacity, size_t item_size, void (*print_func_ptr)(void *)) {
slice this;
this.start = this.length = 0;
this.print_func = print_func_ptr;
this.array = new_dynamic_array(capacity, item_size);
return this;
}
slice new_slice_from_array(void *array, size_t capacity, size_t item_size, void (*print_func_ptr)(void *)) {
slice this = new_slice(capacity, item_size, print_func_ptr);
this = set_slice_array(this, array, capacity);
return this;
}
void print_int(void *data_item) {
int value;
memcpy(&value, data_item, sizeof(int));
printf("[%d] ", value);
}
void print_slice(slice this) {
for (size_t i = this.start; i < this.start + this.length; ++i) {
this.print_func(this.array->data + (i * this.array->item_size));
}
printf("\n");
}
void debug_slice(slice this) {
dynamic_array da = *this.array;
printf("Length: %ld\nStart: %ld\nArray: %p\nCapacity: %ld\nItem_size: %ld\nData: %p\n",
this.length,
this.start,
(void *) this.array,
da.capacity,
da.item_size,
(void *) da.data
);
print_slice(this);
}
slice sub_slice(slice source, size_t sub_start, size_t sub_length) {
slice portion = source;
portion.start = source.start + sub_start;
portion.length = sub_length;
return portion;
}
slice extend_slice(slice this, const void *item, size_t count) {
slice extension = set_slice_array(sub_slice(this, this.length, 0), item, count);
this.length = this.length + extension.length;
return this;
}
slice append_slice(slice this, const void *item) {
return extend_slice(this, item, 1);
}
slice join_slices(slice base, slice extension) {
return extend_slice(base, get_slice_ptr(extension), extension.length);
}
int main(void) {
int test_array_ints[] = { 1, 2, 3, 4, 5 };
// First slice & debug print
slice test_slice1 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
debug_slice(test_slice1);
printf("\n"); // Second slice & debug print
slice test_slice2 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
int to_add = 6;
test_slice2 = append_slice(test_slice2, &to_add); // One culprit?
debug_slice(test_slice2);
printf("\n"); // Merge the 2 slices and then debug print
test_slice2 = join_slices(test_slice2, test_slice1);
debug_slice(test_slice2);
printf("\n"); // Create a third slice (which triggers the assert)
slice test_slice3 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
return 0;
}
如有任何帮助，我们将不胜感激！
size_t capacity_required = capacity;
memcpy(get_slice_ptr(this),
好吧，决定 - capacity_required 是包括 this.start 的容量，或者 capacity_required 是整个容量，您正在复制到 this.array->data。
size_t capacity_required = capacity + this.start;
memcpy(get_slice_ptr(this),
或
size_t capacity_required = capacity;
this.start = 0;
memcpy(this.array->data,
取决于 set_slice_array 应该做什么。它应该重新分配和替换底层存储中的元素，还是应该将切片“设置”到一个区域和 re-construct 切片？不知道，没有评论。
循环 while (capacity_required >= da->capacity) 是奇数，即 if。无论如何，我会把 if 移到 grow_dynamic_array 里面。
如何解决此 sysmalloc 断言：
main: malloc.c:2542: sysmalloc: Assertion `(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize - 1)) == 0)' failed.
我是否在 Valgrind 引用的两个函数（即 set_slice_array() 和 print_int()）中犯了一些明显的内存相关错误？
经过一些研究，我看到的错误似乎可能是由于我在其过去分配的堆上覆盖了一些记录（malloc 需要）造成的。但我仍在学习 C 中的动态内存分配，所以我不确定如何解决问题。
运行 我通过 Valgrind 编写的程序提供了以下信息（以及关于“无效写入”和“无效读取”的两个提示）：
==2328== **Invalid write of size 2**
==2328== at 0x48452E3: memmove (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x4019FB: set_slice_array (main.c:44)
==2328== by 0x4019FB: extend_slice (main.c:97)
==2328== by 0x4019FB: join_slices (main.c:107)
==2328== by 0x4019FB: main (main.c:124)
==2328== Address 0x4a14698 is 0 bytes after a block of size 40 alloc'd
==2328== at 0x4840B68: realloc (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x40189D: grow_dynamic_array (main.c:29)
==2328== by 0x40189D: set_slice_array (main.c:41)
==2328== by 0x40189D: new_slice_from_array (main.c:59)
==2328== by 0x40189D: main (main.c:118)
==2328==
==2328== **Invalid read of size 4**
==2328== at 0x401B59: print_int (main.c:65)
==2328== by 0x401B59: print_slice (main.c:71)
==2328== by 0x401B59: debug_slice (main.c:86)
==2328== by 0x401B59: main (main.c:125)
==2328== Address 0x4a14698 is 0 bytes after a block of size 40 alloc'd
==2328== at 0x4840B68: realloc (in /nix/store/7p3q3hn63ya4c46swsxlbmy03sbxz3d9-valgrind-3.16.1/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2328== by 0x40189D: grow_dynamic_array (main.c:29)
==2328== by 0x40189D: set_slice_array (main.c:41)
==2328== by 0x40189D: new_slice_from_array (main.c:59)
==2328== by 0x40189D: main (main.c:118)
==2328==
==2328==
==2328== HEAP SUMMARY:
==2328== in use at exit: 168 bytes in 5 blocks
==2328== total heap usage: 9 allocs, 4 frees, 1,252 bytes allocated
==2328==
==2328== LEAK SUMMARY:
==2328== definitely lost: 88 bytes in 3 blocks
==2328== indirectly lost: 80 bytes in 2 blocks
==2328== possibly lost: 0 bytes in 0 blocks
==2328== still reachable: 0 bytes in 0 blocks
==2328== suppressed: 0 bytes in 0 blocks
参考下面的代码（在 main.c 中）我试图在 C:
#include <stdio.h>
#include <stdlib.h>
typedef char byte;
typedef struct dynamic_array {
size_t capacity;
size_t item_size;
byte *data;
} dynamic_array;
typedef struct slice {
size_t start;
size_t length;
void (*print_func)(void *);
dynamic_array *array;
} slice;
dynamic_array *new_dynamic_array(capacity, item_size) {
dynamic_array *this = malloc(sizeof(dynamic_array));
this->capacity = capacity;
this->item_size = item_size;
this->data = malloc(capacity * item_size * sizeof(byte));
return this;
}
void grow_dynamic_array(dynamic_array *da, size_t length_needed) {
da->capacity = length_needed;
da->data = realloc(da->data, length_needed * sizeof(byte) * da->item_size);
}
void *get_slice_ptr(slice this) {
return (this.array->data + (this.start * this.array->item_size));
}
slice set_slice_array(slice this, void *array, size_t capacity) {
dynamic_array *da = this.array;
size_t capacity_required = capacity;
while (capacity_required >= da->capacity) {
grow_dynamic_array(da, 2 * capacity_required);
}
memcpy(get_slice_ptr(this), array, da->item_size * capacity); // Culprit?
this.length += capacity;
return this;
}
slice new_slice(size_t capacity, size_t item_size, void (*print_func_ptr)(void *)) {
slice this;
this.start = this.length = 0;
this.print_func = print_func_ptr;
this.array = new_dynamic_array(capacity, item_size);
return this;
}
slice new_slice_from_array(void *array, size_t capacity, size_t item_size, void (*print_func_ptr)(void *)) {
slice this = new_slice(capacity, item_size, print_func_ptr);
this = set_slice_array(this, array, capacity);
return this;
}
void print_int(void *data_item) {
int value;
memcpy(&value, data_item, sizeof(int));
printf("[%d] ", value);
}
void print_slice(slice this) {
for (size_t i = this.start; i < this.start + this.length; ++i) {
this.print_func(this.array->data + (i * this.array->item_size));
}
printf("\n");
}
void debug_slice(slice this) {
dynamic_array da = *this.array;
printf("Length: %ld\nStart: %ld\nArray: %p\nCapacity: %ld\nItem_size: %ld\nData: %p\n",
this.length,
this.start,
(void *) this.array,
da.capacity,
da.item_size,
(void *) da.data
);
print_slice(this);
}
slice sub_slice(slice source, size_t sub_start, size_t sub_length) {
slice portion = source;
portion.start = source.start + sub_start;
portion.length = sub_length;
return portion;
}
slice extend_slice(slice this, const void *item, size_t count) {
slice extension = set_slice_array(sub_slice(this, this.length, 0), item, count);
this.length = this.length + extension.length;
return this;
}
slice append_slice(slice this, const void *item) {
return extend_slice(this, item, 1);
}
slice join_slices(slice base, slice extension) {
return extend_slice(base, get_slice_ptr(extension), extension.length);
}
int main(void) {
int test_array_ints[] = { 1, 2, 3, 4, 5 };
// First slice & debug print
slice test_slice1 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
debug_slice(test_slice1);
printf("\n"); // Second slice & debug print
slice test_slice2 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
int to_add = 6;
test_slice2 = append_slice(test_slice2, &to_add); // One culprit?
debug_slice(test_slice2);
printf("\n"); // Merge the 2 slices and then debug print
test_slice2 = join_slices(test_slice2, test_slice1);
debug_slice(test_slice2);
printf("\n"); // Create a third slice (which triggers the assert)
slice test_slice3 = new_slice_from_array(&test_array_ints, 5, sizeof(int), print_int);
return 0;
}
如有任何帮助，我们将不胜感激！
size_t capacity_required = capacity; memcpy(get_slice_ptr(this),
好吧，决定 - capacity_required 是包括 this.start 的容量，或者 capacity_required 是整个容量，您正在复制到 this.array->data。
size_t capacity_required = capacity + this.start;
memcpy(get_slice_ptr(this),
或
size_t capacity_required = capacity;
this.start = 0;
memcpy(this.array->data,
取决于 set_slice_array 应该做什么。它应该重新分配和替换底层存储中的元素，还是应该将切片“设置”到一个区域和 re-construct 切片？不知道，没有评论。
循环 while (capacity_required >= da->capacity) 是奇数，即 if。无论如何，我会把 if 移到 grow_dynamic_array 里面。