c语言 - munmap_chunk():释放数组中的结构时指针无效

Question

所以我写了一个程序，每当我想添加一些东西时，我都必须重新分配一个结构数组。 但是当我尝试释放数组时，我会单独释放每个元素，但在某些时候我会得到munmap_chunk(): invalid pointer。

这是完整的代码：

#include <stdlib.h>
#include <string.h>
struct Date {
int day;
int month;
int year;
};
struct Person {
char *name;
char *surname;
struct Date birth;
};
struct Directory {
int size;
struct Person *array;
};
struct Date create_date() {
struct Date date = {
.day = 0,
.month = 0,
.year = 0
};
return date;
}
struct Directory create_directory() {
struct Directory directory = {
.size = 0,
.array = NULL
};
return directory;
}
struct Person *create_person() {
struct Person *person_ptr = (struct Person *) malloc(sizeof(struct Person));
person_ptr->name = NULL;
person_ptr->surname = NULL;
return person_ptr;
}
void copy_date(struct Date *dest, struct Date *src) {
dest->day = src->day;
dest->month = src->month;
dest->year = src->year;
}
void initialize_person(struct Person *person_ptr, char *name, char *surname, struct Date *birth) {
if (name != NULL && surname != NULL && birth != NULL) {
person_ptr->name = realloc((*person_ptr).name, (strlen(name) * sizeof(char)) + 1);
strcpy(person_ptr->name, name);
person_ptr->surname = realloc((*person_ptr).surname, (strlen(surname) * sizeof(char)) + 1);
strcpy(person_ptr->surname, surname);
copy_date(&person_ptr->birth, birth);
}
}
void copy_person(struct Person *dest, struct Person *src) {
dest->name = realloc((*dest).name, (strlen(src->name) * sizeof(char)) + 1);
dest->surname = realloc((*dest).surname, (strlen(src->surname) * sizeof(char)) + 1);
struct Date date = create_date();
dest->birth = date;
strcpy(dest->name, src->name);
strcpy(dest->surname, src->surname);
copy_date(&dest->birth, &src->birth);
}
int add_person(struct Directory *directory_ptr, const struct Person *new_person_ptr) {
int return_code = 0;
directory_ptr->size++;
directory_ptr->array = realloc(directory_ptr->array, (directory_ptr->size * sizeof(struct Person)));
if (directory_ptr->array) {
copy_person(&directory_ptr->array[directory_ptr->size - 1], (struct Person *) new_person_ptr);
} else {
return_code = 1;
}
return return_code;
}
int add_multiple_persons(struct Directory *directory_ptr, const struct Person **persons_ptr, int nb_persons) {
for (int i = 0; i < nb_persons; i++) {
add_person(directory_ptr, (persons_ptr[i]));
}
return 0;
}
void destroy_person(struct Person *person_ptr) {
free(person_ptr->name);
person_ptr->name = NULL;
free(person_ptr->surname);
person_ptr->surname = NULL;
free(person_ptr);
person_ptr = NULL;
}
void destroy_directory(struct Directory *directory_ptr) {
if (directory_ptr->array) {
for (int i = 0; i < directory_ptr->size; i++) {
destroy_person(&directory_ptr->array[i]);
}
directory_ptr->array = NULL;
directory_ptr->size = 0;
}
}
int main(void) {
struct Directory directory = create_directory();
struct Person *person1 = create_person();
struct Person *person2 = create_person();
struct Person *person3 = create_person();
struct Date date = {
.day = 17,
.month = 04,
.year = 1999};
initialize_person(person1, "Marcel", "Juan", &date);
initialize_person(person2, "Albin", "Michel", &date);
initialize_person(person3, "Suzerain", "Bernard", &date);
const struct Person *array[] = {
person1,
person2,
person3
};
add_multiple_persons(&directory, array, 3);
destroy_person(person1);
destroy_person(person2);
destroy_person(person3);
destroy_directory(&directory);
return 0;
}

我已经在这个错误上呆了一个多星期，它一直困扰着我。 我该如何解决这个问题？

Answer 1

在destroy_directory函数中，您释放了数组中包含的人员。但是在这个数组中，你没有放置指向结构的指针，而是指向结构本身。因此，您必须释放为数组分配的空间，而不是其他任何内容：

void destroy_directory(struct Directory *directory_ptr) {
if (directory_ptr->array) {
free(directory_ptr->array); //<==== Here
directory_ptr->array = NULL;
directory_ptr->size = 0;
}
}

Answer 2

person_ptr是在directory_ptr->array分配的内存的一部分。您需要删除此行。

作为黄金规则，负责的内存在分配和释放时是相同的。在你的代码中，person持有者是directory_ptr内部的array，由add_person分配。尽管它的名字，它是一个directory管理器，所以释放它的记忆应该只在directory驱逐舰上完成。