在C中释放字符串时出现分段错误

Question

当我尝试释放从"new_job-> jobs_adress"指向的字符串的已分配内存时,我出现"分段错误"错误.我已经为我的字符串分配了足够的内存(即使我分配的远远超出我的需要,我仍然有这个问题),但仍然存在这个错误.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct job_t {
    pid_t pid;
    time_t creation_time;
    bool stop;
    bool foreground;
    char * jobs_adress;
} Job;

int main() {

    char * jobs_adress = "string";

    /* creating an object of "Job" Type */
    printf("another try");
    Job * new_job = (Job*)malloc(sizeof(new_job));
    if(!new_job) {
        return;
    }

    /* allocating memory for a new string, and copies the old string
      into the new string*/

    int length2=strlen(jobs_adress);
    char * str2 = malloc(length2+1);
    strcpy(str2,jobs_adress);
    new_job->jobs_adress=str2;               

    new_job->pid = 1;
    new_job->creation_time = time(NULL);
    new_job->stop=false;
    new_job->foreground=true;

    free(new_job->jobs_adress);  // <=== the error is here

}

Answer 1

Job * new_job = (Job*)malloc(sizeof(new_job));

在这一行,sizeof(new_job)是测量变量的大小new_job.

new_job具有类型指针,指针(通常)为4个字节.
所以你分配4个字节.

您打算为Job结构分配足够的空间.
这条线应该是:

Job * new_job = (Job*)malloc(sizeof(Job));