linux c 超限文件覆盖写入，设备重启按文件数按编号依次继续写入

代码

6.27
1.增加写入图片数量限制
2.超过数量限制则从编号0开始覆盖写入
3.设备重启后根据文件夹存在文件数依次继续写入

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <dirent.h>

#define PIC_PATH "test.jpg"
#define SAVE_DIR "./pic"
#define SAVA_PIC_MAX 30
#define SIZE 1000*1000
//#define SAVE_PATH "home/linux/pic"

extern int errno;

unsigned long get_file_size(const char *path)
{
    struct stat statbuff;
    if (stat(path, &statbuff) < 0)
    {
        return -1;
    }
    else
    {
        return statbuff.st_size;
    }
}

int main()
{
    FILE *fp1,*fp2;
    int i = 0;
    int j = 0;
    int count = 0;
    char save_path[256];
    char * pic;
    extern int errno;
    pic = (char *)malloc(SIZE);
    unsigned long pic_len;
    DIR * pDir = NULL;
    struct dirent * pEnt = NULL;

    if (NULL == pic)
    {
        printf("malloc failed,error_num is %d ,error_msg is %s \n", errno, strerror(errno));
        return -1;
    }
    else
    {
        memset(pic,0,SIZE);
        printf("malloc seccess!\n");
    }

    if ((fp1 = fopen(PIC_PATH,"r+")) == NULL)
    {   
        printf("open test.jpg failed,error_num is %d ,error_msg is %s \n", errno, strerror(errno));
        return -1;
    }

    if (0 > (pic_len = get_file_size(PIC_PATH)))
    {
        printf("get file size failed!\n");
    }
    else
    {
        printf("file size is %ld \n",pic_len);
    }

    while (!feof(fp1))
    {   
        if ((count = fread(pic,sizeof(char),pic_len+1,fp1)) < 0)
        {
            printf("fread pic error,error_num is %d ,error_msg is %s \n", errno, strerror(errno));
            return -1;
        }
        printf("pic_len is %d",count);
        printf("read seccess\n");
        fflush(fp1);
    }

    fclose(fp1);
    
    while(j<40)
    {
        count = 0;
        if (i == 0)
        {
            pDir = opendir(SAVE_DIR);
            if(!pDir)
            {
                    if (mkdir(SAVE_DIR, 0777) < 0)
                {
                    if (EEXIST != errno)
                    {
                        printf("mkdir %s, errno: %d(%s)\n", SAVE_DIR, errno, strerror(errno));
                        closedir(pDir);
                    }
                }
            }
            else
            {
                while (1)
                {
                    pEnt = readdir(pDir);
                    if(pEnt != NULL)
                    {
                        if(strcmp(pEnt->d_name, "..")==0 || strcmp(pEnt->d_name, ".")==0)
                        {
                           continue;
                        }
                        printf("count is %d\n",count);
                        count++;
                    }
                    else
                    {
                        break;
                    }
                }
                printf("path contain %d pic_file\n", count); 
                if ( SAVA_PIC_MAX <= count  || 0 == count)
                {
                    i = 0;
                }
                else
                {
                    i = count - 1;
                }
                closedir(pDir);
                sync();
            }
        }

		sprintf(save_path,"./pic/pic_%d.jpg",i);
        if ((fp2 = fopen(save_path,"w+")) == NULL)
        {
            printf("open pic_%d.jpg failed,error_num is %d ,error_msg is %s \n", i, errno, strerror(errno));
            return -1;
        }
        else
        {
            printf("create pic_%d.jpg ok! \n",i);
        }

        count = fwrite(pic,sizeof(char),pic_len,fp2);
        
        if (count < 0)
        {
            printf("fwrite pic error,error_num is %d ,error_msg is %s \n", errno, strerror(errno)); 
            return -1;
        }
        else
        {
            printf("write size is %d \n",count);
        }
        fflush(fp2);
        printf("write pic_%d.jpg ok!\n",i);
        fclose(fp2);
        if (i < SAVA_PIC_MAX - 1)
        {
            i++;
        }
        else
        {
            i = 0;
        }
        j++;       
    }
    return 0;
}