C语言实现stat

mystat 用c语言实现stat

stat命令的作用

stat命令显示文件或目录的详细属性信息包括文件系统状态，比ls命令输出的信息更详细
首先学习一下stat

man stat

man -k stat | grep 2

man 2 stat

伪代码

判断是否包含文件参数
读取结构体目录文件中的信息
输出参数文件信息
关闭退出目录文件

源代码

#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
#include <string.h>
#include <time.h>
#include <sys/timeb.h>

struct stat sb;
struct tm *lt;
struct tm stm;
time_t t;

void timeswitch(struct tm *lt)
{
	char nowtime[24];
	memset(nowtime, 0, sizeof(nowtime));
	strftime(nowtime, 24, "%Y-%m-%d %H:%M:%S", lt);
	printf("%s\n", nowtime);
}

int main(int argc, char *argv[])
{
    int n;
    struct passwd *pwd;
    // = getpwuid(sb.st_uid);
    char nowtime[24];
    int count[3]={0};
    int cou = 0;
    int flag = 0;
    char mode[8]={0};
    if (argc != 2) 
    {
        fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    if (lstat(argv[1], &sb) == -1) 
    {
        perror("lstat");
        exit(EXIT_FAILURE);
    }

    printf("  File： %s\n",argv[1]);
    printf("  Size:  %lld bytes       ",(long long) sb.st_size);
    printf("Block: %lld        ",(long long) sb.st_blocks);
    printf("IO Block: %ld    ",(long) sb.st_blksize);

    switch (sb.st_mode & S_IFMT) 
    {
        case S_IFBLK:  printf("Block Device\n");            break;
        case S_IFCHR:  printf("Character devices\n");        break;
        case S_IFDIR:  printf("directory\n");       flag=1;        break;
        case S_IFIFO:  printf("FIFO/Pipeline\n");               break;
        case S_IFLNK:  printf("symlink\n");                 break;
        case S_IFREG:  printf("Normal files\n");            break;
        case S_IFSOCK: printf("socket\n");                  break;
        default:       printf("unknown?\n");                break;
    }
    printf("Device：%ld                ",(long)sb.st_dev);
    printf("Inode: %ld     ", (long) sb.st_ino);
    printf("Links: %ld\n", (long) sb.st_nlink);
    printf("Access：");
    printf("（");
  
    for(n=8;n>=0;n--)
	{
		if(sb.st_mode&(1<<n))
		{
			switch(n%3)
			{
			case 2:
                mode[8-n] = 'r';
                count[n/3] += 4;
				break;
			case 1:
                mode[8-n] = 'w';
                count[n/3] += 2;
				break;
			case 0:
				mode[8-n] = 'x';
                count[n/3] += 1;
                break;
			default:
				break;
			}
		}
		else
		{
            mode[8-n] = '-';
        }
	}
    printf("0%d%d%d/",count[2],count[1],count[0]);
    
    if(flag)
    {
        printf("d");
    }
    else
    {
        printf("-");
    }
    for ( cou = 0; cou <= 8; cou++)
    {
        printf("%c",mode[cou]);
    }
    printf("）  ");
    pwd = getpwuid(sb.st_uid);
    printf("UID: ( %ld/   %s)   GID: ( %ld/    %s )\n",(long) sb.st_uid,pwd->pw_name, (long) sb.st_gid,pwd->pw_name);

    printf("Access:  "); 
    timeswitch(localtime(&sb.st_atime));

    printf("Modify:  "); 
    timeswitch(localtime(&sb.st_ctime));

    printf("Change:  "); 
    timeswitch(localtime(&sb.st_mtime));

    printf(" Birth:  -\n"); 
    exit(EXIT_SUCCESS);
}

mystat与Linux系统的stat比较