linux opendir和readdir的使用

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1 opendir

#include <sys/types.h>
#include <dirent.h>

DIR *opendir(const char *name);

传入name路径，成功则返回非空DIR指针，否则返回NULL

2 readdir

#include <dirent.h>

struct dirent *readdir(DIR *dirp);

int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);

readdir一般要配合opendir使用，readdir不是线程安全函数，代替他的有readdir_r。

readdir返回 struct dirent *指针，读完目录下所有文件时，返回NULL

如果系统支持readdir_r，建议用readdir_r , readdir_r成功返回0。

关于struct dirent结构体：

On Linux, the dirent structure is defined as follows:

struct dirent {
ino_t d_ino; /* inode number */
off_t d_off; /* not an offset; see NOTES */
unsigned short d_reclen; /* length of this record */
unsigned char d_type; /* type of file; not supported
by all filesystem types */
char d_name[256]; /* filename */
};

3 closedir

#include <sys/types.h>

#include <dirent.h>

int closedir(DIR *dirp);

closedir配合opendir使用。

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/types.h>#include <dirent.h>#include <errno.h>//DIR *opendir(const char *name);#ifndef  LOG_TRACE#define LOG_TRACE printf#define LOG_INFO(msg)  \do{ \LOG_TRACE msg; \LOG_TRACE("[%s %d] \n",__FUNCTION__,__LINE__);\}while(0)#define LOG_ERROR(err_info)  \do{ \LOG_TRACE err_info; \LOG_TRACE("[%s %d]  \n",__FUNCTION__,__LINE__);\}while(0)#endifextern int errno;int open_dir_1(const char *pDirname){DIR * dirp = NULL; struct dirent * pDirent= NULL;if((NULL == pDirname) ||(0 == strlen(pDirname))){LOG_ERROR(("param error"));return -1;}dirp = opendir(pDirname);if (NULL == dirp){LOG_ERROR(("opendir %s failed! error_no: %s",pDirname , strerror(errno)));return -1;}while (NULL != (pDirent = readdir(dirp))){if (pDirent->d_type == DT_DIR ){LOG_ERROR(("dir      [%s]       ",pDirent->d_name));}else if(pDirent->d_type == DT_REG){LOG_ERROR(("file     [%s]        ",pDirent->d_name));}}closedir(dirp);return 0;}int open_dir_2(const char *pDirname){DIR * dirp = NULL; struct dirent * pDirent= NULL;struct dirent *pStResult = NULL;if((NULL == pDirname) ||(0 == strlen(pDirname))){LOG_ERROR(("param error"));return -1;}dirp = opendir(pDirname);if (NULL == dirp){LOG_ERROR(("opendir %s failed! error_no: %s",pDirname , strerror(errno)));return -1;}pDirent = (struct dirent *)malloc(sizeof(struct dirent));if(!pDirent){LOG_ERROR(("pDirent error"));closedir(dirp);return -1;}while (( 0== readdir_r(dirp,pDirent,&pStResult))&&(pStResult != NULL)){if (pDirent->d_type == DT_DIR ){LOG_ERROR(("dir      [%s]       ",pDirent->d_name));}else if(pDirent->d_type == DT_REG){LOG_ERROR(("file     [%s]        ",pDirent->d_name));}}closedir(dirp);return 0;}int main(){LOG_ERROR(("***********"));open_dir_1("/share/");LOG_ERROR(("------------"));open_dir_2("/share/");LOG_ERROR(("-++--+++--"));return 0;}

运行结果：

./a.out [19@gcc test_opendir_readdir.c[C
root@ubuntu:/share#
root@ubuntu:/share#
root@ubuntu:/share# gcc test_opendir_readdir.c
/a.out
***********[main 113]
file [zlib-1.2.8.tar.gz] [open_dir_1 54]
file [1.tmp] [open_dir_1 54]
file [log.c] [open_dir_1 54]
file [list.c] [open_dir_1 54]
dir [11] [open_dir_1 50]
file [test.out] [open_dir_1 54]
file [test_system_func.c] [open_dir_1 54]
file [a.out] [open_dir_1 54]
file [test_strncpy.c] [open_dir_1 54]
file [test_proc_partitions.c] [open_dir_1 54]
file [test.c] [open_dir_1 54]
file [New0001.c] [open_dir_1 54]
dir [curl-7.51.0] [open_dir_1 50]
file [test_ftok.c] [open_dir_1 54]
file [log.h] [open_dir_1 54]
file [test_gettimeofday.c] [open_dir_1 54]
file [csdn.c] [open_dir_1 54]
file [client.c] [open_dir_1 54]
file [1.txt] [open_dir_1 54]
file [test_opendir_readdir.c] [open_dir_1 54]
file [curl-7.51.0.tar.gz] [open_dir_1 54]
file [2.txt] [open_dir_1 54]
file [opendir.c] [open_dir_1 54]
dir [zlib-1.2.8] [open_dir_1 50]
file [123.rmvb] [open_dir_1 54]
dir [ffmpeg_learn] [open_dir_1 50]
file [test_sem.c] [open_dir_1 54]
file [test_list.c] [open_dir_1 54]
file [list.h] [open_dir_1 54]
file [server] [open_dir_1 54]
dir [ProFFmpeg] [open_dir_1 50]
dir [ffmpeg-3.1.6] [open_dir_1 50]
dir [yasm-1.3.0] [open_dir_1 50]
file [New0003.c] [open_dir_1 54]
dir [.] [open_dir_1 50]
dir [..] [open_dir_1 50]
file [ffmpeg-3.1.6.tar.gz] [open_dir_1 54]
file [types.h] [open_dir_1 54]
file [New0002.c] [open_dir_1 54]
file [simple.out] [open_dir_1 54]
file [server.c] [open_dir_1 54]
dir [learn] [open_dir_1 50]
file [simple_ffmpeg_player.c] [open_dir_1 54]
file [client] [open_dir_1 54]
dir [abc] [open_dir_1 50]
file [yasm-1.3.0.tar.gz] [open_dir_1 54]
file [output.yuv] [open_dir_1 54]
file [mySDLFirst.out] [open_dir_1 54]
------------[main 115]
file [zlib-1.2.8.tar.gz] [open_dir_2 100]
file [1.tmp] [open_dir_2 100]
file [log.c] [open_dir_2 100]
file [list.c] [open_dir_2 100]
dir [11] [open_dir_2 96]
file [test.out] [open_dir_2 100]
file [test_system_func.c] [open_dir_2 100]
file [a.out] [open_dir_2 100]
file [test_strncpy.c] [open_dir_2 100]
file [test_proc_partitions.c] [open_dir_2 100]
file [test.c] [open_dir_2 100]
file [New0001.c] [open_dir_2 100]
dir [curl-7.51.0] [open_dir_2 96]
file [test_ftok.c] [open_dir_2 100]
file [log.h] [open_dir_2 100]
file [test_gettimeofday.c] [open_dir_2 100]
file [csdn.c] [open_dir_2 100]
file [client.c] [open_dir_2 100]
file [1.txt] [open_dir_2 100]
file [test_opendir_readdir.c] [open_dir_2 100]
file [curl-7.51.0.tar.gz] [open_dir_2 100]
file [2.txt] [open_dir_2 100]
file [opendir.c] [open_dir_2 100]
dir [zlib-1.2.8] [open_dir_2 96]
file [123.rmvb] [open_dir_2 100]
dir [ffmpeg_learn] [open_dir_2 96]
file [test_sem.c] [open_dir_2 100]
file [test_list.c] [open_dir_2 100]
file [list.h] [open_dir_2 100]
file [server] [open_dir_2 100]
dir [ProFFmpeg] [open_dir_2 96]
dir [ffmpeg-3.1.6] [open_dir_2 96]
dir [yasm-1.3.0] [open_dir_2 96]
file [New0003.c] [open_dir_2 100]
dir [.] [open_dir_2 96]
dir [..] [open_dir_2 96]
file [ffmpeg-3.1.6.tar.gz] [open_dir_2 100]
file [types.h] [open_dir_2 100]
file [New0002.c] [open_dir_2 100]
file [simple.out] [open_dir_2 100]
file [server.c] [open_dir_2 100]
dir [learn] [open_dir_2 96]
file [simple_ffmpeg_player.c] [open_dir_2 100]
file [client] [open_dir_2 100]
dir [abc] [open_dir_2 96]
file [yasm-1.3.0.tar.gz] [open_dir_2 100]
file [output.yuv] [open_dir_2 100]
file [mySDLFirst.out] [open_dir_2 100]
-++--+++--[main 118]
root@ubuntu:/share#

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