inotify使用范例

好久没更新博客了，来写一篇！

一. 应用层接口:
1. 函数原型:

    int fd = inotify_init ();

    //添加一个watch, path 可以使文件或者目录, mask见<linux/inotify.h>

    int wd = inotify_add_watch (fd, path, mask);

    int ret = inotify_rm_watch (fd, wd);//移除一个watch

2. struct inotify_event    

          代表一次事件: IN_CREATE,
IN_DELETE, IN_OPEN, IN_CLOSE

struct inotify_event {
int
wd;
         
      /* watch descriptor */

uint32_t
mask;
/* watch mask */
uint32_t
cookie;
/* cookie to synchronize two events */
uint32_t
len;
    /* length (including nulls) of name */

char
name __flexarr;
/* stub for possible name */
};    

 

3. 读取事件

    //buf指向一个inotify_event的数组, 根据BUF_LEN填充合适的event

    size_t len = read (fd, buf, BUF_LEN);

    

    ioctl( inotify_fd, FIONREAD, &bytes_to_read );

4. poll事件

    fd也可以用select和poll函数

二. kernel接口

1. 函数原型:

        struct inotify_handle *inotify_init(struct inotify_operations
*ops);

inotify_init_watch(struct inotify_watch *watch);

s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch, struct inode *inode, u32 mask);

s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode, struct inotify_watch **watchp);

s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode, u32 mask);

int inotify_rm_wd(struct inotify_handle *ih, u32 wd);

int inotify_rm_watch(struct inotify_handle *ih, struct inotify_watch *watch);

void inotify_remove_watch_locked(struct inotify_handle *ih, struct inotify_watch *watch);

void inotify_destroy(struct inotify_handle *ih);

void get_inotify_watch(struct inotify_watch *watch);

void put_inotify_watch(struct inotify_watch *watch);

附上实现的代码：（哇哈哈）


inotify.h:

/*
* This header is used if <sys/inotify.h> cannot be found.
*
* Inode based directory notification for Linux
*
* Copyright (C) 2005 John McCutchan
*/

#ifndef _LINUX_INOTIFY_H
#define _LINUX_INOTIFY_H

#include <stdint.h>
#include <sys/syscall.h>
#include <unistd.h>

/*
* struct inotify_event - structure read from the inotify device for each event
*
* When you are watching a directory, you will receive the filename for events
* such as IN_CREATE, IN_DELETE, IN_OPEN, IN_CLOSE, ..., relative to the wd.
*/
struct inotify_event {
int		wd;		/* watch descriptor */
uint32_t		mask;		/* watch mask */
uint32_t		cookie;		/* cookie to synchronize two events */
uint32_t		len;		/* length (including nulls) of name */
char		name __flexarr;	/* stub for possible name */
};

/* the following are legal, implemented events that user-space can watch for */
#define IN_ACCESS		0x00000001	/* File was accessed */
#define IN_MODIFY		0x00000002	/* File was modified */
#define IN_ATTRIB		0x00000004	/* Metadata changed */
#define IN_CLOSE_WRITE		0x00000008	/* Writtable file was closed */
#define IN_CLOSE_NOWRITE	0x00000010	/* Unwrittable file closed */
#define IN_OPEN			0x00000020	/* File was opened */
#define IN_MOVED_FROM		0x00000040	/* File was moved from X */
#define IN_MOVED_TO		0x00000080	/* File was moved to Y */
#define IN_CREATE		0x00000100	/* Subfile was created */
#define IN_DELETE		0x00000200	/* Subfile was deleted */
#define IN_DELETE_SELF		0x00000400	/* Self was deleted */
#define IN_MOVE_SELF		0x00000800	/* Self was moved */

/* the following are legal events.  they are sent as needed to any watch */
#define IN_UNMOUNT		0x00002000	/* Backing fs was unmounted */
#define IN_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
#define IN_IGNORED		0x00008000	/* File was ignored */

/* helper events */
#define IN_CLOSE		(IN_CLOSE_WRITE | IN_CLOSE_NOWRITE) /* close */
#define IN_MOVE			(IN_MOVED_FROM | IN_MOVED_TO) /* moves */

/* special flags */
#define IN_ONLYDIR		0x01000000	/* only watch the path if it is a directory */
#define IN_DONT_FOLLOW		0x02000000	/* don't follow a sym link */
#define IN_MASK_ADD		0x20000000	/* add to the mask of an already existing watch */
#define IN_ISDIR		0x40000000	/* event occurred against dir */
#define IN_ONESHOT		0x80000000	/* only send event once */

/*
* All of the events - we build the list by hand so that we can add flags in
* the future and not break backward compatibility.  Apps will get only the
* events that they originally wanted.  Be sure to add new events here!
*/
#define IN_ALL_EVENTS	(IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE | \
IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | \
IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF | \
IN_MOVE_SELF)

#if defined (__alpha__)
# define __NR_inotify_init 444
# define __NR_inotify_add_watch 445
# define __NR_inotify_rm_watch 446

#elif defined (__arm__)
# define __NR_inotify_init (__NR_SYSCALL_BASE+316)
# define __NR_inotify_add_watch (__NR_SYSCALL_BASE+317)
# define __NR_inotify_rm_watch (__NR_SYSCALL_BASE+318)

#elif defined (__frv__)
# define __NR_inotify_init 291
# define __NR_inotify_add_watch 292
# define __NR_inotify_rm_watch 293

#elif defined(__i386__)
# define __NR_inotify_init 291
# define __NR_inotify_add_watch 292
# define __NR_inotify_rm_watch 293

#elif defined (__ia64__)
# define __NR_inotify_init 1277
# define __NR_inotify_add_watch 1278
# define __NR_inotify_rm_watch 1279

#elif defined (__mips__)
# if _MIPS_SIM == _MIPS_SIM_ABI32
#  define __NR_inotify_init (__NR_Linux + 284)
#  define __NR_inotify_add_watch (__NR_Linux + 285)
#  define __NR_inotify_rm_watch (__NR_Linux + 286)
# endif
# if _MIPS_SIM == _MIPS_SIM_ABI64
#  define __NR_inotify_init (__NR_Linux + 243)
#  define __NR_inotify_add_watch (__NR_Linux + 243)
#  define __NR_inotify_rm_watch (__NR_Linux + 243)
# endif
# if _MIPS_SIM == _MIPS_SIM_NABI32
#  define __NR_inotify_init (__NR_Linux + 247)
#  define __NR_inotify_add_watch (__NR_Linux + 248)
#  define __NR_inotify_rm_watch (__NR_Linux + 249)
# endif

#elif defined(__parisc__)
# define __NR_inotify_init (__NR_Linux + 269)
# define __NR_inotify_add_watch (__NR_Linux + 270)
# define __NR_inotify_rm_watch (__NR_Linux + 271)

#elif defined(__powerpc__) || defined(__powerpc64__)
# define __NR_inotify_init 275
# define __NR_inotify_add_watch 276
# define __NR_inotify_rm_watch 277

#elif defined (__s390__)
# define __NR_inotify_init 284
# define __NR_inotify_add_watch 285
# define __NR_inotify_rm_watch 286

#elif defined (__sh__)
# define __NR_inotify_init 290
# define __NR_inotify_add_watch 291
# define __NR_inotify_rm_watch 292

#elif defined (__sh64__)
# define __NR_inotify_init 318
# define __NR_inotify_add_watch 319
# define __NR_inotify_rm_watch 320

#elif defined (__sparc__) || defined (__sparc64__)
# define __NR_inotify_init 151
# define __NR_inotify_add_watch 152
# define __NR_inotify_rm_watch 156

#elif defined(__x86_64__)
# define __NR_inotify_init 253
# define __NR_inotify_add_watch 254
# define __NR_inotify_rm_watch 255

#else
# error "Unsupported architecture!"
#endif

static inline int inotify_init (void)
{
return syscall (__NR_inotify_init);
}

static inline int inotify_add_watch (int fd, const char *name, uint32_t mask)
{
return syscall (__NR_inotify_add_watch, fd, name, mask);
}

static inline int inotify_rm_watch (int fd, uint32_t wd)
{
return syscall (__NR_inotify_rm_watch, fd, wd);
}

#endif	/* _LINUX_INOTIFY_H */

main.c:

#include <poll.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
#include <errno.h>
#include <sys/ioctl.h>

#include "inotify.h"

void show_event(struct inotify_event *events, int num_event)
{
int i;
struct inotify_event *e =events;
for(i = 0; i < num_event; i++){
printf("wd = %d, mask = 0x%02x, cookie = %u, len = %u\n", e->wd, e->mask, e->cookie, e->len);
e++;
}
}

void show_data(char * dat, int len)
{
int i;
int line_num = 16;
for(i = 0; i < len; i ++){
if(i % line_num == 0 && i != 0) printf("\n");
printf("0x%02x ",  dat[i]);
}
printf("\n----------------------------------------\n");
}

void use_read(int fd)
{
#define BUF_LEN 1024
char buf[BUF_LEN];
int len = read(fd, buf, BUF_LEN);
int num_events = len / sizeof(struct inotify_event);
printf("read len = %d, num_events = %d\n", len, num_events);

show_data(buf, len);
show_event((struct inotify_event *)buf, num_events);
}

void use_select(int fd)
{
#define BUF_LEN 1024
char buf[BUF_LEN];

fd_set read_fds;
int rc;
unsigned int bytes_to_read;
/*struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 0;*/

FD_ZERO(&read_fds);
FD_SET(fd, &read_fds);
while(1){
rc = select(fd + 1, &read_fds, NULL, NULL, NULL);
if(rc < 0){
printf("select error: %s\n", strerror(errno));
return;
}

rc = ioctl(fd, FIONREAD, &bytes_to_read );
if(rc < 0){
printf("ioctl error: %s\n", strerror(errno));
return;
}
printf("----->current event queue = %u\n", bytes_to_read);

int len = read(fd, buf, BUF_LEN);
int num_events = len / sizeof(struct inotify_event);
printf("read len = %d, num_events = %d\n", len, num_events);
show_event((struct inotify_event *)buf, num_events);
}
}

int main(int argc, char *argv[])
{
int fd;

if(argc != 2){
printf("usage: ./inotify <path>\n");
exit(1);
}

fd = inotify_init();
int wd = inotify_add_watch(fd, argv[1], IN_ALL_EVENTS);

//use_read(fd);
use_select(fd);

inotify_rm_watch(fd, wd);
return 0;
}

运行后，进入你要监听的目录，ls一下，就会收到事件了！！