linux inotify 監視檔案事件__linux

Inotify 是一個 Linux 核心特性，它監控檔案系統，並且及時向專門的應用程式發出相關的事件警告，比如刪除、讀、寫和卸載操作等。您還可以跟蹤活動的源頭和目標等細節，尤其是設定檔，修改後可以實現自動重載配置資訊，而不必要重啟。

源碼：http://download.csdn.net/detail/liuhongxiangm/6722679

inotify 幾個函數

#include <sys/inotify.h>

1、int inotify_init(void)

      核心中建立一個inotify執行個體，成功返回描述符，失敗返回-1，errno判斷失敗資訊

2、int inotify_add_watch(int fd, const char*pathname, uint32_t mask)

       添加監視事件，參數是inotify描述符， 要監視路徑名， 相關事件

       相關事件有：

       Inotify 可以監視的檔案系統事件包括：
       IN_ACCESS，即檔案被訪問
       IN_MODIFY，檔案被 write
       IN_ATTRIB，檔案屬性被修改，如 chmod、chown、touch 等
       IN_CLOSE_WRITE，可寫檔案被 close
       IN_CLOSE_NOWRITE，不可寫檔案被 close
       IN_OPEN，檔案被 open
       IN_MOVED_FROM，檔案被移走,如 mv
       IN_MOVED_TO，檔案被移來，如 mv、cp
       IN_CREATE，建立新檔案
       IN_DELETE，檔案被刪除，如 rm
       IN_DELETE_SELF，自刪除，即一個可執行檔在執行時刪除自己
       IN_MOVE_SELF，自移動，即一個可執行檔在執行時移動自己
       IN_UNMOUNT，宿主檔案系統被 umount
       IN_CLOSE，檔案被關閉，等同於(IN_CLOSE_WRITE | IN_CLOSE_NOWRITE)
       IN_MOVE，檔案被移動，等同於(IN_MOVED_FROM | IN_MOVED_TO)

3、int inotify_rm_watch(int fd, int wd)

            移一個監視器

4、還需要read（）讀取事件，close（）關閉inotify描述符

      struct inotify_event   
      {  
           int wd;       /* The watch descriptor */  
           uint32_t mask;    /* Watch mask */  
           uint32_t cookie;  /* A cookie to tie two events together */  
           uint32_t len;     /* The length of the filename found in the name field */  
           char name __flexarr;  /* The name of the file, padding to the end with NULs */      
     }  

5、使用例子

CInotify類封裝

CInotify.h        

#ifndef CINOTIFY_H#define CINOTIFY_H#include <stdlib.h>#include <stdio.h>#include <sys/inotify.h>#include <pthread.h>#include <unistd.h>#include <sys/select.h>typedef void (*fun_inotify)(inotify_event *event, void *puser);class CInotify{public:    CInotify();    ~CInotify();    int Init(fun_inotify callback, void *puser);    int AddWatch(const char*pathname, uint32_t mask);    int RemoveWatch(int wd);    int Close();    friend void* WatchThread(void*);private:    int WatchLoop();private:    int         m_fdInotify;    void       *m_pUser;    fun_inotify m_funInotify;    pthread_t   m_thWatch;    char       *m_bufEvent;};#endif // CINOTIFY_H

CInotify.cpp

#include "cinotify.h"#define EVENT_SIZE (sizeof(struct inotify_event))#define BUF_LEN (1024*(EVENT_SIZE+16))void* WatchThread(void* p);void* WatchThread(void* p){    CInotify *thiz = (CInotify*)p;    thiz->WatchLoop();    return  0;}CInotify::CInotify(){    m_fdInotify  = -1;    m_pUser      = NULL;    m_funInotify = NULL;    m_thWatch    = -1;    m_bufEvent   = NULL;}CInotify::~CInotify(){    m_fdInotify  = -1;    m_pUser      = NULL;    m_funInotify = NULL;    m_thWatch    = -1;     m_bufEvent   = NULL;}int CInotify::Init(fun_inotify callback, void *puser){    m_bufEvent  = new char[BUF_LEN];    m_funInotify = callback;    m_pUser = puser;    m_fdInotify = inotify_init();    if(m_fdInotify < 0)    {        return -1;    }    //create watch thread    if( pthread_create(&m_thWatch, NULL,WatchThread, this) < 0)    {        close(m_fdInotify);        return -1;    }    return m_fdInotify;}int CInotify::AddWatch(const char*pathname, uint32_t mask){    return inotify_add_watch(m_fdInotify, pathname, mask);}int CInotify::RemoveWatch(int wd){     return  inotify_rm_watch(m_fdInotify, wd);}int CInotify::Close(){    if(m_fdInotify != -1)    {        close(m_fdInotify);        m_fdInotify = -1;    }    if(m_thWatch != -1)    {        pthread_cancel(m_thWatch);        pthread_join(m_thWatch, NULL);        m_thWatch = -1;    }    return 0;}int CInotify::WatchLoop(){    fd_set rfd;    struct timeval tv;    tv.tv_sec = 1;    tv.tv_usec = 0;    while(true)    {        int retval;        FD_ZERO(&rfd);        FD_SET(m_fdInotify,&rfd);        retval = select(m_fdInotify+1, &rfd, NULL, NULL, &tv);        if(retval == 0)        {            continue;        }        else if(retval == -1)        {            return -1;        }        int len = read(m_fdInotify,m_bufEvent, BUF_LEN);        int index = 0;        while(index < len)        {            inotify_event *event = (inotify_event*)&m_bufEvent[index];            {                //call back                if(m_funInotify != NULL)                {                    m_funInotify(event,m_pUser);                }                index += EVENT_SIZE +  event->len;            }        }    }    return 0;}

main.cpp

#include <iostream>#include <errno.h>#include <stdio.h>#include "cinotify.h"using namespace std;void inotify(inotify_event *event, void *puser){    if ( event->mask & IN_CREATE )    {        if ( event->mask & IN_ISDIR )        {             printf( "The directory %s was created.\n", event->name );        }        else        {              printf( "The file %s was created.\n", event->name );        }    }    if ( event->mask & IN_DELETE )    {          if ( event->mask & IN_ISDIR )          {                 printf( "The directory %s was deleted.\n", event->name );          }          else          {               printf( "The file %s was deleted.\n", event->name );          }    }    if ( event->mask & IN_MODIFY )    {          if ( event->mask & IN_ISDIR )          {                printf( "The directory %s was modified.\n", event->name );          }          else          {               printf( "The file %s was modified.\n", event->name );          }     }    if ( event->mask & IN_ACCESS )    {        if ( event->mask & IN_ISDIR )        {              printf( "The directory %s was access.\n", event->name );        }        else        {             printf( "The file %s was access.\n", event->name );        }    }}int main(){    int iret = 0;    CInotify notify;    iret = notify.Init(&inotify, NULL);    iret = notify.AddWatch("log.txt", IN_MODIFY|IN_ACCESS);    if(iret < 0)    {        perror("inotify error");    }    getchar();    notify.Close();    return 0;}