FileWatchThreaded.H

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/* Copyright 2000-2018 Matt Flax <flatmax@flatmax.org>
   This file is part of GTK+ IOStream class set

   GTK+ IOStream is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   GTK+ IOStream is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You have received a copy of the GNU General Public License
   along with GTK+ IOStream
 */
#ifndef FILEWATCHTHREAD_H_
#define FILEWATCHTHREAD_H_

#include <Thread.H>
#include <sys/inotify.h>
#include <unistd.h>
#include <limits.h>
#include <assert.h>

class FileWatchThreaded : public ThreadedMethod {
    int fd; 
    #define MAX_EVENTS 10 
    #define BUF_SIZE MAX_EVENTS*(sizeof(struct inotify_event) + NAME_MAX + 1)
    char eventBuf[BUF_SIZE] __attribute__ ((aligned(__alignof__(struct inotify_event)))); 

    std::map<std::string, int> pathFds; 

    virtual void *threadMain(void){
      while (int numRead = read(fd, eventBuf, BUF_SIZE)) {
        if (numRead == 0 | numRead == -1){
          printf("FileWatchThreaded::threadMain : read() from inotify fd returned %d !\n",numRead);
          Debug().evaluateError(numRead); // print strerror
          break;
        }
        for (char *p = (char*)eventBuf; p < eventBuf + numRead; p += sizeof(struct inotify_event) + reinterpret_cast<struct inotify_event *>(p)->len) {
          if (reinterpret_cast<struct inotify_event *>(p)->mask & IN_MODIFY)
            modified(reinterpret_cast<struct inotify_event *>(p)->name); // call the modified function
          if (reinterpret_cast<struct inotify_event *>(p)->mask & IN_CLOSE_WRITE)
            closeWrite(reinterpret_cast<struct inotify_event *>(p)->name); // call the modified function
            // Other unhandled events which can be added ...
            // IN_ACCESS, IN_ATTRIB, IN_CLOSE_NOWRITE, IN_CREATE, IN_DELETE, IN_DELETE_SELF,IN_IGNORED
            // IN_ISDIR, IN_MOVE_SELF, IN_MOVED_FROM, IN_MOVED_TO, IN_OPEN, IN_Q_OVERFLOW, IN_UNMOUNT
        }
      }
      return NULL;
    }

    virtual void modified(char *name){
    }

    virtual void closeWrite(char *name){
      // printf("FileWatchThreaded::close write\n");
    }
public:
  FileWatchThreaded(){
    fd = inotify_init();
    if (fd == -1){
        Debug().evaluateError(fd, " FileWatchThreaded : When calling inotify_init.");
        assert(0); // exit on failure
    }
  }

  virtual ~FileWatchThreaded(){
  }

  virtual int add(std::string path){
    int ret = inotify_add_watch(fd, path.c_str(), IN_ALL_EVENTS);
    if (ret == -1)
      return Debug().evaluateError(fd, " FileWatchThreaded : When calling inotify_add_watch.");
    pathFds[path]=ret; // store the path fd
    return 0;
  }

  virtual int addFile(std::string path){
    int ret=add(path);
    if (ret==ESRCH) { // file doesn't exist, attempt to create
      FILE *fid=fopen(path.c_str(), "a");
      if (fid==NULL) // check for failure
        ret=-EIO;
      else {
        fclose(fid);
        ret=add(path); // now try to add the file a second time
      }
    }
    return ret;
  }
};

#endif // FILEWATCHTHREAD_H_