使用inotify向文件添加一段注释

一 需求简介：

在ubuntu系统上任意打开一个文件（vim，touch获取其它方式），该新建的文件都会被写入一段注释。

二 实现：

编译环境：ubuntu 18.04

实现方法：利用inotify监控目录这个特性，当在一个目录里新建文件时，可以read事件，从而获取文件名，然后调用c++ ofstream写入注释。

运行效果：

实现代码：

#include <stdio.h>  
#include <string.h>  
#include <stdlib.h>  
#include <sys/inotify.h>  
#include <unistd.h>  
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
static const int FILE_IN_CREATE_MASK = 256; 
static const char *COMMIT_STR = "/* \n\
 *@auth:hello world\n \
*@file:hello world\n \
*@license:hello world\n \
*@change story:hello world\n \
*------------------------------------\n\
*/";
const char *monitor_path = nullptr;
inline void write_commit(struct inotify_event *event) {
  if (FILE_IN_CREATE_MASK == event->mask) {
    if (event->len > 0 && !(event->mask & IN_ISDIR)) {
      char path[128] = "";
      const char *filename = event->name;
      snprintf(path, sizeof(path), "%s%s", monitor_path, filename);
      ofstream ofs(path);
      if (!ofs) {
        cerr << path << " can not be open...!" << endl;
        return;
      }
      ofs << COMMIT_STR << endl;
      ofs.close();
    }
  }
}
int main(int argc, char **argv) {
  char buf[BUFSIZ] = "";
  int len = 0;
  int nread = 0;
  struct inotify_event *event = nullptr;
  if (argc < 2) {
    fprintf(stderr, "%s path\n", argv[0]);
    return -1;

  }
  int fd = inotify_init();
  if (fd < 0) {
    fprintf(stderr, "inotify_init failed\n");
    return -1;
  }
  monitor_path = argv[1];
  int wd = inotify_add_watch(fd, monitor_path, IN_CREATE);
  if (wd < 0) {
    fprintf(stderr, "inotify_add_watch %s failed\n", argv[1]);
    return -1;
  }
  int n = sizeof(buf) - 1;
  while ((len = read(fd, buf, n)) > 0) {
    nread = 0;
    while (len > 0) {
      event = (struct inotify_event *)&buf[nread];
      write_commit(event);
      nread = nread + sizeof(struct inotify_event) + event->len;
      len = len - sizeof(struct inotify_event) - event->len;
    }
  }
 
  return 0;
}

编译脚本：

g++ -std=c++17 -g -o Test main.cpp

注：不支持递归目录