#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <wait.h>
 
#define IFERROR(s,m) if((s)==-1) {perror(m); exit(errno);}
 
int flog;
char buffer[40]="esecuzione terminata con successo\n";
void cHandler(int);
 
void cercafile(char *ext)
{
 DIR * dir;
 struct dirent *file;
 char new_ext[100], buf_son[200];
 int lung, ll, count;
 
 sprintf(new_ext,".%s",ext);
 lung = strlen(new_ext);
 count = 0;
 
 dir = opendir(".");
 while((file = readdir(dir))!= NULL) {
     if((strcmp(file->d_name,".")!=0) && (strcmp(file->d_name,"..")!=0)) {
        ll = strlen(file->d_name)-lung;
        if(strcmp((file->d_name)+ll,new_ext)==0) count++;
     }
 }
 closedir(dir);
 sprintf(buf_son,"file con estensione %s: %d\n",ext,count);
 IFERROR(write(flog,buf_son,strlen(buf_son)),"write finale");
 
}                                           
 
int main(int argc, char *argv[])
{
 int i, pid, status;
 
    if(argc<3) {
        printf("Uso: report  dir  ext1 ext2 ... extn\n");
        exit(0);
    }
 
  signal(SIGINT, cHandler);
 
  IFERROR(flog = open("log", O_WRONLY|O_CREAT|O_TRUNC, 0644),"aprendo report");
  chdir(argv[1]);
 
  for(i=2 ; i< argc ; i++) {
      pid = fork();
      if(pid==0){
        signal(SIGINT,SIG_IGN);
        cercafile(argv[i]);
        exit(0);
      }
  }
 
  for(i=2 ; i< argc ; i++) {
      wait(&status);
  }
 
  IFERROR(write(flog,buffer,strlen(buffer)),"write finale");
  IFERROR(close(flog),"chiudendo report");
  return(0);
}
 
void cHandler(int id_segnale)
{
  sprintf(buffer,"esecuzione terminata con Control-c\n");
  IFERROR(write(flog,buffer,strlen(buffer)),"write da signal");
  kill(0,SIGKILL);
  exit(0);
}