Thread: pipe

Please post the code on this site, not some link.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>


main(int argc, char* argv[])
{
  int fds[2], pid, i, fd;
  char *pipeBuffer;
  fd = open(argv[1], O_RDWR | O_APPEND);

  if(argc != 2)
  {
    printf("Usage: my_program <filname of textfile>\n");
    exit(0);
  }

  //create a pipe
  if(pipe(fds) == -1)
  {
    perror("pipe");
    exit(EXIT_FAILURE);
  }

  //create a fork
  if((pid = fork()) == -1) 
  {
    perror("fork");
    exit(EXIT_FAILURE);
  }


  if(pid == 0) 
  {
    close(fds[1]); 


    int letterCounter = 0;
    int counter = 0;
    printf("\n");


    //read letters from the pipe
    while(read(fds[0], &pipeBuffer[counter], 1) > 0)
    {
      if(isalpha(pipeBuffer[counter]))
      {
        letterCounter++;
      }


      counter++;
    }


    //write number of letters to end of file
    char tmp[1]={0x0};
    sprintf(tmp,"%d", letterCounter);
    write(fd, tmp, strlen(tmp));


    printf("Letters: %d\n\n", letterCounter);


    close(fd);
    close(fds[0]);
    _exit(EXIT_SUCCESS);
  }
  else 
  {
    close(fds[0]); 


    int c;
    FILE *fdx, *fdy;
    fdx = fdopen(fd, "r");
    fdy = fdopen(fds[1], "w");


    while((c = fgetc(fdx)) != EOF)
    {
      printf("%c", c);
      fputc(c, fdy);
    }


    printf("\n\n");


    fclose(fdx);
    fclose(fdy);


    close(fds[1]); 
    wait(NULL);
    exit(EXIT_SUCCESS);
  }
}