Btukfyl

I make sort program.

     +--------------+                +--------------+

stdin   >0      >== pipe to sort ====>      |

     |   in_out     |        |             sort     |

stdout  <1      <== pipe from sort ==<      |

     +--------------+                +--------------+

my idea is like that. i did not work well....
i don't know where is problem. i think i do well pipe and redirection.
i can't find my mistakes.

first, i get two pipes.
sencend, fork(input_output and sort)
connected stdin and out to pipes then execl sort
get string and send sort and sorting then return and prnit.
then close pipe and sort dies.

 #include   <stdio.h>

    #include    <unistd.h>

    #include    <stdlib.h>

    #include    <sys/types.h>

    #include    <sys/stat.h>

    #include    <sys/wait.h>

    #include    <string.h>

    #include    <fcntl.h>





    #define oops(m,x)   { perror(m); exit(x); }



    void be_sort(int in[2], int out[2]);

    void in_out(int todc[2], int fromdc[2]);

    void fatal(char mess);



    int main()

    {

        int pid, tosort[2], fromsort[2];    /*equipment */



        /* make two pipes */

        if( pipe(tosort) == -1 || pipe(fromsort) == -1 )

            oops("pipe failed", 1);



        /* get a process for user interface */

        if(( pid = fork()) == -1 )

            oops("cannot fork", 2);

        if( pid == 0 )              /* child is sort    */

            be_sort(tosort, fromsort);

        else {

            in_out(tosort, fromsort);       /* parent is ui */

            wait(NULL);         /* wait for child */

        }

        return 0;



    }



    void be_sort(int in[2], int out[2])

    /*

     *  set up stdin and stdout, then execl sort

     */

    {

        /* setuup stdin from pipein */

        if( dup2(in[0], 0) == -1 )  /* copy read end to 0   */

            oops("sort: cannot redirect stdin", 3);

        close(in[0]);           /* moved to fd 0    */

        close(in[1]);           /* won't write here */



        /* setup stdout to pipeout */

        if( dup2(out[1], 1) == -1)  /* dupe write end to 1  */

            oops("sort: cannot redirect stdout", 4);

        close(out[1]);          /* moved to fd 1    */

        close(out[0]);          /* won't read from here */



        /* now execl sort with the - option */

        execlp("sort", "sort", (char *)NULL);

        oops("Cannot run sort", 5);

    }



    void in_out( int tosort[2], int fromsort[2])

    {

        char    operation[BUFSIZ], message[BUFSIZ], *fgets();

        FILE    *fpout, *fpin, *fdopen();



        /* setup */

        close(tosort[0]);           /* won't read from pipe to sort */

        close(fromsort[1]);     /* won't write to pipe from sort*/



        fpout = fdopen( tosort[1], "w" );   /* convert file descriptors to stream */

        fpin  = fdopen( fromsort[0], "r" );



        if( fpout == NULL || fpin == NULL )

            fatal("Error converting pipes to streams");



        /* main loop */

        while( fgets(message, BUFSIZ, stdin) != NULL ) 

        {

            message[strlen(message)-1]=NULL;

            printf("%s ,%ldn",message,strlen(message));



            if (fprintf(fpout, "%s", *message) == EOF)

                fatal("writing");



            fflush( fpout );



            if (fgets(operation, BUFSIZ, fpin) == NULL)

                break;

            printf("%s", operation); // stdout

        }

        fclose(fpout);  /* close pipe       */

        fclose(fpin);   /* sort will see EOF    */

    }

    void fatal( char mess )

    {

        fprintf(stderr, "Error: %sn", mess);

        exit(1);

    }