_pipe.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 89 行

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <fcntl.h>
#include <io.h>
#include <process.h>

static int handles[2] = { 0, 0 };
static int pid;

void create_pipe()
{
    if( _pipe( (int *)&handles, 2048, _O_BINARY ) == -1 ) {
        perror( "create_pipe" );
        exit( EXIT_FAILURE );
    }
}

void create_child( char *name )
{
    char buff[10];

    itoa( handles[0], buff, 10 );
    pid = spawnl( P_NOWAIT, name,
                  "_pipe", buff, NULL );
    close( handles[0] );
    if( pid == -1 ) {
        perror( "create_child" );
        close( handles[1] );
        exit( EXIT_FAILURE );
    }
}

void fill_pipe()
{
    int i;
    int rc;

    for( i = 1; i <= 10; i++ ) {
        printf( "Child, what is 5 times %d\n", i );
        rc = write( handles[1], &i, sizeof( int ) );
        if( rc < sizeof( int ) ) {
            perror( "fill_pipe" );
            close( handles[1] );
            exit( EXIT_FAILURE );
        }
    }
    /* indicate that we are done */
    i = -1;
    write( handles[1], &i, sizeof( int ) );
    close( handles[1] );
}

void empty_pipe( int in_pipe )
{
    int i;
    int amt;

    for(;;) {
        amt = read( in_pipe, &i, sizeof( int ) );
        if( amt != sizeof( int ) || i == -1 )
            break;
        printf( "Parent, 5 times %d is %d\n", i, 5*i );
    }
    if( amt == -1 ) {
        perror( "empty_pipe" );
        exit( EXIT_FAILURE );
    }
    close( in_pipe );
}

void main( int argc, char *argv[] )
{
#if defined( __NT__ )
    _fileinfo = 1;
#endif

    if( argc <= 1 ) {
        /* we are the spawning process */
        create_pipe();
        create_child( argv[0] );
        fill_pipe();
    } else {
        /* we are the spawned process */
        empty_pipe( atoi( argv[1] ) );
    }
    exit( EXIT_SUCCESS );
}