test10.c

华清远见应用培训班例程源码

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

///////////////////////////////////////////////////////////////////////////////
// definitions
///////////////////////////////////////////////////////////////////////////////
#define BUFFER_SIZE	1024

///////////////////////////////////////////////////////////////////////////////
// global variables
///////////////////////////////////////////////////////////////////////////////
int global_pipe_fds[2];
char *global_send_buffer = "some data write to parent.";
char global_read_buffer[BUFFER_SIZE];

///////////////////////////////////////////////////////////////////////////////
// function prototypes
///////////////////////////////////////////////////////////////////////////////
static void cleanup(void);
void parent_process_main(void);
void child_process_main(void);

///////////////////////////////////////////////////////////////////////////////
// functions
///////////////////////////////////////////////////////////////////////////////
int main(int argc, char **argv)
{
  pid_t pid;

  // int pipe(int filedes[2]);
  if (pipe(global_pipe_fds) < 0)
  {
    // FIXME: deal with this error.
    fprintf(stderr, "ERROR: call pipe() failed: %s\n", strerror(errno));
    exit(1);
  }

#ifdef _DEBUG_
  fprintf(stdout, "DEBUG: Create pipe successed, fds[0] = %d, fds[1] = %d\n", global_pipe_fds[0], global_pipe_fds[1]);
#endif

  if ((pid = fork()) < 0)
  {
    fprintf(stderr, "ERROR: call fork() failed: %s\n", strerror(errno));
    cleanup();

    // FIXME: deal with this error.
    exit(1);
  }

  if (pid > 0)
  {
    // XXX: Parent process
    close(global_pipe_fds[1]);
    parent_process_main();
    close(global_pipe_fds[0]);
  }
  else
  {
    // XXX: Child process
    close(global_pipe_fds[0]);
    sleep(1);
    child_process_main();
    close(global_pipe_fds[1]);

    exit(0);
  }

  return 0;
}

void child_process_main(void)
{
  // ssize_t write(int fildes, const void *buf, size_t nbyte);
  ssize_t written;

  if ((written = write(global_pipe_fds[1], global_send_buffer, strlen(global_send_buffer))) < 0)
  {
    fprintf(stderr, "[%d]Child write to pipe failed: %s\n", getpid(), strerror(errno));
    // FIXME: deal with this error.
    exit(1);
  }

#ifdef _DEBUG_
  fprintf(stdout, "[%d] Child write %d bytes to pipe.\n", getpid(), written);
#endif

  if (written < strlen(global_send_buffer))
  {
    // TODO: we should write rest data to pipe, may be we need a loop
  }
}

void parent_process_main(void)
{
  ssize_t n;

  memset(global_read_buffer, 0, BUFFER_SIZE);
  // ssize_t read(int fildes, void *buf, size_t nbyte);
  if ((n = read(global_pipe_fds[0], global_read_buffer, BUFFER_SIZE)) < 0)
  {
    // TODO: deal with read return value and error
  }

  fprintf(stdout, "[%d]Parent read %d bytes from pipe: %s\n", getpid(), n, global_read_buffer);

  // TODO: we should read rest data from pipe, may be we need a loop
}

static void cleanup(void)
{
  close(global_pipe_fds[0]);
  close(global_pipe_fds[1]);
}