进程间通信-信号-pipe-fifo

编译运行附件中的代码，提交运行结果截图
理解代码，特别是相关系统调用的使用。

1. testmf.c

#include  <stdio.h>
#include  <stdlib.h>
#include  <sys/types.h>
#include  <sys/stat.h>

int main()
{
	int res = mkfifo("/tmp/myfifo", 0777);
	if (res == 0) {
		printf("FIFO created \n");
	}
	exit(EXIT_SUCCESS);
}

2. consumer.c

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

#define FIFO_NAME "/tmp/myfifo"
#define BUFFER_SIZE PIPE_BUF


int main()
{
	int pipe_fd;
	int res;

	int open_mode = O_RDONLY;
	char buffer[BUFFER_SIZE + 1];
	int bytes = 0;

	memset(buffer, 0, sizeof(buffer));

	printf("Process %d opeining FIFO O_RDONLY \n", getpid());
	pipe_fd = open(FIFO_NAME, open_mode);
	printf("Process %d result %d\n", getpid(), pipe_fd);

	if (pipe_fd != -1) {
		do {
			res = read(pipe_fd, buffer, BUFFER_SIZE);
			bytes += res;
		} while (res > 0);
		close(pipe_fd);
	} else {
		exit(EXIT_FAILURE);
	}

	printf("Process %d finished, %d bytes read\n", getpid(), bytes);
	exit(EXIT_SUCCESS);
}

3. producer.c

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

#define FIFO_NAME "/tmp/myfifo"
#define BUFFER_SIZE PIPE_BUF
#define TEN_MEG (1024 * 1024 * 10)

int main()
{
	int pipe_fd;
	int res;
	int open_mode = O_WRONLY;

	int bytes = 0;
	char buffer[BUFFER_SIZE + 1];

	if (access(FIFO_NAME, F_OK) == -1) {
		res = mkfifo(FIFO_NAME, 0777);
		if (res != 0) {
			fprintf(stderr, "Could not create fifo %s \n",
				FIFO_NAME);
			exit(EXIT_FAILURE);
		}
	}

	printf("Process %d opening FIFO O_WRONLY\n", getpid());
	pipe_fd = open(FIFO_NAME, open_mode);
	printf("Process %d result %d\n", getpid(), pipe_fd);

	if (pipe_fd != -1) {
		while (bytes < TEN_MEG) {
			res = write(pipe_fd, buffer, BUFFER_SIZE);
			if (res == -1) {
				fprintf(stderr, "Write error on pipe\n");
				exit(EXIT_FAILURE);
			}
			bytes += res;
		}
		close(pipe_fd);
	} else {
		exit(EXIT_FAILURE);
	}

	printf("Process %d finish\n", getpid());
	exit(EXIT_SUCCESS);
}

4. listargs.c

#include<stdio.h>

main( int ac, char *av[] )
{
	int	i;

	printf("Number of args: %d, Args are:\n", ac);
	for(i=0;i<ac;i++)
		printf("args[%d] %s\n", i, av[i]);

	fprintf(stderr,"This message is sent to stderr.\n");
}

5. pipe.c

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

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

int main(int ac, char **av)
{
	int	thepipe[2],
		newfd,
		pid;

	if ( ac != 3 ){
		fprintf(stderr, "usage: pipe cmd1 cmd2\n");
		exit(1);
	}
	if ( pipe( thepipe ) == -1 )
		oops("Cannot get a pipe", 1);

	if ( (pid = fork()) == -1 )
		oops("Cannot fork", 2);

	if ( pid > 0 ){
		close(thepipe[1]);

		if ( dup2(thepipe[0], 0) == -1 )
			oops("could not redirect stdin",3);

		close(thepipe[0]);
		execlp( av[2], av[2], NULL);
		oops(av[2], 4);
	}

	close(thepipe[0]);

	if ( dup2(thepipe[1], 1) == -1 )
		oops("could not redirect stdout", 4);

	close(thepipe[1]);
	execlp( av[1], av[1], NULL);
	oops(av[1], 5);
}