mmcat.c

基于网络编程的例子

/*
 * mmcat.c - Implement the cat command using memory maps
 */
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>

void err_quit(char *msg);

int main(int argc, char *argv[])
{
	int fdin;
	char *src;
	struct stat statbuf;
	off_t len;

	/* make sure we were called properly */
	if(argc != 2) {
		fprintf(stderr, "usage: mmcat {file}\n");
		exit(EXIT_FAILURE);
	}
	
	/* open the input file and stdout */
	if((fdin = open(argv[1], O_RDONLY)) < 0) {
		err_quit("open");
	}

	/* need the size of the input file for mmap call */
	if((fstat(fdin, &statbuf)) < 0) {
		err_quit("fstat");
	}
	len = statbuf.st_size;

	/* map the input file */
	if((src = mmap(0, len, PROT_READ, MAP_SHARED, fdin, 0)) == (void *)-1) { 
		err_quit("mmap");
	}

	/* write it out */
	printf("%s", src);

	/* clean up */
	close(fdin);
	munmap(src, len);

	exit(EXIT_SUCCESS);
}

void err_quit(char *msg) 
{
	perror(msg);
	exit(EXIT_FAILURE);
}