mcopy.c

该代码为unix环境高级编程的源代码

#include	<sys/types.h>
#include	<sys/stat.h>
#include	<sys/mman.h>	/* mmap() */
#include	<fcntl.h>
#include	"ourhdr.h"

#ifndef	MAP_FILE	/* 44BSD defines this & requires it to mmap files */
#define	MAP_FILE	0	/* to compile under systems other than 44BSD */
#endif

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

	if (argc != 3)
		err_quit("usage: a.out <fromfile> <tofile>");

	if ( (fdin = open(argv[1], O_RDONLY)) < 0)
		err_sys("can't open %s for reading", argv[1]);

	if ( (fdout = open(argv[2], O_RDWR | O_CREAT | O_TRUNC,
												FILE_MODE)) < 0)
		err_sys("can't creat %s for writing", argv[1]);

	if (fstat(fdin, &statbuf) < 0)	/* need size of input file */
		err_sys("fstat error");

			/* set size of output file */
	if (lseek(fdout, statbuf.st_size - 1, SEEK_SET) == -1)
		err_sys("lseek error");
	if (write(fdout, "", 1) != 1)
		err_sys("write error");

	if ( (src = mmap(0, statbuf.st_size, PROT_READ,
					 MAP_FILE | MAP_SHARED, fdin, 0)) == (caddr_t) -1)
		err_sys("mmap error for input");

	if ( (dst = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE,
					 MAP_FILE | MAP_SHARED, fdout, 0)) == (caddr_t) -1)
		err_sys("mmap error for output");

	memcpy(dst, src, statbuf.st_size);	/* does the file copy */

	exit(0);
}