linux存储映射mmap()实现文件复制
学习APUE，书里有个例程是利用linux存储映射I/O复制一个文件（类似于cp命令）
#include "apue.h"
#include <fcntl.h>
#include <sys/mman.h>
int main(int argc,char *argv[])
{
int fdin,fdout;
void *src,*dst;
struct stat statbuf;
if(argc != 3)
err_quit("usage: %s <fromfile> <tofile>",argv[0]);
if((fdin = open(argv[1],O_RDONLY)) <0)
err_sys("can't open %s",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[2]);
if(fstat(fdin,&statbuf) < 0)
err_sys("write 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_SHARED,fdin,0)) == MAP_FAILED)
err_sys("mmap error for input");
if((dst = mmap(0,statbuf.st_size,PROT_READ | PROT_WRITE,MAP_SHARED,fdout,0)) ==MAP_FAILED)
err_sys("mmap error for output");
memcpy(dst,src,statbuf.st_size);
return 0;
}
