两种方式(系统调用、映射)实现文件的创建、移动、合并
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
void traditional();
void write_xiaohei();
void copy_toheidan();
void mergertoheihei();
void mapping();
int main(void)
{
traditional();
mapping();
return 0;
}
void mapping()
{
write_xiaohei();
copy_toheidan();
mergertoheihei();
}
void traditional()
{
printf("*****************create a file named xiaohei\n");
int fw;
char ch[20];
fw=open("xiaohei",O_WRONLY|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create error");
exit(1);
}
sprintf(ch,"hello,world!");
write(fw,ch,strlen(ch));
close(fw);
printf("*****************copy the content from xiaohei to heidan\n");
int fr,len;
fr=open("xiaohei",O_RDONLY);
if(fr<0){
perror("open xiaohei error");
exit(1);
}
fw=open("heidan",O_WRONLY|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create heidan error");
exit(1);
}
while((len=read(fr,ch,5))>0)
{
write(fw,ch,len);
}
close(fr);
close(fr);
printf("*****************merger xiaohei and heidan into heihei\n");
int fd;
fd=open("xiaohei",O_RDONLY);
if(fd<0){
perror("open xiaohei error");
exit(1);
}
fr=open("heidan",O_RDONLY);
if(fr<0){
perror("open heidan error");
exit(1);
}
fw=open("heihei",O_WRONLY|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create heihei error");
exit(1);
}
while((len=read(fr,ch,5))>0)
{
write(fw,ch,len);
}
while((len=read(fd,ch,5))>0)
{
write(fw,ch,len);
}
close(fd);
close(fr);
close(fw);
}
void write_xiaohei()
{
printf("*****************create a file named xiaohei\n");
int fw,size,*p;
char data[20]="hello world!";
fw=open("xiaohei",O_RDWR|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create xiaohei error");
exit(1);
}
size=strlen(data);
write(fw,data,size);
p=mmap(NULL,size,PROT_WRITE|PROT_READ,MAP_SHARED,fw,0);
if(p==MAP_FAILED){
perror("error");
exit(1);
}
close(fw);
munmap(p,size);
}
void copy_toheidan()
{
printf("*****************copy the content from xiaohei to heidan\n");
int fr,size,*p,fw,*q;
fr=open("xiaohei",O_RDONLY);
if(fr<0){
perror("create xiaohei error");
exit(1);
}
fw=open("heidan",O_RDWR|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create heidan error");
exit(1);
size=lseek(fr,0,SEEK_END);
p=mmap(NULL,size,PROT_READ,MAP_PRIVATE,fr,0);
if(p==MAP_FAILED){
perror("error");
exit(1);
}
lseek(fw,size-1,SEEK_END);
write(fw," ",1);
q=mmap(NULL,size,PROT_WRITE|PROT_READ,MAP_SHARED,fw,0);
//without the use of MAP_PRIVATE in here
if(q==MAP_FAILED){
perror("error");
exit(1);
}
close(fr);
close(fw);
memcpy(q,p,size);
munmap(p,size);
munmap(q,size);
}
void mergertoheihei()
{
printf("*****************merger xiaohei and heidan into heihei\n");
int fr,size=0,fw,fd,i,len,filenum;
char *p,*q,*m;
char *filename[2]={"xiaohei","heidan"};
filenum=sizeof(filename)/sizeof(filename[0]);
for(i=0;i<filenum;i++)
{
fr=open(filename[i],O_RDONLY);
if(fr<0){
perror("create error");
exit(1);
}
size+=lseek(fr,0,SEEK_END);
}
fw=open("heihei",O_RDWR|O_CREAT|O_TRUNC,0644);
if(fw<0){
perror("create heihei error");
exit(1);
}
lseek(fw,size-1,SEEK_END);
write(fw," ",1);
q=mmap(NULL,size,PROT_WRITE|PROT_READ,MAP_SHARED,fw,0);
//without the use of MAP_PRIVATE in here
if(q==MAP_FAILED){
perror("error");
exit(1);
}
for(i=0;i<filenum;i++)
{
fr=open(filename[i],O_RDONLY);
if(fr<0){
perror("create error");
exit(1);
}
len=lseek(fr,0,SEEK_END);
p=mmap(NULL,len,PROT_READ,MAP_PRIVATE,fr,0);
if(p==MAP_FAILED){
perror("error");
exit(1);
}
close(fr);
memcpy(q,p,size);
q+=len;
munmap(p,len);
}
close(fw);
munmap(q,size);
}