5.7 File copy

1. Lab 4-1: File copy

• Experimental Purpose:

Familiar with Linux system IO programming

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• Experimental requirements:

1, according to the interface given by IO.h to implement the general IO operation interface

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2. The mycpy file Copy tool is completed using IO operation interface:

The file copy function is completed by redirection:./mycpy < Srcfile > Desfile

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• Experimental steps:

1. Experiment Code:

#include <sys/types.h>

#include <errno.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdlib.h>

#include <unistd.h>

#include <stdio.h>

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#define BUFFER_SIZE 1024

int main (int argc,char **argv)

{

int from_fd,to_fd;

int bytes_read,bytes_write;

Char Buffer[buffer_size];

Char *ptr;

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if (argc!=3) {

fprintf (stderr, "usage:%s fromfile tofile\n\a", argv[0]);

Exit (1);

}

/* Open source file */

if ((From_fd=open (argv[1],o_rdonly)) ==-1) {

fprintf (stderr, "Open%s error:%s\n", Argv[1],strerror (errno));

Exit (1);

}

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/* Create destination file */

if (To_fd=open (argv[2],o_wronly| o_creat,s_irusr| S_IWUSR)) ==-1) {

fprintf (stderr, "Open%s error:%s\n", Argv[2],strerror (errno));

Exit (1);

}

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/* The following code is the code of a classic copy file */

while (Bytes_read=read (from_fd,buffer,buffer_size)) {

if ((bytes_read==-1) && (ERRNO!=EINTR)) break; /* Read error occurred, exit Loop */

else if (bytes_read>0) {

Ptr=buffer;

while (Bytes_write=write (To_fd,ptr,bytes_read)) {

if ((bytes_write==-1) && (ERRNO!=EINTR)) break; /* If you write an error, exit the loop */

/* Write down all read bytes */

else if (bytes_write==bytes_read) break;/* Read and write section not equal to exit loop */

else if (bytes_write>0) {/* Write only a portion, continue writing */

Ptr+=bytes_write;

Bytes_read-=bytes_write;

}

}

if (bytes_write==-1) break; /* Fatal error occurred while writing */

}

}

Close (FROM_FD);

Close (TO_FD);

Exit (0);

}

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2. Compiling

3, before the operation:

[Email protected]:~/desktop#./copyfile main.c hello.c

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After execution:

Successful copy.

Experiment Experience:

???? This is the first experiment in the Linux file operation: A copy of the file is implemented in the lab's operating system. The above is the result of my experiment. The whole process was very smooth. Thank you.

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5.7 File copy