Copy files in C language in Linux

In Linux, copy files in C language-general Linux technology-Linux programming and kernel information. The following is a detailed description. /*
Function: copy file from file1 to file2
How to execute:./copyfile file1 file2 (under Linux)
Data: 2007-05-09
*/

# Include /* Fprintf (), stderr, BUFSIZ */
# Include /**/
# Include /* Stderror ()*/
# Include /* Open (), flag */
# Include /* Errno */
# Include /* Ssize_t */
# Include
# Include /* Mode_t */

# Define BUFFER_SIZE 3

Int main (int argc, char ** argv)
{
Int from_fd, to_fd;
Int bytes_read, bytes_write;
Char buffer [BUFFER_SIZE];
Char * ptr;

If (argc! = 3)
{
Fprintf (stderr, "Usage: % s fromfile tofile \ n \ a", argv [0]);
Exit (1 );
}

/* Open the source file */
If (from_fd = open (argv [1], O_RDONLY) =-1)/* open file readonly, return-1 indicates an error; otherwise, return the file descriptor */
{
Fprintf (stderr, "Open % s Error: % s \ n", argv [1], strerror (errno ));
Exit (1 );
}

/* Create the target file */
/* The O_CREAT option is used to create a file. The open () function requires 3rd parameters,
Mode = S_IRUSR | S_IWUSR indicates S_IRUSR users can read S_IWUSR users can write */
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 );
}

/* The following code is a classic copy file code */
While (bytes_read = read (from_fd, buffer, BUFFER_SIZE ))
{
/* A fatal error occurred */
If (bytes_read =-1) & (errno! = EINTR ))
Break;
Else if (bytes_read> 0)
{
Ptr = buffer;
While (bytes_write = write (to_fd, ptr, bytes_read ))
{
/* A fatal error occurred */
If (bytes_write =-1) & (errno! = EINTR ))
Break;
/* All read bytes have been written */
Else if (bytes_write = bytes_read)
Break;
/* Write only a part and continue writing */
Else if (bytes_write> 0)
{
Ptr + = bytes_write;
Bytes_read-= bytes_write;
}
}
/* Fatal error during write */
If (bytes_write =-1)
Break;
}
}
Close (from_fd );
Close (to_fd );
Return;
}