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COPY2.C
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─────Run-Time Library───────────────────────────────────────────────────────
/* COPY2.C illustrates DOS file I/O and DOS memory allocation functions
* including: (DOS-only)
* _dos_open _dos_close _dos_creatnew _dos_creat
* _dos_read _dos_write _dos_allocmem _dos_free
*
* See COPY1.C for another version of the copyfile function.
*/
#include <dos.h>
#include <fcntl.h>
#include <conio.h>
#include <stdio.h>
int copyfile( char *source, char *destin ); /* Prototype */
void main( int argc, char *argv[] )
{
if( argc == 3 )
if( copyfile( argv[1], argv[2] ) )
printf( "Copy failed\n" );
else
printf( "Copy successful\n" );
else
printf( " SYNTAX: COPY2 <source> <target>\n" );
}
/* Copies one file to another (both specified by path). Dynamically
* allocates memory for the file buffer. Prompts before overwriting
* existing file. Returns 0 if successful, or an error number if
* unsuccessful. This function uses _dos_ functions only; standard
* C functions are not used.
*/
#define EXIST 80
enum ATTRIB { NORMAL, RDONLY, HIDDEN, SYSTEM = 4 };
int copyfile( char *source, char *target )
{
char __far *buf = NULL;
char prompt[] = "Target exists. Overwrite? ", newline[] = "\n\r";
int hsource, htarget, ch;
unsigned ret, segbuf, count;
/* Attempt to dynamically allocate all of memory (0xffff paragraphs).
* This will fail, but will return the amount actually available
* in segbuf. Then allocate this amount.
*/
_dos_allocmem( 0xffff, &segbuf );
count = segbuf;
if( ret = _dos_allocmem( count, &segbuf ) )
return ret;
_FP_SEG( buf ) = segbuf;
/* Open source file and create target, overwriting if necessary. */
if( ret = _dos_open( source, _O_RDONLY, &hsource ) )
return ret;
ret = _dos_creatnew( target, NORMAL, &htarget );
if( ret == EXIST )
{
/* Use _dos_write to display prompts. Use _bdos to call
* function 1 to get and echo keystroke.
*/
_dos_write( 1, prompt, sizeof( prompt ) - 1, &ch );
ch = _bdos( 1, 0, 0 ) & 0x00ff;
if( (ch == 'y') || (ch == 'Y') )
ret = _dos_creat( target, NORMAL, &htarget );
_dos_write( 1, newline, sizeof( newline ) - 1, &ch );
}
if( ret )
return ret;
/* Read and write until there is nothing left. */
while( count )
{
/* Read and write input. */
if( (ret = _dos_read( hsource, buf, count, &count )) )
return ret;
if( (ret = _dos_write( htarget, buf, count, &count )) )
return ret;
}
/* Close files and free memory. */
_dos_close( hsource );
_dos_close( htarget );
_dos_freemem( segbuf );
return 0;
}
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