need a little help for my assignment

[neversell]

here is my code:
/* ===== Part1Main.c ===== */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include "SharedDisk.h"
#include "FDisk.h"

int main()
{
Disk *theDisk;
char buffer;

if ( DiskOpen( theDisk ) == 0 )
{
printf( "Open file failed.\n" );
exit( 0 );
}
else
{
printf( "Open file successful.\n" );
fflush( stdout );
}
DumpSector ( buffer );
DiskClose( theDisk );
return 0;
}

/* ===== FDisk.c ===== */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include "SharedDisk.h"
#include "FDisk.h"


int DiskOpen( Disk *theDisk )
{
int i, j;
int fd;
int len;
char buffer[SIZE];

fd = open ("disk.img", O_RDONLY );

len = read ( fd, buffer, 512 );
if ( len == -1 )
{
printf("Unable to read file.\n");
}
printf( "%c\n", buffer[ 3 ] );

return fd;
}


void DiskClose( Disk *theDisk )
{
int fd;

close( fd );
}


void DumpSector ( unsigned char *buffer )
{
int i, j;


for( i = 0; i < SIZE; i += UPPERSIZE )
{
printf( "0x%04x : ", i );
for( j = i; j <= i + UPPERSIZE; j++ )
{
printf( "%02x ", buffer[ j ] );
fflush( stdout );
}
printf( "\t" );

for( j = i; j <= i + UPPERSIZE; j++ )
{
if ( isprint( buffer[ j ] ) )
printf( "%c", buffer[ j ] );
else
printf( ".");
fflush( stdout );
}
printf("\n");
}
}


/* ===== FDisk.h ===== */

#ifndef __FDISk__
#define __FDISK__

#define SIZE 512
#define UPPERSIZE 15

#include "SharedDisk.h"

int DiskOpen( Disk *theDisk );

void DiskClose( Disk *theDisk );

void DumpSector( unsigned char *buffer );

#endif

/* ===== SharedDisk.h ===== */

#ifndef __SHAREDISK__
#define __SHAREDISK__


typedef struct
{
char *Jump;
char *Manufacturer;
char *BytesPerSector;
char *SectorsPerCluster;
char *ReservedSectors;
char *FATs;
char *RootDirectoryEntries;
char *LogicalSectors;
char *MediaDescriptorByte;
char *SectorsPerFAT;
char *SectorsPerTrack;
char *Surfaces;
char *HiddenSectors;
} Disk;

#endif

i am new to c. so i donot really know.

my question is how do i pass buffer in DiskOpen to DumpSector ( unsigned char *buffer )?

how do i initialize members of Disk

how do i close file?
i do not know how to pass fd in DiskOpen to DiskClose.

thx for ur help

[shaik786]

>my question is how do i pass buffer in DiskOpen to DumpSector ( unsigned char *buffer )?

DumpSector(&buffer);

Since, DumpSector() expects a pointer to a variable and not the value itself.

>how do i initialize members of Disk
Disk is not an instance, it's a datatype. You need to initialize it's Instance. 'theDisk' is a pointer to a type Disk, you need to allocate memory to this before you can use this, so:

theDisk = malloc(sizeof(Disk));
if(theDisk == NULL) {
        perror(" malloc");
        exit(-1);
}

To allocate memory to it's members:

theDisk->Jump         = malloc(20);
if(theDisk->Jump == NULL) {
        perror(" malloc");
        exit(-1);
}
theDisk->Manufacturer = malloc(20);
if(theDisk->Manufacturer == NULL) {
        perror(" malloc");
        exit(-1);
}
/* ... */

strcpy(theDisk->Jump,         "Here");
strcpy(theDisk->Manufacturer, "ABC");

printf(" %s %s\n",  theDisk->Jump, theDisk->Manufacturer);

free(theDisk->Jump);
free(theDisk->Manufacturer);
free(theDisk);

>how do i close file?
How did you open it? If you opened the file with fopen(), use fclose() and if you opened with open(), use close() to close the file.

>i do not know how to pass fd in DiskOpen to DiskClose.
Add another parameter to the function DiskClose()

DiskClose(Disk *theDisk, int fd)

and from DiskOpen()

DiskOpen(theDisk, fd);

Also, check your code for error trapping, you haven't done any:

fd = open ("disk.img", O_RDONLY );
if(fd == -1) {
         perror(" open");
         exit(-1);
}

You haven't initialised 'buffer'

[neversell]

thx for the help