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/*
* $Id: ntstream.c,v 1.1 2003/01/25 15:10:03 andrew_belov Exp $
* ---------------------------------------------------------------------------
* A convenient interface to the NT backup stream functions (Backup*)
*
*/
#include "arj.h"
DEBUGHDR(__FILE__) /* Debug information block */
#define W32_SID_HEADER_SIZE 20
#if TARGET==WIN32
/* Open a file for stream operation */
struct nt_sid *open_streams(char *name, int is_write)
{
struct nt_sid *rc;
if((rc=(struct nt_sid *)malloc(sizeof(struct nt_sid)))==NULL)
return(NULL);
if((rc->hf=CreateFile(name, is_write?GENERIC_WRITE:GENERIC_READ,
FILE_SHARE_READ|FILE_SHARE_WRITE, NULL,
OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS,
0))==INVALID_HANDLE_VALUE)
{
free(rc);
return(NULL);
}
rc->is_write=is_write;
rc->lpcontext=NULL;
rc->rem.LowPart=rc->rem.HighPart=0;
return(rc);
}
/* Finalize a backup operation before closing the stream */
static void finalize_backup(struct nt_sid *sid)
{
DWORD dummy;
if(sid->lpcontext!=NULL)
{
if(sid->is_write)
BackupWrite(sid->hf, NULL, 0, &dummy, TRUE, FALSE, &sid->lpcontext);
#if SFX_LEVEL>=ARJ
else
BackupRead(sid->hf, NULL, 0, &dummy, TRUE, FALSE, &sid->lpcontext);
#endif
sid->lpcontext=NULL;
}
}
/* Close a stream operations handle */
void close_streams(struct nt_sid *sid)
{
finalize_backup(sid);
CloseHandle(sid->hf);
}
/* Skip to the next stream */
int next_stream(WIN32_STREAM_ID *dest, struct nt_sid *sid)
{
DWORD lo, hi, b;
if(sid->is_write)
return(-1);
if(sid->rem.LowPart!=0||sid->rem.HighPart!=0)
{
if(!BackupSeek(sid->hf, sid->rem.LowPart, sid->rem.HighPart, &lo, &hi, &sid->lpcontext))
return(-1);
if(lo!=sid->rem.LowPart||hi!=sid->rem.HighPart)
return(-1);
sid->rem.LowPart=sid->rem.HighPart=0;
}
if(!BackupRead(sid->hf, (unsigned char *)dest, W32_SID_HEADER_SIZE, &b, FALSE, TRUE, &sid->lpcontext))
return(-1);
if(b!=W32_SID_HEADER_SIZE)
return(-1);
sid->rem=dest->Size;
return(0);
}
/* Looks for a specific stream ID. Returns stream size. */
unsigned long seek_stream_id(DWORD id, struct nt_sid *sid)
{
int tampered;
WIN32_STREAM_ID winsid;
/* Perform 1st iteration for "virgin" streams (that haven't yet been operated
with). Redo the lookup in a second operation if the streams were in use. */
tampered=(sid->lpcontext!=NULL)?1:0;
do
{
while(!next_stream(&winsid, sid))
{
if(winsid.dwStreamId==id)
return((winsid.Size.HighPart>0)?0xFFFFFFFF:winsid.Size.LowPart);
}
finalize_backup(sid);
} while(tampered--);
return(0);
}
#if SFX_LEVEL>=ARJ
/* Read from a stream */
unsigned long read_stream(unsigned char *dest, unsigned long bytes, struct nt_sid *sid)
{
unsigned long br, rc;
if(sid->is_write)
return(0);
br=(sid->rem.HighPart==0&&sid->rem.LowPart<bytes)?sid->rem.LowPart:bytes;
if(br==0)
return(0);
if(!BackupRead(sid->hf, dest, br, &rc, FALSE, TRUE, &sid->lpcontext))
return(0);
sid->rem=LargeIntegerSubtract(sid->rem, ConvertUlongToLargeInteger(rc));
return(rc);
}
#endif
/* Initialize a new stream before writing */
int create_stream(WIN32_STREAM_ID *src, struct nt_sid *sid)
{
DWORD lo, hi, b;
if(!sid->is_write)
return(-1);
if(sid->rem.LowPart!=0&&sid->rem.HighPart!=0)
{
if(!BackupSeek(sid->hf, sid->rem.LowPart, sid->rem.HighPart, &lo, &hi, &sid->lpcontext))
return(-1);
if(lo!=sid->rem.LowPart||hi!=sid->rem.HighPart)
return(-1);
sid->rem.LowPart=sid->rem.HighPart=0;
}
if(!BackupWrite(sid->hf, (unsigned char *)src, W32_SID_HEADER_SIZE, &b, FALSE, TRUE, &sid->lpcontext))
return(-1);
if(b!=W32_SID_HEADER_SIZE)
return(-1);
sid->rem=src->Size;
return(0);
}
/* Write to a stream */
unsigned long write_stream(unsigned char *src, unsigned long bytes, struct nt_sid *sid)
{
unsigned long bw, rc;
if(!sid->is_write)
return(0);
/* This is crucial to prevent overflow */
bw=(sid->rem.HighPart==0&&sid->rem.LowPart<bytes)?sid->rem.LowPart:bytes;
if(bw==0)
return(0);
if(!BackupWrite(sid->hf, src, bw, &rc, FALSE, TRUE, &sid->lpcontext))
return(0);
sid->rem=LargeIntegerSubtract(sid->rem, ConvertUlongToLargeInteger(rc));
return(rc);
}
#endif
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