copying file to Stream

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Correct me if im wrong. As per Structured Storage, Storage corresponds to Directory/folder and Stream corresponds to file.
Now Using Structured Storage concept, I have created a storage using StgCreateDocfile() with .stg extension. I have created a Stream inside it using IStream->CreateStream().
I want add my Hard disk file eg. Abstract.doc to this stream of created Storage(.stg). How can I do that??

I tried it using IStream::Write method

C++

HRESULT Write( 
  void const* pv, 
  ULONG cb,
  ULONG* pcbWritten 
);

can pointer pv be the direct pointer to my hard disk file eg. here abstract.doc instead of Buffer?

Thanking you in advance....

Posted 16-Mar-11 10:24am

MartinTaylor

Updated 16-Mar-11 11:20am

Henry Minute

v3

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Ozer Karaagac · Accepted Answer · 2011-03-16T11:31:00

Solution 1

Yes you are right. You can consider like that.
You need to read your file content into a buffer (partially or as a whole). Then you call IStream::Write().

#define BUFFERSIZE 4096  // (edit)

unsigned char * pBuffer = new unsigned char [BUFFERSIZE];

HANDLE hFile = CreateFile(pszFileName, ...);

// you can determine file size and set initially
// pStream->SetSize(...)

DWORD dwRead = 0;
ULONG ulWritten = 0;
do
{
    if(!ReadFile(hFile, pBuffer, BUFFERSIZE, &dwRead, NULL))
        break;

    if(0 == dwRead) // means EOF
        break;

    pStream->Write(pBuffer, dwRead, &ulWritten);

    // you can also check (ulWritten == dwRead) just to make sure

} while(BUFFERSIZE == dwRead);    // be careful (edit)

CloseFile(hFile);

delete [] pBuffer;

Posted 16-Mar-11 11:31am

Ozer Karaagac

Updated 16-Mar-11 12:11pm

v4

Comments

Ozer Karaagac 16-Mar-11 17:40pm

BTW, You can also use CFile or CStdioFile MFC classes for file operations if you are using MFC.

MartinTaylor 16-Mar-11 18:01pm

Thank u , Sir

Ozer Karaagac 16-Mar-11 18:16pm

Not at all!
I had written pStorage instead of pStream mistakenly. I've fixed it though IStorage doesn't have a Write method.

MartinTaylor 22-Mar-11 11:54am

Now i have tried the reverse procedure..to restore file(stream) from storage i am getting first 1024 bytes as junk chars like "ÍÍÍÍÍÍÍÍÍÍÍÍ...." and bcoz of my mistake in 'do..while()' condn of data writting, the restored file size is going in MB and increasing rapidly for following code..
#include <stdio.h>
#include<conio.h>
#include <windows.h>
#include<shobjidl.h>
#include <ole2.h>
#include<objidl.h>
#define BUFFERSIZE 1024

EXTERN_C void wmain()
{
IStorage* pStorage;
IStream* pStream;
HRESULT hr,hr1,hr3;
hr = StgOpenStorageEx(L"E:\\Root2.stg",STGM_READ|STGM_SHARE_DENY_WRITE,STGFMT_DOCFILE,0, NULL, 0,IID_IStorage,(void**)&pStorage);
if(S_OK==hr)
{
printf("Storage opened........\n");
hr1=pStorage->OpenStream(L"file.txt",NULL, STGM_READ | STGM_SHARE_EXCLUSIVE,0,&pStream);
if(hr1==S_OK)
{
unsigned char * pBuffer = new unsigned char [BUFFERSIZE];
HANDLE hFile = CreateFile(L"E:\\sumit2.txt",GENERIC_WRITE,FILE_SHARE_READ, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
if(hFile != INVALID_HANDLE_VALUE)
printf("\n\n\n File created");
DWORD dwWrite=0 ;
ULONG ulRead=0 ;
do
{
hr3=pStream->Read(pBuffer,dwWrite, &ulRead);
if(hr3==S_OK)
printf("\t Read Successful");
WriteFile(hFile, pBuffer, BUFFERSIZE, &dwWrite, NULL);
if(0 == dwWrite) // for checking EOF
break;
} while(ulRead = dwWrite); // also tried with dw
printf("\n\n DONE");
CloseHandle(hFile);
delete [] pBuffer;
//------------------------------------------
pStream->Release();
}
pStorage->Release();
}
_getch();
}
Sir plz help me out of this...

Ozer Karaagac 22-Mar-11 12:40pm

I posted a reply for your new Q.
http://www.codeproject.com/Questions/171679/Problem-in-Reading-Data-from-stream-of-Structured-.aspx

MartinTaylor 22-Mar-11 13:04pm

Yes Sir..I got it.. Thank u very much...