RtlUnicodeStringToAnsiString problem

[OSR_Community_User]

I am struggling with RtlUnicodeStringToAnsiString function. This is my code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr, FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);

Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)

What is wrong in this code? ansi_string length is OK, but buffer is empty.

---

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[OSR_Community_User]

So I’m guessing that RUSTAS returns an error, right? Like dude, where’s your
buffer?

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 10:06 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] RtlUnicodeStringToAnsiString problem

I am struggling with RtlUnicodeStringToAnsiString function. This is my code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr,
FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);

Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)

What is wrong in this code? ansi_string length is OK, but buffer is empty.

---

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[OSR_Community_User]

Try reading the docs for RtlUnicodeToAnsi…

It says:

Pointer to an ANSI_STRING structure to hold the converted ANSI string. If
AllocateDestinationString is TRUE, the routine allocates a new buffer to
hold the string data, and updates the Buffer member of DestinationString to
point to the new buffer. Otherwise, the routine uses the
currently-specified buffer to hold the string.

So, set the last parameter in your string to “TRUE”, and my guess is that
you’ll get a much better result. Alternatively, supply a “long enough”
pre-determined string in RtlInitAnsiString(), such as
“XXXXXXXXXXXXXXXXXXXXXXXXXXXX” that is long enough to hold your final
string.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:06:00 PM:

I am struggling with RtlUnicodeStringToAnsiString function. This is my
code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
uStr, FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);
Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)
What is wrong in this code? ansi_string length is OK, but buffer is
empty.
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[OSR_Community_User]

I would think that it does, since the DDK doc’s say that it’s supposed to
return STATUS_SUCCESS if it’s succeeded, and “Otherwise, no storage was
allocated, and no conversion done”. It doesn’t explain what possible errors
you could get, but something along the lines of “Dude, where’s your buffer”
seems like a likely one (STATUS_INVALID_PARAMETER, perhaps?).

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:14:15 PM:

So I’m guessing that RUSTAS returns an error, right? Like dude,
where’s your buffer?

=====================
Mark Roddy

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 10:06 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] RtlUnicodeStringToAnsiString problem

I am struggling with RtlUnicodeStringToAnsiString function. This is my
code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
uStr, FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);
Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)
What is wrong in this code? ansi_string length is OK, but buffer is
empty.
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[OSR_Community_User]

You should have either allocated a the ansi_string.Buffer your self before
calling RtlUnicodeStringToAnsiString() or put TRUE in the third parameter to
RtlUnicodeStringToAnsiString() so it will allocate.
Either way the problem is that no one allocated the ansi string’s buffer.

Shahar

---

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Alex Farber
Sent: Tuesday, October 26, 2004 4:06 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] RtlUnicodeStringToAnsiString problem

I am struggling with RtlUnicodeStringToAnsiString function. This is my code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr,
FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);

Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)

What is wrong in this code? ansi_string length is OK, but buffer is empty.

---

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[OSR_Community_User]

It looks like problem is solved by changing the code by this way:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
ansi_string.MaximumLength = (USHORT) pDevExt->ustrDeviceName.uStr.Length;
ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.MaximumLength);
RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr, FALSE);
…
RtlFreeAnsiString(&ansi_string);

I works but I am not sure that RtlFreeAnsiString releases memory correct after such allocation. Is this OK to allocate ansi_string.Buffer with ExAllocatePool and call RtlFreeAnsiString for clean-up?

“Roddy, Mark” wrote:
So I’m guessing that RUSTAS returns an error, right? Like dude, where’s your buffer?

=====================
Mark Roddy

---------------------------------
From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 10:06 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] RtlUnicodeStringToAnsiString problem

I am struggling with RtlUnicodeStringToAnsiString function. This is my code:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);

RtlInitAnsiString(&ansi_string, NULL);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length before conversion: %d\n”, nLength);

RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr, FALSE);
nLength = ansi_string.Length;
DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);

Debug output is:
Source: \Device\LOOPBACK0
ANSI string length before conversion: 0
ANSI string length after conversion: 17
ANSI string after conversion:: (null)
Destination: (null)

What is wrong in this code? ansi_string length is OK, but buffer is empty.

---------------------------------
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[OSR_Community_User]

Alex,

That would work, I suppose, but why not just pass in TRUE as the last
parameter, and RUSTAS will do it for you automatically. That is what the
last parameter is there for…

Unless of course, you have some special reason to call ExAllocatePool
specificially (to set some special mode of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

It looks like problem is solved by changing the code by this way:

// pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
ANSI_STRING ansi_string;
ansi_string.MaximumLength = (USHORT) pDevExt->ustrDeviceName.uStr.Length;
ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
MaximumLength);
RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
uStr, FALSE);
…
RtlFreeAnsiString(&ansi_string);
I works but I am not sure that RtlFreeAnsiString releases memory
correct after such allocation. Is this OK to allocate ansi_string.
Buffer with ExAllocatePool and call RtlFreeAnsiString for clean-up?

“Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, October 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0
> ANSI string length after conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
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> ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
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[OSR_Community_User]

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the last
parameter, and RUSTAS will do it for you automatically. That is what the
last parameter is there for…

Unless of course, you have some special reason to call ExAllocatePool
specificially (to set some special mode of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT) pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, October 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”, ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0
> ANSI string length after conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
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[OSR_Community_User]

You should of course check the returned status value from RUSTAS and deal
with error cases regardless of when where and how you allocate the buffer.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the
last
parameter, and RUSTAS will do it for you automatically. That is what
the
last parameter is there for…

Unless of course, you have some special reason to call
ExAllocatePool
specificially (to set some special mode of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it
yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString
uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT)
pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for
clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This
is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”,
ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0> ANSI string length after
conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer
is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
> Questions? First check the Kernel Driver FAQ at http://www.
> osronline.com/article.cfm?id=256 You are currently subscribed to
> ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
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[OSR_Community_User]

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string, &pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:
You should of course check the returned status value from RUSTAS and deal
with error cases regardless of when where and how you allocate the buffer.

=====================
Mark Roddy



From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the
last
parameter, and RUSTAS will do it for you automatically. That is what
the
last parameter is there for…

Unless of course, you have some special reason to call
ExAllocatePool
specificially (to set some special mode of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it
yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString
uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT)
pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for
clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This
is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”,
ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0> ANSI string length after
conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer
is
empty.
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> Y! Messenger - Communicate in real time. Download now. —
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[OSR_Community_User]

Agreed. Checking status of any function is NECESSARY to guarantee
functional drivers for instance when running in low-memory situations. Or
BSOD’s will be quite quick to happen.

Oh, and of course DEALING with the error condition in a suitable way. The
first step is to print out any unexpected failed functions and perhaps even
stopping (DebugBreak or similar) when the driver encounters anything
unexpected. Second, you need to figure out what to do when this happens
(Continue anyways isn’t a particularly good idea if you failed to allocate
memory, so failing whatever is going on is probably the right method at
such a case, but it all depends on exactly what is happening in the system
and what the consequences are of “just continuing”).

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 04:26:59 PM:

You should of course check the returned status value from RUSTAS and deal
with error cases regardless of when where and how you allocate the
buffer.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:
>
>
>
>
>
>
> Alex,
>
> That would work, I suppose, but why not just pass in TRUE as the
> last
> parameter, and RUSTAS will do it for you automatically. That is what
> the
> last parameter is there for…
>
> Unless of course, you have some special reason to call
> ExAllocatePool
> specificially (to set some special mode of the pool parameters for
> instance).
>
> I think, if you’re using your own allocation, you should free it
> yourself
> too, as the (looking at the code in the debugger) RtlFreeXXXString
> uses an
> internal RtlHeapFree which isn’t the same as ExFreePool…
>
> So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
> can be
> used to free it.
>
> –
> Mats
>
> xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:
>
> > It looks like problem is solved by changing the code by this way:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > ansi_string.MaximumLength = (USHORT)
> pDevExt->ustrDeviceName.uStr.Length;
> > ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> > MaximumLength);
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > …
> > RtlFreeAnsiString(&ansi_string);
> > I works but I am not sure that RtlFreeAnsiString releases memory
> > correct after such allocation. Is this OK to allocate ansi_string.
> > Buffer with ExAllocatePool and call RtlFreeAnsiString for
> clean-up?
> >
> > “Roddy, Mark” wrote:
> > So I’m guessing that RUSTAS returns an error, right? Like dude,
> > where’s your buffer?
> >
> >
> > =====================
> > Mark Roddy
> >
> >
> > From: Alex Farber [mailto:xxxxx@yahoo.com]
> > Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] RtlUnicodeStringToAnsiString problem
>
> > I am struggling with RtlUnicodeStringToAnsiString function. This
> is my
> code:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
> >
> > RtlInitAnsiString(&ansi_string, NULL);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
> >
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> > DbgPrint(“ANSI string after conversion:: %s\n”,
> ansi_string.Buffer);
> > Debug output is:
> > Source: \Device\LOOPBACK0
> > ANSI string length before conversion: 0> ANSI string length after
> conversion: 17
> > ANSI string after conversion:: (null)
> > Destination: (null)
> > What is wrong in this code? ansi_string length is OK, but buffer
> is
> empty.
> > Do you Yahoo!?
> > Y! Messenger - Communicate in real time. Download now. —
> > Questions? First check the Kernel Driver FAQ at http://www.
> > osronline.com/article.cfm?id=256 You are currently subscribed to
> > ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> > to xxxxx@lists.osr.com —
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> > osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@yahoo.com
> > To unsubscribe send a blank email to
> xxxxx@lists.osr.com
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>
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> > send a blank email to xxxxx@lists.osr.com
> > ForwardSourceID:NT000060F2
>
>
>
> —
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> http://www.osronline.com/article.cfm?id=256
>
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>
>
>
>
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> Yahoo! Mail Address AutoComplete
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[OSR_Community_User]

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:

You should of course check the returned status value from RUSTAS and
deal
with error cases regardless of when where and how you allocate the
buffer.

=====================
Mark Roddy



From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the
last
parameter, and RUSTAS will do it for you automatically. That is what
the
last parameter is there for…

Unless of course, you have some special reason to call
ExAllocatePool
specificially (to set some special mode! of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it
yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString
uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT)
pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for
clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This
is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”,
ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0> ANSI string length after
conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer
is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
> Questions? First check the Kernel Driver FAQ a! t http://www.
> osronline.com/article.cfm?id=256 You are currently subscribed to
> ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> to xxxxx@lists.osr.com —
> Questions? First check the Kernel Driver FAQ at http://www.
> osronline.com/article.cfm?id=256
>
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[OSR_Community_User]

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:12 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:

You should of course check the returned status value from RUSTAS and
deal
with error cases regardless of when where and how you allocate the
buffer.

=====================
Mark Roddy



From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the
last
parameter, and RUSTAS will do it for you automatically. That is what
the
last parameter is there for…

Unless of course, you have some special reason to call
ExAllocatePool
specificially (to set some special mode! of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it
yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString
uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT)
pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for
clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This
is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”,
ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0> ANSI string length after
conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer
is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
> Questions? First check the Kernel Driver FAQ a! t http://www.
> osronline.com/article.cfm?id=256 You are currently subscribed to
> ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> to xxxxx@lists.osr.com —
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> osronline.com/article.cfm?id=256
>
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[OSR_Community_User]

xxxxx@lists.osr.com wrote on 10/26/2004 05:18:26 PM:

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

I think what Mark was referring to, and what I pointed out in my excerpt
from the RUSTAS Doc’s, that if the call doesn’t return Succes, you didn’t
get any allocation, and thus YOU SHOULD NOT FREE it. Because you’ll either
try to free NULL, or worse, some random value. Freeing something that
hasn’t been allocated is a bad idea.

Now it may be OK to try to free a NULL, becasue from memory from looking at
the RtlFreeXXXString, it looked like it was checking for NULL and skipping
out. But I wouldn’t rely on such behaviour, since it may change in future
code (unless it’s specified that you can call RtlFreeXXXString with NULL in
the Doc’s). Also relying on a “Failed allocation” to be NULL is probably a
bit doubtful.

So, to keep the code clean and reliable, only free if it was a success.

–
Mats

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:12 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:
>
> You should of course check the returned status value from RUSTAS and
> deal
> with error cases regardless of when where and how you allocate the
> buffer.
>
>
>
> =====================
> Mark Roddy
>
>
>
>
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, October 26, 2004 11:17 AM
> To: Windows System Software Devs Interest List
> Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem
>
>
> Thanks.
>
> Mats PETERSSON wrote:
>
>
>
>
>
>
> Alex,
>
> That would work, I suppose, but why not just pass in TRUE as the
> last
> parameter, and RUSTAS will do it for you automatically. That is what
> the
> last parameter is there for…
>
> Unless of course, you have some special reason to call
> ExAllocatePool
> specificially (to set some special mode! of the pool parameters for
> instance).
>
> I think, if you’re using your own allocation, you should free it
> yourself
> too, as the (looking at the code in the debugger) RtlFreeXXXString
> uses an
> internal RtlHeapFree which isn’t the same as ExFreePool…
>
> So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
> can be
> used to free it.
>
> –
> Mats
>
> xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:
>
> > It looks like problem is solved by changing the code by this way:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > ansi_string.MaximumLength = (USHORT)
> pDevExt->ustrDeviceName.uStr.Length;
> > ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> > MaximumLength);
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > …
> > RtlFreeAnsiString(&ansi_string);
> > I works but I am not sure that RtlFreeAnsiString releases memory
> > correct after such allocation. Is this OK to allocate ansi_string.
> > Buffer with ExAllocatePool and call RtlFreeAnsiString for
> clean-up?
> >
> > “Roddy, Mark” wrote:
> > So I’m guessing that RUSTAS returns an error, right? Like dude,
> > where’s your buffer?
> >
> >
> > =====================
> > Mark Roddy
> >
> >
> > From: Alex Farber [mailto:xxxxx@yahoo.com]
> > Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] RtlUnicodeStringToAnsiString problem
>
> > I am struggling with RtlUnicodeStringToAnsiString function. This
> is my
> code:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
> >
> > RtlInitAnsiString(&ansi_string, NULL);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
> >
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> > DbgPrint(“ANSI string after conversion:: %s\n”,
> ansi_string.Buffer);
> > Debug output is:
> > Source: \Device\LOOPBACK0
> > ANSI string length before conversion: 0> ANSI string length after
> conversion: 17
> > ANSI string after conversion:: (null)
> > Destination: (null)
> > What is wrong in this code? ansi_string length is OK, but buffer
> is
> empty.
> > Do you Yahoo!?
> > Y! Messenger - Communicate in real time. Download now. —
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> > osronline.com/article.cfm?id=256 You are currently subscribed to
> > ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> > to xxxxx@lists.osr.com —
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> > osronline.com/article.cfm?id=256
> >
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> —
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>
>
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[OSR_Community_User]

In the error case the buffer is not allocated. Calling RtlFreeAnsiString on
failure may or may not work depending on how RtlFreeAnsiString and
RtlUnicodeStringToAnsiString are implemented. RtlUnicodeStringToAnsiString
has to set the Buffer value of the string to NULL and RtlFreeAnsiString has
to not do anything if the Buffer value is NULL. You are depending on a lot
of internal behavior in these functions. It might work on one platform with
one OS release and fail on another.

=====================
Mark Roddy

-----Original Message-----
From: Alexander Krol [mailto:xxxxx@creo.com]
Sent: Tuesday, October 26, 2004 12:18 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:12 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:

You should of course check the returned status value from RUSTAS and
deal
with error cases regardless of when where and how you allocate the
buffer.

=====================
Mark Roddy



From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:17 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks.

Mats PETERSSON wrote:

Alex,

That would work, I suppose, but why not just pass in TRUE as the
last
parameter, and RUSTAS will do it for you automatically. That is what
the
last parameter is there for…

Unless of course, you have some special reason to call
ExAllocatePool
specificially (to set some special mode! of the pool parameters for
instance).

I think, if you’re using your own allocation, you should free it
yourself
too, as the (looking at the code in the debugger) RtlFreeXXXString
uses an
internal RtlHeapFree which isn’t the same as ExFreePool…

So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
can be
used to free it.

–
Mats

xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:

> It looks like problem is solved by changing the code by this way:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> ansi_string.MaximumLength = (USHORT)
pDevExt->ustrDeviceName.uStr.Length;
> ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> MaximumLength);
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> …
> RtlFreeAnsiString(&ansi_string);
> I works but I am not sure that RtlFreeAnsiString releases memory
> correct after such allocation. Is this OK to allocate ansi_string.
> Buffer with ExAllocatePool and call RtlFreeAnsiString for
clean-up?
>
> “Roddy, Mark” wrote:
> So I’m guessing that RUSTAS returns an error, right? Like dude,
> where’s your buffer?
>
>
> =====================
> Mark Roddy
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] RtlUnicodeStringToAnsiString problem

> I am struggling with RtlUnicodeStringToAnsiString function. This
is my
code:
>
> // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> ANSI_STRING ansi_string;
> DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
>
> RtlInitAnsiString(&ansi_string, NULL);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
>
> RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.
> uStr, FALSE);
> nLength = ansi_string.Length;
> DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> DbgPrint(“ANSI string after conversion:: %s\n”,
ansi_string.Buffer);
> Debug output is:
> Source: \Device\LOOPBACK0
> ANSI string length before conversion: 0> ANSI string length after
conversion: 17
> ANSI string after conversion:: (null)
> Destination: (null)
> What is wrong in this code? ansi_string length is OK, but buffer
is
empty.
> Do you Yahoo!?
> Y! Messenger - Communicate in real time. Download now. —
> Questions? First check the Kernel Driver FAQ a! t http://www.
> osronline.com/article.cfm?id=256 You are currently subscribed to
> ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> to xxxxx@lists.osr.com —
> Questions? First check the Kernel Driver FAQ at http://www.
> osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@yahoo.com
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xxxxx@lists.osr.com
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> subscribed to ntdev as: xxxxx@3dlabs.com To unsubscribe
> send a blank email to xxxxx@lists.osr.com
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[OSR_Community_User]

If RUSTAS doesn’t return success, one should not touch the damned stuff,
certainly - since nowhere it is documented that it will be NULL. On the
other side, standard deallocating routines safely accept NULL, and, though
it is not documented, I would be very surprised if RtlFreeXXXString would
duffer from the bunch.

-----Original Message-----
From: Mats PETERSSON [mailto:xxxxx@3dlabs.com]
Sent: Tuesday, October 26, 2004 6:33 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

xxxxx@lists.osr.com wrote on 10/26/2004 05:18:26 PM:

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

I think what Mark was referring to, and what I pointed out in my excerpt
from the RUSTAS Doc’s, that if the call doesn’t return Succes, you didn’t
get any allocation, and thus YOU SHOULD NOT FREE it. Because you’ll either
try to free NULL, or worse, some random value. Freeing something that
hasn’t been allocated is a bad idea.

Now it may be OK to try to free a NULL, becasue from memory from looking at
the RtlFreeXXXString, it looked like it was checking for NULL and skipping
out. But I wouldn’t rely on such behaviour, since it may change in future
code (unless it’s specified that you can call RtlFreeXXXString with NULL in
the Doc’s). Also relying on a “Failed allocation” to be NULL is probably a
bit doubtful.

So, to keep the code clean and reliable, only free if it was a success.

–
Mats

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:12 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:
>
> You should of course check the returned status value from RUSTAS and
> deal
> with error cases regardless of when where and how you allocate the
> buffer.
>
>
>
> =====================
> Mark Roddy
>
>
>
>
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, October 26, 2004 11:17 AM
> To: Windows System Software Devs Interest List
> Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem
>
>
> Thanks.
>
> Mats PETERSSON wrote:
>
>
>
>
>
>
> Alex,
>
> That would work, I suppose, but why not just pass in TRUE as the
> last
> parameter, and RUSTAS will do it for you automatically. That is what
> the
> last parameter is there for…
>
> Unless of course, you have some special reason to call
> ExAllocatePool
> specificially (to set some special mode! of the pool parameters for
> instance).
>
> I think, if you’re using your own allocation, you should free it
> yourself
> too, as the (looking at the code in the debugger) RtlFreeXXXString
> uses an
> internal RtlHeapFree which isn’t the same as ExFreePool…
>
> So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
> can be
> used to free it.
>
> –
> Mats
>
> xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:
>
> > It looks like problem is solved by changing the code by this way:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > ansi_string.MaximumLength = (USHORT)
> pDevExt->ustrDeviceName.uStr.Length;
> > ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> > MaximumLength);
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > …
> > RtlFreeAnsiString(&ansi_string);
> > I works but I am not sure that RtlFreeAnsiString releases memory
> > correct after such allocation. Is this OK to allocate ansi_string.
> > Buffer with ExAllocatePool and call RtlFreeAnsiString for
> clean-up?
> >
> > “Roddy, Mark” wrote:
> > So I’m guessing that RUSTAS returns an error, right? Like dude,
> > where’s your buffer?
> >
> >
> > =====================
> > Mark Roddy
> >
> >
> > From: Alex Farber [mailto:xxxxx@yahoo.com]
> > Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] RtlUnicodeStringToAnsiString problem
>
> > I am struggling with RtlUnicodeStringToAnsiString function. This
> is my
> code:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
> >
> > RtlInitAnsiString(&ansi_string, NULL);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
> >
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> > DbgPrint(“ANSI string after conversion:: %s\n”,
> ansi_string.Buffer);
> > Debug output is:
> > Source: \Device\LOOPBACK0
> > ANSI string length before conversion: 0> ANSI string length after
> conversion: 17
> > ANSI string after conversion:: (null)
> > Destination: (null)
> > What is wrong in this code? ansi_string length is OK, but buffer
> is
> empty.
> > Do you Yahoo!?
> > Y! Messenger - Communicate in real time. Download now. —
> > Questions? First check the Kernel Driver FAQ a! t http://www.
> > osronline.com/article.cfm?id=256 You are currently subscribed to
> > ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> > to xxxxx@lists.osr.com —
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> >
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> xxxxx@lists.osr.com
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>
> —
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> http://www.osronline.com/article.cfm?id=256
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To unsubscribe send a blank email to xxxxx@lists.osr.com</http:>

[OSR_Community_User]

Well I was going to proclaim that it would just crash and burn, but at least
on w2k3 it happens to be safe to call RtlFreeAnsiString after
RtlUnicodeStringToAnsiString fails. Relying on this behavior is rather
foolish.

=====================
Mark Roddy

-----Original Message-----
From: Alexander Krol [mailto:xxxxx@creo.com]
Sent: Tuesday, October 26, 2004 12:44 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

If RUSTAS doesn’t return success, one should not touch the damned stuff,
certainly - since nowhere it is documented that it will be NULL. On the
other side, standard deallocating routines safely accept NULL, and, though
it is not documented, I would be very surprised if RtlFreeXXXString would
duffer from the bunch.

-----Original Message-----
From: Mats PETERSSON [mailto:xxxxx@3dlabs.com]
Sent: Tuesday, October 26, 2004 6:33 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

xxxxx@lists.osr.com wrote on 10/26/2004 05:18:26 PM:

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

I think what Mark was referring to, and what I pointed out in my excerpt
from the RUSTAS Doc’s, that if the call doesn’t return Succes, you didn’t
get any allocation, and thus YOU SHOULD NOT FREE it. Because you’ll either
try to free NULL, or worse, some random value. Freeing something that hasn’t
been allocated is a bad idea.

Now it may be OK to try to free a NULL, becasue from memory from looking at
the RtlFreeXXXString, it looked like it was checking for NULL and skipping
out. But I wouldn’t rely on such behaviour, since it may change in future
code (unless it’s specified that you can call RtlFreeXXXString with NULL in
the Doc’s). Also relying on a “Failed allocation” to be NULL is probably a
bit doubtful.

So, to keep the code clean and reliable, only free if it was a success.

–
Mats

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:12 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Uh - you might want to rethink that code segment. Freeing unallocated
buffers generally has dire results.

=====================
Mark Roddy

---

From: Alex Farber [mailto:xxxxx@yahoo.com]
Sent: Tuesday, October 26, 2004 11:40 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Thanks for the help, my final code is:

ANSI_STRING ansi_string;
RtlInitAnsiString(&ansi_string, NULL);

status = RtlUnicodeStringToAnsiString(&ansi_string,
&pDevExt->ustrDeviceName.uStr, TRUE);

if ( status == STATUS_SUCCESS )
{
…
}

RtlFreeAnsiString(&ansi_string);

…
pIrp->IoStatus.Status = status;
return status;

“Roddy, Mark” wrote:
>
> You should of course check the returned status value from RUSTAS
> and deal
> with error cases regardless of when where and how you allocate the
> buffer.
>
>
>
> =====================
> Mark Roddy
>
>
>
>
>
>
> From: Alex Farber [mailto:xxxxx@yahoo.com]
> Sent: Tuesday, October 26, 2004 11:17 AM
> To: Windows System Software Devs Interest List
> Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem
>
>
> Thanks.
>
> Mats PETERSSON wrote:
>
>
>
>
>
>
> Alex,
>
> That would work, I suppose, but why not just pass in TRUE as the
> last
> parameter, and RUSTAS will do it for you automatically. That is what
> the
> last parameter is there for…
>
> Unless of course, you have some special reason to call
> ExAllocatePool
> specificially (to set some special mode! of the pool parameters for
> instance).
>
> I think, if you’re using your own allocation, you should free it
> yourself
> too, as the (looking at the code in the debugger) RtlFreeXXXString
> uses an
> internal RtlHeapFree which isn’t the same as ExFreePool…
>
> So if you allocate it, you free it. If RtlXXX allocates it, RtlFree
> can be
> used to free it.
>
> –
> Mats
>
> xxxxx@lists.osr.com wrote on 10/26/2004 03:36:48 PM:
>
> > It looks like problem is solved by changing the code by this way:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > ansi_string.MaximumLength = (USHORT)
> pDevExt->ustrDeviceName.uStr.Length;
> > ansi_string.Buffer = (PSTR)ExAllocatePool(PagedPool, ansi_string.
> > MaximumLength);
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > …
> > RtlFreeAnsiString(&ansi_string);
> > I works but I am not sure that RtlFreeAnsiString releases memory
> > correct after such allocation. Is this OK to allocate ansi_string.
> > Buffer with ExAllocatePool and call RtlFreeAnsiString for
> clean-up?
> >
> > “Roddy, Mark” wrote:
> > So I’m guessing that RUSTAS returns an error, right? Like dude,
> > where’s your buffer?
> >
> >
> > =====================
> > Mark Roddy
> >
> >
> > From: Alex Farber [mailto:xxxxx@yahoo.com]
> > Sent: Tuesday, Octo! ber 26, 2004 10:06 AM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] RtlUnicodeStringToAnsiString problem
>
> > I am struggling with RtlUnicodeStringToAnsiString function. This
> is my
> code:
> >
> > // pDevExt->ustrDeviceName.uStr is valid UNICODE_STRING
> > ANSI_STRING ansi_string;
> > DbgPrint(“Source: %ws\n”,pDevExt->ustrDeviceName.uStr.Buffer);
> >
> > RtlInitAnsiString(&ansi_string, NULL);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length before conversion: %d\n”, nLength);
> >
> > RtlUnicodeStringToAnsiString(&ansi_string,
> &pDevExt->ustrDeviceName.
> > uStr, FALSE);
> > nLength = ansi_string.Length;
> > DbgPrint(“ANSI string length after conversion: %d\n”, nLength);
> > DbgPrint(“ANSI string after conversion:: %s\n”,
> ansi_string.Buffer);
> > Debug output is:
> > Source: \Device\LOOPBACK0
> > ANSI string length before conversion: 0> ANSI string length after
> conversion: 17
> > ANSI string after conversion:: (null)
> > Destination: (null)
> > What is wrong in this code? ansi_string length is OK, but buffer
> is
> empty.
> > Do you Yahoo!?
> > Y! Messenger - Communicate in real time. Download now. —
> > Questions? First check the Kernel Driver FAQ a! t http://www.
> > osronline.com/article.cfm?id=256 You are currently subscribed to
> > ntdev as: xxxxx@stratus.com To unsubscribe send a blank email
> > to xxxxx@lists.osr.com —
> > Questions? First check the Kernel Driver FAQ at http://www.
> > osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@yahoo.com
> > To unsubscribe send a blank email to
> xxxxx@lists.osr.com
> >__________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com — Questions? First check the Kernel Driver
> FAQ at
>
> > http://www.osronline.com/article.cfm?id=256 You are currently
> > subscribed to ntdev as: xxxxx@3dlabs.com To unsubscribe
> > send a blank email to xxxxx@lists.osr.com
> > ForwardSourceID:NT000060F2
>
>
>
> —
> Questions? F! irst check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@yahoo.com
> To unsubscribe send a blank email to
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>
>
>
>
> Do you Yahoo!?
> Yahoo! Mail Address AutoComplete
>
> w_mail/static/ease.html> - You start. We finish. — Questions?
> First check
> the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
> You are
> currently subscribed to ntdev as: xxxxx@stratus.com To
> unsubscribe send
> a blank email to xxxxx@lists.osr.com
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> http://www.osronline.com/article.cfm?id=256
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> Yahoo! Mail Address AutoComplete
>
http:
> w_mail/static/ease.html> - You start. We finish. — Questions? First
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—
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http://www.osronline.com/article.cfm?id=256

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unsubscribe send a blank email to xxxxx@lists.osr.com

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unsubscribe send a blank email to xxxxx@lists.osr.com</http:>

[OSR_Community_User]

Returning NULL pointer on failed allocation is C idiom; ditto safely feeding
that same pointer to deallocation function (see both C and C++ standards).
Is this such a big deal to ask for this behavior to be legal and documented
in RTLXXX functions and in DDK environment in general?

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:57 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Well I was going to proclaim that it would just crash and burn, but at least
on w2k3 it happens to be safe to call RtlFreeAnsiString after
RtlUnicodeStringToAnsiString fails. Relying on this behavior is rather
foolish.

=====================
Mark Roddy

-----Original Message-----
From: Alexander Krol [mailto:xxxxx@creo.com]
Sent: Tuesday, October 26, 2004 12:44 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

If RUSTAS doesn’t return success, one should not touch the damned stuff,
certainly - since nowhere it is documented that it will be NULL. On the
other side, standard deallocating routines safely accept NULL, and, though
it is not documented, I would be very surprised if RtlFreeXXXString would
duffer from the bunch.

-----Original Message-----
From: Mats PETERSSON [mailto:xxxxx@3dlabs.com]
Sent: Tuesday, October 26, 2004 6:33 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

xxxxx@lists.osr.com wrote on 10/26/2004 05:18:26 PM:

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

I think what Mark was referring to, and what I pointed out in my excerpt
from the RUSTAS Doc’s, that if the call doesn’t return Succes, you didn’t
get any allocation, and thus YOU SHOULD NOT FREE it. Because you’ll either
try to free NULL, or worse, some random value. Freeing something that hasn’t
been allocated is a bad idea.

Now it may be OK to try to free a NULL, becasue from memory from looking at
the RtlFreeXXXString, it looked like it was checking for NULL and skipping
out. But I wouldn’t rely on such behaviour, since it may change in future
code (unless it’s specified that you can call RtlFreeXXXString with NULL in
the Doc’s). Also relying on a “Failed allocation” to be NULL is probably a
bit doubtful.

So, to keep the code clean and reliable, only free if it was a success.

–
Mats

[OSR_Community_User]

Oh I agree that this should be the documented behavior of all varieties of
delete in the kernel, however it isn’t.

=====================
Mark Roddy

-----Original Message-----
From: Alexander Krol [mailto:xxxxx@creo.com]
Sent: Wednesday, October 27, 2004 3:55 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Returning NULL pointer on failed allocation is C idiom; ditto safely feeding
that same pointer to deallocation function (see both C and C++ standards).
Is this such a big deal to ask for this behavior to be legal and documented
in RTLXXX functions and in DDK environment in general?

-----Original Message-----
From: Roddy, Mark [mailto:xxxxx@stratus.com]
Sent: Tuesday, October 26, 2004 6:57 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

Well I was going to proclaim that it would just crash and burn, but at least
on w2k3 it happens to be safe to call RtlFreeAnsiString after
RtlUnicodeStringToAnsiString fails. Relying on this behavior is rather
foolish.

=====================
Mark Roddy

-----Original Message-----
From: Alexander Krol [mailto:xxxxx@creo.com]
Sent: Tuesday, October 26, 2004 12:44 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

If RUSTAS doesn’t return success, one should not touch the damned stuff,
certainly - since nowhere it is documented that it will be NULL. On the
other side, standard deallocating routines safely accept NULL, and, though
it is not documented, I would be very surprised if RtlFreeXXXString would
duffer from the bunch.

-----Original Message-----
From: Mats PETERSSON [mailto:xxxxx@3dlabs.com]
Sent: Tuesday, October 26, 2004 6:33 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] RtlUnicodeStringToAnsiString problem

xxxxx@lists.osr.com wrote on 10/26/2004 05:18:26 PM:

Buffer is allocated by RtlUnicodeStringToAnsiString because of TRUE flag.
Not the clearest of possible APIs, certainly - but documented.

I think what Mark was referring to, and what I pointed out in my excerpt
from the RUSTAS Doc’s, that if the call doesn’t return Succes, you didn’t
get any allocation, and thus YOU SHOULD NOT FREE it. Because you’ll either
try to free NULL, or worse, some random value. Freeing something that hasn’t
been allocated is a bad idea.

Now it may be OK to try to free a NULL, becasue from memory from looking at
the RtlFreeXXXString, it looked like it was checking for NULL and skipping
out. But I wouldn’t rely on such behaviour, since it may change in future
code (unless it’s specified that you can call RtlFreeXXXString with NULL in
the Doc’s). Also relying on a “Failed allocation” to be NULL is probably a
bit doubtful.

So, to keep the code clean and reliable, only free if it was a success.

–
Mats

---

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: xxxxx@stratus.com To
unsubscribe send a blank email to xxxxx@lists.osr.com