Advice On DllImport

[A_StClaire_]

hi guys,

I am working on a C# app that needs to create directories on the fly.

security settings enforced by our ISP do not allow us to use the
standard .NET calls, so I am forced to resort to a DllImport of the COM
library 'msvcrt.dll'. however I am not familiar with calling COM
objects so I have questions...

1) how does the "destroy every COM object you create" rule apply here?
with the code below am I creating something that needs to be
destroyed?

2) if this function is called often what are the performance
consequences?
[DllImport("msvc rt.dll", SetLastError=tr ue)]
static extern int _mkdir(string path);

/// <summary>
/// This function should provide safe substitude for
Directory.Creat eDirectory()
/// </summary>
/// <param name="path"></param>
/// <returns></returns>
static DirectoryInfo CreateDirectory (string sPath)
{
int iCode = _mkdir(sPath);

if (iCode != 0)
{
throw new ApplicationExce ption("Error calling [msvcrt.dll]:_mkdir(" +
sPath + "), error code: " + iCode.ToString( ));
}

return new DirectoryInfo(s Path);
}
thx a million

[Nicholas Paldino [.NET/C# MVP]]

What do you mean that your ISP doesn't allow these calls? Are you
running this on ASP.NET? If this is the case, then there is no way that
these calls are going to work either.

It most likely is a permissions issue, not you accessing parts of the
framework that are supposedly "off-limits".
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

<A_*********@ho tmail.comwrote in message
news:11******** **************@ p79g2000cwp.goo glegroups.com.. .

hi guys,

I am working on a C# app that needs to create directories on the fly.

security settings enforced by our ISP do not allow us to use the
standard .NET calls, so I am forced to resort to a DllImport of the COM
library 'msvcrt.dll'. however I am not familiar with calling COM
objects so I have questions...

1) how does the "destroy every COM object you create" rule apply here?
with the code below am I creating something that needs to be
destroyed?

2) if this function is called often what are the performance
consequences?
[DllImport("msvc rt.dll", SetLastError=tr ue)]
static extern int _mkdir(string path);

/// <summary>
/// This function should provide safe substitude for
Directory.Creat eDirectory()
/// </summary>
/// <param name="path"></param>
/// <returns></returns>
static DirectoryInfo CreateDirectory (string sPath)
{
int iCode = _mkdir(sPath);

if (iCode != 0)
{
throw new ApplicationExce ption("Error calling [msvcrt.dll]:_mkdir(" +
sPath + "), error code: " + iCode.ToString( ));
}

return new DirectoryInfo(s Path);
}
thx a million

[Arne Vajhøj]

A_*********@hot mail.com wrote:

I am working on a C# app that needs to create directories on the fly.

security settings enforced by our ISP do not allow us to use the
standard .NET calls, so I am forced to resort to a DllImport of the COM
library 'msvcrt.dll'. however I am not familiar with calling COM
objects so I have questions...

1) how does the "destroy every COM object you create" rule apply here?
with the code below am I creating something that needs to be
destroyed?

2) if this function is called often what are the performance
consequences?

msvcrt.dll is not a COM DLL but a Win32 DLL.

I find it hard to believe that your ISP does not
allow Directory.Creat eDirectory but allow usage
of msvcrt.dll - it does not make any sense.

Arne

[Michael C]

<A_*********@ho tmail.comwrote in message
news:11******** **************@ p79g2000cwp.goo glegroups.com.. .

hi guys,

I am working on a C# app that needs to create directories on the fly.

security settings enforced by our ISP do not allow us to use the
standard .NET calls, so I am forced to resort to a DllImport of the COM
library 'msvcrt.dll'. however I am not familiar with calling COM
objects so I have questions...

1) how does the "destroy every COM object you create" rule apply here?
with the code below am I creating something that needs to be
destroyed?

You are not creating a COM object here so there is nothing to destroy.

2) if this function is called often what are the performance
consequences?

None. But as other's have said I'd imagine this aint gunna work either.

Michael

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

I find extremely weird that. In case it's true it sounds more like a
misconfiguratio n than anything else.

Why don't you post the code that is giving you error?


--
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

[A_StClaire_]

Nicholas Paldino [.NET/C# MVP] wrote:

What do you mean that your ISP doesn't allow these calls? Are you
running this on ASP.NET? If this is the case, then there is no way that
these calls are going to work either.

It most likely is a permissions issue, not you accessing parts of the
framework that are supposedly "off-limits".
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

Nicholas,

I used MapPath() to find the root directory of our webspace, then
uploaded a webpage that attempted a simple CreateDirectory () there.
that produced a 'DirectoryNotFo undException - Could not find a part of
the path...' message.

when contacted our service provider actually pointed me to a "common
workaround" mentioned often on the net:

"This is a relatively known .NET bug or "feature".. .

Both Directory.Creat eDirectory(path ) and
DirectoryInfo.C reateSubdirecto ry(path) require user to have Read access
to
the drive's root directory (i.e. <Drive>:\).

Many ASP.NET hosting providers (especially those running Windows 2003
Server) will not allow user running ASP.NET working process read access
to
the root folder, so CreateDirectory will always fail. You can not blame
hosting providers - they do right thing, securing shared environment
from
users with malicious intents.

The only workaround I have found is to replace call to
Directory.Creat eDirectory() with call to unmanaged code, like msvcrt's
_mkdir(char*):"

I then implemented this and testing confirms it works.

[A_StClaire_]

Arne Vajhøj wrote:

msvcrt.dll is not a COM DLL but a Win32 DLL.

sorry, I guess you are right.

I find it hard to believe that your ISP does not
allow Directory.Creat eDirectory but allow usage
of msvcrt.dll - it does not make any sense.

Arne

yes I was somewhat surprised to find the DllImport was allowed, but it
was.

[A_StClaire_]

Michael C wrote:

<A_*********@ho tmail.comwrote in message
news:11******** **************@ p79g2000cwp.goo glegroups.com.. .

hi guys,

I am working on a C# app that needs to create directories on the fly.

security settings enforced by our ISP do not allow us to use the
standard .NET calls, so I am forced to resort to a DllImport of the COM
library 'msvcrt.dll'. however I am not familiar with calling COM
objects so I have questions...

1) how does the "destroy every COM object you create" rule apply here?
with the code below am I creating something that needs to be
destroyed?

You are not creating a COM object here so there is nothing to destroy.

2) if this function is called often what are the performance
consequences?

None. But as other's have said I'd imagine this aint gunna work either.

Michael

thx for your answers.

[A_StClaire_]

Ignacio Machin ( .NET/ C# MVP ) wrote:

Hi,

I find extremely weird that. In case it's true it sounds more like a
misconfiguratio n than anything else.

Why don't you post the code that is giving you error?


--
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

I did this, Ignacio:

try
{
System.IO.Direc toryInfo oDI = new
DirectoryInfo(@ "D:\WWWRoot\our domain.com");
ShowResult("Dir ectoryInfo succeeded");
System.IO.Direc tory.CreateDire ctory(@"D:\WWWR oot\ourdomain.c om\stclaire");
ShowResult("Cre ateDirectory succeeded");
}
catch(Exception ex)
{
ShowResult(ex.M essage + "<BR><BR>" + ex.StackTrace, true);
}

I ran this page on our hosted server and got a
DirectoryNotFou ndException. switching code lines allowed me to verify
that both the DirectoryInfo() constructor and the CreateDirectory ()
method result in this same exception.

the only thing ShowResult() does is display text on a label.

[Willy Denoyette [MVP]]

Whatever method you use (calling the framework class methods or DllImport
functions) you won't be able to create directories if your ISP has set an
ACL that prohibits this from your asp account.

Willy.

<A_*********@ho tmail.comwrote in message
news:11******** *************@i 3g2000cwc.googl egroups.com...
| Ignacio Machin ( .NET/ C# MVP ) wrote:
| Hi,
| >
| I find extremely weird that. In case it's true it sounds more like a
| misconfiguratio n than anything else.
| >
| Why don't you post the code that is giving you error?
| >
| >
| >
| >
| --
| --
| Ignacio Machin,
| ignacio.machin AT dot.state.fl.us
| Florida Department Of Transportation
|
| I did this, Ignacio:
|
| try
| {
| System.IO.Direc toryInfo oDI = new
| DirectoryInfo(@ "D:\WWWRoot\our domain.com");
| ShowResult("Dir ectoryInfo succeeded");
| System.IO.Direc tory.CreateDire ctory(@"D:\WWWR oot\ourdomain.c om\stclaire");
| ShowResult("Cre ateDirectory succeeded");
| }
| catch(Exception ex)
| {
| ShowResult(ex.M essage + "<BR><BR>" + ex.StackTrace, true);
| }
|
| I ran this page on our hosted server and got a
| DirectoryNotFou ndException. switching code lines allowed me to verify
| that both the DirectoryInfo() constructor and the CreateDirectory ()
| method result in this same exception.
|
| the only thing ShowResult() does is display text on a label.
|