Got SIGSEGV exception when calling CreateProcess

[speller]

I'm stuck with the following code:

Code: Pascal  [Select][+][-]

1. var
2.   SI : STARTUPINFOW;
3.   PI: TPROCESSINFORMATION;
4. begin
5.   FillChar(SI,SizeOf(SI),0);
6.   SI.cb := SizeOf(SI);
7.   FillChar(PI,SizeOf(PI),0);
8.  
9.   CreateProcessW (
10.     nil,
11.     'cmd.exe -v',
12.     nil,
13.     nil,
14.     false,
15.     0,
16.     nil,
17.     nil,
18.     SI,
19.     PI
20.   );
21. end;

It produces the following error:

Project anyfs raised exception class 'External: SIGSEGV'.

At address 7FF8D8FA800C

What I'm doing wrong?

[Zvoni]

From https://docs.microsoft.com/de-de/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessw

lpStartupInfo

A pointer to a STARTUPINFO or STARTUPINFOEX structure.

lpProcessInformation

A pointer to a PROCESS_INFORMATION structure that receives identification information about the new process.

I just look at the Source-code in
C:\lazarus\fpc\3.2.0\source\rtl\win\wininc\redef.inc

Code: [Select]

function CreateProcessW(lpApplicationName: LPWSTR; lpCommandLine: LPWSTR; lpProcessAttributes, lpThreadAttributes: PSecurityAttributes; bInheritHandles: BOOL; dwCreationFlags: DWORD; lpEnvironment: Pointer; lpCurrentDirectory: LPWSTR;
  const lpStartupInfo: TStartupInfoW; var lpProcessInformation: TProcessInformation): BOOL; external 'kernel32' name 'CreateProcessW';   
This is not making any sense to me.
Mode Delphi?

[speller]

The declaration for the mentioned parameters is as follows:

Code: Pascal  [Select][+][-]

1. function CreateProcessW(lpApplicationName: LPWSTR; lpCommandLine: LPWSTR; lpProcessAttributes, lpThreadAttributes: PSecurityAttributes; bInheritHandles: BOOL; dwCreationFlags: DWORD; lpEnvironment: Pointer; lpCurrentDirectory: LPWSTR;
2.   const lpStartupInfo: TStartupInfoW; var lpProcessInformation: TProcessInformation): BOOL; external 'kernel32' name 'CreateProcessW';
3.  

const and var parameters are passed by reference, isn't it?

[Zvoni]

const and var parameters are passed by reference, isn't it?

From: https://freepascal.org/docs-html/current/ref/refsu65.html#x181-20500014.4.2

The procedure gets a pointer to the variable that was passed, and uses this pointer to access the variable’s value.

Then what i said above is wrong

EDIT: Just took a closer look: You pass an empty StartupInfo-Record (except setting cb)
but that record has a member dwFlags, which the MS-Docs don't mention zero being a valid value
https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/ns-processthreadsapi-startupinfow

That said: i'm poking in the dark.....

[jamie]

Or use TProcess class and don't worry about it. its even cross the river floatable ! 

[dseligo]

Try to swap first two parameters:

Code: Pascal  [Select][+][-]

1. CreateProcessW (
2.     'cmd.exe -v',
3.     nil,
4.     nil,
5.     nil,
6.     false,
7.     0,
8.     nil,
9.     nil,
10.     SI,
11.     PI
12.   );

[marcov]

The idea behind redef is this:

Originally the windows headers were generated with VAR and CONST support for a more pascal feel, but this turned out to be a problem because some calls allowed to pass NIL to the parameters.

Most core functions were changed to pointer syntax only, but often used functions where either old FPC or Delphi had a VAR construct were overloaded in redef.inc.

IOW this means that there also is a version with only pointers in func.inc