The likely cause is identified by

try_pl_f4a3.xs: In function 'get_proc_name':
try_pl_f4a3.xs:35:1: warning: function returns address of local variab
+le
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Which is telling you that this:

char* get_proc_name( int processID )
{
    TCHAR szProcessName[MAX_PATH] = TEXT("<unknown>");

    ...

    return szProcessName;
}
[download]

Is a fundamentally flawed piece of code. You are allocating a string on the stack, and then returning a pointer to it from the function. But when the function returns, the stack is unwound and can be reused by other parts of the code.

The only surprising thing here is that you actually get something returned and it doesn't crash.

You need to correct that by allocating space on the heap using Newx() or Newxc() or Newxz(). See perlapi

That said. I wonder why you aren't using Win32::Process::Info?

Many Thanks, BrowserUk! Returning a variable on stack is a fundamental mistake indeed. I change

TCHAR szProcessName[MAX_PATH] = TEXT("<unknown>");

into

TCHAR * szProcessName = (TCHAR*) malloc( MAX_PATH * sizeof(TCHAR) );
[download]

it looks like working well now. but sequenced question is, how free this memory I allocate in C?

That said. I wonder why you aren't using Win32::Process::Info?

I don't using Wi32::Process::Info is because it's running a bit slowly. it uses variable way to get Process info and return too large info to me. In my case, I just want to check process name.




---

---

I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

I change = TEXT("<unknown>"); into = (TCHAR*) malloc( MAX_PATH * sizeof(TCHAR) ); it looks like working well now. but sequenced question is, how free this memory I allocate in C?

You should not be using malloc(). Did you miss my mention of Newx(), Newxc() Newxz() and the associated link?

how free this memory I allocate in C?

If you followed the link, you would have seen Safefree()

In my case, I just want to check process name.

I tend to use tasklist for that:

perl -E"my @tasks = map[ (split)[0,1] ], `tasklist /nh`; say qq[@$_] f
+or @tasks"
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---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Read perlclib, use Safefree

but sequenced question is, how free this memory I allocate in C?

One way is to create a copy, free the memory, then return the copy.

The following rewrite of get_proc_name() works for me, and frees the memory:

SV * get_proc_name( int processID )
{
    char * szProcessName;
    SV * outsv;
    Newxz(szProcessName, MAX_PATH, char);


    HANDLE hProcess = OpenProcess
                     ( PROCESS_QUERY_INFORMATION |
                     PROCESS_VM_READ,
                     FALSE, processID );


    if (NULL != hProcess )
    {
        HMODULE hMod;
        DWORD cbNeeded;

        if ( EnumProcessModules( hProcess, &hMod, sizeof(hMod), &cbNee
+ded) )
        {
            GetModuleBaseName( hProcess, hMod, szProcessName, MAX_PATH
+ - 1);
        }
        else {
            szProcessName[0] = '#';
            szProcessName[1] = 0;
        }
    }
    else {
       szProcessName[0] = '*';
       szProcessName[1] = 0;
    }

    CloseHandle( hProcess );
    outsv = newSVpv(szProcessName, 0);
    Safefree(szProcessName);
    return outsv;
}
[download]

Cheers,
Rob

return newRV_inc(AV_procs);
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AV* process_list(){

DWORD aProcesses[1024], cbNeeded, cProcesses;
    unsigned int i;
EnumProcesses( aProcesses, sizeof(aProcesses),  &cbNeeded );

cProcesses = cbNeeded / sizeof(DWORD);
AV* AV_procs = newAV();
    for ( i = 0; i < cProcesses; i++ )
    {
        if( aProcesses[i] != 0 )
        {
            av_push(AV_procs, newSViv( aProcesses[i] ) );
        }
    }
    return AV_procs;
}
[download]

new function does avoid the warning, but what does AV* mean in perl? a SV* are able to be a reference of array other than a AV*. though I'm still digging how this warning come, I insist using SV* as returning.




---

---

I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

The typemap automatically creates a reference to it and returns the reference. It's refcount is off by one, though.

use strict;
use warnings;

use Devel::Peek qw( Dump );

use Inline C => <<'__EOI__';

AV* f() {
   return newAV();
}

__EOI__

Dump(f());
[download]

>perl -MInline=FORCE,NOISY,NOCLEAN a.pl
...
SV = IV(0x7bbf18) at 0x7bbf1c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x7bc05c
  SV = PVAV(0x7bcec8) at 0x7bc05c
    REFCNT = 2         <--- XXX
    FLAGS = ()
    ARRAY = 0x0
    FILL = -1
    MAX = -1
    ARYLEN = 0x0
    FLAGS = (REAL)
[download]

Making it mortal doesn't help. So unless I'm missing something, this can only be used if you actually hold a reference to the array you return.

and I think that's not quite the right thing to be doing. According to perlapi, newRV_inc() takes an SV* arg, but AV_procs is an AV*.

An AV is a type of SV. That's indeed the way to create a reference to an array. You just need to cast.

newRV_noinc(MUTABLE_SV(av))
[download]