The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Listing information on all active interfaces on MacOS part 1: getting the active interface names

Posted by jpluimers on 2021/07/29

Listing Listing information on all active interfaces on MacOS is a process involving multiple pieces, which then can be combined together.

Listing all active interfaces try 1

This involves both the -l (list with optional criteria) and -u parameter (the up criterion) as per excerpts from the [] ifconfig(8) [osx man page] / [WayBack] ifconfig Man Page – macOS –

     ifconfig -- configure network interface parameters

     ifconfig -l [-d] [-u] [address_family]

     The ifconfig utility is used to assign an address to a network interface and/or configure network interface parameters.

     The following options are available:


             Specify the address family which affects interpretation of the remaining parameters.  Since an interface can receive transmissions
             in differing protocols with different naming schemes, specifying the address family is recommended.  The address or protocol fami-
             lies currently supported are ``inet'', ``inet6'', and ``link''.  The default is ``inet''.  ``ether'' and ``lladdr'' are synonyms
             for ``link''.


     The -l flag may be used to list all available interfaces on the system, with no other additional information.  Use of this flag is mutually
     exclusive with all other flags and commands, except for -d (only list interfaces that are down) and -u (only list interfaces that are up).


ifconfig -l -u

Each interface on one line:

ifconfig -l -u | xargs -n1 echo

The problem is that on my system, it also lists bridges as active, whereas they are not:

# ifconfig -l -u | xargs -n1 echo

# ifconfig bridge0
    ether 6a:00:02:9a:23:f0 
        id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
        maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
        root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
        ipfilter disabled flags 0x2
    member: en1 flags=3<LEARNING,DISCOVER>
            ifmaxaddr 0 port 5 priority 0 path cost 0
    member: en2 flags=3<LEARNING,DISCOVER>
            ifmaxaddr 0 port 6 priority 0 path cost 0
    Address cache:
    nd6 options=201<PERFORMNUD,DAD>
    status: inactive

So this is where the MacOS and BSD documentation is inaccurate.

Interface types

The above interfaces are many more than just ethernet or WiFi interfaces; there is a list at [WayBack] macos – What are en0, en1, p2p, and so on, that are displayed after executing ifconfig? – Stack Overflow by [WayBackmcint:

In arbitrary order of my familarity / widespread relevance:

lo0 is loopback.

en0 at one point “ethernet”, now is WiFi (and I have no idea what extra en1 or en2 are used for).

fw0 is the FireWire network interface.

stf0 is an IPv6 to IPv4 tunnel interface to support the transition from IPv4 to the IPv6 standard.

gif0 is a more generic tunneling interface [46]-to-[46].

awdl0 is Apple Wireless Direct Link

p2p0 is related to AWDL features. Either as an old version, or virtual interface with different semantics than awdl.

many VPNs will add additional devices, often “utun#” or “utap#” following TUN/TAP (L3/L2)virtual networking devices.

More on AWDL at [WayBack] ios – What is AWDL (Apple Wireless Direct Link) and how does it work? – Stack Overflow.

Listing all active interfaces try 2

Read the rest of this entry »

Posted in *nix, *nix-tools, Apple, bash, Development, ifconfig, Mac OS X / OS X / MacOS, Power User, Scripting, Software Development | Leave a Comment »

Delphi run-time errors

Posted by jpluimers on 2021/07/29

Since I always forget where to get the full list: there is none in the documentation. Only parts.

Usually the mapping is from run-time errors to exceptions:

In addition, exceptions are converted to run-time errors when the exception handling mechanism in the SysUtils unit is not up.

This can happen early in start-up, or late un shut-down of an application.

The one I encountered most is the runtime error 216 during shutdown: it is an Access Violation (EAccessViolation).

Run-time errors (not changed since Delphi 2007)

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Posted in Delphi, Development, Software Development | Leave a Comment »

Frank A. Krueger on Twitter: “I made a build status IoT thing! Automatically polls @bitrise and is even Alexa controlled (for brightness and to turn off). Now I want to add github issue and PR counts. Just a $12 ESP32 and a $30 led matrix.”

Posted by jpluimers on 2021/07/28

[WayBack] Frank A. Krueger on Twitter: “I made a build status IoT thing! Automatically polls @bitrise and is even Alexa controlled (for brightness and to turn off). Now I want to add github issue and PR counts. Just a $12 ESP32 and a $30 led matrix.”



Posted in Development, DVCS - Distributed Version Control, ESP32, GitHub, Hardware Development, Software Development, Source Code Management | Leave a Comment »

-r argument to pipe (no argument for MacOS)- If no input is given to xargs, don’t let xargs run the utility – Unix & Linux Stack Exchange

Posted by jpluimers on 2021/07/28


There is a non-standard -r option to xargs that allows it to skip executing when there are no arguments at all.

On some operating systems, the -r is default.

MacOS has no -r, but does not execute xargs if there are no arguments given.

Read the rest of this entry »

Posted in *nix, *nix-tools, bash, bash, Development, Power User, Scripting, Software Development, xargs | Leave a Comment »

“Unexpected Memory Leak” after “MyTestApplication.exe: Memory Leak Detected”

Posted by jpluimers on 2021/07/28

Sometimes after a regular FastMM memory leak test report you get a dialog like this:

Unexpected Memory Leak
An unexpected memory leak has occurred. The unexpected small block leaks are:

61 - 68 bytes: Unknown x 1

The normal FastMM memory leak reporting dialog looks like this:

MyTestApplication.exe: Memory Leak Detected
Note: Memory leak detail is logged to a text file in the same folder as this application. To disable this memory leak check, undefine "EnableMemoryLeakReporting".

Searching for “Unexpected Memory Leak” in RTL or FastMM code did not reveal results, but that might be me not doing a proper search.

One big problem is that the regular memory leak dialog is being suppressed by setting SuppressMessageBoxes to True (see for instance my blog post Application shutdown: wait for all threads to terminate or not? or [WayBack] delphi – Generating a FASTMM report WITHOUT the shutdown dialog – Stack Overflow).

However the “Unexpected Memory Leak” message box is always shown.


Location of the error message caption

  • GETMEM.INC has an identifier LeakMessageTitle:
    LeakMessageTitle: _PAnsiChr = 'Unexpected Memory Leak';
  • Unlike FastMM4.pas, GETMEM.INC does not take into account SuppressMessageBoxes.
  • Like FastMM4.pas, GETMEM.INC does take into account ReportMemoryLeaksOnShutdown.

More on GETMEM.INC: [WayBack] delphi – Reporting memory leaks on shutdown with a console application – Stack Overflow

Versioned FastMM4.pas.

Complicating the hunt

Not all allocations go via the memory manager. A complicating factor is that:

  • ALL TMonitor.Create allocations go through SysAllocMem:
class function TMonitor.Create: PMonitor;
  if CacheLineSize = 0 then
    AtomicExchange(CacheLineSize, GetCacheLineSize);
  if (CPUCount > 1) and (FDefaultSpinCount = 0) then
    AtomicExchange(FDefaultSpinCount, 1000);
  if CacheLineSize > SizeOf(Result^) then
    Result := SysAllocMem(CacheLineSize)
    Result := SysAllocMem(SizeOf(Result^));
  Result.FSpinCount := FDefaultSpinCount;
  • ALL TMonitor.Destroy deallocations go through SysFreeMem:
procedure TMonitor.Destroy;
  if (MonitorSupport <> nil) and (FLockEvent <> nil) then

Debugging this is easiest to set a breakpoint in the FastMM4.pas finalization section enabling a breakpoint group that has breakpoints on these methods inside GETMEM.INC:

  • function SysGetMem(Size: NativeInt): Pointer;
  • function SysFreeMem(P: Pointer): Integer;
  • function SysReallocMem(P: Pointer; Size: NativeInt): Pointer;
  • function SysAllocMem(Size: NativeInt): Pointer;

For inspecting for instance an asm construct like TSmallPoolBlockPoolHeader[edx], use a conversion PSmallBlockPoolHeader(Pointer(EDX))^,r

Poor mans shotgun approach

This will hide all the SysAllocMem related leaks:

unit FastMM4WrapperUnit;


{$ifdef UseFastMM4}
{$endif UseFastMM4}


// Disable GETMEM.INC reports that neglect SuppressMessageBoxes and NoErrMsg; this will effectively hide the leak as GETMEM.INC also does not write the leaks to a log file
{$ifdef UseFastMM4}
  if SuppressMessageBoxes then
    {$WARN SYMBOL_PLATFORM OFF} NoErrMsg := True {$WARN SYMBOL_PLATFORM ON}; // no ShowMessage from the RTL (except for memory leaks)
    ReportMemoryLeaksOnShutdown := False; // No ShowMessage from the RTL in the GETMEM.INC teardown
{$endif UseFastMM4}

IsConsole: needs linker option

Note that I tried embedding this in the then portion, but enabling IsConsole fails:

    IsConsole := True; // can only force run-time error messages to be written to the console if the "Project/Options/Linking/Generate console application" is set.

The reason is that this does not allocate a console handle, so you really need to ensure the linker has allocated a console for you by enabling Project/Options/Linking/Generate console application (or option DCC_ConsoleTarget in the .dproj file)

For more details, see my post console – When is System.IsConsole true in Delphi? – Stack Overflow.


Posted in Conference Topics, Conferences, Delphi, Development, Event, FastMM, Software Development | Leave a Comment »

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