Re: [Bug?] Stack Overflow with callback from external library

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Le 17/03/2024 à 18:02, T Lee Davidson a écrit :
> I am working with 'libmicrohttpd' which is available on Debian, Ubuntu, 
> Arch, and probably many others.
>
> A stack overflow occurs when a call is made to the microhttp server, 
> which is started by the project, using `curl localhost:8080`. I have 
> also tried a project with CivetWeb 
> [https://github.com/civetweb/civetweb] and have gotten the same behavior 
> (ie. "No stack." - see below). It seems that the callback Sub is not 
> even executed as the break-point set at the top of the subroutine is not 
> reached.
>
> So, either I am doing something consistently wrong, there is something 
> wrong with both libraries, or Gambas has a bug. I doubt there is 
> something wrong with *both* libraries. But if it is that I am 
> consistently doing something wrong, then, great, at least I'm consistent.
>
> The project is based on the minimal example from 
> https://www.gnu.org/software/libmicrohttpd/#quickintro which I have 
> updated based on minimal_example.c from the libmicrohttpd-0.9.57 source 
> and included in the project. The compiled C example works fine as does a 
> simple example from CivetWeb.
>
> Also included in the project are the output from GDB and, in case it 
> helps, timestamped traces (following forks) from the minimal C example 
> and this 'MicroHttp' project (attached).
>
> GDB's 'bt' command reports, "No stack." And, in those respective traces 
> the incoming HTTP connection is accepted at timestamp 12:01:21 and at 
> timestamp 12:12:04.
>
> Relevant links:
> Reference Manual: 
> https://www.gnu.org/software/libmicrohttpd/manual/libmicrohttpd.html
> Source code: https://ftp.gnu.org/gnu/libmicrohttpd/
>
> [System]
> Gambas=3.19.0 05b63581 (stable)
> OperatingSystem=Linux
> Distribution=openSUSE Leap 15.5
> Kernel=5.14.21-150500.55.52-default
> Architecture=x86_64
> Cores=6
> Memory=15981M
> Language=en_US.UTF-8
> Desktop=KDE
> DesktopResolution=96
> DesktopScale=7
> WidgetTheme=breeze
> Font=Noto Sans,10
> ** Full System Information in project **

It can't work as soon as libmicrohttpd tries to run the callback in 
multiple threads. Gambas interpreter can only work in one same thread.

Regards,

--
Benoît Minisini.