[Issue 17102] std.write.file generates a segmentation fault when the file name is a string with a default value

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17102

Vladimir Panteleev <thecybershadow at gmail.com> changed:

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
                 CC|                            |thecybershadow at gmail.com
         Resolution|---                         |WONTFIX

--- Comment #3 from Vladimir Panteleev <thecybershadow at gmail.com> ---
(In reply to donte5379 from comment #2)
> I think that std.file.write should throw an exception before the null gets
> passed to the C API.

I don't think it's the job of the standard library to validate that the input
parameter is valid before passing it to a C API.

> Even if I add a try-catch block all I see is a message
> "Segmentation fault" on the terminal. 
> 
>   std.file.write(file_name, the_text);
>   } catch (Exception e){
>     writeln(e);
>   }

Writing to a file whose file name is unset is a logic error in the user's code,
so if such a check would be present in std.file.write, its correct behavior
would be to throw an Error, which would also bypass your try/catch block (as
you only catch an Exception), so the program would behave similarly.

The main difference would be that on POSIX, by default the D runtime doesn't
attempt to handle and print a stack trace on unhandled signals (which would
otherwise terminate the program). On Linux, there exists etc.linux.memoryerror,
which translates segmentation faults to D exceptions. On Windows, access
violations are already translated to D exceptions through D's support for
Windows structured exception handling.

Either way, finding the cause of the segmentation fault would have been as
simple as running your program under a debugger.

> As an added frustration the redirection is corrupted in bash (and tcsh) and
> so it is difficult to run dustmite.

The DustMite documentation contains examples on correctly reducing segmentation
faults. I've also created a page to explain the basics:
https://github.com/CyberShadow/DustMite/wiki/Reducing-a-segmentation-fault

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