[fpc-devel] stat and nil

[Martin Frb]

Strange fpstat adds #0, so it should never be nil.

But valgrind said it was

On 04/10/2026 11:08, Martin Frb via fpc-devel wrote:
> Are older Linux versions safe to  call stat with a nil pointer?
>
> https://man7.org/linux/man-pages/man2/stat.2.html
> >  If /path/ is an empty string (or NULL, since Linux 6.11)
>
> (According to google 6.11 is from 2024 / if so, older versions are 
> still out there)
>
>
>
> 3.3.1\source\rtl\unix\sysutils.pp
>
> Function DirectoryExists (Const Directory : RawByteString; FollowLink 
> : Boolean) : Boolean;
> Var
>   Info : Stat;
>   SystemFileName: RawByteString;
>   exists: Boolean;
> begin
> SystemFileName:=ToSingleByteFileSystemEncodedFileName(Directory);
>   exists:=fpstat(pointer(SystemFileName),Info)>=0;
>
>
> If the filename is empty, then path is nil.
>
> Valgrind annotates that (even on a new Linux)
> ==28712== Syscall param stat(file_name) points to unaddressable byte(s)
> ==28712==    at 0x4B2B64: SYSTEM_$$_FPSYSCALL$INT64$INT64$INT64$$INT64 
> (in /home/me/lazgit/lazarus)
> ==28712==    by 0x4B3884: SYSTEM_$$_FPSTAT$PCHAR$STAT$$LONGINT (in 
> /home/me/lazgit/lazarus)
> ==28712==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
>
>
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