On Wed, Nov 20, 2019 at 12:28 AM Thomas Munro <thomas.munro@gmail.com> wrote:
>
> On Wed, Nov 20, 2019 at 1:14 AM Juan José Santamaría Flecha
> <juanjo.santamaria@gmail.com> wrote:
> > On Tue, Nov 19, 2019 at 12:49 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> >> On Wed, Nov 20, 2019 at 12:28 AM Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
> >> > On Windows, it is documented that ReadFile() (which is called by
> >> > pg_pread) will return false on EOF but only when the file is open for
> >> > asynchronous reads/writes. But here we are just dealing with usual
> >> > synchronous reads. So pg_pread() code should indeed return 0 on EOF on
> >> > Windows. Not yet able to figure out how FileRead() managed to return
> >> > this error on Windows. But from your symptoms, it does look like
> >> > pg_pread()=>ReadFile() returned false (despite doing asynchronous
> >> > reads), and so _dosmaperr() gets called, and then it does not find the
> >> > eof error in doserrors[], so the "unrecognized win32 error code"
> >> > message is printed. May have to dig up more on this.
> >>
> >> Hmm. See also this report:
> >>
> >>
https://www.postgresql.org/message-id/flat/CABuU89MfEvJE%3DWif%2BHk7SCqjSOF4rhgwJWW6aR3hjojpGqFbjQ%40mail.gmail.com
> >>
> >
> > The files from pgwin32_open() are open for synchronous access, while pg_pread() uses the asynchronous functionality
tooffset the read. Under these circunstances, a read past EOF will return ERROR_HANDLE_EOF (38), as explained in:
>
> Oh, thanks.
>
> > https://devblogs.microsoft.com/oldnewthing/20150121-00/?p=44863
>
> !?!
>
> Amit, since it looks like you are Windows-enabled and have a repro,
> would you mind confirming that this fixes the problem?
>
> --- a/src/port/pread.c
> +++ b/src/port/pread.c
> @@ -41,6 +41,9 @@ pg_pread(int fd, void *buf, size_t size, off_t offset)
> overlapped.Offset = offset;
> if (!ReadFile(handle, buf, size, &result, &overlapped))
> {
> + if (GetLastError() == ERROR_HANDLE_EOF)
> + return 0;
> +
> _dosmaperr(GetLastError());
> return -1;
> }
Yes, this works for me.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
