Re: Add lasterrno setting for dir_existsfile()

On Mon, Jan 10, 2022 at 12:19:28AM +0800, Wei Sun wrote:
> Hi,
>
> Some time ago,the following patch clean up error handling in pg_basebackup's
> walmethods.c.
> https://github.com/postgres/postgres/commit/248c3a9
>
> This patch keep the error state in the DirectoryMethodData struct,
> in most functions, the lasterrno is set correctly, but in function
> dir_existsfile(),
> the lasterrno is not set when the file fails to open.
>
> If this is a correction omission, I think this patch can fix this.
>
> Cheers

> diff --git a/src/bin/pg_basebackup/walmethods.c b/src/bin/pg_basebackup/walmethods.c
> index f74bd13..35cf5a8 100644
> --- a/src/bin/pg_basebackup/walmethods.c
> +++ b/src/bin/pg_basebackup/walmethods.c
> @@ -580,7 +580,10 @@ dir_existsfile(const char *pathname)
>
> fd = open(tmppath, O_RDONLY | PG_BINARY, 0);
> if (fd < 0)
> + {
> + dir_data->lasterrno = errno;
> return false;
> + }
> close(fd);
> return true;
> }

Looking at this, the function is used to check if something exists, and
return a boolean. I am not sure it is helpful to also return a ENOENT in
the lasterrno status field. It might be useful to set lasterrno if the
open fails and it is _not_ ENOENT.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson