From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
To: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: readdir is incorrectly implemented at Windows
Date: Fri, 1 Mar 2019 12:36:55 -0500
Message-ID: <7b740522-3c48-1217-03f0-e2acf8f6b345@2ndQuadrant.com> (raw)
In-Reply-To: <2cad7829-8d66-e39c-b937-ac825db5203d@postgrespro.ru>
References: <2cad7829-8d66-e39c-b937-ac825db5203d@postgrespro.ru>
On 2/25/19 10:38 AM, Konstantin Knizhnik wrote:
> Hi hackers,
>
> Small issue with readir implementation for Windows.
> Right now it returns ENOENT in case of any error returned by
> FindFirstFile.
> So all places in Postgres where opendir/listdir are used will assume
> that directory is empty and
> do nothing without reporting any error.
> It is not so good if directory is actually not empty but there are not
> enough permissions for accessing the directory and FindFirstFile
> returns ERROR_ACCESS_DENIED:
>
> struct dirent *
> readdir(DIR *d)
> {
> WIN32_FIND_DATA fd;
>
> if (d->handle == INVALID_HANDLE_VALUE)
> {
> d->handle = FindFirstFile(d->dirname, &fd);
> if (d->handle == INVALID_HANDLE_VALUE)
> {
> errno = ENOENT;
> return NULL;
> }
> }
>
>
> Attached please find small patch fixing the problem.
>
Diagnosis seems correct. I wonder if this is responsible for some odd
things we've seen over time on Windows.
This reads a bit oddly:
{
- errno = ENOENT;
+ if (GetLastError() == ERROR_FILE_NOT_FOUND)
+ {
+ /* No more files, force errno=0 (unlike mingw) */
+ errno = 0;
+ return NULL;
+ }
+ _dosmaperr(GetLastError());
return NULL;
}
Why not something like:
if (GetLastError() == ERROR_FILE_NOT_FOUND)
errno = 0;
else
_dosmaperr(GetLastError());
return NULL;
cheers
andrew
--
Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: andrew.dunstan@2ndquadrant.com, k.knizhnik@postgrespro.ru
Subject: Re: readdir is incorrectly implemented at Windows
In-Reply-To: <7b740522-3c48-1217-03f0-e2acf8f6b345@2ndQuadrant.com>
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