Originally bug was reported by Yuri Kurenkov:
https://github.com/postgrespro/pg_probackup/issues/48

As pg_probackup rely on readdir() for listing files to backup, wrong permissions could lead to a broken backup.

On 02/25/2019 06:38 PM, 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.


--
Grigory Smolkin
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company


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