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From: Dmitry Koval <d.koval@postgrespro.ru>
To: Michael Paquier <michael@paquier.xyz>
Cc: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17288: PSQL bug with COPY command (Windows)
Date: Fri, 19 Nov 2021 11:47:02 +0300
Message-ID: <4c22d38f-efa9-4d83-c551-707f1770e585@postgrespro.ru> (raw)
In-Reply-To: <YZdK6DjbtCT7rz9S@paquier.xyz>
References: <17288-6b58a91025a8a8a3@postgresql.org>
	<b95273fb-a51a-d0a9-e4a8-501e32e204e5@postgrespro.ru>
	<YZYDZwDtw/Ioojb4@paquier.xyz>
	<9e4efe29-0ff9-0808-fe32-d1d50e0be4fa@postgrespro.ru>
	<CAC+AXB3BKByL8O39qARu3XYMWmrNqMWhcHZZ_2ygqvrK-W6O1g@mail.gmail.com>
	<fe1cde9e-1e52-4f24-3ff7-d01f28a63790@postgrespro.ru>
	<YZdK6DjbtCT7rz9S@paquier.xyz>

 >I still think that we should not call GetFileInformationByHandle()
 >when it comes to an argument that we know will fail, ...

Our program calls function freopen() (this function is used in file
src\backend\utils\error\elog.c). So we don't know exactly that
GetFileInformationByHandle() will fails for stdin/stdout/stderr.

Ior illustration, I attached small example (test.c) for this case:
1) GetFileInformationByHandle() for "stdout" works without error;
2) file "1.txt" after running test contains:

Sample string
attributes = 0x2020, file size = 15

 >Each fileno is going to be 0, 1 or 2 in those cases, still
 >it would be better to rely on the result of fileno() as v3 is
 >doing?

I think fileno() is safer. We can call fclose(stdout) and
_fileno(stdout) returns -1 after that. But I don't know:
can OS reuse fileno=1 or not in this case?

With best regards,
Dmitry.

Attachments:


test.c (text/plain, 726B) download
#include <windows.h>
#include <stdio.h>
#include <io.h>

int main()
{
	int err;
	FILE* stream;
	HANDLE hFile;
	BY_HANDLE_FILE_INFORMATION fiData;

	if (err = freopen_s(&stream, "1.txt", "a", stdout))
	{
		printf("freopen_s error %d\n", err);
		return 1;
	}

	printf("Sample string\n");
	fflush(stdout);

	hFile = (HANDLE)_get_osfhandle(_fileno(stdout));
	if (hFile == INVALID_HANDLE_VALUE)
	{
		printf("_get_osfhandle error\n");
		return 1;
	}

	if (!GetFileInformationByHandle(hFile, &fiData))
	{
		printf("GetFileInformationByHandle error %d\n", GetLastError());
		return 1;
	}

	printf("attributes = 0x%X, file size = %d\n", fiData.dwFileAttributes, fiData.nFileSizeLow);

	return 0;
}

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  Cc: d.koval@postgrespro.ru, michael@paquier.xyz, juanjo.santamaria@gmail.com, pgsql-bugs@lists.postgresql.org
  Subject: Re: BUG #17288: PSQL bug with COPY command (Windows)
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