Date: Fri, 4 Sep 2026 16:58:11 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Sehrope Sarkuni <sehrope@jackdb.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PATCH] Fix getopt_long() argument handling and add tests
Message-ID: <aps-8xDMYZfVQ5rQ@nathan>
References: 
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On Sat, Aug 29, 2026 at 12:57:00PM -0400, Sehrope Sarkuni wrote:
> While reworking the pg_waldump TAP test [1] I ran "pg_waldump --stats
> --limit 5" and it failed on Windows CI with 'could not locate WAL file
> "5"'.  For a long option with optional_argument and no "=", the port
> getopt_long() increments optind in the missing-argument branch and
> again at the end of the long option path, so the next option is
> skipped and its value becomes a positional argument.  The same branch
> returns BADARG when optstring starts with a colon although nothing is
> missing.
> 
> [...]
> 
> 0003 fixes a second problem the tests turned up.  The port moves each
> non-option to the end of argv as soon as it sees it, so by the time a
> following option looks for its argument, a non-option that came before
> it on the command line is already sitting after it and gets taken:
> "pg_amcheck mydb --jobs" parses as --jobs=mydb rather than reporting
> the missing argument.  The system getopt_long() reports the missing
> argument.  The fix bounds the argument search by the start of the
> moved block.  0004 adds the test cases for it, kept separate in case
> 0003 is backpatched without the test module.

Nice finds.  I've attached what I have staged for commit.  I've tried to
simplify the diffs a bit, and I also got rid of the new test module in
favor of adding cases to existing test files.  I don't think we need to
bother back-patching 0001; the bug went undiscovered for ~23 years.  I can
try back-patching 0002 to v17, though.

-- 
nathan

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	filename=v2-0001-Fix-optional-argument-handling-in-in-tree-getopt_.patch

From f04a179b4f24f79f54ce81c6060f45c86a803c34 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Fri, 4 Sep 2026 16:37:01 -0500
Subject: [PATCH v2 1/2] Fix optional-argument handling in in-tree
 getopt_long().

A long option with an optional argument that is given without "="
advances optind twice, so the following argument is skipped.  For
example, "pg_waldump --stats --limit 5" complains that it cannot
locate WAL file "5".  The same path also returns BADARG when
optstring starts with a colon, even though nothing is missing.  To
fix, handle optional arguments before the missing-argument code,
which then only needs to deal with required arguments.

This is a bug fix and could be back-patched, but since this issue
went unnoticed for 23 years, I'm not going to bother.

Author: Sehrope Sarkuni <sehrope@jackdb.com>
Discussion: https://postgr.es/m/CAH7T-arxDuVCSkorO%3Dk7%2BM-_JV0JFzMpN_EtKMyD2K0RDqZ2OA%40mail.gmail.com
---
 src/bin/pg_waldump/t/001_basic.pl |  3 +--
 src/port/getopt_long.c            | 11 +++++------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/bin/pg_waldump/t/001_basic.pl b/src/bin/pg_waldump/t/001_basic.pl
index 8beac19eaff..7b33efc6299 100644
--- a/src/bin/pg_waldump/t/001_basic.pl
+++ b/src/bin/pg_waldump/t/001_basic.pl
@@ -340,11 +340,10 @@ sub test_pg_waldump
 	my ($stdout, $stderr);
 
 	my $result = IPC::Run::run [
-		'pg_waldump',
+		'pg_waldump', @opts,
 		'--start' => $startlsn,
 		'--end' => $endlsn,
 		'--path' => $path,
-		@opts
 	  ],
 	  '>' => \$stdout,
 	  '2>' => \$stderr;
diff --git a/src/port/getopt_long.c b/src/port/getopt_long.c
index 2e869fed58b..0a9a50189f1 100644
--- a/src/port/getopt_long.c
+++ b/src/port/getopt_long.c
@@ -137,8 +137,9 @@ retry:
 					{
 						if (place[namelen] == '=')
 							optarg = place + namelen + 1;
-						else if (optind < argc - 1 &&
-								 has_arg == required_argument)
+						else if (has_arg == optional_argument)
+							optarg = NULL;
+						else if (optind < argc - 1)
 						{
 							optind++;
 							optarg = argv[optind];
@@ -152,16 +153,14 @@ retry:
 								return BADARG;
 							}
 
-							if (opterr && has_arg == required_argument)
+							if (opterr)
 								fprintf(stderr,
 										"%s: option requires an argument -- %s\n",
 										argv[0], place);
 
 							place = EMSG;
 
-							if (has_arg == required_argument)
-								return BADCH;
-							optarg = NULL;
+							return BADCH;
 						}
 					}
 					else
-- 
2.55.0


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	filename=v2-0002-Fix-option-argument-lookup-in-in-tree-getopt_long.patch

From b0fcd1a01b01e9e15d76dcadfae13f33f9ab8bb1 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Fri, 4 Sep 2026 16:47:53 -0500
Subject: [PATCH v2 2/2] Fix option argument lookup in in-tree getopt_long().

The in-tree getopt_long() moves each non-option to the end of argv
as soon as it finds one, which puts a non-option that preceded an
option right where the option's argument lookup expects to find it.
For example, "vacuumdb postgres --jobs" takes "postgres" as the
number of jobs instead of complaining that --jobs is missing its
argument.  To fix, stop the argument lookups at the start of the
moved non-options, which we already track to know when to stop
scanning.

Oversight in commit 411b720343.

Author: Sehrope Sarkuni <sehrope@jackdb.com>
Discussion: https://postgr.es/m/CAH7T-arxDuVCSkorO%3Dk7%2BM-_JV0JFzMpN_EtKMyD2K0RDqZ2OA%40mail.gmail.com
Backpatch-through: 17
---
 src/bin/scripts/t/100_vacuumdb.pl |  4 ++++
 src/port/getopt_long.c            | 14 +++++++-------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/bin/scripts/t/100_vacuumdb.pl b/src/bin/scripts/t/100_vacuumdb.pl
index 7c4e35a6717..b78fa2a38de 100644
--- a/src/bin/scripts/t/100_vacuumdb.pl
+++ b/src/bin/scripts/t/100_vacuumdb.pl
@@ -240,6 +240,10 @@ $node->command_fails_like(
 	[ 'vacuumdb', '--all', 'postgres' ],
 	qr/cannot vacuum all databases and a specific one at the same time/,
 	'cannot use option --all and a dbname as argument at the same time');
+$node->command_fails_like(
+	[ 'vacuumdb', 'postgres', '--jobs' ],
+	qr/requires an argument/,
+	'option missing its argument after a non-option');
 
 $node->safe_psql(
 	'postgres', q|
diff --git a/src/port/getopt_long.c b/src/port/getopt_long.c
index 0a9a50189f1..f2edadb59d5 100644
--- a/src/port/getopt_long.c
+++ b/src/port/getopt_long.c
@@ -66,6 +66,9 @@ getopt_long(int argc, char *const argv[],
 	static int	nonopt_start = -1;
 	static bool force_nonopt = false;
 
+	if (nonopt_start == -1)
+		nonopt_start = argc;
+
 	if (!*place)
 	{							/* update scanning pointer */
 		char	  **args = (char **) argv;
@@ -75,7 +78,7 @@ retry:
 		/*
 		 * If we are out of arguments or only non-options remain, return -1.
 		 */
-		if (optind >= argc || optind == nonopt_start)
+		if (optind >= nonopt_start)
 		{
 			place = EMSG;
 			nonopt_start = -1;
@@ -99,10 +102,7 @@ retry:
 				args[i] = args[i + 1];
 			args[argc - 1] = place;
 
-			if (nonopt_start == -1)
-				nonopt_start = argc - 1;
-			else
-				nonopt_start--;
+			nonopt_start--;
 
 			goto retry;
 		}
@@ -139,7 +139,7 @@ retry:
 							optarg = place + namelen + 1;
 						else if (has_arg == optional_argument)
 							optarg = NULL;
-						else if (optind < argc - 1)
+						else if (optind < nonopt_start - 1)
 						{
 							optind++;
 							optarg = argv[optind];
@@ -222,7 +222,7 @@ retry:
 	{							/* need an argument */
 		if (*place)				/* no white space */
 			optarg = place;
-		else if (argc <= ++optind)
+		else if (nonopt_start <= ++optind)
 		{						/* no arg */
 			place = EMSG;
 			if (*optstring == ':')
-- 
2.55.0


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