From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@gmail.com>
cc: Bryan Green <dbryan.green@gmail.com>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PATCH] O_CLOEXEC not honored on Windows - handle inheritance
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Comments: In-reply-to Thomas Munro <thomas.munro@gmail.com>
	message dated "Wed, 10 Dec 2025 10:03:07 +1300"
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Date: Fri, 12 Dec 2025 21:44:11 -0500
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Thomas Munro <thomas.munro@gmail.com> writes:
> Hearing nothing, pushed.

fairywren is unimpressed:

../pgsql/src/test/modules/test_cloexec/test_cloexec.c: In function 'run_pa=
rent_tests':
../pgsql/src/test/modules/test_cloexec/test_cloexec.c:137:29: warning: unu=
sed variable 'space_pos' [-Wunused-variable]
  137 |                 char       *space_pos;
      |                             ^~~~~~~~~

It's right, but it seems to me that this stanza needs more help than
that:

    /*
     * Spawn child process with bInheritHandles=3DTRUE, passing handle val=
ues as
     * hex strings
     */
    snprintf(cmdline, sizeof(cmdline), "\"%s\" %p %p",
             GetCommandLine(), h1, h2);

    /*
     * Find the actual executable path by removing any arguments from
     * GetCommandLine().
     */
    {
        char        exe_path[MAX_PATH];
        char       *space_pos;

        GetModuleFileName(NULL, exe_path, sizeof(exe_path));
        snprintf(cmdline, sizeof(cmdline), "\"%s\" %p %p",
                 exe_path, h1, h2);
    }

What is the point of that first snprintf(cmdline, ...), when its
result is guaranteed to be overwritten just below?

I'm also dubious about using MAX_PATH here; see the commentary
about MAXPGPATH in pg_config_manual.h.  Also, what's the point of
using MAX_PATH when the result is going to be transferred into
cmdline (with a hardwired size of 1024)?

			regards, tom lane