Re: Can we avoid chdir'ing in resolve_symlinks() ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Can we avoid chdir'ing in resolve_symlinks() ?
Date: 2022-09-04 02:41:53
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Here's a draft patch for this. It seems to work on Linux,
but the Windows code is just speculation. In particular,
I did

path = _fullpath(NULL, fname, 0);
if (path == NULL)

but I'm not really sure that the _dosmaperr bit is needed,
because the _fullpath man page I found makes reference to
setting "errno" [1]. It's likely to be hard to test, because
most of the possible error cases should be nigh unreachable
in our usage; we already know the input is a valid reference
to an executable file.

BTW, I noticed what seems a flat-out bug in validate_exec:

/* Win32 requires a .exe suffix for stat() */
- if (strlen(path) >= strlen(".exe") &&
+ if (strlen(path) < strlen(".exe") ||
pg_strcasecmp(path + strlen(path) - strlen(".exe"), ".exe") != 0)

Nobody's noticed because none of our executables have base names
shorter than 4 characters, but it's still a bug.

regards, tom lane


Attachment Content-Type Size
use-realpath-in-find_my_exec-1.patch text/x-diff 8.3 KB

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