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md5: Encode non-printable filenames
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Authored by des on Apr 24 2026, 11:42 AM.

Details

Reviewers

kevans
markj
bcr

Group Reviewers

security

Commits

rGd23df52343be: md5: Encode non-printable filenames
rG69588094a112: md5: Encode non-printable filenames
rG70fde0ed6bbb: md5: Encode non-printable filenames

Summary

Encode filenames in the VIS_CSTYLE | VIS_OCTAL style regardless of
output mode. When reading filenames from a checksum file, attempt to
decode them, and use the decoded name unless the decoded name does not
exist but the undecoded one does.

This breaks compatibility with GNU coreutils, which unfortunately uses
a non-reversible encoding when outputting filenames containing
non-printable characters.

While here, drop a sentence about preimage attacks against MD5 and SHA1
from the manual page, as I no longer trust it to be true.

MFC after: 1 week

Diff Detail

Repository

rG FreeBSD src repository

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Unit

Tests Not Applicable

Event Timeline

des created this revision.Apr 24 2026, 11:42 AM

Herald added subscribers: ziaee, imp. · View Herald TranscriptApr 24 2026, 11:42 AM

des requested review of this revision.Apr 24 2026, 11:42 AM

Harbormaster completed remote builds in B72515: Diff 176323.Apr 24 2026, 11:42 AM

Harbormaster completed remote builds in B72522: Diff 176339.Apr 24 2026, 2:36 PM

OK for the man page part of the change.

This revision is now accepted and ready to land.Sat, Apr 25, 8:25 AM

markj added inline comments.Mon, Apr 27, 2:17 PM

sbin/md5/md5.c
402	Why _GLOB and _SHELL? The concern is related to terminal escape sequences. I'd think that VIS_SAFE (and VIS_NL) is sufficient.
656	Missing newline after variable declarations.

des marked an inline comment as done.Mon, Apr 27, 4:56 PM

des added inline comments.

sbin/md5/md5.c
402	Because I'm also concerned about scripts parsing the output and being careless with the result...

markj added inline comments.Mon, Apr 27, 5:01 PM

sbin/md5/md5.c
402	Ok, but then we should explicitly include VIS_SAFE in the list too. ANSI escape sequences get mangled as a consequence of embedding '[', covered by VIS_GLOB, but we probably shouldn't rely on that.

des added inline comments.Mon, Apr 27, 5:14 PM

sbin/md5/md5.c
402	No, we should most definitely not add `VIS_SAFE`. It prevents the backspace, bell, and carriage return characters from being encoded.

markj added inline comments.Mon, Apr 27, 5:18 PM

sbin/md5/md5.c
402	Why would you expect to find those in a filename?

des added inline comments.Mon, Apr 27, 6:29 PM

sbin/md5/md5.c
402	I wouldn't, but that's the whole point of this change.

markj added inline comments.Mon, Apr 27, 9:19 PM

sbin/md5/md5.c
402	Right, so why not escape those characters?

des added inline comments.Tue, Apr 28, 10:28 AM

sbin/md5/md5.c
402	Exactly. Right now they are being escaped. If we add `VIS_SAFE` they won't be.

markj accepted this revision.Wed, Apr 29, 6:28 PM

markj added inline comments.

sbin/md5/md5.c
402	Ok I finally get it, I misunderstood what VIS_SAFE actually does.

des added inline comments.Wed, Apr 29, 6:32 PM

sbin/md5/md5.c
402	I'll submit a patch for the manual page.

Closed by commit rG70fde0ed6bbb: md5: Encode non-printable filenames (authored by des). · Explain WhyWed, Apr 29, 6:41 PM

This revision was automatically updated to reflect the committed changes.

des added a commit: rG70fde0ed6bbb: md5: Encode non-printable filenames.

des added a commit: rG69588094a112: md5: Encode non-printable filenames.Thu, Apr 30, 9:07 PM

des added a commit: rGd23df52343be: md5: Encode non-printable filenames.

Revision Contents
Changeset List

Path

Size

sbin/

md5/

md5.1

30 lines

md5.c

41 lines

Diff 176821

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sbin/md5/md5.1