Your message dated Sat, 01 Aug 2026 15:19:01 +0000
with message-id <[email protected]>
and subject line Bug#1142663: fixed in libsocket-msghdr-perl 0.06-2
has caused the Debian Bug report #1142663,
regarding libsocket-msghdr-perl: recvmsg fails to set flags (.msg_flags)
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
1142663: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1142663
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: libsocket-msghdr-perl
Version: 0.05-2+b4
Severity: normal
Tags: patch upstream
Dear Maintainer,
recvmsg in Socket::MsgHdr fails to set the `flags' value to
what the recvmsg(2) syscall writes to `struct msghdr'.msg_flags.
This makes it impossible to detect truncation errors such as
MSG_TRUNC and MSG_CTRUNC when the `buflen' and `controllen'
fields are too small. Attached is a patch which fixes the
issue in upstream.
Unfortunately, I cannot contribute directly to upstream due to
Terms of Service and JS requirement of Github causing
accessibility problems.
>From af9d3624155ab51cd752f27981ef3b7287d24153 Mon Sep 17 00:00:00 2001
From: Eric Wong <[email protected]>
Date: Thu, 23 Jul 2026 20:54:15 +0000
Subject: [PATCH] recvmsg: set `flags' field according to .msg_flags
The .msg_flags field of `struct msghdr' gets populated by the
recvmsg(2) syscall. Most notably, .msg_flags allows the
receiver to detect truncation via MSG_TRUNC and MSG_CTRUNC flags
when the supplied `buflen' and/or `controllen' fields are too
small.
Note that MSG_TRUNC set in .msg_flags by recvfrom is different
from the `flags' argument. MSG_TRUNC in the `flags' argument
changes the return value of recvfrom(2) to the intended length
of the data, whereas .msg_flags merely tells the caller the
buffer is too small and does not tell the intended length.
MSG_TRUNC in the `flags' argument probably makes the most sense
with MSG_PEEK, as shown in the below example to dynamically
size `buflen' to the necessary value to avoid MSG_TRUNC in
.msg_flags in a subsequent recvmsg call:
use Socket;
use Socket::MsgHdr;
my ($rd, $wr);
socketpair($rd, $wr, AF_UNIX, SOCK_DGRAM, 0) or die "socketpair: $!";
my $hdr = Socket::MsgHdr->new(buf => 'ab');
sendmsg($wr, $hdr, 0) or die "sendmsg: $!";
my $m = Socket::MsgHdr->new(buflen => 1);
my $r = recvmsg($rd, $m, MSG_TRUNC|MSG_PEEK) or die "recvmsg: $!";
print "MSG_TRUNC=", MSG_TRUNC, "\n";
print "before: r=$r flags=", $m->flags,
" (expecting (flags & MSG_TRUNC=${\MSG_TRUNC}))\n";
$m = Socket::MsgHdr->new(buflen => $r);
recvmsg($rd, $m, 0) or die "recvmsg: $!";
print " after: r=$r flags=", $m->flags, " (expecting flags==0)\n";
---
MsgHdr.xs | 4 ++++
t/30recv.t | 40 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/MsgHdr.xs b/MsgHdr.xs
index 0e4b932..9b7123a 100644
--- a/MsgHdr.xs
+++ b/MsgHdr.xs
@@ -158,6 +158,10 @@ smh_recvmsg(s, msg_hdr, flags = 0)
SvCUR_set(*svp, RETVAL);
if ((svp = hv_fetch(hsh, "control", 7, FALSE)))
SvCUR_set(*svp, mh.m.msg_controllen);
+ if ((svp = hv_fetch(hsh, "flags", 5, FALSE))) {
+ SvUPGRADE(*svp, SVt_IV);
+ SvIV_set(*svp, mh.m.msg_flags);
+ }
}
OUTPUT:
RETVAL
diff --git a/t/30recv.t b/t/30recv.t
index 7bb2b8e..c12daa4 100644
--- a/t/30recv.t
+++ b/t/30recv.t
@@ -6,7 +6,7 @@
# change 'tests => 1' to 'tests => last_test_to_print';
use Test::More;
-BEGIN { plan tests => 9 };
+BEGIN { plan tests => 11 };
use bytes;
use strict;
use Socket;
@@ -124,4 +124,42 @@ SKIP: {
cmp_ok($dev1, '==', $dev2, "scm_rights fds on same device");
cmp_ok($ino1, '==', $ino2, "scm_rights fds are same inode");
+
+ eval { &MSG_CTRUNC; }; # autoloaded, may not be defined yet
+ skip "msg_ctrunc not defined", 1 if $@;
+
+ socketpair(Rd, Wr, AF_UNIX, SOCK_DGRAM, 0)
+ or die "socketpair: $!\n";
+
+ $hdr = new Socket::MsgHdr(buf => "hello!");
+ $hdr->cmsghdr(SOL_SOCKET, SCM_RIGHTS, pack('i', fileno STDIN));
+ sendmsg(\*Wr, $hdr, 0)
+ or die "sendmsg: $!\n";
+
+ $m = new Socket::MsgHdr(buflen => 256, controllen => 1);
+ recvmsg(\*Rd, $m, 0)
+ or die "recvmsg: $!\n";
+
+ ok($m->flags & MSG_CTRUNC, 'MSG_CTRUNC set when controllen is too short');
+
+ close Rd; close Wr;
+};
+
+# 11
+SKIP: {
+ local (*Rd, *Wr);
+ socketpair(Rd, Wr, AF_UNIX, SOCK_DGRAM, 0)
+ or die "socketpair: $!\n";
+
+ my $hdr = new Socket::MsgHdr(buf => 'ab');
+ sendmsg(\*Wr, $hdr, 0)
+ or die "sendmsg: $!\n";
+
+ my $m = new Socket::MsgHdr(buflen => 1);
+ recvmsg(\*Rd, $m, 0)
+ or die "recvmsg: $!\n";
+
+ ok($m->flags & MSG_TRUNC, 'MSG_TRUNC set when buflen is too short');
+
+ close Rd; close Wr;
};
--- End Message ---
--- Begin Message ---
Source: libsocket-msghdr-perl
Source-Version: 0.06-2
Done: gregor herrmann <[email protected]>
We believe that the bug you reported is fixed in the latest version of
libsocket-msghdr-perl, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to [email protected],
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
gregor herrmann <[email protected]> (supplier of updated libsocket-msghdr-perl
package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing [email protected])
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Format: 1.8
Date: Sat, 01 Aug 2026 16:54:00 +0200
Source: libsocket-msghdr-perl
Architecture: source
Version: 0.06-2
Distribution: unstable
Urgency: medium
Maintainer: Debian Perl Group <[email protected]>
Changed-By: gregor herrmann <[email protected]>
Closes: 1142663
Changes:
libsocket-msghdr-perl (0.06-2) unstable; urgency=medium
.
* Team upload.
* Re-upload after git-debpush error.
.
libsocket-msghdr-perl (0.06-1) unstable; urgency=medium
.
* Team upload.
* Import upstream version 0.06.
Fixes "recvmsg fails to set flags (.msg_flags)"
(Closes: #1142663)
* Declare compliance with Debian Policy 4.7.4.
* Remove «Rules-Requires-Root: no», which is the current default.
* Remove «Priority: optional», which is the current default.
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