From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 2/4] syscall: more idiomatic cmsghdr space allocation
Date: Mon, 18 Apr 2022 09:50:02 +0000 [thread overview]
Message-ID: <20220418095004.466-3-e@80x24.org> (raw)
In-Reply-To: <20220418095004.466-1-e@80x24.org>
Since we know the space required under Linux, we can use the
same initialization as the Inline::C version instead of
hard-coding 256 as we do for Socket::MsgHdr.
---
lib/PublicInbox/Syscall.pm | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm
index e972aa41..cc282f9f 100644
--- a/lib/PublicInbox/Syscall.pm
+++ b/lib/PublicInbox/Syscall.pm
@@ -418,6 +418,7 @@ sub CMSG_ALIGN ($) { ($_[0] + SIZEOF_size_t - 1) & ~(SIZEOF_size_t - 1) }
use constant CMSG_ALIGN_SIZEOF_cmsghdr => CMSG_ALIGN(SIZEOF_cmsghdr);
sub CMSG_SPACE ($) { CMSG_ALIGN($_[0]) + CMSG_ALIGN_SIZEOF_cmsghdr }
sub CMSG_LEN ($) { CMSG_ALIGN_SIZEOF_cmsghdr + $_[0] }
+use constant msg_controllen => CMSG_SPACE(10 * SIZEOF_int) + 16; # 10 FDs
if (defined($SYS_sendmsg) && defined($SYS_recvmsg)) {
no warnings 'once';
@@ -457,7 +458,7 @@ no warnings 'once';
*recv_cmd4 = sub ($$$) {
my ($sock, undef, $len) = @_;
vec($_[1], ($len + 1) * 8, 1) = 0;
- vec(my $cmsghdr = '', 256 * 8 - 1, 1) = 1;
+ my $cmsghdr = "\0" x msg_controllen; # 10 * sizeof(int)
my $iov = pack('P'.TMPL_size_t, $_[1], $len);
my $mh = pack('PL' . # msg_name, msg_namelen (socklen_t (U32))
BYTES_4_hole . # 4-byte padding on 64-bit
@@ -468,7 +469,7 @@ no warnings 'once';
@BYTES_4_hole,
$iov, 1, # msg_iov, msg_iovlen
$cmsghdr, # msg_control
- 256, # msg_controllen
+ msg_controllen,
0); # msg_flags
my $r = syscall($SYS_recvmsg, fileno($sock), $mh, 0);
return (undef) if $r < 0; # $! set
next prev parent reply other threads:[~2022-04-18 9:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-18 9:50 [PATCH 0/4] lei: finish wiring up pure-Perl stuff for Linux Eric Wong
2022-04-18 9:50 ` [PATCH 1/4] lei: clobber recvmsg buffer on errors Eric Wong
2022-04-18 9:50 ` Eric Wong [this message]
2022-04-18 9:50 ` [PATCH 3/4] lei: wire up pure Perl sendmsg/recvmsg for Linux users Eric Wong
2022-04-18 9:50 ` [PATCH 4/4] syscall: golf + more idiomatic buffer initialization Eric Wong
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