From acefd91b302dc1bffded901c3ecd0db8f9916e9b Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Wed, 23 Mar 2022 08:54:35 +0000 Subject: syscall: implement sendmsg+recvmsg in pure Perl Socket::MsgHdr is only packaged for Debian and derivatives at the moment, and Inline::C pulling in gcc/clang is a huge amount of disk space and bandwidth for some users. This enables disk space and/or bandwidth-limited users to use lei. Only Linux guarantees a stable ABI and syscall numbers, but that's the majority of our userbase. FreeBSD users will still have to use Inline::C (or get Socket::MsgHdr packaged). x86, x32, and x86-64 are all currently supported, more to be added. --- lib/PublicInbox/Syscall.pm | 95 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) (limited to 'lib/PublicInbox') diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm index 806c192e..e9175ceb 100644 --- a/lib/PublicInbox/Syscall.pm +++ b/lib/PublicInbox/Syscall.pm @@ -2,6 +2,9 @@ # specifically the Debian libsys-syscall-perl 0.25-6 version to # fix upstream regressions in 0.25. # +# See devel/syscall-list in the public-inbox source tree for maintenance +# +# # This license differs from the rest of public-inbox # # This module is Copyright (c) 2005 Six Apart, Ltd. @@ -16,6 +19,7 @@ use strict; use v5.10.1; use parent qw(Exporter); use POSIX qw(ENOENT ENOSYS EINVAL O_NONBLOCK); +use Socket qw(SOL_SOCKET SCM_RIGHTS); use Config; # $VERSION = '0.25'; # Sys::Syscall version @@ -42,8 +46,19 @@ use constant { EPOLL_CTL_ADD => 1, EPOLL_CTL_DEL => 2, EPOLL_CTL_MOD => 3, + SIZEOF_int => $Config{intsize}, + SIZEOF_size_t => $Config{sizesize}, + NUL => "\0", +}; + +use constant { + TMPL_size_t => SIZEOF_size_t == 8 ? 'Q' : 'L', + BYTES_4_hole => SIZEOF_size_t == 8 ? 'L' : '', + # cmsg_len, cmsg_level, cmsg_type + SIZEOF_cmsghdr => SIZEOF_int * 2 + SIZEOF_size_t, }; +my @BYTES_4_hole = BYTES_4_hole ? (0) : (); our $loaded_syscall = 0; sub _load_syscall { @@ -68,6 +83,7 @@ our ( $SYS_renameat2, ); +my ($SYS_sendmsg, $SYS_recvmsg); my $SYS_fstatfs; # don't need fstatfs64, just statfs.f_type my ($FS_IOC_GETFLAGS, $FS_IOC_SETFLAGS); my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC @@ -99,6 +115,8 @@ if ($^O eq "linux") { $SYS_signalfd4 = 327; $SYS_renameat2 //= 353; $SYS_fstatfs = 100; + $SYS_sendmsg = 370; + $SYS_recvmsg = 372; $FS_IOC_GETFLAGS = 0x80046601; $FS_IOC_SETFLAGS = 0x40046602; } elsif ($machine eq "x86_64") { @@ -108,6 +126,8 @@ if ($^O eq "linux") { $SYS_signalfd4 = 289; $SYS_renameat2 //= 316; $SYS_fstatfs = 138; + $SYS_sendmsg = 46; + $SYS_recvmsg = 47; $FS_IOC_GETFLAGS = 0x80086601; $FS_IOC_SETFLAGS = 0x40086602; } elsif ($machine eq 'x32') { @@ -117,6 +137,8 @@ if ($^O eq "linux") { $SYS_signalfd4 = 1073742113; $SYS_renameat2 //= 0x40000000 + 316; $SYS_fstatfs = 138; + $SYS_sendmsg = 0x40000206; + $SYS_recvmsg = 0x40000207; $FS_IOC_GETFLAGS = 0x80046601; $FS_IOC_SETFLAGS = 0x40046602; } elsif ($machine eq 'sparc64') { @@ -378,6 +400,79 @@ sub nodatacow_dir { if (open my $fh, '<', $_[0]) { nodatacow_fh($fh) } } +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 + $_[0] } + +if (defined($SYS_sendmsg) && defined($SYS_recvmsg)) { +no warnings 'once'; +*send_cmd4 = sub ($$$$) { + my ($sock, $fds, undef, $flags) = @_; + my $iov = pack('P'.TMPL_size_t, + $_[2] // NUL, length($_[2] // NUL) || 1); + my $cmsghdr = pack(TMPL_size_t . # cmsg_len + 'LL' . # cmsg_level, cmsg_type, + ('i' x scalar(@$fds)), + CMSG_LEN(scalar(@$fds) * SIZEOF_int), # cmsg_len + SOL_SOCKET, SCM_RIGHTS, # cmsg_{level,type} + @$fds); # CMSG_DATA + my $mh = pack('PL' . # msg_name, msg_namelen (socklen_t (U32)) + BYTES_4_hole . # 4-byte padding on 64-bit + 'P'.TMPL_size_t . # msg_iov, msg_iovlen, + 'P'.TMPL_size_t . # msg_control, msg_controllen, + 'i', # msg_flags + NUL, 0, # msg_name, msg_namelen (unused) + @BYTES_4_hole, + $iov, 1, # msg_iov, msg_iovlen + $cmsghdr, # msg_control + CMSG_SPACE(scalar(@$fds) * SIZEOF_int), # msg_controllen + 0); # msg_flags + my $sent; + my $try = 0; + do { + $sent = syscall($SYS_sendmsg, fileno($sock), $mh, $flags); + } while ($sent < 0 && + ($!{ENOBUFS} || $!{ENOMEM} || $!{ETOOMANYREFS}) && + (++$try < 50) && + warn "sleeping on sendmsg: $! (#$try)\n" && + select(undef, undef, undef, 0.1) == 0); + $sent >= 0 ? $sent : undef; +}; + +*recv_cmd4 = sub ($$$) { + my ($sock, undef, $len) = @_; + vec($_[1], ($len + 1) * 8, 1) = 0; + vec(my $cmsghdr = '', 256 * 8 - 1, 1) = 1; + 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 + 'P'.TMPL_size_t . # msg_iov, msg_iovlen, + 'P'.TMPL_size_t . # msg_control, msg_controllen, + 'i', # msg_flags + NUL, 0, # msg_name, msg_namelen (unused) + @BYTES_4_hole, + $iov, 1, # msg_iov, msg_iovlen + $cmsghdr, # msg_control + 256, # msg_controllen + 0); # msg_flags + my $r = syscall($SYS_recvmsg, fileno($sock), $mh, 0); + return (undef) if $r < 0; # $! set + substr($_[1], $r, length($_[1]), ''); + my @ret; + if ($r > 0) { + my ($len, $lvl, $type, @fds) = unpack(TMPL_size_t . # cmsg_len + 'LLi*', # cmsg_level, cmsg_type, @fds + $cmsghdr); + if ($lvl == SOL_SOCKET && $type == SCM_RIGHTS) { + $len -= CMSG_ALIGN_SIZEOF_cmsghdr; + @ret = @fds[0..(($len / SIZEOF_int) - 1)]; + } + } + @ret; +}; +} + 1; =head1 WARRANTY -- cgit v1.2.3-24-ge0c7