From 0a989e8abd36599abe13c36c2b30ab75232f9756 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Mon, 29 Jan 2024 21:23:19 +0000 Subject: syscall: use pure Perl sendmsg/recvmsg on *BSD While syscall symbols (e.g. SYS_*) have changed on us in FreeBSD during the history of Sys::Syscall and this project and did bite us in some cases; the actual numbers don't get recycled for new syscalls. We're also fortunate that sendmsg and recvmsg syscalls and associated msghdr and cmsg structs predate the BSD forks and are compatible across all the BSDs I've tried. OpenBSD routes Perl `syscall' through libc; while NetBSD + FreeBSD document procedures for maintaining backwards compatibility. It looks like Dragonfly follows FreeBSD, here. Tested on i386 OpenBSD, and amd64 {Free,Net,Open,Dragonfly}BSD This enables *BSD users to use lei, -cindex and future SCM_RIGHTS-only features without needing Inline::C. [1] https://cvsweb.openbsd.org/src/gnu/usr.bin/perl/gen_syscall_emulator.pl [2] https://www.netbsd.org/docs/internals/en/chap-processes.html#syscall_versioning [3] https://wiki.freebsd.org/AddingSyscalls#Backward_compatibily --- lib/PublicInbox/Syscall.pm | 102 ++++++++++++++++++++++++++++----------------- 1 file changed, 63 insertions(+), 39 deletions(-) (limited to 'lib') diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm index 9071e6b1..829cfa3c 100644 --- a/lib/PublicInbox/Syscall.pm +++ b/lib/PublicInbox/Syscall.pm @@ -22,7 +22,7 @@ use POSIX qw(ENOENT ENOSYS EINVAL O_NONBLOCK); use Socket qw(SOL_SOCKET SCM_RIGHTS); use Config; our %SIGNUM = (WINCH => 28); # most Linux, {Free,Net,Open}BSD, *Darwin -our $INOTIFY; +our ($INOTIFY, %PACK); # $VERSION = '0.25'; # Sys::Syscall version our @EXPORT_OK = qw(epoll_ctl epoll_create epoll_wait @@ -44,26 +44,21 @@ use constant { EPOLL_CTL_MOD => 3, SIZEOF_int => $Config{intsize}, SIZEOF_size_t => $Config{sizesize}, + SIZEOF_ptr => $Config{ptrsize}, NUL => "\0", }; -use constant { - TMPL_size_t => SIZEOF_size_t == 8 ? 'Q' : 'L', - BYTES_4_hole => SIZEOF_size_t == 8 ? 'L' : '', - # cmsg_len, cmsg_level, cmsg_type - SIZEOF_cmsghdr => SIZEOF_int * 2 + SIZEOF_size_t, -}; - -my @BYTES_4_hole = BYTES_4_hole ? (0) : (); +use constant TMPL_size_t => SIZEOF_size_t == 8 ? 'Q' : 'L'; our ($SYS_epoll_create, $SYS_epoll_ctl, $SYS_epoll_wait, $SYS_signalfd4, $SYS_renameat2, - $F_SETPIPE_SZ); + $F_SETPIPE_SZ, + $SYS_sendmsg, + $SYS_recvmsg); -my ($SYS_sendmsg, $SYS_recvmsg); my $SYS_fstatfs; # don't need fstatfs64, just statfs.f_type my ($FS_IOC_GETFLAGS, $FS_IOC_SETFLAGS); my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC @@ -78,7 +73,7 @@ if ($^O eq "linux") { # boundaries. my $u64_mod_8 = 0; - if ($Config{ptrsize} == 4) { + if (SIZEOF_ptr == 4) { # if we're running on an x86_64 kernel, but a 32-bit process, # we need to use the x32 or i386 syscall numbers. if ($machine eq 'x86_64') { @@ -281,16 +276,52 @@ EOM *epoll_wait = \&epoll_wait_mod4; *epoll_ctl = \&epoll_ctl_mod4; } +} elsif ($^O =~ /\A(?:freebsd|openbsd|netbsd|dragonfly)\z/) { +# don't use syscall.ph here, name => number mappings are not stable on *BSD +# but the actual numbers are. +# OpenBSD perl redirects syscall perlop to libc functions +# https://cvsweb.openbsd.org/src/gnu/usr.bin/perl/gen_syscall_emulator.pl +# https://www.netbsd.org/docs/internals/en/chap-processes.html#syscall_versioning +# https://wiki.freebsd.org/AddingSyscalls#Backward_compatibily +# (I'm assuming Dragonfly copies FreeBSD, here, too) + $SYS_recvmsg = 27; + $SYS_sendmsg = 28; +} + +BEGIN { + if ($^O eq 'linux') { + %PACK = ( + TMPL_cmsg_len => TMPL_size_t, + # cmsg_len, cmsg_level, cmsg_type + SIZEOF_cmsghdr => SIZEOF_int * 2 + SIZEOF_size_t, + CMSG_DATA_off => '', + TMPL_msghdr => 'PL' . # msg_name, msg_namelen + '@'.(2 * SIZEOF_ptr).'P'. # msg_iov + 'i'. # msg_iovlen + '@'.(4 * SIZEOF_ptr).'P'. # msg_control + 'L'. # msg_controllen (socklen_t) + 'i', # msg_flags + ); + } elsif ($^O =~ /\A(?:freebsd|openbsd|netbsd|dragonfly)\z/) { + %PACK = ( + TMPL_cmsg_len => 'L', # socklen_t + SIZEOF_cmsghdr => SIZEOF_int * 3, + CMSG_DATA_off => SIZEOF_ptr == 8 ? '@16' : '', + TMPL_msghdr => 'PL' . # msg_name, msg_namelen + '@'.(2 * SIZEOF_ptr).'P'. # msg_iov + TMPL_size_t. # msg_iovlen + '@'.(4 * SIZEOF_ptr).'P'. # msg_control + TMPL_size_t. # msg_controllen + 'i', # msg_flags + + ) + } + $PACK{CMSG_ALIGN_size} = SIZEOF_size_t; } # SFD_CLOEXEC is arch-dependent, so IN_CLOEXEC may be, too $INOTIFY->{IN_CLOEXEC} //= 0x80000 if $INOTIFY; -# use Inline::C for *BSD-only or general POSIX stuff. -# Linux guarantees stable syscall numbering, BSDs only offer a stable libc -# use devel/sysdefs-list on Linux to detect new syscall numbers and -# other system constants - sub epoll_create { syscall($SYS_epoll_create, $no_deprecated ? 0 : 100); } @@ -420,11 +451,13 @@ 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 \%PACK; +sub CMSG_ALIGN ($) { ($_[0] + CMSG_ALIGN_size - 1) & ~(CMSG_ALIGN_size - 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 + $_[0] } -use constant msg_controllen => CMSG_SPACE(10 * SIZEOF_int) + 16; # 10 FDs +use constant msg_controllen_max => + CMSG_SPACE(10 * SIZEOF_int) + SIZEOF_cmsghdr; # space for 10 FDs if (defined($SYS_sendmsg) && defined($SYS_recvmsg)) { no warnings 'once'; @@ -436,20 +469,15 @@ require PublicInbox::CmdIPC4; $_[2] // NUL, length($_[2] // NUL) || 1); my $fd_space = scalar(@$fds) * SIZEOF_int; my $msg_controllen = CMSG_SPACE($fd_space); - my $cmsghdr = pack(TMPL_size_t . # cmsg_len + my $cmsghdr = pack(TMPL_cmsg_len . 'LL' . # cmsg_level, cmsg_type, - ('i' x scalar(@$fds)) . # CMSG_DATA + CMSG_DATA_off.('i' x scalar(@$fds)). # CMSG_DATA '@'.($msg_controllen - 1).'x1', # pad to space, not len CMSG_LEN($fd_space), # cmsg_len SOL_SOCKET, SCM_RIGHTS, # cmsg_{level,type} @$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, + my $mh = pack(TMPL_msghdr, + undef, 0, # msg_name, msg_namelen (unused) $iov, 1, # msg_iov, msg_iovlen $cmsghdr, # msg_control $msg_controllen, @@ -465,18 +493,13 @@ require PublicInbox::CmdIPC4; *recv_cmd4 = sub ($$$) { my ($sock, undef, $len) = @_; vec($_[1] //= '', $len - 1, 8) = 0; - my $cmsghdr = "\0" x msg_controllen; # 10 * sizeof(int) + my $cmsghdr = "\0" x msg_controllen_max; # 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 - '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, + my $mh = pack(TMPL_msghdr, + undef, 0, # msg_name, msg_namelen (unused) $iov, 1, # msg_iov, msg_iovlen $cmsghdr, # msg_control - msg_controllen, + msg_controllen_max, 0); # msg_flags my $r; do { @@ -489,8 +512,9 @@ require PublicInbox::CmdIPC4; substr($_[1], $r, length($_[1]), ''); my @ret; if ($r > 0) { - my ($len, $lvl, $type, @fds) = unpack(TMPL_size_t . # cmsg_len - 'LLi*', # cmsg_level, cmsg_type, @fds + my ($len, $lvl, $type, @fds) = unpack(TMPL_cmsg_len. + 'LL'. # cmsg_level, cmsg_type + CMSG_DATA_off.'i*', # @fds $cmsghdr); if ($lvl == SOL_SOCKET && $type == SCM_RIGHTS) { $len -= CMSG_ALIGN_SIZEOF_cmsghdr; -- cgit v1.2.3-24-ge0c7