# This is a fork of the (for now) unmaintained Sys::Syscall 0.25,
# specifically the Debian libsys-syscall-perl 0.25-6 version to
# fix upstream regressions in 0.25.
#
# This license differs from the rest of public-inbox
#
# This module is Copyright (c) 2005 Six Apart, Ltd.
# Copyright (C) 2019-2021 all contributors
#
# All rights reserved.
#
# You may distribute under the terms of either the GNU General Public
# License or the Artistic License, as specified in the Perl README file.
package PublicInbox::Syscall;
use strict;
use v5.10.1;
use parent qw(Exporter);
use POSIX qw(ENOENT EEXIST ENOSYS O_NONBLOCK);
use Config;
# $VERSION = '0.25'; # Sys::Syscall version
our @EXPORT_OK = qw(epoll_ctl epoll_create epoll_wait
EPOLLIN EPOLLOUT EPOLLET
EPOLL_CTL_ADD EPOLL_CTL_DEL EPOLL_CTL_MOD
EPOLLONESHOT EPOLLEXCLUSIVE
signalfd rename_noreplace);
our %EXPORT_TAGS = (epoll => [qw(epoll_ctl epoll_create epoll_wait
EPOLLIN EPOLLOUT
EPOLL_CTL_ADD EPOLL_CTL_DEL EPOLL_CTL_MOD
EPOLLONESHOT EPOLLEXCLUSIVE)],
);
use constant {
EPOLLIN => 1,
EPOLLOUT => 4,
# EPOLLERR => 8,
# EPOLLHUP => 16,
# EPOLLRDBAND => 128,
EPOLLEXCLUSIVE => (1 << 28),
EPOLLONESHOT => (1 << 30),
EPOLLET => (1 << 31),
EPOLL_CTL_ADD => 1,
EPOLL_CTL_DEL => 2,
EPOLL_CTL_MOD => 3,
};
our $loaded_syscall = 0;
sub _load_syscall {
# props to Gaal for this!
return if $loaded_syscall++;
my $clean = sub {
delete @INC{qw};
};
$clean->(); # don't trust modules before us
my $rv = eval { require 'syscall.ph'; 1 } || eval { require 'sys/syscall.ph'; 1 };
$clean->(); # don't require modules after us trust us
$rv;
}
our (
$SYS_epoll_create,
$SYS_epoll_ctl,
$SYS_epoll_wait,
$SYS_signalfd4,
$SYS_renameat2,
);
my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC
our $no_deprecated = 0;
if ($^O eq "linux") {
my (undef, undef, $release, undef, $machine) = POSIX::uname();
my ($maj, $min) = ($release =~ /\A([0-9]+)\.([0-9]+)/);
$SYS_renameat2 = 0 if "$maj.$min" < 3.15;
# whether the machine requires 64-bit numbers to be on 8-byte
# boundaries.
my $u64_mod_8 = 0;
# if we're running on an x86_64 kernel, but a 32-bit process,
# we need to use the x32 or i386 syscall numbers.
if ($machine eq "x86_64" && $Config{ptrsize} == 4) {
$machine = $Config{cppsymbols} =~ /\b__ILP32__=1\b/ ? 'x32' : 'i386';
}
# Similarly for mips64 vs mips
if ($machine eq "mips64" && $Config{ptrsize} == 4) {
$machine = "mips";
}
if ($machine =~ m/^i[3456]86$/) {
$SYS_epoll_create = 254;
$SYS_epoll_ctl = 255;
$SYS_epoll_wait = 256;
$SYS_signalfd4 = 327;
$SYS_renameat2 //= 353;
} elsif ($machine eq "x86_64") {
$SYS_epoll_create = 213;
$SYS_epoll_ctl = 233;
$SYS_epoll_wait = 232;
$SYS_signalfd4 = 289;
$SYS_renameat2 //= 316;
} elsif ($machine eq 'x32') {
$SYS_epoll_create = 1073742037;
$SYS_epoll_ctl = 1073742057;
$SYS_epoll_wait = 1073742056;
$SYS_signalfd4 = 1073742113;
$SYS_renameat2 //= 0x40000000 + 316;
} elsif ($machine eq 'sparc64') {
$SYS_epoll_create = 193;
$SYS_epoll_ctl = 194;
$SYS_epoll_wait = 195;
$u64_mod_8 = 1;
$SYS_signalfd4 = 317;
$SYS_renameat2 //= 345;
$SFD_CLOEXEC = 020000000;
} elsif ($machine =~ m/^parisc/) {
$SYS_epoll_create = 224;
$SYS_epoll_ctl = 225;
$SYS_epoll_wait = 226;
$u64_mod_8 = 1;
$SYS_signalfd4 = 309;
} elsif ($machine =~ m/^ppc64/) {
$SYS_epoll_create = 236;
$SYS_epoll_ctl = 237;
$SYS_epoll_wait = 238;
$u64_mod_8 = 1;
$SYS_signalfd4 = 313;
$SYS_renameat2 //= 357;
} elsif ($machine eq "ppc") {
$SYS_epoll_create = 236;
$SYS_epoll_ctl = 237;
$SYS_epoll_wait = 238;
$u64_mod_8 = 1;
$SYS_signalfd4 = 313;
$SYS_renameat2 //= 357;
} elsif ($machine =~ m/^s390/) {
$SYS_epoll_create = 249;
$SYS_epoll_ctl = 250;
$SYS_epoll_wait = 251;
$u64_mod_8 = 1;
$SYS_signalfd4 = 322;
$SYS_renameat2 //= 347;
} elsif ($machine eq "ia64") {
$SYS_epoll_create = 1243;
$SYS_epoll_ctl = 1244;
$SYS_epoll_wait = 1245;
$u64_mod_8 = 1;
$SYS_signalfd4 = 289;
} elsif ($machine eq "alpha") {
# natural alignment, ints are 32-bits
$SYS_epoll_create = 407;
$SYS_epoll_ctl = 408;
$SYS_epoll_wait = 409;
$u64_mod_8 = 1;
$SYS_signalfd4 = 484;
$SFD_CLOEXEC = 010000000;
} elsif ($machine eq "aarch64") {
$SYS_epoll_create = 20; # (sys_epoll_create1)
$SYS_epoll_ctl = 21;
$SYS_epoll_wait = 22; # (sys_epoll_pwait)
$u64_mod_8 = 1;
$no_deprecated = 1;
$SYS_signalfd4 = 74;
$SYS_renameat2 //= 276;
} elsif ($machine =~ m/arm(v\d+)?.*l/) {
# ARM OABI
$SYS_epoll_create = 250;
$SYS_epoll_ctl = 251;
$SYS_epoll_wait = 252;
$u64_mod_8 = 1;
$SYS_signalfd4 = 355;
$SYS_renameat2 //= 382;
} elsif ($machine =~ m/^mips64/) {
$SYS_epoll_create = 5207;
$SYS_epoll_ctl = 5208;
$SYS_epoll_wait = 5209;
$u64_mod_8 = 1;
$SYS_signalfd4 = 5283;
$SYS_renameat2 //= 5311;
} elsif ($machine =~ m/^mips/) {
$SYS_epoll_create = 4248;
$SYS_epoll_ctl = 4249;
$SYS_epoll_wait = 4250;
$u64_mod_8 = 1;
$SYS_signalfd4 = 4324;
$SYS_renameat2 //= 4351;
} else {
# as a last resort, try using the *.ph files which may not
# exist or may be wrong
_load_syscall();
$SYS_epoll_create = eval { &SYS_epoll_create; } || 0;
$SYS_epoll_ctl = eval { &SYS_epoll_ctl; } || 0;
$SYS_epoll_wait = eval { &SYS_epoll_wait; } || 0;
# Note: do NOT add new syscalls to depend on *.ph, here.
# Better to miss syscalls (so we can fallback to IO::Poll)
# than to use wrong ones, since the names are not stable
# (at least not on FreeBSD), if the actual numbers are.
}
if ($u64_mod_8) {
*epoll_wait = \&epoll_wait_mod8;
*epoll_ctl = \&epoll_ctl_mod8;
} else {
*epoll_wait = \&epoll_wait_mod4;
*epoll_ctl = \&epoll_ctl_mod4;
}
}
# use Inline::C for *BSD-only or general POSIX stuff.
# Linux guarantees stable syscall numbering, BSDs only offer a stable libc
# use scripts/syscall-list on Linux to detect new syscall numbers
############################################################################
# epoll functions
############################################################################
sub epoll_defined { $SYS_epoll_create ? 1 : 0; }
sub epoll_create {
syscall($SYS_epoll_create, $no_deprecated ? 0 : 100);
}
# epoll_ctl wrapper
# ARGS: (epfd, op, fd, events_mask)
sub epoll_ctl_mod4 {
syscall($SYS_epoll_ctl, $_[0]+0, $_[1]+0, $_[2]+0, pack("LLL", $_[3], $_[2], 0));
}
sub epoll_ctl_mod8 {
syscall($SYS_epoll_ctl, $_[0]+0, $_[1]+0, $_[2]+0, pack("LLLL", $_[3], 0, $_[2], 0));
}
# epoll_wait wrapper
# ARGS: (epfd, maxevents, timeout (milliseconds), arrayref)
# arrayref: values modified to be [$fd, $event]
our $epoll_wait_events = '';
our $epoll_wait_size = 0;
sub epoll_wait_mod4 {
my ($epfd, $maxevents, $timeout_msec, $events) = @_;
# resize our static buffer if maxevents bigger than we've ever done
if ($maxevents > $epoll_wait_size) {
$epoll_wait_size = $maxevents;
vec($epoll_wait_events, $maxevents * 12 * 8 - 1, 1) = 0;
}
@$events = ();
my $ct = syscall($SYS_epoll_wait, $epfd, $epoll_wait_events,
$maxevents, $timeout_msec);
for (0..$ct - 1) {
# 12-byte struct epoll_event
# 4 bytes uint32_t events mask (skipped, useless to us)
# 8 bytes: epoll_data_t union (first 4 bytes are the fd)
# So we skip the first 4 bytes and take the middle 4:
$events->[$_] = unpack('L', substr($epoll_wait_events,
12 * $_ + 4, 4));
}
}
sub epoll_wait_mod8 {
my ($epfd, $maxevents, $timeout_msec, $events) = @_;
# resize our static buffer if maxevents bigger than we've ever done
if ($maxevents > $epoll_wait_size) {
$epoll_wait_size = $maxevents;
vec($epoll_wait_events, $maxevents * 16 * 8 - 1, 1) = 0;
}
@$events = ();
my $ct = syscall($SYS_epoll_wait, $epfd, $epoll_wait_events,
$maxevents, $timeout_msec,
$no_deprecated ? undef : ());
for (0..$ct - 1) {
# 16-byte struct epoll_event
# 4 bytes uint32_t events mask (skipped, useless to us)
# 4 bytes padding (skipped, useless)
# 8 bytes epoll_data_t union (first 4 bytes are the fd)
# So skip the first 8 bytes, take 4, and ignore the last 4:
$events->[$_] = unpack('L', substr($epoll_wait_events,
16 * $_ + 8, 4));
}
}
sub signalfd ($$) {
my ($signos, $nonblock) = @_;
if ($SYS_signalfd4) {
my $set = POSIX::SigSet->new(@$signos);
syscall($SYS_signalfd4, -1, "$$set",
# $Config{sig_count} is NSIG, so this is NSIG/8:
int($Config{sig_count}/8),
# SFD_NONBLOCK == O_NONBLOCK for every architecture
($nonblock ? O_NONBLOCK : 0) |$SFD_CLOEXEC);
} else {
$! = ENOSYS;
undef;
}
}
sub _rename_noreplace_racy ($$) {
my ($old, $new) = @_;
if (link($old, $new)) {
warn "unlink $old: $!\n" if !unlink($old) && $! != ENOENT;
1
} else {
undef;
}
}
# TODO: support FD args?
sub rename_noreplace ($$) {
my ($old, $new) = @_;
if ($SYS_renameat2) { # RENAME_NOREPLACE = 1, AT_FDCWD = -100
my $ret = syscall($SYS_renameat2, -100, $old, -100, $new, 1);
if ($ret == 0) {
1; # like rename() perlop
} elsif ($! == ENOSYS) {
undef $SYS_renameat2;
_rename_noreplace_racy($old, $new);
} else {
undef
}
} else {
_rename_noreplace_racy($old, $new);
}
}
1;
=head1 WARRANTY
This is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.
=head1 AUTHORS
Brad Fitzpatrick