1 # This is a fork of the (for now) unmaintained Sys::Syscall 0.25,
2 # specifically the Debian libsys-syscall-perl 0.25-6 version to
3 # fix upstream regressions in 0.25.
5 # See devel/syscall-list in the public-inbox source tree for maintenance
6 # <https://80x24.org/public-inbox.git>, and machines from the GCC Farm:
7 # <https://cfarm.tetaneutral.net/>
9 # This license differs from the rest of public-inbox
11 # This module is Copyright (c) 2005 Six Apart, Ltd.
12 # Copyright (C) all contributors <meta@public-inbox.org>
14 # All rights reserved.
16 # You may distribute under the terms of either the GNU General Public
17 # License or the Artistic License, as specified in the Perl README file.
18 package PublicInbox::Syscall;
20 use parent qw(Exporter);
21 use POSIX qw(ENOENT ENOSYS EINVAL O_NONBLOCK);
22 use Socket qw(SOL_SOCKET SCM_RIGHTS);
25 # $VERSION = '0.25'; # Sys::Syscall version
26 our @EXPORT_OK = qw(epoll_ctl epoll_create epoll_wait
27 EPOLLIN EPOLLOUT EPOLLET
28 EPOLL_CTL_ADD EPOLL_CTL_DEL EPOLL_CTL_MOD
29 EPOLLONESHOT EPOLLEXCLUSIVE
30 signalfd rename_noreplace);
31 our %EXPORT_TAGS = (epoll => [qw(epoll_ctl epoll_create epoll_wait
33 EPOLL_CTL_ADD EPOLL_CTL_DEL EPOLL_CTL_MOD
34 EPOLLONESHOT EPOLLEXCLUSIVE)],
43 EPOLLEXCLUSIVE => (1 << 28),
44 EPOLLONESHOT => (1 << 30),
49 SIZEOF_int => $Config{intsize},
50 SIZEOF_size_t => $Config{sizesize},
55 TMPL_size_t => SIZEOF_size_t == 8 ? 'Q' : 'L',
56 BYTES_4_hole => SIZEOF_size_t == 8 ? 'L' : '',
57 # cmsg_len, cmsg_level, cmsg_type
58 SIZEOF_cmsghdr => SIZEOF_int * 2 + SIZEOF_size_t,
61 my @BYTES_4_hole = BYTES_4_hole ? (0) : ();
62 our $loaded_syscall = 0;
65 # props to Gaal for this!
66 return if $loaded_syscall++;
68 delete @INC{qw<syscall.ph asm/unistd.ph bits/syscall.ph
69 _h2ph_pre.ph sys/syscall.ph>};
71 $clean->(); # don't trust modules before us
72 my $rv = eval { require 'syscall.ph'; 1 } || eval { require 'sys/syscall.ph'; 1 };
73 $clean->(); # don't require modules after us trust us
86 my ($SYS_sendmsg, $SYS_recvmsg);
87 my $SYS_fstatfs; # don't need fstatfs64, just statfs.f_type
88 my ($FS_IOC_GETFLAGS, $FS_IOC_SETFLAGS);
89 my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC
90 our $no_deprecated = 0;
93 my (undef, undef, $release, undef, $machine) = POSIX::uname();
94 my ($maj, $min) = ($release =~ /\A([0-9]+)\.([0-9]+)/);
95 $SYS_renameat2 = 0 if "$maj.$min" < 3.15;
96 # whether the machine requires 64-bit numbers to be on 8-byte
100 # if we're running on an x86_64 kernel, but a 32-bit process,
101 # we need to use the x32 or i386 syscall numbers.
102 if ($machine eq "x86_64" && $Config{ptrsize} == 4) {
103 $machine = $Config{cppsymbols} =~ /\b__ILP32__=1\b/ ? 'x32' : 'i386';
106 # Similarly for mips64 vs mips
107 if ($machine eq "mips64" && $Config{ptrsize} == 4) {
111 if ($machine =~ m/^i[3456]86$/) {
112 $SYS_epoll_create = 254;
113 $SYS_epoll_ctl = 255;
114 $SYS_epoll_wait = 256;
115 $SYS_signalfd4 = 327;
116 $SYS_renameat2 //= 353;
120 $FS_IOC_GETFLAGS = 0x80046601;
121 $FS_IOC_SETFLAGS = 0x40046602;
122 } elsif ($machine eq "x86_64") {
123 $SYS_epoll_create = 213;
124 $SYS_epoll_ctl = 233;
125 $SYS_epoll_wait = 232;
126 $SYS_signalfd4 = 289;
127 $SYS_renameat2 //= 316;
131 $FS_IOC_GETFLAGS = 0x80086601;
132 $FS_IOC_SETFLAGS = 0x40086602;
133 } elsif ($machine eq 'x32') {
134 $SYS_epoll_create = 1073742037;
135 $SYS_epoll_ctl = 1073742057;
136 $SYS_epoll_wait = 1073742056;
137 $SYS_signalfd4 = 1073742113;
138 $SYS_renameat2 //= 0x40000000 + 316;
140 $SYS_sendmsg = 0x40000206;
141 $SYS_recvmsg = 0x40000207;
142 $FS_IOC_GETFLAGS = 0x80046601;
143 $FS_IOC_SETFLAGS = 0x40046602;
144 } elsif ($machine eq 'sparc64') {
145 $SYS_epoll_create = 193;
146 $SYS_epoll_ctl = 194;
147 $SYS_epoll_wait = 195;
149 $SYS_signalfd4 = 317;
150 $SYS_renameat2 //= 345;
151 $SFD_CLOEXEC = 020000000;
155 $FS_IOC_GETFLAGS = 0x40086601;
156 $FS_IOC_SETFLAGS = 0x80086602;
157 } elsif ($machine =~ m/^parisc/) {
158 $SYS_epoll_create = 224;
159 $SYS_epoll_ctl = 225;
160 $SYS_epoll_wait = 226;
162 $SYS_signalfd4 = 309;
163 } elsif ($machine =~ m/^ppc64/) {
164 $SYS_epoll_create = 236;
165 $SYS_epoll_ctl = 237;
166 $SYS_epoll_wait = 238;
168 $SYS_signalfd4 = 313;
169 $SYS_renameat2 //= 357;
173 $FS_IOC_GETFLAGS = 0x40086601;
174 $FS_IOC_SETFLAGS = 0x80086602;
175 } elsif ($machine eq "ppc") {
176 $SYS_epoll_create = 236;
177 $SYS_epoll_ctl = 237;
178 $SYS_epoll_wait = 238;
180 $SYS_signalfd4 = 313;
181 $SYS_renameat2 //= 357;
183 $FS_IOC_GETFLAGS = 0x40086601;
184 $FS_IOC_SETFLAGS = 0x80086602;
185 } elsif ($machine =~ m/^s390/) { # untested, no machine on cfarm
186 $SYS_epoll_create = 249;
187 $SYS_epoll_ctl = 250;
188 $SYS_epoll_wait = 251;
190 $SYS_signalfd4 = 322;
191 $SYS_renameat2 //= 347;
195 } elsif ($machine eq 'ia64') { # untested, no machine on cfarm
196 $SYS_epoll_create = 1243;
197 $SYS_epoll_ctl = 1244;
198 $SYS_epoll_wait = 1245;
200 $SYS_signalfd4 = 289;
201 } elsif ($machine eq "alpha") { # untested, no machine on cfarm
202 # natural alignment, ints are 32-bits
203 $SYS_epoll_create = 407;
204 $SYS_epoll_ctl = 408;
205 $SYS_epoll_wait = 409;
207 $SYS_signalfd4 = 484;
208 $SFD_CLOEXEC = 010000000;
209 } elsif ($machine eq 'aarch64' || $machine eq 'loongarch64') {
210 $SYS_epoll_create = 20; # (sys_epoll_create1)
212 $SYS_epoll_wait = 22; # (sys_epoll_pwait)
216 $SYS_renameat2 //= 276;
220 $FS_IOC_GETFLAGS = 0x80086601;
221 $FS_IOC_SETFLAGS = 0x40086602;
222 } elsif ($machine =~ m/arm(v\d+)?.*l/) { # ARM OABI (untested on cfarm)
223 $SYS_epoll_create = 250;
224 $SYS_epoll_ctl = 251;
225 $SYS_epoll_wait = 252;
227 $SYS_signalfd4 = 355;
228 $SYS_renameat2 //= 382;
232 } elsif ($machine =~ m/^mips64/) { # cfarm only has 32-bit userspace
233 $SYS_epoll_create = 5207;
234 $SYS_epoll_ctl = 5208;
235 $SYS_epoll_wait = 5209;
237 $SYS_signalfd4 = 5283;
238 $SYS_renameat2 //= 5311;
242 $FS_IOC_GETFLAGS = 0x40046601;
243 $FS_IOC_SETFLAGS = 0x80046602;
244 } elsif ($machine =~ m/^mips/) { # 32-bit, tested on mips64 cfarm machine
245 $SYS_epoll_create = 4248;
246 $SYS_epoll_ctl = 4249;
247 $SYS_epoll_wait = 4250;
249 $SYS_signalfd4 = 4324;
250 $SYS_renameat2 //= 4351;
254 $FS_IOC_GETFLAGS = 0x40046601;
255 $FS_IOC_SETFLAGS = 0x80046602;
257 # as a last resort, try using the *.ph files which may not
258 # exist or may be wrong
260 $SYS_epoll_create = eval { &SYS_epoll_create; } || 0;
261 $SYS_epoll_ctl = eval { &SYS_epoll_ctl; } || 0;
262 $SYS_epoll_wait = eval { &SYS_epoll_wait; } || 0;
264 # Note: do NOT add new syscalls to depend on *.ph, here.
265 # Better to miss syscalls (so we can fallback to IO::Poll)
266 # than to use wrong ones, since the names are not stable
267 # (at least not on FreeBSD), if the actual numbers are.
271 *epoll_wait = \&epoll_wait_mod8;
272 *epoll_ctl = \&epoll_ctl_mod8;
274 *epoll_wait = \&epoll_wait_mod4;
275 *epoll_ctl = \&epoll_ctl_mod4;
278 # use Inline::C for *BSD-only or general POSIX stuff.
279 # Linux guarantees stable syscall numbering, BSDs only offer a stable libc
280 # use scripts/syscall-list on Linux to detect new syscall numbers
282 ############################################################################
284 ############################################################################
286 sub epoll_defined { $SYS_epoll_create ? 1 : 0; }
289 syscall($SYS_epoll_create, $no_deprecated ? 0 : 100);
293 # ARGS: (epfd, op, fd, events_mask)
295 syscall($SYS_epoll_ctl, $_[0]+0, $_[1]+0, $_[2]+0, pack("LLL", $_[3], $_[2], 0));
298 syscall($SYS_epoll_ctl, $_[0]+0, $_[1]+0, $_[2]+0, pack("LLLL", $_[3], 0, $_[2], 0));
302 # ARGS: (epfd, maxevents, timeout (milliseconds), arrayref)
303 # arrayref: values modified to be [$fd, $event]
304 our $epoll_wait_events = '';
305 our $epoll_wait_size = 0;
306 sub epoll_wait_mod4 {
307 my ($epfd, $maxevents, $timeout_msec, $events) = @_;
308 # resize our static buffer if maxevents bigger than we've ever done
309 if ($maxevents > $epoll_wait_size) {
310 $epoll_wait_size = $maxevents;
311 vec($epoll_wait_events, $maxevents * 12 * 8 - 1, 1) = 0;
314 my $ct = syscall($SYS_epoll_wait, $epfd, $epoll_wait_events,
315 $maxevents, $timeout_msec);
317 # 12-byte struct epoll_event
318 # 4 bytes uint32_t events mask (skipped, useless to us)
319 # 8 bytes: epoll_data_t union (first 4 bytes are the fd)
320 # So we skip the first 4 bytes and take the middle 4:
321 $events->[$_] = unpack('L', substr($epoll_wait_events,
326 sub epoll_wait_mod8 {
327 my ($epfd, $maxevents, $timeout_msec, $events) = @_;
329 # resize our static buffer if maxevents bigger than we've ever done
330 if ($maxevents > $epoll_wait_size) {
331 $epoll_wait_size = $maxevents;
332 vec($epoll_wait_events, $maxevents * 16 * 8 - 1, 1) = 0;
335 my $ct = syscall($SYS_epoll_wait, $epfd, $epoll_wait_events,
336 $maxevents, $timeout_msec,
337 $no_deprecated ? undef : ());
339 # 16-byte struct epoll_event
340 # 4 bytes uint32_t events mask (skipped, useless to us)
341 # 4 bytes padding (skipped, useless)
342 # 8 bytes epoll_data_t union (first 4 bytes are the fd)
343 # So skip the first 8 bytes, take 4, and ignore the last 4:
344 $events->[$_] = unpack('L', substr($epoll_wait_events,
350 my ($signos, $nonblock) = @_;
351 if ($SYS_signalfd4) {
352 my $set = POSIX::SigSet->new(@$signos);
353 syscall($SYS_signalfd4, -1, "$$set",
354 # $Config{sig_count} is NSIG, so this is NSIG/8:
355 int($Config{sig_count}/8),
356 # SFD_NONBLOCK == O_NONBLOCK for every architecture
357 ($nonblock ? O_NONBLOCK : 0) |$SFD_CLOEXEC);
364 sub _rename_noreplace_racy ($$) {
365 my ($old, $new) = @_;
366 if (link($old, $new)) {
367 warn "unlink $old: $!\n" if !unlink($old) && $! != ENOENT;
374 # TODO: support FD args?
375 sub rename_noreplace ($$) {
376 my ($old, $new) = @_;
377 if ($SYS_renameat2) { # RENAME_NOREPLACE = 1, AT_FDCWD = -100
378 my $ret = syscall($SYS_renameat2, -100, $old, -100, $new, 1);
380 1; # like rename() perlop
381 } elsif ($! == ENOSYS || $! == EINVAL) {
382 undef $SYS_renameat2;
383 _rename_noreplace_racy($old, $new);
388 _rename_noreplace_racy($old, $new);
392 sub nodatacow_fh ($) {
394 my $buf = "\0" x 120;
395 syscall($SYS_fstatfs // return, fileno($fh), $buf) == 0 or
396 return warn("fstatfs: $!\n");
397 my $f_type = unpack('l!', $buf); # statfs.f_type is a signed word
398 return if $f_type != 0x9123683E; # BTRFS_SUPER_MAGIC
401 return warn('FS_IOC_GETFLAGS undefined for platform');
402 ioctl($fh, $FS_IOC_GETFLAGS, $buf) //
403 return warn("FS_IOC_GETFLAGS: $!\n");
404 my $attr = unpack('l!', $buf);
405 return if ($attr & 0x00800000); # FS_NOCOW_FL;
406 ioctl($fh, $FS_IOC_SETFLAGS, pack('l', $attr | 0x00800000)) //
407 warn("FS_IOC_SETFLAGS: $!\n");
411 if (open my $fh, '<', $_[0]) { nodatacow_fh($fh) }
414 sub CMSG_ALIGN ($) { ($_[0] + SIZEOF_size_t - 1) & ~(SIZEOF_size_t - 1) }
415 use constant CMSG_ALIGN_SIZEOF_cmsghdr => CMSG_ALIGN(SIZEOF_cmsghdr);
416 sub CMSG_SPACE ($) { CMSG_ALIGN($_[0]) + CMSG_ALIGN_SIZEOF_cmsghdr }
417 sub CMSG_LEN ($) { CMSG_ALIGN_SIZEOF_cmsghdr + $_[0] }
418 use constant msg_controllen => CMSG_SPACE(10 * SIZEOF_int) + 16; # 10 FDs
420 if (defined($SYS_sendmsg) && defined($SYS_recvmsg)) {
422 *send_cmd4 = sub ($$$$) {
423 my ($sock, $fds, undef, $flags) = @_;
424 my $iov = pack('P'.TMPL_size_t,
425 $_[2] // NUL, length($_[2] // NUL) || 1);
426 my $cmsghdr = pack(TMPL_size_t . # cmsg_len
427 'LL' . # cmsg_level, cmsg_type,
428 ('i' x scalar(@$fds)),
429 CMSG_LEN(scalar(@$fds) * SIZEOF_int), # cmsg_len
430 SOL_SOCKET, SCM_RIGHTS, # cmsg_{level,type}
432 my $mh = pack('PL' . # msg_name, msg_namelen (socklen_t (U32))
433 BYTES_4_hole . # 4-byte padding on 64-bit
434 'P'.TMPL_size_t . # msg_iov, msg_iovlen,
435 'P'.TMPL_size_t . # msg_control, msg_controllen,
437 NUL, 0, # msg_name, msg_namelen (unused)
439 $iov, 1, # msg_iov, msg_iovlen
440 $cmsghdr, # msg_control
441 CMSG_SPACE(scalar(@$fds) * SIZEOF_int), # msg_controllen
446 $sent = syscall($SYS_sendmsg, fileno($sock), $mh, $flags);
447 } while ($sent < 0 &&
448 ($!{ENOBUFS} || $!{ENOMEM} || $!{ETOOMANYREFS}) &&
450 warn "sleeping on sendmsg: $! (#$try)\n" &&
451 select(undef, undef, undef, 0.1) == 0);
452 $sent >= 0 ? $sent : undef;
455 *recv_cmd4 = sub ($$$) {
456 my ($sock, undef, $len) = @_;
457 vec($_[1], ($len + 1) * 8, 1) = 0;
458 my $cmsghdr = "\0" x msg_controllen; # 10 * sizeof(int)
459 my $iov = pack('P'.TMPL_size_t, $_[1], $len);
460 my $mh = pack('PL' . # msg_name, msg_namelen (socklen_t (U32))
461 BYTES_4_hole . # 4-byte padding on 64-bit
462 'P'.TMPL_size_t . # msg_iov, msg_iovlen,
463 'P'.TMPL_size_t . # msg_control, msg_controllen,
465 NUL, 0, # msg_name, msg_namelen (unused)
467 $iov, 1, # msg_iov, msg_iovlen
468 $cmsghdr, # msg_control
471 my $r = syscall($SYS_recvmsg, fileno($sock), $mh, 0);
472 return (undef) if $r < 0; # $! set
473 substr($_[1], $r, length($_[1]), '');
476 my ($len, $lvl, $type, @fds) = unpack(TMPL_size_t . # cmsg_len
477 'LLi*', # cmsg_level, cmsg_type, @fds
479 if ($lvl == SOL_SOCKET && $type == SCM_RIGHTS) {
480 $len -= CMSG_ALIGN_SIZEOF_cmsghdr;
481 @ret = @fds[0..(($len / SIZEOF_int) - 1)];
492 This is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.
496 Brad Fitzpatrick <brad@danga.com>