syscall: support sparc64 (and maybe other big-endian systems)

Thanks to the GCC compile farm project, we can wire up syscalls
for sparc64 and set system-specific SFD_* constants properly.

I've FINALLY figured out how to use POSIX::SigSet to generate
a usable buffer for the syscall perlfunc.  This is required
for endian-neutral behavior and relevant to sparc64, at least.

There's no need for signalfd-related stuff to be constants,
either.  signalfd initialization is never a hot path and a stub
subroutine for constants uses several KB of memory in the
interpreter.

We'll drop the needless SEEK_CUR import while we're importing
O_NONBLOCK, too.

1 files changed, 17 insertions, 12 deletions

diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm
index ce6b0f3a..e4f00a2a 100644
--- a/lib/PublicInbox/Syscall.pm
+++ b/lib/PublicInbox/Syscall.pm
@@ -14,7 +14,7 @@
 package PublicInbox::Syscall;
 use strict;
 use parent qw(Exporter);
-use POSIX qw(ENOSYS SEEK_CUR);
+use POSIX qw(ENOSYS O_NONBLOCK);
 use Config;
 
 # $VERSION = '0.25'; # Sys::Syscall version
@@ -22,7 +22,7 @@ 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 SFD_NONBLOCK);
+                  signalfd $SFD_NONBLOCK);
 our %EXPORT_TAGS = (epoll => [qw(epoll_ctl epoll_create epoll_wait
                              EPOLLIN EPOLLOUT
                              EPOLL_CTL_ADD EPOLL_CTL_DEL EPOLL_CTL_MOD
@@ -41,9 +41,6 @@ use constant {
         EPOLL_CTL_ADD => 1,
         EPOLL_CTL_DEL => 2,
         EPOLL_CTL_MOD => 3,
-
-        SFD_CLOEXEC => 02000000,
-        SFD_NONBLOCK => 00004000,
 };
 
 our $loaded_syscall = 0;
@@ -69,6 +66,8 @@ our (
      $SYS_signalfd4,
      );
 
+my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC
+our $SFD_NONBLOCK = O_NONBLOCK;
 our $no_deprecated = 0;
 
 if ($^O eq "linux") {
@@ -103,6 +102,13 @@ if ($^O eq "linux") {
         $SYS_epoll_ctl = 1073742057;
         $SYS_epoll_wait = 1073742056;
         $SYS_signalfd4 = 1073742113;
+    } elsif ($machine eq 'sparc64') {
+        $SYS_epoll_create = 193;
+        $SYS_epoll_ctl = 194;
+        $SYS_epoll_wait = 195;
+        $u64_mod_8 = 1;
+        $SYS_signalfd4 = 317;
+        $SFD_CLOEXEC = 020000000;
     } elsif ($machine =~ m/^parisc/) {
         $SYS_epoll_create = 224;
         $SYS_epoll_ctl    = 225;
@@ -140,6 +146,7 @@ if ($^O eq "linux") {
         $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;
@@ -257,13 +264,11 @@ sub epoll_wait_mod8 {
 sub signalfd ($$$) {
         my ($fd, $signos, $flags) = @_;
         if ($SYS_signalfd4) {
-                # Not sure if there's a way to get pack/unpack to get the
-                # contents of POSIX::SigSet to a buffer, but prepping the
-                # bitmap like one would for select() works:
-                my $buf = "\0" x 8;
-                vec($buf, $_ - 1, 1) = 1 for @$signos;
-
-                syscall($SYS_signalfd4, $fd, $buf, 8, $flags|SFD_CLOEXEC);
+                my $set = POSIX::SigSet->new(@$signos);
+                syscall($SYS_signalfd4, $fd, "$$set",
+                        # $Config{sig_count} is NSIG, so this is NSIG/8:
+                        int($Config{sig_count}/8),
+                        $flags|$SFD_CLOEXEC);
         } else {
                 $! = ENOSYS;
                 undef;