# Copyright (C) 2016 all contributors # License: AGPL-3.0+ # # This allows vfork to be used for spawning subprocesses if # PERL_INLINE_DIRECTORY is explicitly defined in the environment. # Under Linux, vfork can make a big difference in spawning performance # as process size increases (fork still needs to mark pages for CoW use). # Currently, we only use this for code intended for long running # daemons (inside the PSGI code (-httpd) and -nntpd). The short-lived # scripts (-mda, -index, -learn, -init) either use IPC::run or standard # Perl routines. package PublicInbox::Spawn; use strict; use warnings; use base qw(Exporter); use Symbol qw(gensym); use IO::Handle; use PublicInbox::ProcessPipe; our @EXPORT_OK = qw/which spawn popen_rd/; my $vfork_spawn = <<'VFORK_SPAWN'; #include #include #include #include #include #include #define AV_ALLOCA(av, max) alloca((max = (av_len((av)) + 1)) * sizeof(char *)) static void av2c_copy(char **dst, AV *src, I32 max) { I32 i; for (i = 0; i < max; i++) { SV **sv = av_fetch(src, i, 0); dst[i] = sv ? SvPV_nolen(*sv) : 0; } dst[max] = 0; } static void *deconst(const char *s) { union { const char *in; void *out; } u; u.in = s; return u.out; } /* needs to be safe inside a vfork'ed process */ static void xerr(const char *msg) { struct iovec iov[3]; const char *err = strerror(errno); /* should be safe in practice */ iov[0].iov_base = deconst(msg); iov[0].iov_len = strlen(msg); iov[1].iov_base = deconst(err); iov[1].iov_len = strlen(err); iov[2].iov_base = deconst("\n"); iov[2].iov_len = 1; writev(2, iov, 3); _exit(1); } #define REDIR(var,fd) do { \ if (var != fd && dup2(var, fd) < 0) \ xerr("error redirecting std"#var ": "); \ } while (0) /* * unstable internal API. This was easy to implement but does not * support arbitrary redirects. It'll be updated depending on * whatever we'll need in the future. * Be sure to update PublicInbox::SpawnPP if this changes */ int public_inbox_fork_exec(int in, int out, int err, SV *file, SV *cmdref, SV *envref) { AV *cmd = (AV *)SvRV(cmdref); AV *env = (AV *)SvRV(envref); const char *filename = SvPV_nolen(file); pid_t pid; char **argv, **envp; I32 max; sigset_t set, old; int ret; argv = AV_ALLOCA(cmd, max); av2c_copy(argv, cmd, max); envp = AV_ALLOCA(env, max); av2c_copy(envp, env, max); ret = sigfillset(&set); assert(ret == 0 && "BUG calling sigfillset"); ret = sigprocmask(SIG_SETMASK, &set, &old); assert(ret == 0 && "BUG calling sigprocmask to block"); pid = vfork(); if (pid == 0) { int sig; REDIR(in, 0); REDIR(out, 1); REDIR(err, 2); for (sig = 1; sig < NSIG; sig++) signal(sig, SIG_DFL); /* ignore errorrs on signals */ ret = sigprocmask(SIG_SETMASK, &old, NULL); if (ret != 0) xerr("sigprocmask failed in vfork child"); execve(filename, argv, envp); xerr("execve failed"); } ret = sigprocmask(SIG_SETMASK, &old, NULL); assert(ret == 0 && "BUG calling sigprocmask to restore"); return (int)pid; } VFORK_SPAWN my $inline_dir = $ENV{PERL_INLINE_DIRECTORY}; $vfork_spawn = undef unless defined $inline_dir && -d $inline_dir && -w _; if (defined $vfork_spawn) { # Inline 0.64 or later has locking in multi-process env, # but we support 0.5 on Debian wheezy use Fcntl qw(:flock); eval { my $f = "$inline_dir/.public-inbox.lock"; open my $fh, '>', $f or die "failed to open $f: $!\n"; flock($fh, LOCK_EX) or die "LOCK_EX failed on $f: $!\n"; eval 'use Inline C => $vfork_spawn'; #, BUILD_NOISY => 1'; my $err = $@; flock($fh, LOCK_UN) or die "LOCK_UN failed on $f: $!\n"; die $err if $err; }; if ($@) { warn "Inline::C failed for vfork: $@\n"; $vfork_spawn = undef; } } unless (defined $vfork_spawn) { require PublicInbox::SpawnPP; no warnings 'once'; *public_inbox_fork_exec = *PublicInbox::SpawnPP::public_inbox_fork_exec } sub which ($) { my ($file) = @_; foreach my $p (split(':', $ENV{PATH})) { $p .= "/$file"; return $p if -x $p; } undef; } sub spawn ($;$$) { my ($cmd, $env, $opts) = @_; my $f = which($cmd->[0]); defined $f or die "$cmd->[0]: command not found\n"; my @env; $opts ||= {}; my %env = $opts->{-env} ? () : %ENV; if ($env) { foreach my $k (keys %$env) { my $v = $env->{$k}; if (defined $v) { $env{$k} = $v; } else { delete $env{$k}; } } } while (my ($k, $v) = each %env) { push @env, "$k=$v"; } my $in = $opts->{0} || 0; my $out = $opts->{1} || 1; my $err = $opts->{2} || 2; public_inbox_fork_exec($in, $out, $err, $f, $cmd, \@env); } sub popen_rd { my ($cmd, $env, $opts) = @_; pipe(my ($r, $w)) or die "pipe: $!\n"; $opts ||= {}; my $blocking = $opts->{Blocking}; IO::Handle::blocking($r, $blocking) if defined $blocking; $opts->{1} = fileno($w); my $pid = spawn($cmd, $env, $opts); return ($r, $pid) if wantarray; my $ret = gensym; tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r; $ret; } 1;