# Copyright (C) 2016-2019 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/; sub RLIMITS () { qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA) } my $vfork_spawn = <<'VFORK_SPAWN'; #include #include #include #include #include #include /* some platforms need alloca.h, but some don't */ #if defined(__GNUC__) && !defined(alloca) # define alloca(sz) __builtin_alloca(sz) #endif #include #include /* * From the av_len apidoc: * Note that, unlike what the name implies, it returns * the highest index in the array, so to get the size of * the array you need to use "av_len(av) + 1". * This is unlike "sv_len", which returns what you would expect. */ #define AV2C_COPY(dst, src) do { \ I32 i; \ I32 top_index = av_len(src); \ I32 real_len = top_index + 1; \ I32 capa = real_len + 1; \ dst = alloca(capa * sizeof(char *)); \ for (i = 0; i < real_len; i++) { \ SV **sv = av_fetch(src, i, 0); \ dst[i] = SvPV_nolen(*sv); \ } \ dst[real_len] = 0; \ } while (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 pi_fork_exec(int in, int out, int err, SV *file, SV *cmdref, SV *envref, SV *rlimref) { AV *cmd = (AV *)SvRV(cmdref); AV *env = (AV *)SvRV(envref); AV *rlim = (AV *)SvRV(rlimref); const char *filename = SvPV_nolen(file); pid_t pid; char **argv, **envp; sigset_t set, old; int ret, errnum; AV2C_COPY(argv, cmd); AV2C_COPY(envp, env); 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; I32 i, max; REDIR(in, 0); REDIR(out, 1); REDIR(err, 2); for (sig = 1; sig < NSIG; sig++) signal(sig, SIG_DFL); /* ignore errors on signals */ max = av_len(rlim); for (i = 0; i < max; i += 3) { struct rlimit rl; SV **res = av_fetch(rlim, i, 0); SV **soft = av_fetch(rlim, i + 1, 0); SV **hard = av_fetch(rlim, i + 2, 0); rl.rlim_cur = SvIV(*soft); rl.rlim_max = SvIV(*hard); if (setrlimit(SvIV(*res), &rl) < 0) xerr("sertlimit"); } /* * don't bother unblocking, we don't want signals * to the group taking out a subprocess */ execve(filename, argv, envp); xerr("execve failed"); } errnum = errno; ret = sigprocmask(SIG_SETMASK, &old, NULL); assert(ret == 0 && "BUG calling sigprocmask to restore"); errno = errnum; 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 $vfork_spawn) { require PublicInbox::SpawnPP; no warnings 'once'; *pi_fork_exec = *PublicInbox::SpawnPP::pi_fork_exec } sub which ($) { my ($file) = @_; return $file if index($file, '/') == 0; 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; my $rlim = []; foreach my $l (RLIMITS()) { defined(my $v = $opts->{$l}) or next; my $r = eval "require BSD::Resource; BSD::Resource::$l();"; unless (defined $r) { warn "$l undefined by BSD::Resource: $@\n"; next; } push @$rlim, $r, @$v; } my $pid = pi_fork_exec($in, $out, $err, $f, $cmd, \@env, $rlim); $pid < 0 ? undef : $pid; } sub popen_rd { my ($cmd, $env, $opts) = @_; pipe(my ($r, $w)) or die "pipe: $!\n"; $opts ||= {}; $opts->{1} = fileno($w); my $pid = spawn($cmd, $env, $opts); return unless defined $pid; return ($r, $pid) if wantarray; my $ret = gensym; tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r; $ret; } 1;