# Copyright (C) all contributors
# License: AGPL-3.0+
#
# This allows vfork to be used for spawning subprocesses if
# ~/.cache/public-inbox/inline-c is writable or if PERL_INLINE_DIRECTORY
# is explicitly defined in the environment (and writable).
# Under Linux, vfork can make a big difference in spawning performance
# as process size increases (fork still needs to mark pages for CoW use).
# None of this is intended to be thread-safe since Perl5 maintainers
# officially discourage the use of threads.
#
# There'll probably be more OS-level C stuff here, down the line.
# We don't want too many DSOs: https://udrepper.livejournal.com/8790.html
package PublicInbox::Spawn;
use v5.12;
use parent qw(Exporter);
use PublicInbox::Lock;
use Fcntl qw(SEEK_SET);
use IO::Handle ();
use Carp qw(croak);
use PublicInbox::IO;
our @EXPORT_OK = qw(which spawn popen_rd popen_wr run_die run_wait run_qx);
our (@RLIMITS, %RLIMITS);
use autodie qw(close open pipe seek sysseek truncate);
BEGIN {
@RLIMITS = qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA);
my $all_libc = <<'ALL_LIBC'; # all *nix systems we support
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#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 { \
static size_t dst##__capa; \
I32 i; \
I32 top_index = av_len(src); \
I32 real_len = top_index + 1; \
I32 capa = real_len + 1; \
if (capa > dst##__capa) { \
dst##__capa = 0; /* in case Newx croaks */ \
Safefree(dst); \
Newx(dst, capa, char *); \
dst##__capa = capa; \
} \
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)
/* needs to be safe inside a vfork'ed process */
static void exit_err(const char *fn, volatile int *cerrnum)
{
*cerrnum = errno;
write(2, fn, strlen(fn));
_exit(1);
}
/*
* unstable internal API. 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(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
const char *cd, int pgid)
{
AV *redir = (AV *)SvRV(redirref);
AV *cmd = (AV *)SvRV(cmdref);
AV *env = (AV *)SvRV(envref);
AV *rlim = (AV *)SvRV(rlimref);
const char *filename = SvPV_nolen(file);
pid_t pid = -1;
static char **argv, **envp;
sigset_t set, old;
int ret, perrnum;
volatile int cerrnum = 0; /* shared due to vfork */
int chld_is_member; /* needed due to shared memory w/ vfork */
I32 max_fd = av_len(redir);
AV2C_COPY(argv, cmd);
AV2C_COPY(envp, env);
if (sigfillset(&set)) goto out;
if (sigdelset(&set, SIGABRT)) goto out;
if (sigdelset(&set, SIGBUS)) goto out;
if (sigdelset(&set, SIGFPE)) goto out;
if (sigdelset(&set, SIGILL)) goto out;
if (sigdelset(&set, SIGSEGV)) goto out;
/* no XCPU/XFSZ here */
if (sigprocmask(SIG_SETMASK, &set, &old)) goto out;
chld_is_member = sigismember(&old, SIGCHLD);
if (chld_is_member < 0) goto out;
if (chld_is_member > 0 && sigdelset(&old, SIGCHLD)) goto out;
pid = vfork();
if (pid == 0) {
int sig;
I32 i, child_fd, max_rlim;
for (child_fd = 0; child_fd <= max_fd; child_fd++) {
SV **parent = av_fetch(redir, child_fd, 0);
int parent_fd = SvIV(*parent);
if (parent_fd == child_fd)
continue;
if (dup2(parent_fd, child_fd) < 0)
exit_err("dup2", &cerrnum);
}
if (pgid >= 0 && setpgid(0, pgid) < 0)
exit_err("setpgid", &cerrnum);
for (sig = 1; sig < NSIG; sig++)
signal(sig, SIG_DFL); /* ignore errors on signals */
if (*cd && chdir(cd) < 0) {
write(2, "cd ", 3);
exit_err(cd, &cerrnum);
}
max_rlim = av_len(rlim);
for (i = 0; i < max_rlim; 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)
exit_err("setrlimit", &cerrnum);
}
(void)sigprocmask(SIG_SETMASK, &old, NULL);
execve(filename, argv, envp);
exit_err("execve", &cerrnum);
}
perrnum = errno;
if (chld_is_member > 0)
sigaddset(&old, SIGCHLD);
ret = sigprocmask(SIG_SETMASK, &old, NULL);
assert(ret == 0 && "BUG calling sigprocmask to restore");
if (cerrnum) {
int err_fd = STDERR_FILENO;
if (err_fd <= max_fd) {
SV **parent = av_fetch(redir, err_fd, 0);
err_fd = SvIV(*parent);
}
if (pid > 0)
waitpid(pid, NULL, 0);
pid = -1;
/* continue message started by exit_err in child */
dprintf(err_fd, ": %s\n", strerror(cerrnum));
errno = cerrnum;
} else if (perrnum) {
errno = perrnum;
}
out:
if (pid < 0)
croak("E: fork_exec %s: %s\n", filename, strerror(errno));
return (int)pid;
}
static int sendmsg_retry(int *tries)
{
const struct timespec req = { 0, 100000000 }; /* 100ms */
int err = errno;
switch (err) {
case EINTR: PERL_ASYNC_CHECK(); return 1;
case ENOBUFS: case ENOMEM: case ETOOMANYREFS:
if (--*tries < 0) return 0;
fprintf(stderr, "# sleeping on sendmsg: %s (%d tries left)\n",
strerror(err), *tries);
nanosleep(&req, NULL);
PERL_ASYNC_CHECK();
return 1;
default: return 0;
}
}
#if defined(CMSG_SPACE) && defined(CMSG_LEN)
#define SEND_FD_CAPA 10
#define SEND_FD_SPACE (SEND_FD_CAPA * sizeof(int))
union my_cmsg {
struct cmsghdr hdr;
char pad[sizeof(struct cmsghdr) + 16 + SEND_FD_SPACE];
};
SV *send_cmd4_(PerlIO *s, SV *svfds, SV *data, int flags, int tries)
{
struct msghdr msg = { 0 };
union my_cmsg cmsg = { 0 };
STRLEN dlen = 0;
struct iovec iov;
ssize_t sent;
AV *fds = (AV *)SvRV(svfds);
I32 i, nfds = av_len(fds) + 1;
int *fdp;
if (SvOK(data)) {
iov.iov_base = SvPV(data, dlen);
iov.iov_len = dlen;
}
if (!dlen) { /* must be non-zero */
iov.iov_base = &msg.msg_namelen; /* whatever */
iov.iov_len = 1;
}
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
if (nfds) {
if (nfds > SEND_FD_CAPA) {
fprintf(stderr, "FIXME: bump SEND_FD_CAPA=%d\n", nfds);
nfds = SEND_FD_CAPA;
}
msg.msg_control = &cmsg.hdr;
msg.msg_controllen = CMSG_SPACE(nfds * sizeof(int));
cmsg.hdr.cmsg_level = SOL_SOCKET;
cmsg.hdr.cmsg_type = SCM_RIGHTS;
cmsg.hdr.cmsg_len = CMSG_LEN(nfds * sizeof(int));
fdp = (int *)CMSG_DATA(&cmsg.hdr);
for (i = 0; i < nfds; i++) {
SV **fd = av_fetch(fds, i, 0);
*fdp++ = SvIV(*fd);
}
}
do {
sent = sendmsg(PerlIO_fileno(s), &msg, flags);
} while (sent < 0 && sendmsg_retry(&tries));
return sent >= 0 ? newSViv(sent) : &PL_sv_undef;
}
void recv_cmd4(PerlIO *s, SV *buf, STRLEN n)
{
union my_cmsg cmsg = { 0 };
struct msghdr msg = { 0 };
struct iovec iov;
ssize_t i;
Inline_Stack_Vars;
Inline_Stack_Reset;
if (!SvOK(buf))
sv_setpvn(buf, "", 0);
iov.iov_base = SvGROW(buf, n + 1);
iov.iov_len = n;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &cmsg.hdr;
msg.msg_controllen = CMSG_SPACE(SEND_FD_SPACE);
for (;;) {
i = recvmsg(PerlIO_fileno(s), &msg, 0);
if (i >= 0 || errno != EINTR) break;
PERL_ASYNC_CHECK();
}
if (i >= 0) {
SvCUR_set(buf, i);
if (cmsg.hdr.cmsg_level == SOL_SOCKET &&
cmsg.hdr.cmsg_type == SCM_RIGHTS) {
size_t len = cmsg.hdr.cmsg_len;
int *fdp = (int *)CMSG_DATA(&cmsg.hdr);
for (i = 0; CMSG_LEN((i + 1) * sizeof(int)) <= len; i++)
Inline_Stack_Push(sv_2mortal(newSViv(*fdp++)));
}
} else {
Inline_Stack_Push(&PL_sv_undef);
SvCUR_set(buf, 0);
}
Inline_Stack_Done;
}
#endif /* defined(CMSG_SPACE) && defined(CMSG_LEN) */
void rlimit_map()
{
Inline_Stack_Vars;
Inline_Stack_Reset;
ALL_LIBC
my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} // (
$ENV{XDG_CACHE_HOME} //
( ($ENV{HOME} // '/nonexistent').'/.cache' )
).'/public-inbox/inline-c';
undef $all_libc unless -d $inline_dir;
if (defined $all_libc) {
for (@RLIMITS, 'RLIM_INFINITY') {
$all_libc .= <new($inline_dir.
'/.public-inbox.lock');
my $fh = $lk->lock_acquire;
open my $oldout, '>&', \*STDOUT;
open my $olderr, '>&', \*STDERR;
open STDOUT, '>&', $fh;
open STDERR, '>&', $fh;
STDERR->autoflush(1);
STDOUT->autoflush(1);
eval 'use Inline C => $all_libc, BUILD_NOISY => 1';
my $err = $@;
open(STDERR, '>&', $olderr);
open(STDOUT, '>&', $oldout);
if ($err) {
seek($fh, 0, SEEK_SET);
my @msg = <$fh>;
truncate($fh, 0);
warn "Inline::C build failed:\n", $err, "\n", @msg;
$all_libc = undef;
}
}
if (defined $all_libc) { # set for Gcf2
$ENV{PERL_INLINE_DIRECTORY} = $inline_dir;
%RLIMITS = rlimit_map();
*send_cmd4 = sub ($$$$;$) {
send_cmd4_($_[0], $_[1], $_[2], $_[3], 50);
}
} else {
require PublicInbox::SpawnPP;
*pi_fork_exec = \&PublicInbox::SpawnPP::pi_fork_exec
}
} # /BEGIN
sub which ($) {
my ($file) = @_;
return $file if index($file, '/') >= 0;
for my $p (split(/:/, $ENV{PATH})) {
$p .= "/$file";
return $p if -x $p;
}
undef;
}
sub spawn ($;$$) {
my ($cmd, $env, $opt) = @_;
my $f = which($cmd->[0]) // die "$cmd->[0]: command not found\n";
my (@env, @rdr);
my %env = (%ENV, $env ? %$env : ());
while (my ($k, $v) = each %env) {
push @env, "$k=$v" if defined($v);
}
for my $child_fd (0..2) {
my $pfd = $opt->{$child_fd};
if ('SCALAR' eq ref($pfd)) {
open my $fh, '+>', undef;
$opt->{"fh.$child_fd"} = $fh; # for read_out_err
if ($child_fd == 0) {
print $fh $$pfd;
$fh->flush or die "flush: $!";
sysseek($fh, 0, SEEK_SET);
}
$pfd = fileno($fh);
} elsif (defined($pfd) && $pfd !~ /\A[0-9]+\z/) {
my $fd = fileno($pfd) //
croak "BUG: $pfd not an IO GLOB? $!";
$pfd = $fd;
}
$rdr[$child_fd] = $pfd // $child_fd;
}
my $rlim = [];
foreach my $l (@RLIMITS) {
my $v = $opt->{$l} // next;
my $r = $RLIMITS{$l} //
eval "require BSD::Resource; BSD::Resource::$l();" //
do {
warn "$l undefined by BSD::Resource: $@\n";
next;
};
push @$rlim, $r, @$v;
}
my $cd = $opt->{'-C'} // ''; # undef => NULL mapping doesn't work?
my $pgid = $opt->{pgid} // -1;
pi_fork_exec(\@rdr, $f, $cmd, \@env, $rlim, $cd, $pgid);
}
sub popen_rd {
my ($cmd, $env, $opt, @cb_arg) = @_;
pipe(my $r, local $opt->{1});
PublicInbox::IO::attach_pid($r, spawn($cmd, $env, $opt), @cb_arg);
}
sub popen_wr {
my ($cmd, $env, $opt, @cb_arg) = @_;
pipe(local $opt->{0}, my $w);
$w->autoflush(1);
PublicInbox::IO::attach_pid($w, spawn($cmd, $env, $opt), @cb_arg);
}
sub read_out_err ($) {
my ($opt) = @_;
for my $fd (1, 2) { # read stdout/stderr
my $fh = delete($opt->{"fh.$fd"}) // next;
seek($fh, 0, SEEK_SET);
PublicInbox::IO::read_all $fh, undef, $opt->{$fd};
}
}
sub run_wait ($;$$) {
my ($cmd, $env, $opt) = @_;
waitpid(spawn($cmd, $env, $opt), 0);
read_out_err($opt);
$?
}
sub run_die ($;$$) {
my ($cmd, $env, $rdr) = @_;
run_wait($cmd, $env, $rdr) and croak "E: @$cmd failed: \$?=$?";
}
sub run_qx {
my ($cmd, $env, $opt) = @_;
my $fh = popen_rd($cmd, $env, $opt);
my @ret;
if (wantarray) {
@ret = <$fh>;
} else {
local $/;
$ret[0] = <$fh>;
}
$fh->close; # caller should check $?
read_out_err($opt);
wantarray ? @ret : $ret[0];
}
1;