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libphutil/src/phage/bootloader/PhagePHPAgentBootloader.php
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PhagePHPAgentBootloader.php
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<?php
final class PhagePHPAgentBootloader extends PhageAgentBootloader {
private $bootSequence;
private $bootLength;
private $mainLength;
public function getName() {
return 'php';
}
public function getBootCommand() {
$this->buildBootSequence();
$len = $this->bootLength;
// We need to run a command which will bootload a full agent by reading
// and evaulating source code from stdin. This is the smallest bootstrap
// I was able to construct:
//
// - Using `fread(STDIN, ...)` is only good up to 8192 bytes.
// - Using `fread(STDIN, ...)` or various other constructs prevents us
// from opening STDIN later.
//
// Instead, we `fread()` a second-stage bootstrap which has enough code
// to do arbitrary-length reads from stdin. The second-stage bootstrap
// reads and evaluates the main agent program.
return csprintf(
'php -r %s',
"eval(fread(\$I=fopen('php://stdin', 'r'), {$len})); /* phage! */");
}
public function getBootSequence() {
$boot = $this->buildBootSequence();
return $boot->toString();
}
private function buildBootSequence() {
if (!$this->bootSequence) {
$files = array(
'utils/utils.php',
'xsprintf/xsprintf.php',
'xsprintf/csprintf.php',
'serviceprofiler/PhutilServiceProfiler.php',
'future/Future.php',
'future/FutureIterator.php',
'future/exec/ExecFuture.php',
'future/exec/CommandException.php',
'channel/PhutilChannel.php',
'channel/PhutilSocketChannel.php',
'channel/PhutilChannelChannel.php',
'channel/PhutilProtocolChannel.php',
'channel/PhutilJSONProtocolChannel.php',
'phage/agent/PhagePHPAgent.php',
);
$main_sequence = new PhutilBallOfPHP();
$root = phutil_get_library_root('phutil');
foreach ($files as $file) {
$main_sequence->addFile($root.'/'.$file);
}
$main_sequence->addText('id(new PhagePHPAgent($I))->execute();');
$main_length = strlen($main_sequence->toString());
$boot_sequence = new PhutilBallOfPHP();
$boot = '
$length = '.$main_length.';
$buffer = "";
while (strlen($buffer) < $length) {
$data = fread($I, $length - strlen($buffer));
if (!strlen($data)) {
exit(1);
}
$buffer .= $data;
}
eval($buffer);';
$boot_sequence->addText($boot);
$boot_length = strlen($boot_sequence->toString());
$boot_sequence->addText($main_sequence->toString());
if (strlen($boot_length) > 8192) {
throw new Exception("Stage 1 bootloader is too large!");
}
$this->bootSequence = $boot_sequence;
$this->bootLength = $boot_length;
$this->mainLength = $main_length;
}
return $this->bootSequence;
}
}
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