includes/shell/Command.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  */
  20
  21 namespace MediaWiki\Shell;
  22
  23 use Exception;
  24 use MediaWiki\ProcOpenError;
  25 use MediaWiki\ShellDisabledError;
  26 use Profiler;
  27 use Psr\Log\LoggerAwareTrait;
  28 use Psr\Log\NullLogger;
  29
  30 /**
  31  * Class used for executing shell commands
  32  *
  33  * @since 1.30
  34  */
  35 class Command {
  36         use LoggerAwareTrait;
  37
  38         /** @var string */
  39         private $command = '';
  40
  41         /** @var array */
  42         private $limits = [
  43                 // seconds
  44                 'time' => 180,
  45                 // seconds
  46                 'walltime' => 180,
  47                 // KB
  48                 'memory' => 307200,
  49                 // KB
  50                 'filesize' => 102400,
  51         ];
  52
  53         /** @var string[] */
  54         private $env = [];
  55
  56         /** @var string */
  57         private $method;
  58
  59         /** @var bool */
  60         private $useStderr = false;
  61
  62         /** @var bool */
  63         private $everExecuted = false;
  64
  65         /** @var string|false */
  66         private $cgroup = false;
  67
  68         /**
  69          * Constructor. Don't call directly, instead use Shell::command()
  70          *
  71          * @throws ShellDisabledError
  72          */
  73         public function __construct() {
  74                 if ( Shell::isDisabled() ) {
  75                         throw new ShellDisabledError();
  76                 }
  77
  78                 $this->setLogger( new NullLogger() );
  79         }
  80
  81         /**
  82          * Destructor. Makes sure programmer didn't forget to execute the command after all
  83          */
  84         public function __destruct() {
  85                 if ( !$this->everExecuted ) {
  86                         $context = [ 'command' => $this->command ];
  87                         $message = __CLASS__ . " was instantiated, but execute() was never called.";
  88                         if ( $this->method ) {
  89                                 $message .= ' Calling method: {method}.';
  90                                 $context['method'] = $this->method;
  91                         }
  92                         $message .= ' Command: {command}';
  93                         $this->logger->warning( $message, $context );
  94                 }
  95         }
  96
  97         /**
  98          * Adds parameters to the command. All parameters are sanitized via Shell::escape().
  99          *
 100          * @param string|string[] $args,...
 101          * @return $this
 102          */
 103         public function params( /* ... */ ) {
 104                 $args = func_get_args();
 105                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 106                         // If only one argument has been passed, and that argument is an array,
 107                         // treat it as a list of arguments
 108                         $args = reset( $args );
 109                 }
 110                 $this->command .= ' ' . Shell::escape( $args );
 111
 112                 return $this;
 113         }
 114
 115         /**
 116          * Adds unsafe parameters to the command. These parameters are NOT sanitized in any way.
 117          *
 118          * @param string|string[] $args,...
 119          * @return $this
 120          */
 121         public function unsafeParams( /* ... */ ) {
 122                 $args = func_get_args();
 123                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 124                         // If only one argument has been passed, and that argument is an array,
 125                         // treat it as a list of arguments
 126                         $args = reset( $args );
 127                 }
 128                 $this->command .= implode( ' ', $args );
 129
 130                 return $this;
 131         }
 132
 133         /**
 134          * Sets execution limits
 135          *
 136          * @param array $limits Associative array of limits. Keys (all optional):
 137          *   filesize (for ulimit -f), memory, time, walltime.
 138          * @return $this
 139          */
 140         public function limits( array $limits ) {
 141                 if ( !isset( $limits['walltime'] ) && isset( $limits['time'] ) ) {
 142                         // Emulate the behavior of old wfShellExec() where walltime fell back on time
 143                         // if the latter was overridden and the former wasn't
 144                         $limits['walltime'] = $limits['time'];
 145                 }
 146                 $this->limits = $limits + $this->limits;
 147
 148                 return $this;
 149         }
 150
 151         /**
 152          * Sets environment variables which should be added to the executed command environment
 153          *
 154          * @param string[] $env array of variable name => value
 155          * @return $this
 156          */
 157         public function environment( array $env ) {
 158                 $this->env = $env;
 159
 160                 return $this;
 161         }
 162
 163         /**
 164          * Sets calling function for profiler. By default, the caller for execute() will be used.
 165          *
 166          * @param string $method
 167          * @return $this
 168          */
 169         public function profileMethod( $method ) {
 170                 $this->method = $method;
 171
 172                 return $this;
 173         }
 174
 175         /**
 176          * Controls whether stderr should be included in stdout, including errors from limit.sh.
 177          * Default: don't include.
 178          *
 179          * @param bool $yesno
 180          * @return $this
 181          */
 182         public function includeStderr( $yesno = true ) {
 183                 $this->useStderr = $yesno;
 184
 185                 return $this;
 186         }
 187
 188         /**
 189          * Sets cgroup for this command
 190          *
 191          * @param string|false $cgroup Absolute file path to the cgroup, or false to not use a cgroup
 192          * @return $this
 193          */
 194         public function cgroup( $cgroup ) {
 195                 $this->cgroup = $cgroup;
 196
 197                 return $this;
 198         }
 199
 200         /**
 201          * String together all the options and build the final command
 202          * to execute
 203          *
 204          * @return array [ command, whether to use log pipe ]
 205          */
 206         protected function buildFinalCommand() {
 207                 $envcmd = '';
 208                 foreach ( $this->env as $k => $v ) {
 209                         if ( wfIsWindows() ) {
 210                                 /* Surrounding a set in quotes (method used by wfEscapeShellArg) makes the quotes themselves
 211                                  * appear in the environment variable, so we must use carat escaping as documented in
 212                                  * https://technet.microsoft.com/en-us/library/cc723564.aspx
 213                                  * Note however that the quote isn't listed there, but is needed, and the parentheses
 214                                  * are listed there but doesn't appear to need it.
 215                                  */
 216                                 $envcmd .= "set $k=" . preg_replace( '/([&|()<>^"])/', '^\\1', $v ) . '&& ';
 217                         } else {
 218                                 /* Assume this is a POSIX shell, thus required to accept variable assignments before the command
 219                                  * http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_09_01
 220                                  */
 221                                 $envcmd .= "$k=" . escapeshellarg( $v ) . ' ';
 222                         }
 223                 }
 224
 225                 $useLogPipe = false;
 226                 $cmd = $envcmd . trim( $this->command );
 227
 228                 if ( is_executable( '/bin/bash' ) ) {
 229                         $time = intval( $this->limits['time'] );
 230                         $wallTime = intval( $this->limits['walltime'] );
 231                         $mem = intval( $this->limits['memory'] );
 232                         $filesize = intval( $this->limits['filesize'] );
 233
 234                         if ( $time > 0 || $mem > 0 || $filesize > 0 || $wallTime > 0 ) {
 235                                 $cmd = '/bin/bash ' . escapeshellarg( __DIR__ . '/limit.sh' ) . ' ' .
 236                                         escapeshellarg( $cmd ) . ' ' .
 237                                         escapeshellarg(
 238                                                 "MW_INCLUDE_STDERR=" . ( $this->useStderr ? '1' : '' ) . ';' .
 239                                                 "MW_CPU_LIMIT=$time; " .
 240                                                 'MW_CGROUP=' . escapeshellarg( $this->cgroup ) . '; ' .
 241                                                 "MW_MEM_LIMIT=$mem; " .
 242                                                 "MW_FILE_SIZE_LIMIT=$filesize; " .
 243                                                 "MW_WALL_CLOCK_LIMIT=$wallTime; " .
 244                                                 "MW_USE_LOG_PIPE=yes"
 245                                         );
 246                                 $useLogPipe = true;
 247                         }
 248                 }
 249                 if ( !$useLogPipe && $this->useStderr ) {
 250                         $cmd .= ' 2>&1';
 251                 }
 252
 253                 return [ $cmd, $useLogPipe ];
 254         }
 255
 256         /**
 257          * Executes command. Afterwards, getExitCode() and getOutput() can be used to access execution
 258          * results.
 259          *
 260          * @return Result
 261          * @throws Exception
 262          * @throws ProcOpenError
 263          * @throws ShellDisabledError
 264          */
 265         public function execute() {
 266                 $this->everExecuted = true;
 267
 268                 $profileMethod = $this->method ?: wfGetCaller();
 269
 270                 list( $cmd, $useLogPipe ) = $this->buildFinalCommand();
 271
 272                 $this->logger->debug( __METHOD__ . ": $cmd" );
 273
 274                 // Don't try to execute commands that exceed Linux's MAX_ARG_STRLEN.
 275                 // Other platforms may be more accomodating, but we don't want to be
 276                 // accomodating, because very long commands probably include user
 277                 // input. See T129506.
 278                 if ( strlen( $cmd ) > SHELL_MAX_ARG_STRLEN ) {
 279                         throw new Exception( __METHOD__ .
 280                                 '(): total length of $cmd must not exceed SHELL_MAX_ARG_STRLEN' );
 281                 }
 282
 283                 $desc = [
 284                         0 => [ 'file', 'php://stdin', 'r' ],
 285                         1 => [ 'pipe', 'w' ],
 286                         2 => [ 'pipe', 'w' ],
 287                 ];
 288                 if ( $useLogPipe ) {
 289                         $desc[3] = [ 'pipe', 'w' ];
 290                 }
 291                 $pipes = null;
 292                 $scoped = Profiler::instance()->scopedProfileIn( __FUNCTION__ . '-' . $profileMethod );
 293                 $proc = proc_open( $cmd, $desc, $pipes );
 294                 if ( !$proc ) {
 295                         $this->logger->error( "proc_open() failed: {command}", [ 'command' => $cmd ] );
 296                         throw new ProcOpenError();
 297                 }
 298                 $outBuffer = $logBuffer = '';
 299                 $errBuffer = null;
 300                 $emptyArray = [];
 301                 $status = false;
 302                 $logMsg = false;
 303
 304                 /* According to the documentation, it is possible for stream_select()
 305                  * to fail due to EINTR. I haven't managed to induce this in testing
 306                  * despite sending various signals. If it did happen, the error
 307                  * message would take the form:
 308                  *
 309                  * stream_select(): unable to select [4]: Interrupted system call (max_fd=5)
 310                  *
 311                  * where [4] is the value of the macro EINTR and "Interrupted system
 312                  * call" is string which according to the Linux manual is "possibly"
 313                  * localised according to LC_MESSAGES.
 314                  */
 315                 $eintr = defined( 'SOCKET_EINTR' ) ? SOCKET_EINTR : 4;
 316                 $eintrMessage = "stream_select(): unable to select [$eintr]";
 317
 318                 $running = true;
 319                 $timeout = null;
 320                 $numReadyPipes = 0;
 321
 322                 while ( $running === true || $numReadyPipes !== 0 ) {
 323                         if ( $running ) {
 324                                 $status = proc_get_status( $proc );
 325                                 // If the process has terminated, switch to nonblocking selects
 326                                 // for getting any data still waiting to be read.
 327                                 if ( !$status['running'] ) {
 328                                         $running = false;
 329                                         $timeout = 0;
 330                                 }
 331                         }
 332
 333                         $readyPipes = $pipes;
 334
 335                         // clear get_last_error without actually raising an error
 336                         // from http://php.net/manual/en/function.error-get-last.php#113518
 337                         // TODO replace with clear_last_error when requirements are bumped to PHP7
 338                         set_error_handler( function () {
 339                         }, 0 );
 340                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 341                         @trigger_error( '' );
 342                         // @codingStandardsIgnoreEnd
 343                         restore_error_handler();
 344
 345                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 346                         $numReadyPipes = @stream_select( $readyPipes, $emptyArray, $emptyArray, $timeout );
 347                         // @codingStandardsIgnoreEnd
 348                         if ( $numReadyPipes === false ) {
 349                                 $error = error_get_last();
 350                                 if ( strncmp( $error['message'], $eintrMessage, strlen( $eintrMessage ) ) == 0 ) {
 351                                         continue;
 352                                 } else {
 353                                         trigger_error( $error['message'], E_USER_WARNING );
 354                                         $logMsg = $error['message'];
 355                                         break;
 356                                 }
 357                         }
 358                         foreach ( $readyPipes as $fd => $pipe ) {
 359                                 $block = fread( $pipe, 65536 );
 360                                 if ( $block === '' ) {
 361                                         // End of file
 362                                         fclose( $pipes[$fd] );
 363                                         unset( $pipes[$fd] );
 364                                         if ( !$pipes ) {
 365                                                 break 2;
 366                                         }
 367                                 } elseif ( $block === false ) {
 368                                         // Read error
 369                                         $logMsg = "Error reading from pipe";
 370                                         break 2;
 371                                 } elseif ( $fd == 1 ) {
 372                                         // From stdout
 373                                         $outBuffer .= $block;
 374                                 } elseif ( $fd == 2 ) {
 375                                         // From stderr
 376                                         $errBuffer .= $block;
 377                                 } elseif ( $fd == 3 ) {
 378                                         // From log FD
 379                                         $logBuffer .= $block;
 380                                         if ( strpos( $block, "\n" ) !== false ) {
 381                                                 $lines = explode( "\n", $logBuffer );
 382                                                 $logBuffer = array_pop( $lines );
 383                                                 foreach ( $lines as $line ) {
 384                                                         $this->logger->info( $line );
 385                                                 }
 386                                         }
 387                                 }
 388                         }
 389                 }
 390
 391                 foreach ( $pipes as $pipe ) {
 392                         fclose( $pipe );
 393                 }
 394
 395                 // Use the status previously collected if possible, since proc_get_status()
 396                 // just calls waitpid() which will not return anything useful the second time.
 397                 if ( $running ) {
 398                         $status = proc_get_status( $proc );
 399                 }
 400
 401                 if ( $logMsg !== false ) {
 402                         // Read/select error
 403                         $retval = -1;
 404                         proc_close( $proc );
 405                 } elseif ( $status['signaled'] ) {
 406                         $logMsg = "Exited with signal {$status['termsig']}";
 407                         $retval = 128 + $status['termsig'];
 408                         proc_close( $proc );
 409                 } else {
 410                         if ( $status['running'] ) {
 411                                 $retval = proc_close( $proc );
 412                         } else {
 413                                 $retval = $status['exitcode'];
 414                                 proc_close( $proc );
 415                         }
 416                         if ( $retval == 127 ) {
 417                                 $logMsg = "Possibly missing executable file";
 418                         } elseif ( $retval >= 129 && $retval <= 192 ) {
 419                                 $logMsg = "Probably exited with signal " . ( $retval - 128 );
 420                         }
 421                 }
 422
 423                 if ( $logMsg !== false ) {
 424                         $this->logger->warning( "$logMsg: {command}", [ 'command' => $cmd ] );
 425                 }
 426
 427                 return new Result( $retval, $outBuffer, $errBuffer );
 428         }
 429 }