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 $doIncludeStderr = false;
  61
  62         /** @var bool */
  63         private $doLogStderr = false;
  64
  65         /** @var bool */
  66         private $everExecuted = false;
  67
  68         /** @var string|false */
  69         private $cgroup = false;
  70
  71         /**
  72          * Constructor. Don't call directly, instead use Shell::command()
  73          *
  74          * @throws ShellDisabledError
  75          */
  76         public function __construct() {
  77                 if ( Shell::isDisabled() ) {
  78                         throw new ShellDisabledError();
  79                 }
  80
  81                 $this->setLogger( new NullLogger() );
  82         }
  83
  84         /**
  85          * Destructor. Makes sure programmer didn't forget to execute the command after all
  86          */
  87         public function __destruct() {
  88                 if ( !$this->everExecuted ) {
  89                         $context = [ 'command' => $this->command ];
  90                         $message = __CLASS__ . " was instantiated, but execute() was never called.";
  91                         if ( $this->method ) {
  92                                 $message .= ' Calling method: {method}.';
  93                                 $context['method'] = $this->method;
  94                         }
  95                         $message .= ' Command: {command}';
  96                         $this->logger->warning( $message, $context );
  97                 }
  98         }
  99
 100         /**
 101          * Adds parameters to the command. All parameters are sanitized via Shell::escape().
 102          *
 103          * @param string|string[] $args,...
 104          * @return $this
 105          */
 106         public function params( /* ... */ ) {
 107                 $args = func_get_args();
 108                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 109                         // If only one argument has been passed, and that argument is an array,
 110                         // treat it as a list of arguments
 111                         $args = reset( $args );
 112                 }
 113                 $this->command .= ' ' . Shell::escape( $args );
 114
 115                 return $this;
 116         }
 117
 118         /**
 119          * Adds unsafe parameters to the command. These parameters are NOT sanitized in any way.
 120          *
 121          * @param string|string[] $args,...
 122          * @return $this
 123          */
 124         public function unsafeParams( /* ... */ ) {
 125                 $args = func_get_args();
 126                 if ( count( $args ) === 1 && is_array( reset( $args ) ) ) {
 127                         // If only one argument has been passed, and that argument is an array,
 128                         // treat it as a list of arguments
 129                         $args = reset( $args );
 130                 }
 131                 $this->command .= implode( ' ', $args );
 132
 133                 return $this;
 134         }
 135
 136         /**
 137          * Sets execution limits
 138          *
 139          * @param array $limits Associative array of limits. Keys (all optional):
 140          *   filesize (for ulimit -f), memory, time, walltime.
 141          * @return $this
 142          */
 143         public function limits( array $limits ) {
 144                 if ( !isset( $limits['walltime'] ) && isset( $limits['time'] ) ) {
 145                         // Emulate the behavior of old wfShellExec() where walltime fell back on time
 146                         // if the latter was overridden and the former wasn't
 147                         $limits['walltime'] = $limits['time'];
 148                 }
 149                 $this->limits = $limits + $this->limits;
 150
 151                 return $this;
 152         }
 153
 154         /**
 155          * Sets environment variables which should be added to the executed command environment
 156          *
 157          * @param string[] $env array of variable name => value
 158          * @return $this
 159          */
 160         public function environment( array $env ) {
 161                 $this->env = $env;
 162
 163                 return $this;
 164         }
 165
 166         /**
 167          * Sets calling function for profiler. By default, the caller for execute() will be used.
 168          *
 169          * @param string $method
 170          * @return $this
 171          */
 172         public function profileMethod( $method ) {
 173                 $this->method = $method;
 174
 175                 return $this;
 176         }
 177
 178         /**
 179          * Controls whether stderr should be included in stdout, including errors from limit.sh.
 180          * Default: don't include.
 181          *
 182          * @param bool $yesno
 183          * @return $this
 184          */
 185         public function includeStderr( $yesno = true ) {
 186                 $this->doIncludeStderr = $yesno;
 187
 188                 return $this;
 189         }
 190
 191         /**
 192          * When enabled, text sent to stderr will be logged with a level of 'error'.
 193          *
 194          * @param bool $yesno
 195          * @return $this
 196          */
 197         public function logStderr( $yesno = true ) {
 198                 $this->doLogStderr = $yesno;
 199
 200                 return $this;
 201         }
 202
 203         /**
 204          * Sets cgroup for this command
 205          *
 206          * @param string|false $cgroup Absolute file path to the cgroup, or false to not use a cgroup
 207          * @return $this
 208          */
 209         public function cgroup( $cgroup ) {
 210                 $this->cgroup = $cgroup;
 211
 212                 return $this;
 213         }
 214
 215         /**
 216          * String together all the options and build the final command
 217          * to execute
 218          *
 219          * @return array [ command, whether to use log pipe ]
 220          */
 221         protected function buildFinalCommand() {
 222                 $envcmd = '';
 223                 foreach ( $this->env as $k => $v ) {
 224                         if ( wfIsWindows() ) {
 225                                 /* Surrounding a set in quotes (method used by wfEscapeShellArg) makes the quotes themselves
 226                                  * appear in the environment variable, so we must use carat escaping as documented in
 227                                  * https://technet.microsoft.com/en-us/library/cc723564.aspx
 228                                  * Note however that the quote isn't listed there, but is needed, and the parentheses
 229                                  * are listed there but doesn't appear to need it.
 230                                  */
 231                                 $envcmd .= "set $k=" . preg_replace( '/([&|()<>^"])/', '^\\1', $v ) . '&& ';
 232                         } else {
 233                                 /* Assume this is a POSIX shell, thus required to accept variable assignments before the command
 234                                  * http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_09_01
 235                                  */
 236                                 $envcmd .= "$k=" . escapeshellarg( $v ) . ' ';
 237                         }
 238                 }
 239
 240                 $useLogPipe = false;
 241                 $cmd = $envcmd . trim( $this->command );
 242
 243                 if ( is_executable( '/bin/bash' ) ) {
 244                         $time = intval( $this->limits['time'] );
 245                         $wallTime = intval( $this->limits['walltime'] );
 246                         $mem = intval( $this->limits['memory'] );
 247                         $filesize = intval( $this->limits['filesize'] );
 248
 249                         if ( $time > 0 || $mem > 0 || $filesize > 0 || $wallTime > 0 ) {
 250                                 $cmd = '/bin/bash ' . escapeshellarg( __DIR__ . '/limit.sh' ) . ' ' .
 251                                         escapeshellarg( $cmd ) . ' ' .
 252                                         escapeshellarg(
 253                                                 "MW_INCLUDE_STDERR=" . ( $this->doIncludeStderr ? '1' : '' ) . ';' .
 254                                                 "MW_CPU_LIMIT=$time; " .
 255                                                 'MW_CGROUP=' . escapeshellarg( $this->cgroup ) . '; ' .
 256                                                 "MW_MEM_LIMIT=$mem; " .
 257                                                 "MW_FILE_SIZE_LIMIT=$filesize; " .
 258                                                 "MW_WALL_CLOCK_LIMIT=$wallTime; " .
 259                                                 "MW_USE_LOG_PIPE=yes"
 260                                         );
 261                                 $useLogPipe = true;
 262                         }
 263                 }
 264                 if ( !$useLogPipe && $this->doIncludeStderr ) {
 265                         $cmd .= ' 2>&1';
 266                 }
 267
 268                 return [ $cmd, $useLogPipe ];
 269         }
 270
 271         /**
 272          * Executes command. Afterwards, getExitCode() and getOutput() can be used to access execution
 273          * results.
 274          *
 275          * @return Result
 276          * @throws Exception
 277          * @throws ProcOpenError
 278          * @throws ShellDisabledError
 279          */
 280         public function execute() {
 281                 $this->everExecuted = true;
 282
 283                 $profileMethod = $this->method ?: wfGetCaller();
 284
 285                 list( $cmd, $useLogPipe ) = $this->buildFinalCommand();
 286
 287                 $this->logger->debug( __METHOD__ . ": $cmd" );
 288
 289                 // Don't try to execute commands that exceed Linux's MAX_ARG_STRLEN.
 290                 // Other platforms may be more accomodating, but we don't want to be
 291                 // accomodating, because very long commands probably include user
 292                 // input. See T129506.
 293                 if ( strlen( $cmd ) > SHELL_MAX_ARG_STRLEN ) {
 294                         throw new Exception( __METHOD__ .
 295                                 '(): total length of $cmd must not exceed SHELL_MAX_ARG_STRLEN' );
 296                 }
 297
 298                 $desc = [
 299                         0 => [ 'file', 'php://stdin', 'r' ],
 300                         1 => [ 'pipe', 'w' ],
 301                         2 => [ 'pipe', 'w' ],
 302                 ];
 303                 if ( $useLogPipe ) {
 304                         $desc[3] = [ 'pipe', 'w' ];
 305                 }
 306                 $pipes = null;
 307                 $scoped = Profiler::instance()->scopedProfileIn( __FUNCTION__ . '-' . $profileMethod );
 308                 $proc = proc_open( $cmd, $desc, $pipes );
 309                 if ( !$proc ) {
 310                         $this->logger->error( "proc_open() failed: {command}", [ 'command' => $cmd ] );
 311                         throw new ProcOpenError();
 312                 }
 313                 $outBuffer = $logBuffer = '';
 314                 $errBuffer = null;
 315                 $emptyArray = [];
 316                 $status = false;
 317                 $logMsg = false;
 318
 319                 /* According to the documentation, it is possible for stream_select()
 320                  * to fail due to EINTR. I haven't managed to induce this in testing
 321                  * despite sending various signals. If it did happen, the error
 322                  * message would take the form:
 323                  *
 324                  * stream_select(): unable to select [4]: Interrupted system call (max_fd=5)
 325                  *
 326                  * where [4] is the value of the macro EINTR and "Interrupted system
 327                  * call" is string which according to the Linux manual is "possibly"
 328                  * localised according to LC_MESSAGES.
 329                  */
 330                 $eintr = defined( 'SOCKET_EINTR' ) ? SOCKET_EINTR : 4;
 331                 $eintrMessage = "stream_select(): unable to select [$eintr]";
 332
 333                 $running = true;
 334                 $timeout = null;
 335                 $numReadyPipes = 0;
 336
 337                 while ( $running === true || $numReadyPipes !== 0 ) {
 338                         if ( $running ) {
 339                                 $status = proc_get_status( $proc );
 340                                 // If the process has terminated, switch to nonblocking selects
 341                                 // for getting any data still waiting to be read.
 342                                 if ( !$status['running'] ) {
 343                                         $running = false;
 344                                         $timeout = 0;
 345                                 }
 346                         }
 347
 348                         $readyPipes = $pipes;
 349
 350                         // clear get_last_error without actually raising an error
 351                         // from http://php.net/manual/en/function.error-get-last.php#113518
 352                         // TODO replace with clear_last_error when requirements are bumped to PHP7
 353                         set_error_handler( function () {
 354                         }, 0 );
 355                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 356                         @trigger_error( '' );
 357                         // @codingStandardsIgnoreEnd
 358                         restore_error_handler();
 359
 360                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 361                         $numReadyPipes = @stream_select( $readyPipes, $emptyArray, $emptyArray, $timeout );
 362                         // @codingStandardsIgnoreEnd
 363                         if ( $numReadyPipes === false ) {
 364                                 $error = error_get_last();
 365                                 if ( strncmp( $error['message'], $eintrMessage, strlen( $eintrMessage ) ) == 0 ) {
 366                                         continue;
 367                                 } else {
 368                                         trigger_error( $error['message'], E_USER_WARNING );
 369                                         $logMsg = $error['message'];
 370                                         break;
 371                                 }
 372                         }
 373                         foreach ( $readyPipes as $fd => $pipe ) {
 374                                 $block = fread( $pipe, 65536 );
 375                                 if ( $block === '' ) {
 376                                         // End of file
 377                                         fclose( $pipes[$fd] );
 378                                         unset( $pipes[$fd] );
 379                                         if ( !$pipes ) {
 380                                                 break 2;
 381                                         }
 382                                 } elseif ( $block === false ) {
 383                                         // Read error
 384                                         $logMsg = "Error reading from pipe";
 385                                         break 2;
 386                                 } elseif ( $fd == 1 ) {
 387                                         // From stdout
 388                                         $outBuffer .= $block;
 389                                 } elseif ( $fd == 2 ) {
 390                                         // From stderr
 391                                         $errBuffer .= $block;
 392                                 } elseif ( $fd == 3 ) {
 393                                         // From log FD
 394                                         $logBuffer .= $block;
 395                                         if ( strpos( $block, "\n" ) !== false ) {
 396                                                 $lines = explode( "\n", $logBuffer );
 397                                                 $logBuffer = array_pop( $lines );
 398                                                 foreach ( $lines as $line ) {
 399                                                         $this->logger->info( $line );
 400                                                 }
 401                                         }
 402                                 }
 403                         }
 404                 }
 405
 406                 foreach ( $pipes as $pipe ) {
 407                         fclose( $pipe );
 408                 }
 409
 410                 // Use the status previously collected if possible, since proc_get_status()
 411                 // just calls waitpid() which will not return anything useful the second time.
 412                 if ( $running ) {
 413                         $status = proc_get_status( $proc );
 414                 }
 415
 416                 if ( $logMsg !== false ) {
 417                         // Read/select error
 418                         $retval = -1;
 419                         proc_close( $proc );
 420                 } elseif ( $status['signaled'] ) {
 421                         $logMsg = "Exited with signal {$status['termsig']}";
 422                         $retval = 128 + $status['termsig'];
 423                         proc_close( $proc );
 424                 } else {
 425                         if ( $status['running'] ) {
 426                                 $retval = proc_close( $proc );
 427                         } else {
 428                                 $retval = $status['exitcode'];
 429                                 proc_close( $proc );
 430                         }
 431                         if ( $retval == 127 ) {
 432                                 $logMsg = "Possibly missing executable file";
 433                         } elseif ( $retval >= 129 && $retval <= 192 ) {
 434                                 $logMsg = "Probably exited with signal " . ( $retval - 128 );
 435                         }
 436                 }
 437
 438                 if ( $logMsg !== false ) {
 439                         $this->logger->warning( "$logMsg: {command}", [ 'command' => $cmd ] );
 440                 }
 441
 442                 if ( $errBuffer && $this->doLogStderr ) {
 443                         $this->logger->error( "Error running {command}: {error}", [
 444                                 'command' => $cmd,
 445                                 'error' => $errBuffer,
 446                                 'exitcode' => $retval,
 447                                 'exception' => new Exception( 'Shell error' ),
 448                         ] );
 449                 }
 450
 451                 return new Result( $retval, $outBuffer, $errBuffer );
 452         }
 453 }