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          * Executes command. Afterwards, getExitCode() and getOutput() can be used to access execution
 202          * results.
 203          *
 204          * @return Result
 205          * @throws Exception
 206          * @throws ProcOpenError
 207          * @throws ShellDisabledError
 208          */
 209         public function execute() {
 210                 $this->everExecuted = true;
 211
 212                 $profileMethod = $this->method ?: wfGetCaller();
 213
 214                 $envcmd = '';
 215                 foreach ( $this->env as $k => $v ) {
 216                         if ( wfIsWindows() ) {
 217                                 /* Surrounding a set in quotes (method used by wfEscapeShellArg) makes the quotes themselves
 218                                  * appear in the environment variable, so we must use carat escaping as documented in
 219                                  * https://technet.microsoft.com/en-us/library/cc723564.aspx
 220                                  * Note however that the quote isn't listed there, but is needed, and the parentheses
 221                                  * are listed there but doesn't appear to need it.
 222                                  */
 223                                 $envcmd .= "set $k=" . preg_replace( '/([&|()<>^"])/', '^\\1', $v ) . '&& ';
 224                         } else {
 225                                 /* Assume this is a POSIX shell, thus required to accept variable assignments before the command
 226                                  * http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_09_01
 227                                  */
 228                                 $envcmd .= "$k=" . escapeshellarg( $v ) . ' ';
 229                         }
 230                 }
 231
 232                 $cmd = $envcmd . trim( $this->command );
 233
 234                 $useLogPipe = false;
 235                 if ( is_executable( '/bin/bash' ) ) {
 236                         $time = intval( $this->limits['time'] );
 237                         $wallTime = intval( $this->limits['walltime'] );
 238                         $mem = intval( $this->limits['memory'] );
 239                         $filesize = intval( $this->limits['filesize'] );
 240
 241                         if ( $time > 0 || $mem > 0 || $filesize > 0 || $wallTime > 0 ) {
 242                                 $cmd = '/bin/bash ' . escapeshellarg( __DIR__ . '/limit.sh' ) . ' ' .
 243                                            escapeshellarg( $cmd ) . ' ' .
 244                                            escapeshellarg(
 245                                                    "MW_INCLUDE_STDERR=" . ( $this->useStderr ? '1' : '' ) . ';' .
 246                                                    "MW_CPU_LIMIT=$time; " .
 247                                                    'MW_CGROUP=' . escapeshellarg( $this->cgroup ) . '; ' .
 248                                                    "MW_MEM_LIMIT=$mem; " .
 249                                                    "MW_FILE_SIZE_LIMIT=$filesize; " .
 250                                                    "MW_WALL_CLOCK_LIMIT=$wallTime; " .
 251                                                    "MW_USE_LOG_PIPE=yes"
 252                                            );
 253                                 $useLogPipe = true;
 254                         }
 255                 }
 256                 if ( !$useLogPipe && $this->useStderr ) {
 257                         $cmd .= ' 2>&1';
 258                 }
 259                 $this->logger->debug( __METHOD__ . ": $cmd" );
 260
 261                 // Don't try to execute commands that exceed Linux's MAX_ARG_STRLEN.
 262                 // Other platforms may be more accomodating, but we don't want to be
 263                 // accomodating, because very long commands probably include user
 264                 // input. See T129506.
 265                 if ( strlen( $cmd ) > SHELL_MAX_ARG_STRLEN ) {
 266                         throw new Exception( __METHOD__ .
 267                                 '(): total length of $cmd must not exceed SHELL_MAX_ARG_STRLEN' );
 268                 }
 269
 270                 $desc = [
 271                         0 => [ 'file', 'php://stdin', 'r' ],
 272                         1 => [ 'pipe', 'w' ],
 273                         2 => [ 'pipe', 'w' ],
 274                 ];
 275                 if ( $useLogPipe ) {
 276                         $desc[3] = [ 'pipe', 'w' ];
 277                 }
 278                 $pipes = null;
 279                 $scoped = Profiler::instance()->scopedProfileIn( __FUNCTION__ . '-' . $profileMethod );
 280                 $proc = proc_open( $cmd, $desc, $pipes );
 281                 if ( !$proc ) {
 282                         $this->logger->error( "proc_open() failed: {command}", [ 'command' => $cmd ] );
 283                         throw new ProcOpenError();
 284                 }
 285                 $outBuffer = $logBuffer = '';
 286                 $errBuffer = null;
 287                 $emptyArray = [];
 288                 $status = false;
 289                 $logMsg = false;
 290
 291                 /* According to the documentation, it is possible for stream_select()
 292                  * to fail due to EINTR. I haven't managed to induce this in testing
 293                  * despite sending various signals. If it did happen, the error
 294                  * message would take the form:
 295                  *
 296                  * stream_select(): unable to select [4]: Interrupted system call (max_fd=5)
 297                  *
 298                  * where [4] is the value of the macro EINTR and "Interrupted system
 299                  * call" is string which according to the Linux manual is "possibly"
 300                  * localised according to LC_MESSAGES.
 301                  */
 302                 $eintr = defined( 'SOCKET_EINTR' ) ? SOCKET_EINTR : 4;
 303                 $eintrMessage = "stream_select(): unable to select [$eintr]";
 304
 305                 $running = true;
 306                 $timeout = null;
 307                 $numReadyPipes = 0;
 308
 309                 while ( $running === true || $numReadyPipes !== 0 ) {
 310                         if ( $running ) {
 311                                 $status = proc_get_status( $proc );
 312                                 // If the process has terminated, switch to nonblocking selects
 313                                 // for getting any data still waiting to be read.
 314                                 if ( !$status['running'] ) {
 315                                         $running = false;
 316                                         $timeout = 0;
 317                                 }
 318                         }
 319
 320                         $readyPipes = $pipes;
 321
 322                         // clear get_last_error without actually raising an error
 323                         // from http://php.net/manual/en/function.error-get-last.php#113518
 324                         // TODO replace with clear_last_error when requirements are bumped to PHP7
 325                         set_error_handler( function () {
 326                         }, 0 );
 327                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 328                         @trigger_error( '' );
 329                         // @codingStandardsIgnoreEnd
 330                         restore_error_handler();
 331
 332                         // @codingStandardsIgnoreStart Generic.PHP.NoSilencedErrors.Discouraged
 333                         $numReadyPipes = @stream_select( $readyPipes, $emptyArray, $emptyArray, $timeout );
 334                         // @codingStandardsIgnoreEnd
 335                         if ( $numReadyPipes === false ) {
 336                                 $error = error_get_last();
 337                                 if ( strncmp( $error['message'], $eintrMessage, strlen( $eintrMessage ) ) == 0 ) {
 338                                         continue;
 339                                 } else {
 340                                         trigger_error( $error['message'], E_USER_WARNING );
 341                                         $logMsg = $error['message'];
 342                                         break;
 343                                 }
 344                         }
 345                         foreach ( $readyPipes as $fd => $pipe ) {
 346                                 $block = fread( $pipe, 65536 );
 347                                 if ( $block === '' ) {
 348                                         // End of file
 349                                         fclose( $pipes[$fd] );
 350                                         unset( $pipes[$fd] );
 351                                         if ( !$pipes ) {
 352                                                 break 2;
 353                                         }
 354                                 } elseif ( $block === false ) {
 355                                         // Read error
 356                                         $logMsg = "Error reading from pipe";
 357                                         break 2;
 358                                 } elseif ( $fd == 1 ) {
 359                                         // From stdout
 360                                         $outBuffer .= $block;
 361                                 } elseif ( $fd == 2 ) {
 362                                         // From stderr
 363                                         $errBuffer .= $block;
 364                                 } elseif ( $fd == 3 ) {
 365                                         // From log FD
 366                                         $logBuffer .= $block;
 367                                         if ( strpos( $block, "\n" ) !== false ) {
 368                                                 $lines = explode( "\n", $logBuffer );
 369                                                 $logBuffer = array_pop( $lines );
 370                                                 foreach ( $lines as $line ) {
 371                                                         $this->logger->info( $line );
 372                                                 }
 373                                         }
 374                                 }
 375                         }
 376                 }
 377
 378                 foreach ( $pipes as $pipe ) {
 379                         fclose( $pipe );
 380                 }
 381
 382                 // Use the status previously collected if possible, since proc_get_status()
 383                 // just calls waitpid() which will not return anything useful the second time.
 384                 if ( $running ) {
 385                         $status = proc_get_status( $proc );
 386                 }
 387
 388                 if ( $logMsg !== false ) {
 389                         // Read/select error
 390                         $retval = -1;
 391                         proc_close( $proc );
 392                 } elseif ( $status['signaled'] ) {
 393                         $logMsg = "Exited with signal {$status['termsig']}";
 394                         $retval = 128 + $status['termsig'];
 395                         proc_close( $proc );
 396                 } else {
 397                         if ( $status['running'] ) {
 398                                 $retval = proc_close( $proc );
 399                         } else {
 400                                 $retval = $status['exitcode'];
 401                                 proc_close( $proc );
 402                         }
 403                         if ( $retval == 127 ) {
 404                                 $logMsg = "Possibly missing executable file";
 405                         } elseif ( $retval >= 129 && $retval <= 192 ) {
 406                                 $logMsg = "Probably exited with signal " . ( $retval - 128 );
 407                         }
 408                 }
 409
 410                 if ( $logMsg !== false ) {
 411                         $this->logger->warning( "$logMsg: {command}", [ 'command' => $cmd ] );
 412                 }
 413
 414                 return new Result( $retval, $outBuffer, $errBuffer );
 415         }
 416 }