java -Xmx8000000000 -Xss4m -jar ./plugins/org.eclipse.equinox.launcher_1.3.100.v20150511-1540.jar -data @noDefault -ultimatedata ./data -tc ../../../trunk/examples/toolchains/SifaC.xml -s ../../../trunk/examples/settings/default/automizer/svcomp-Reach-32bit-Automizer_Default.epf -i ../../../trunk/examples/svcomp/eca-rers2012/Problem04_label47.c -------------------------------------------------------------------------------- This is Ultimate 0.1.24-2989841 [2019-08-09 16:54:47,485 INFO L177 SettingsManager]: Resetting all preferences to default values... [2019-08-09 16:54:47,487 INFO L181 SettingsManager]: Resetting UltimateCore preferences to default values [2019-08-09 16:54:47,499 INFO L184 SettingsManager]: Ultimate Commandline Interface provides no preferences, ignoring... [2019-08-09 16:54:47,499 INFO L181 SettingsManager]: Resetting Boogie Preprocessor preferences to default values [2019-08-09 16:54:47,500 INFO L181 SettingsManager]: Resetting Boogie Procedure Inliner preferences to default values [2019-08-09 16:54:47,502 INFO L181 SettingsManager]: Resetting Abstract Interpretation preferences to default values [2019-08-09 16:54:47,503 INFO L181 SettingsManager]: Resetting LassoRanker preferences to default values [2019-08-09 16:54:47,505 INFO L181 SettingsManager]: Resetting Reaching Definitions preferences to default values [2019-08-09 16:54:47,506 INFO L181 SettingsManager]: Resetting SyntaxChecker preferences to default values [2019-08-09 16:54:47,507 INFO L181 SettingsManager]: Resetting Symbolic Interpretation preferences to default values [2019-08-09 16:54:47,508 INFO L184 SettingsManager]: Büchi Program Product provides no preferences, ignoring... [2019-08-09 16:54:47,508 INFO L181 SettingsManager]: Resetting LTL2Aut preferences to default values [2019-08-09 16:54:47,509 INFO L181 SettingsManager]: Resetting PEA to Boogie preferences to default values [2019-08-09 16:54:47,510 INFO L181 SettingsManager]: Resetting BlockEncodingV2 preferences to default values [2019-08-09 16:54:47,511 INFO L181 SettingsManager]: Resetting ChcToBoogie preferences to default values [2019-08-09 16:54:47,512 INFO L181 SettingsManager]: Resetting AutomataScriptInterpreter preferences to default values [2019-08-09 16:54:47,513 INFO L181 SettingsManager]: Resetting BuchiAutomizer preferences to default values [2019-08-09 16:54:47,515 INFO L181 SettingsManager]: Resetting CACSL2BoogieTranslator preferences to default values [2019-08-09 16:54:47,517 INFO L181 SettingsManager]: Resetting CodeCheck preferences to default values [2019-08-09 16:54:47,519 INFO L181 SettingsManager]: Resetting InvariantSynthesis preferences to default values [2019-08-09 16:54:47,520 INFO L181 SettingsManager]: Resetting RCFGBuilder preferences to default values [2019-08-09 16:54:47,521 INFO L181 SettingsManager]: Resetting Referee preferences to default values [2019-08-09 16:54:47,522 INFO L181 SettingsManager]: Resetting TraceAbstraction preferences to default values [2019-08-09 16:54:47,525 INFO L184 SettingsManager]: TraceAbstractionConcurrent provides no preferences, ignoring... [2019-08-09 16:54:47,525 INFO L184 SettingsManager]: TraceAbstractionWithAFAs provides no preferences, ignoring... [2019-08-09 16:54:47,525 INFO L181 SettingsManager]: Resetting TreeAutomizer preferences to default values [2019-08-09 16:54:47,526 INFO L181 SettingsManager]: Resetting IcfgToChc preferences to default values [2019-08-09 16:54:47,527 INFO L181 SettingsManager]: Resetting IcfgTransformer preferences to default values [2019-08-09 16:54:47,528 INFO L184 SettingsManager]: ReqToTest provides no preferences, ignoring... [2019-08-09 16:54:47,528 INFO L181 SettingsManager]: Resetting Boogie Printer preferences to default values [2019-08-09 16:54:47,529 INFO L181 SettingsManager]: Resetting ChcSmtPrinter preferences to default values [2019-08-09 16:54:47,530 INFO L181 SettingsManager]: Resetting ReqPrinter preferences to default values [2019-08-09 16:54:47,530 INFO L181 SettingsManager]: Resetting Witness Printer preferences to default values [2019-08-09 16:54:47,532 INFO L184 SettingsManager]: Boogie PL CUP Parser provides no preferences, ignoring... [2019-08-09 16:54:47,532 INFO L181 SettingsManager]: Resetting CDTParser preferences to default values [2019-08-09 16:54:47,533 INFO L184 SettingsManager]: AutomataScriptParser provides no preferences, ignoring... [2019-08-09 16:54:47,533 INFO L184 SettingsManager]: ReqParser provides no preferences, ignoring... [2019-08-09 16:54:47,533 INFO L181 SettingsManager]: Resetting SmtParser preferences to default values [2019-08-09 16:54:47,534 INFO L181 SettingsManager]: Resetting Witness Parser preferences to default values [2019-08-09 16:54:47,535 INFO L188 SettingsManager]: Finished resetting all preferences to default values... [2019-08-09 16:54:47,536 INFO L101 SettingsManager]: Beginning loading settings from /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/settings/default/automizer/svcomp-Reach-32bit-Automizer_Default.epf [2019-08-09 16:54:47,551 INFO L113 SettingsManager]: Loading preferences was successful [2019-08-09 16:54:47,551 INFO L115 SettingsManager]: Preferences different from defaults after loading the file: [2019-08-09 16:54:47,552 INFO L136 SettingsManager]: Preferences of BlockEncodingV2 differ from their defaults: [2019-08-09 16:54:47,552 INFO L138 SettingsManager]: * Create parallel compositions if possible=false [2019-08-09 16:54:47,553 INFO L138 SettingsManager]: * Use SBE=true [2019-08-09 16:54:47,553 INFO L136 SettingsManager]: Preferences of CACSL2BoogieTranslator differ from their defaults: [2019-08-09 16:54:47,553 INFO L138 SettingsManager]: * sizeof long=4 [2019-08-09 16:54:47,553 INFO L138 SettingsManager]: * Overapproximate operations on floating types=true [2019-08-09 16:54:47,553 INFO L138 SettingsManager]: * sizeof POINTER=4 [2019-08-09 16:54:47,554 INFO L138 SettingsManager]: * Check division by zero=IGNORE [2019-08-09 16:54:47,554 INFO L138 SettingsManager]: * Pointer to allocated memory at dereference=IGNORE [2019-08-09 16:54:47,554 INFO L138 SettingsManager]: * If two pointers are subtracted or compared they have the same base address=IGNORE [2019-08-09 16:54:47,557 INFO L138 SettingsManager]: * Check array bounds for arrays that are off heap=IGNORE [2019-08-09 16:54:47,557 INFO L138 SettingsManager]: * sizeof long double=12 [2019-08-09 16:54:47,557 INFO L138 SettingsManager]: * Check if freed pointer was valid=false [2019-08-09 16:54:47,557 INFO L138 SettingsManager]: * Use constant arrays=true [2019-08-09 16:54:47,558 INFO L138 SettingsManager]: * Pointer base address is valid at dereference=IGNORE [2019-08-09 16:54:47,558 INFO L136 SettingsManager]: Preferences of RCFGBuilder differ from their defaults: [2019-08-09 16:54:47,558 INFO L138 SettingsManager]: * Size of a code block=SequenceOfStatements [2019-08-09 16:54:47,558 INFO L138 SettingsManager]: * To the following directory=./dump/ [2019-08-09 16:54:47,558 INFO L138 SettingsManager]: * SMT solver=External_DefaultMode [2019-08-09 16:54:47,559 INFO L138 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 [2019-08-09 16:54:47,559 INFO L136 SettingsManager]: Preferences of TraceAbstraction differ from their defaults: [2019-08-09 16:54:47,561 INFO L138 SettingsManager]: * Compute Interpolants along a Counterexample=FPandBP [2019-08-09 16:54:47,561 INFO L138 SettingsManager]: * Positions where we compute the Hoare Annotation=LoopsAndPotentialCycles [2019-08-09 16:54:47,561 INFO L138 SettingsManager]: * Trace refinement strategy=CAMEL [2019-08-09 16:54:47,561 INFO L138 SettingsManager]: * SMT solver=External_ModelsAndUnsatCoreMode [2019-08-09 16:54:47,561 INFO L138 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in [2019-08-09 16:54:47,562 INFO L138 SettingsManager]: * Compute Hoare Annotation of negated interpolant automaton, abstraction and CFG=true [2019-08-09 16:54:47,599 INFO L81 nceAwareModelManager]: Repository-Root is: /tmp [2019-08-09 16:54:47,614 INFO L258 ainManager$Toolchain]: [Toolchain 1]: Applicable parser(s) successfully (re)initialized [2019-08-09 16:54:47,618 INFO L214 ainManager$Toolchain]: [Toolchain 1]: Toolchain selected. [2019-08-09 16:54:47,620 INFO L271 PluginConnector]: Initializing CDTParser... [2019-08-09 16:54:47,621 INFO L275 PluginConnector]: CDTParser initialized [2019-08-09 16:54:47,622 INFO L428 ainManager$Toolchain]: [Toolchain 1]: Parsing single file: /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/svcomp/eca-rers2012/Problem04_label47.c [2019-08-09 16:54:47,712 INFO L220 CDTParser]: Created temporary CDT project at /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/data/e74b369da/27d794a302544595a057e0ea9f764230/FLAGfa7d18515 [2019-08-09 16:54:48,510 INFO L306 CDTParser]: Found 1 translation units. [2019-08-09 16:54:48,513 INFO L160 CDTParser]: Scanning /storage/repos/ultimate/trunk/examples/svcomp/eca-rers2012/Problem04_label47.c [2019-08-09 16:54:48,547 INFO L349 CDTParser]: About to delete temporary CDT project at /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/data/e74b369da/27d794a302544595a057e0ea9f764230/FLAGfa7d18515 [2019-08-09 16:54:49,015 INFO L357 CDTParser]: Successfully deleted /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/data/e74b369da/27d794a302544595a057e0ea9f764230 [2019-08-09 16:54:49,025 INFO L296 ainManager$Toolchain]: ####################### [Toolchain 1] ####################### [2019-08-09 16:54:49,027 INFO L131 ToolchainWalker]: Walking toolchain with 4 elements. [2019-08-09 16:54:49,028 INFO L113 PluginConnector]: ------------------------CACSL2BoogieTranslator---------------------------- [2019-08-09 16:54:49,028 INFO L271 PluginConnector]: Initializing CACSL2BoogieTranslator... [2019-08-09 16:54:49,031 INFO L275 PluginConnector]: CACSL2BoogieTranslator initialized [2019-08-09 16:54:49,033 INFO L185 PluginConnector]: Executing the observer ACSLObjectContainerObserver from plugin CACSL2BoogieTranslator for "CDTParser AST 09.08 04:54:49" (1/1) ... [2019-08-09 16:54:49,035 INFO L205 PluginConnector]: Invalid model from CACSL2BoogieTranslator for observer de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator.ACSLObjectContainerObserver@3d7a848d and model type de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:49, skipping insertion in model container [2019-08-09 16:54:49,036 INFO L185 PluginConnector]: Executing the observer CACSL2BoogieTranslatorObserver from plugin CACSL2BoogieTranslator for "CDTParser AST 09.08 04:54:49" (1/1) ... [2019-08-09 16:54:49,044 INFO L142 MainTranslator]: Starting translation in SV-COMP mode [2019-08-09 16:54:49,197 INFO L173 MainTranslator]: Built tables and reachable declarations [2019-08-09 16:54:50,826 INFO L206 PostProcessor]: Analyzing one entry point: main [2019-08-09 16:54:50,838 INFO L188 MainTranslator]: Completed pre-run [2019-08-09 16:54:51,604 INFO L206 PostProcessor]: Analyzing one entry point: main [2019-08-09 16:54:51,661 INFO L192 MainTranslator]: Completed translation [2019-08-09 16:54:51,663 INFO L202 PluginConnector]: Adding new model de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51 WrapperNode [2019-08-09 16:54:51,664 INFO L132 PluginConnector]: ------------------------ END CACSL2BoogieTranslator---------------------------- [2019-08-09 16:54:51,665 INFO L113 PluginConnector]: ------------------------Boogie Preprocessor---------------------------- [2019-08-09 16:54:51,665 INFO L271 PluginConnector]: Initializing Boogie Preprocessor... [2019-08-09 16:54:51,666 INFO L275 PluginConnector]: Boogie Preprocessor initialized [2019-08-09 16:54:51,687 INFO L185 PluginConnector]: Executing the observer EnsureBoogieModelObserver from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:51,688 INFO L185 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:51,777 INFO L185 PluginConnector]: Executing the observer ConstExpander from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:51,780 INFO L185 PluginConnector]: Executing the observer StructExpander from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:51,942 INFO L185 PluginConnector]: Executing the observer UnstructureCode from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:51,996 INFO L185 PluginConnector]: Executing the observer FunctionInliner from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:52,028 INFO L185 PluginConnector]: Executing the observer BoogieSymbolTableConstructor from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... [2019-08-09 16:54:52,059 INFO L132 PluginConnector]: ------------------------ END Boogie Preprocessor---------------------------- [2019-08-09 16:54:52,060 INFO L113 PluginConnector]: ------------------------RCFGBuilder---------------------------- [2019-08-09 16:54:52,060 INFO L271 PluginConnector]: Initializing RCFGBuilder... [2019-08-09 16:54:52,060 INFO L275 PluginConnector]: RCFGBuilder initialized [2019-08-09 16:54:52,062 INFO L185 PluginConnector]: Executing the observer RCFGBuilderObserver from plugin RCFGBuilder for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 09.08 04:54:51" (1/1) ... No working directory specified, using /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/z3 Starting monitored process 1 with z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 (exit command is (exit), workingDir is null) Waiting until toolchain timeout for monitored process 1 with z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:2000 [2019-08-09 16:54:52,157 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.init [2019-08-09 16:54:52,157 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.start [2019-08-09 16:54:52,157 INFO L138 BoogieDeclarations]: Found implementation of procedure calculate_output [2019-08-09 16:54:52,158 INFO L138 BoogieDeclarations]: Found implementation of procedure calculate_output2 [2019-08-09 16:54:52,158 INFO L138 BoogieDeclarations]: Found implementation of procedure calculate_output3 [2019-08-09 16:54:52,158 INFO L138 BoogieDeclarations]: Found implementation of procedure calculate_output4 [2019-08-09 16:54:52,158 INFO L138 BoogieDeclarations]: Found implementation of procedure main [2019-08-09 16:54:52,159 INFO L130 BoogieDeclarations]: Found specification of procedure calculate_output [2019-08-09 16:54:52,160 INFO L130 BoogieDeclarations]: Found specification of procedure calculate_output2 [2019-08-09 16:54:52,160 INFO L130 BoogieDeclarations]: Found specification of procedure calculate_output3 [2019-08-09 16:54:52,161 INFO L130 BoogieDeclarations]: Found specification of procedure calculate_output4 [2019-08-09 16:54:52,161 INFO L130 BoogieDeclarations]: Found specification of procedure __VERIFIER_error [2019-08-09 16:54:52,162 INFO L130 BoogieDeclarations]: Found specification of procedure __VERIFIER_nondet_int [2019-08-09 16:54:52,162 INFO L130 BoogieDeclarations]: Found specification of procedure exit [2019-08-09 16:54:52,163 INFO L130 BoogieDeclarations]: Found specification of procedure main [2019-08-09 16:54:52,164 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.init [2019-08-09 16:54:52,165 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.start [2019-08-09 16:54:57,467 INFO L278 CfgBuilder]: Using the 1 location(s) as analysis (start of procedure ULTIMATE.start) [2019-08-09 16:54:57,467 INFO L283 CfgBuilder]: Removed 1 assume(true) statements. [2019-08-09 16:54:57,470 INFO L202 PluginConnector]: Adding new model de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 09.08 04:54:57 BoogieIcfgContainer [2019-08-09 16:54:57,470 INFO L132 PluginConnector]: ------------------------ END RCFGBuilder---------------------------- [2019-08-09 16:54:57,471 INFO L113 PluginConnector]: ------------------------Symbolic Interpretation---------------------------- [2019-08-09 16:54:57,471 INFO L271 PluginConnector]: Initializing Symbolic Interpretation... [2019-08-09 16:54:57,471 INFO L275 PluginConnector]: Symbolic Interpretation initialized [2019-08-09 16:54:57,472 INFO L185 PluginConnector]: Executing the observer SymbolicInterpretationObserver from plugin Symbolic Interpretation for "de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 09.08 04:54:57" (1/1) ... [2019-08-09 16:55:02,347 WARN L88 terpretationObserver]: Some locations of interest might be reachable, see reported results. [2019-08-09 16:55:02,355 INFO L132 PluginConnector]: ------------------------ END Symbolic Interpretation---------------------------- [2019-08-09 16:55:02,358 INFO L168 Benchmark]: Toolchain (without parser) took 13330.05 ms. Allocated memory was 140.5 MB in the beginning and 610.8 MB in the end (delta: 470.3 MB). Free memory was 72.2 MB in the beginning and 368.2 MB in the end (delta: -296.0 MB). Peak memory consumption was 406.2 MB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,359 INFO L168 Benchmark]: CDTParser took 0.53 ms. Allocated memory is still 140.5 MB. Free memory was 106.6 MB in the beginning and 106.4 MB in the end (delta: 212.8 kB). Peak memory consumption was 212.8 kB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,362 INFO L168 Benchmark]: CACSL2BoogieTranslator took 2636.70 ms. Allocated memory was 140.5 MB in the beginning and 272.6 MB in the end (delta: 132.1 MB). Free memory was 72.0 MB in the beginning and 200.0 MB in the end (delta: -128.0 MB). Peak memory consumption was 110.1 MB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,363 INFO L168 Benchmark]: Boogie Preprocessor took 394.42 ms. Allocated memory is still 272.6 MB. Free memory was 200.0 MB in the beginning and 169.3 MB in the end (delta: 30.7 MB). Peak memory consumption was 30.7 MB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,366 INFO L168 Benchmark]: RCFGBuilder took 5410.58 ms. Allocated memory was 272.6 MB in the beginning and 427.8 MB in the end (delta: 155.2 MB). Free memory was 169.3 MB in the beginning and 305.9 MB in the end (delta: -136.6 MB). Peak memory consumption was 202.0 MB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,368 INFO L168 Benchmark]: Symbolic Interpretation took 4884.25 ms. Allocated memory was 427.8 MB in the beginning and 610.8 MB in the end (delta: 183.0 MB). Free memory was 305.9 MB in the beginning and 368.2 MB in the end (delta: -62.3 MB). Peak memory consumption was 352.6 MB. Max. memory is 7.1 GB. [2019-08-09 16:55:02,379 INFO L335 ainManager$Toolchain]: ####################### End [Toolchain 1] ####################### --- Results --- * Results from de.uni_freiburg.informatik.ultimate.plugins.symbolicinterpretation: - UnprovableResult [Line: 4715]: Unable to prove that call of __VERIFIER_error() unreachable Unable to prove that call of __VERIFIER_error() unreachable Reason: Interpreter reached this location of interest. Location might be reachable. Predicate is 66118#(and (= 1 ~a1~0) (= 1 ~a7~0) (= 1 ~a3~0) (= ~a28~0 17) (= ~a14~0 20) (= ~a25~0 1) (= ~a26~0 17) (= 16 ~a4~0)). Possible FailurePath: * Results from de.uni_freiburg.informatik.ultimate.core: - StatisticsResult: Toolchain Benchmarks Benchmark results are: * CDTParser took 0.53 ms. Allocated memory is still 140.5 MB. Free memory was 106.6 MB in the beginning and 106.4 MB in the end (delta: 212.8 kB). Peak memory consumption was 212.8 kB. Max. memory is 7.1 GB. * CACSL2BoogieTranslator took 2636.70 ms. Allocated memory was 140.5 MB in the beginning and 272.6 MB in the end (delta: 132.1 MB). Free memory was 72.0 MB in the beginning and 200.0 MB in the end (delta: -128.0 MB). Peak memory consumption was 110.1 MB. Max. memory is 7.1 GB. * Boogie Preprocessor took 394.42 ms. Allocated memory is still 272.6 MB. Free memory was 200.0 MB in the beginning and 169.3 MB in the end (delta: 30.7 MB). Peak memory consumption was 30.7 MB. Max. memory is 7.1 GB. * RCFGBuilder took 5410.58 ms. Allocated memory was 272.6 MB in the beginning and 427.8 MB in the end (delta: 155.2 MB). Free memory was 169.3 MB in the beginning and 305.9 MB in the end (delta: -136.6 MB). Peak memory consumption was 202.0 MB. Max. memory is 7.1 GB. * Symbolic Interpretation took 4884.25 ms. Allocated memory was 427.8 MB in the beginning and 610.8 MB in the end (delta: 183.0 MB). Free memory was 305.9 MB in the beginning and 368.2 MB in the end (delta: -62.3 MB). Peak memory consumption was 352.6 MB. Max. memory is 7.1 GB. RESULT: Ultimate could not prove your program: unable to determine feasibility of some traces Received shutdown request...