java -Xmx8000000000 -Xss4m -jar ./plugins/org.eclipse.equinox.launcher_1.3.100.v20150511-1540.jar -data @noDefault -ultimatedata ./data -tc ../../../trunk/examples/toolchains/Sifa.xml -i ../../../trunk/examples/programs/20181010-MemSafetyPathprograms/ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl -------------------------------------------------------------------------------- This is Ultimate 0.1.24-3b9210c [2019-08-06 16:57:13,578 INFO L177 SettingsManager]: Resetting all preferences to default values... [2019-08-06 16:57:13,580 INFO L181 SettingsManager]: Resetting UltimateCore preferences to default values [2019-08-06 16:57:13,592 INFO L184 SettingsManager]: Ultimate Commandline Interface provides no preferences, ignoring... [2019-08-06 16:57:13,593 INFO L181 SettingsManager]: Resetting Boogie Preprocessor preferences to default values [2019-08-06 16:57:13,594 INFO L181 SettingsManager]: Resetting Boogie Procedure Inliner preferences to default values [2019-08-06 16:57:13,595 INFO L181 SettingsManager]: Resetting Abstract Interpretation preferences to default values [2019-08-06 16:57:13,597 INFO L181 SettingsManager]: Resetting LassoRanker preferences to default values [2019-08-06 16:57:13,599 INFO L181 SettingsManager]: Resetting Reaching Definitions preferences to default values [2019-08-06 16:57:13,600 INFO L181 SettingsManager]: Resetting SyntaxChecker preferences to default values [2019-08-06 16:57:13,601 INFO L181 SettingsManager]: Resetting Symbolic Interpretation preferences to default values [2019-08-06 16:57:13,602 INFO L184 SettingsManager]: Büchi Program Product provides no preferences, ignoring... [2019-08-06 16:57:13,603 INFO L181 SettingsManager]: Resetting LTL2Aut preferences to default values [2019-08-06 16:57:13,604 INFO L181 SettingsManager]: Resetting PEA to Boogie preferences to default values [2019-08-06 16:57:13,605 INFO L181 SettingsManager]: Resetting BlockEncodingV2 preferences to default values [2019-08-06 16:57:13,606 INFO L181 SettingsManager]: Resetting ChcToBoogie preferences to default values [2019-08-06 16:57:13,607 INFO L181 SettingsManager]: Resetting AutomataScriptInterpreter preferences to default values [2019-08-06 16:57:13,608 INFO L181 SettingsManager]: Resetting BuchiAutomizer preferences to default values [2019-08-06 16:57:13,610 INFO L181 SettingsManager]: Resetting CACSL2BoogieTranslator preferences to default values [2019-08-06 16:57:13,612 INFO L181 SettingsManager]: Resetting CodeCheck preferences to default values [2019-08-06 16:57:13,614 INFO L181 SettingsManager]: Resetting InvariantSynthesis preferences to default values [2019-08-06 16:57:13,619 INFO L181 SettingsManager]: Resetting RCFGBuilder preferences to default values [2019-08-06 16:57:13,620 INFO L181 SettingsManager]: Resetting Referee preferences to default values [2019-08-06 16:57:13,621 INFO L181 SettingsManager]: Resetting TraceAbstraction preferences to default values [2019-08-06 16:57:13,627 INFO L184 SettingsManager]: TraceAbstractionConcurrent provides no preferences, ignoring... [2019-08-06 16:57:13,627 INFO L184 SettingsManager]: TraceAbstractionWithAFAs provides no preferences, ignoring... [2019-08-06 16:57:13,629 INFO L181 SettingsManager]: Resetting TreeAutomizer preferences to default values [2019-08-06 16:57:13,631 INFO L181 SettingsManager]: Resetting IcfgToChc preferences to default values [2019-08-06 16:57:13,631 INFO L181 SettingsManager]: Resetting IcfgTransformer preferences to default values [2019-08-06 16:57:13,633 INFO L184 SettingsManager]: ReqToTest provides no preferences, ignoring... [2019-08-06 16:57:13,634 INFO L181 SettingsManager]: Resetting Boogie Printer preferences to default values [2019-08-06 16:57:13,634 INFO L181 SettingsManager]: Resetting ChcSmtPrinter preferences to default values [2019-08-06 16:57:13,637 INFO L181 SettingsManager]: Resetting ReqPrinter preferences to default values [2019-08-06 16:57:13,638 INFO L181 SettingsManager]: Resetting Witness Printer preferences to default values [2019-08-06 16:57:13,639 INFO L184 SettingsManager]: Boogie PL CUP Parser provides no preferences, ignoring... [2019-08-06 16:57:13,639 INFO L181 SettingsManager]: Resetting CDTParser preferences to default values [2019-08-06 16:57:13,640 INFO L184 SettingsManager]: AutomataScriptParser provides no preferences, ignoring... [2019-08-06 16:57:13,640 INFO L184 SettingsManager]: ReqParser provides no preferences, ignoring... [2019-08-06 16:57:13,642 INFO L181 SettingsManager]: Resetting SmtParser preferences to default values [2019-08-06 16:57:13,646 INFO L181 SettingsManager]: Resetting Witness Parser preferences to default values [2019-08-06 16:57:13,646 INFO L188 SettingsManager]: Finished resetting all preferences to default values... [2019-08-06 16:57:13,691 INFO L81 nceAwareModelManager]: Repository-Root is: /tmp [2019-08-06 16:57:13,703 INFO L258 ainManager$Toolchain]: [Toolchain 1]: Applicable parser(s) successfully (re)initialized [2019-08-06 16:57:13,706 INFO L214 ainManager$Toolchain]: [Toolchain 1]: Toolchain selected. [2019-08-06 16:57:13,708 INFO L271 PluginConnector]: Initializing Boogie PL CUP Parser... [2019-08-06 16:57:13,709 INFO L275 PluginConnector]: Boogie PL CUP Parser initialized [2019-08-06 16:57:13,709 INFO L428 ainManager$Toolchain]: [Toolchain 1]: Parsing single file: /storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/programs/20181010-MemSafetyPathprograms/ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl [2019-08-06 16:57:13,710 INFO L110 BoogieParser]: Parsing: '/storage/repos/ultimate/releaseScripts/default/UAutomizer-linux/../../../trunk/examples/programs/20181010-MemSafetyPathprograms/ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl' [2019-08-06 16:57:13,755 INFO L296 ainManager$Toolchain]: ####################### [Toolchain 1] ####################### [2019-08-06 16:57:13,756 INFO L131 ToolchainWalker]: Walking toolchain with 3 elements. [2019-08-06 16:57:13,757 INFO L113 PluginConnector]: ------------------------Boogie Preprocessor---------------------------- [2019-08-06 16:57:13,757 INFO L271 PluginConnector]: Initializing Boogie Preprocessor... [2019-08-06 16:57:13,757 INFO L275 PluginConnector]: Boogie Preprocessor initialized [2019-08-06 16:57:13,777 INFO L185 PluginConnector]: Executing the observer EnsureBoogieModelObserver from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,778 INFO L185 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,790 INFO L185 PluginConnector]: Executing the observer ConstExpander from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,790 INFO L185 PluginConnector]: Executing the observer StructExpander from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,795 INFO L185 PluginConnector]: Executing the observer UnstructureCode from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,797 INFO L185 PluginConnector]: Executing the observer FunctionInliner from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,799 INFO L185 PluginConnector]: Executing the observer BoogieSymbolTableConstructor from plugin Boogie Preprocessor for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (1/1) ... [2019-08-06 16:57:13,801 INFO L132 PluginConnector]: ------------------------ END Boogie Preprocessor---------------------------- [2019-08-06 16:57:13,802 INFO L113 PluginConnector]: ------------------------RCFGBuilder---------------------------- [2019-08-06 16:57:13,802 INFO L271 PluginConnector]: Initializing RCFGBuilder... [2019-08-06 16:57:13,803 INFO L275 PluginConnector]: RCFGBuilder initialized [2019-08-06 16:57:13,804 INFO L185 PluginConnector]: Executing the observer RCFGBuilderObserver from plugin RCFGBuilder for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.boogie.parser AST 06.08 04:57:13" (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:1024 -smt2 -in -t:12000 (exit command is (exit), workingDir is null) Waiting until toolchain timeout for monitored process 1 with z3 SMTLIB2_COMPLIANT=true -memory:1024 -smt2 -in -t:12000 [2019-08-06 16:57:13,879 INFO L124 BoogieDeclarations]: Specification and implementation of procedure ULTIMATE.start given in one single declaration [2019-08-06 16:57:13,880 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.start [2019-08-06 16:57:13,880 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.start [2019-08-06 16:57:14,192 INFO L278 CfgBuilder]: Using the 1 location(s) as analysis (start of procedure ULTIMATE.start) [2019-08-06 16:57:14,192 INFO L283 CfgBuilder]: Removed 0 assume(true) statements. [2019-08-06 16:57:14,194 INFO L202 PluginConnector]: Adding new model ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 06.08 04:57:14 BoogieIcfgContainer [2019-08-06 16:57:14,194 INFO L132 PluginConnector]: ------------------------ END RCFGBuilder---------------------------- [2019-08-06 16:57:14,195 INFO L113 PluginConnector]: ------------------------Symbolic Interpretation---------------------------- [2019-08-06 16:57:14,195 INFO L271 PluginConnector]: Initializing Symbolic Interpretation... [2019-08-06 16:57:14,195 INFO L275 PluginConnector]: Symbolic Interpretation initialized [2019-08-06 16:57:14,196 INFO L185 PluginConnector]: Executing the observer SymbolicInterpretationObserver from plugin Symbolic Interpretation for "ArraysOfVariableLength5_true-valid-memsafety.c_9.bpl de.uni_freiburg.informatik.ultimate.plugins.generator.rcfgbuilder CFG 06.08 04:57:14" (1/1) ... [2019-08-06 16:57:14,224 INFO L148 IcfgInterpreter]: Started Sifa with 1 locations of interest [2019-08-06 16:57:14,227 INFO L155 IcfgInterpreter]: Building call graph [2019-08-06 16:57:14,234 INFO L160 IcfgInterpreter]: Initial procedures are [ULTIMATE.start] [2019-08-06 16:57:14,246 INFO L165 IcfgInterpreter]: Starting interpretation [2019-08-06 16:57:14,249 INFO L185 IcfgInterpreter]: Interpreting procedure ULTIMATE.start with input of size 1 [2019-08-06 16:57:14,410 INFO L169 IcfgInterpreter]: Interpretation finished [2019-08-06 16:57:14,410 INFO L177 IcfgInterpreter]: Final predicates for locations of interest are: [2019-08-06 16:57:14,414 INFO L179 IcfgInterpreter]: Location ULTIMATE.startErr0ASSERT_VIOLATIONASSERT has predicate 18#(and (<= |ULTIMATE.start_write~int_#value| 2147483647) (= |ULTIMATE.start_read~int_#ptr.offset| (+ ULTIMATE.start_foo_~i~0 ULTIMATE.start_foo_~b.offset)) (<= ULTIMATE.start_main_~i~1 (+ |ULTIMATE.start_write~int_#value| 1)) (<= 0 ULTIMATE.start_foo_~i~0) (= 0 ULTIMATE.start_foo_~i~0) (= (select |#valid| |ULTIMATE.start_write~int_#ptr.base|) 1) (or (not (<= (+ |ULTIMATE.start_read~int_#sizeOfReadType| |ULTIMATE.start_read~int_#ptr.offset|) (select |#length| |ULTIMATE.start_read~int_#ptr.base|))) (not (<= 0 |ULTIMATE.start_read~int_#ptr.offset|))) (= 1 (select |#valid| |ULTIMATE.start_read~int_#ptr.base|)) (< ULTIMATE.start_foo_~i~0 ULTIMATE.start_foo_~size) (= ULTIMATE.start_main_~c~0.offset |ULTIMATE.start_main_~#mask~0.offset|) (or (and (= 0 |ULTIMATE.start_#Ultimate.alloc_#res.offset|) (= 0 |#NULL.base|) (= 0 (+ ULTIMATE.start_main_~i~1 (- 1))) (= |#valid| (store |ULTIMATE.start_#Ultimate.alloc_old_#valid| |ULTIMATE.start_#Ultimate.alloc_#res.base| 1)) (= |ULTIMATE.start_#Ultimate.alloc_#res.offset| |ULTIMATE.start_main_~#mask~0.offset|) (= |ULTIMATE.start_main_~#mask~0.base| |ULTIMATE.start_#Ultimate.alloc_#res.base|) (not (= |ULTIMATE.start_#Ultimate.alloc_#res.base| 0)) (= 0 (select |ULTIMATE.start_#Ultimate.alloc_old_#valid| |ULTIMATE.start_#Ultimate.alloc_#res.base|)) (not (= 0 |ULTIMATE.start_main_~#b~0.base|)) (exists ((|v_#valid_7| (Array Int Int))) (and (= |ULTIMATE.start_main_old_#valid| (store |v_#valid_7| 0 0)) (= |ULTIMATE.start_#Ultimate.alloc_old_#valid| (store (store |v_#valid_7| 0 0) |ULTIMATE.start_main_~#b~0.base| 1)) (= 0 (select (store |v_#valid_7| 0 0) |ULTIMATE.start_main_~#b~0.base|)))) (= (store |ULTIMATE.start_#Ultimate.alloc_old_#length| |ULTIMATE.start_#Ultimate.alloc_#res.base| |ULTIMATE.start_#Ultimate.alloc_~size|) |#length|) (= |ULTIMATE.start_main_~#b~0.offset| 0) (exists ((|v_#length_6| (Array Int Int))) (= |ULTIMATE.start_#Ultimate.alloc_old_#length| (store |v_#length_6| |ULTIMATE.start_main_~#b~0.base| 128))) (= 32 |ULTIMATE.start_#Ultimate.alloc_~size|) (= |#NULL.offset| 0)) (and (= 0 |ULTIMATE.start_#Ultimate.alloc_#res.offset|) (= 0 |#NULL.base|) (= |#valid| (store |ULTIMATE.start_#Ultimate.alloc_old_#valid| |ULTIMATE.start_#Ultimate.alloc_#res.base| 1)) (<= (+ |ULTIMATE.start_main_~#b~0.offset| 4) (select |#length| |ULTIMATE.start_main_~#b~0.base|)) (exists ((|v_ULTIMATE.start_write~int_old_#memory_int_2| (Array Int (Array Int Int)))) (= |ULTIMATE.start_write~int_old_#memory_int| (store |v_ULTIMATE.start_write~int_old_#memory_int_2| |ULTIMATE.start_main_~#b~0.base| (store (select |v_ULTIMATE.start_write~int_old_#memory_int_2| |ULTIMATE.start_main_~#b~0.base|) |ULTIMATE.start_main_~#b~0.offset| 0)))) (<= 0 |ULTIMATE.start_main_~#b~0.offset|) (= 1 (select |#valid| |ULTIMATE.start_main_~#b~0.base|)) (= |ULTIMATE.start_main_~#mask~0.base| |ULTIMATE.start_#Ultimate.alloc_#res.base|) (= |ULTIMATE.start_#Ultimate.alloc_#res.offset| |ULTIMATE.start_main_~#mask~0.offset|) (not (= |ULTIMATE.start_#Ultimate.alloc_#res.base| 0)) (exists ((|v_#valid_7| (Array Int Int))) (and (= |ULTIMATE.start_main_old_#valid| (store |v_#valid_7| 0 0)) (= |ULTIMATE.start_#Ultimate.alloc_old_#valid| (store (store |v_#valid_7| 0 0) |ULTIMATE.start_main_~#b~0.base| 1)) (= 0 (select (store |v_#valid_7| 0 0) |ULTIMATE.start_main_~#b~0.base|)))) (= 0 (select |ULTIMATE.start_#Ultimate.alloc_old_#valid| |ULTIMATE.start_#Ultimate.alloc_#res.base|)) (not (= 0 |ULTIMATE.start_main_~#b~0.base|)) (= (store |ULTIMATE.start_#Ultimate.alloc_old_#length| |ULTIMATE.start_#Ultimate.alloc_#res.base| |ULTIMATE.start_#Ultimate.alloc_~size|) |#length|) (= |ULTIMATE.start_main_~#b~0.offset| 0) (exists ((|v_#length_6| (Array Int Int))) (= |ULTIMATE.start_#Ultimate.alloc_old_#length| (store |v_#length_6| |ULTIMATE.start_main_~#b~0.base| 128))) (= 32 |ULTIMATE.start_#Ultimate.alloc_~size|) (= |#NULL.offset| 0) (= 1 (+ ULTIMATE.start_main_~i~1 (- 1))))) (= ULTIMATE.start_main_~i~1 |ULTIMATE.start_foo_#in~size|) (= |ULTIMATE.start_foo_#in~size| ULTIMATE.start_foo_~size) (= |ULTIMATE.start_write~int_#ptr.base| |ULTIMATE.start_main_~#b~0.base|) (= |ULTIMATE.start_read~int_#sizeOfReadType| 1) (<= 0 |ULTIMATE.start_write~int_#ptr.offset|) (= |ULTIMATE.start_write~int_#sizeOfWrittenType| 4) (= (+ |ULTIMATE.start_main_~#b~0.offset| (* 4 ULTIMATE.start_main_~i~1)) (+ |ULTIMATE.start_write~int_#ptr.offset| 4)) (= |ULTIMATE.start_foo_#in~b.base| ULTIMATE.start_foo_~b.base) (<= 0 (+ |ULTIMATE.start_write~int_#value| 2147483648)) (< ULTIMATE.start_main_~i~1 33) (= |ULTIMATE.start_foo_#in~b.offset| ULTIMATE.start_foo_~b.offset) (= ULTIMATE.start_foo_~b.base |ULTIMATE.start_read~int_#ptr.base|) (< ULTIMATE.start_foo_~i~0 32) (= (store |ULTIMATE.start_write~int_old_#memory_int| |ULTIMATE.start_write~int_#ptr.base| (store (select |ULTIMATE.start_write~int_old_#memory_int| |ULTIMATE.start_write~int_#ptr.base|) |ULTIMATE.start_write~int_#ptr.offset| |ULTIMATE.start_write~int_#value|)) |#memory_int|) (< ULTIMATE.start_main_~i~1 32) (= |ULTIMATE.start_main_~#mask~0.base| ULTIMATE.start_main_~c~0.base) (<= (+ |ULTIMATE.start_write~int_#sizeOfWrittenType| |ULTIMATE.start_write~int_#ptr.offset|) (select |#length| |ULTIMATE.start_write~int_#ptr.base|)) (= |ULTIMATE.start_foo_#in~b.offset| ULTIMATE.start_main_~c~0.offset) (= |ULTIMATE.start_write~int_#value| 0) (= |ULTIMATE.start_foo_#in~b.base| ULTIMATE.start_main_~c~0.base)) [2019-08-06 16:57:14,416 WARN L88 terpretationObserver]: Some locations of interest might be reachable, see reported results. [2019-08-06 16:57:14,425 INFO L132 PluginConnector]: ------------------------ END Symbolic Interpretation---------------------------- [2019-08-06 16:57:14,428 INFO L168 Benchmark]: Toolchain (without parser) took 670.84 ms. Allocated memory is still 131.6 MB. Free memory was 107.7 MB in the beginning and 85.2 MB in the end (delta: 22.5 MB). Peak memory consumption was 22.5 MB. Max. memory is 7.1 GB. [2019-08-06 16:57:14,429 INFO L168 Benchmark]: Boogie PL CUP Parser took 0.22 ms. Allocated memory is still 131.6 MB. Free memory was 109.2 MB in the beginning and 109.0 MB in the end (delta: 209.8 kB). Peak memory consumption was 209.8 kB. Max. memory is 7.1 GB. [2019-08-06 16:57:14,431 INFO L168 Benchmark]: Boogie Preprocessor took 44.97 ms. Allocated memory is still 131.6 MB. Free memory was 107.5 MB in the beginning and 105.4 MB in the end (delta: 2.2 MB). Peak memory consumption was 2.2 MB. Max. memory is 7.1 GB. [2019-08-06 16:57:14,432 INFO L168 Benchmark]: RCFGBuilder took 392.18 ms. Allocated memory is still 131.6 MB. Free memory was 105.4 MB in the beginning and 92.9 MB in the end (delta: 12.5 MB). Peak memory consumption was 12.5 MB. Max. memory is 7.1 GB. [2019-08-06 16:57:14,434 INFO L168 Benchmark]: Symbolic Interpretation took 230.48 ms. Allocated memory is still 131.6 MB. Free memory was 92.9 MB in the beginning and 85.2 MB in the end (delta: 7.6 MB). Peak memory consumption was 7.6 MB. Max. memory is 7.1 GB. [2019-08-06 16:57:14,438 INFO L335 ainManager$Toolchain]: ####################### End [Toolchain 1] ####################### --- Results --- * Results from de.uni_freiburg.informatik.ultimate.plugins.symbolicinterpretation: - UnprovableResult [Line: 124]: Unable to prove that assertion always holds Unable to prove that assertion always holds Reason: Interpreter reached this location of interest. Location might be reachable.. Possible FailurePath: * Results from de.uni_freiburg.informatik.ultimate.core: - StatisticsResult: Toolchain Benchmarks Benchmark results are: * Boogie PL CUP Parser took 0.22 ms. Allocated memory is still 131.6 MB. Free memory was 109.2 MB in the beginning and 109.0 MB in the end (delta: 209.8 kB). Peak memory consumption was 209.8 kB. Max. memory is 7.1 GB. * Boogie Preprocessor took 44.97 ms. Allocated memory is still 131.6 MB. Free memory was 107.5 MB in the beginning and 105.4 MB in the end (delta: 2.2 MB). Peak memory consumption was 2.2 MB. Max. memory is 7.1 GB. * RCFGBuilder took 392.18 ms. Allocated memory is still 131.6 MB. Free memory was 105.4 MB in the beginning and 92.9 MB in the end (delta: 12.5 MB). Peak memory consumption was 12.5 MB. Max. memory is 7.1 GB. * Symbolic Interpretation took 230.48 ms. Allocated memory is still 131.6 MB. Free memory was 92.9 MB in the beginning and 85.2 MB in the end (delta: 7.6 MB). Peak memory consumption was 7.6 MB. Max. memory is 7.1 GB. RESULT: Ultimate could not prove your program: unable to determine feasibility of some traces Received shutdown request...