296

Image 296

HP gnu source-level debugger 5992-4701 manual 296

Contents

Debugging with GDB Manual Page Table of Contents Continuing and stepping Signals Print settings Value historyBreakpoints Stack frames Examining the Symbol Table Specifying a Debugging Target Stop when freeing unallocated or deallocated blocks Scramble previous memory contents at malloc/free callsBatch Mode Commands for heap profiling Support for the info target Command Support for the dumpcore commandEnhancements to the dumpcore command Example Illustrating Execution Path Recovery Command for evaluating the address of an expression Support for steplast command for C and C++Debugging the application using GDB under Aries Detecting memory leaks using GDB under Aries HP-UX Terminal User Interface Miscellaneous commands 265 16.3 Setting Command History Feature in GDB 281 17.4User-defined commands 287 18.2 Command files 289 Commands for controlled output 290 20.7 Errors 302 20.8 22.2 How to report bugs 36120.9 Invalidation notices 303 304 List of Tables List of Examples Contributors to GDB Summary of GDBFree Software Page Contributors to GDB Page Loading the Executable Let us use GDB to try to see what is going onSample GDB Session Setting Display width Setting BreakpointsHere we describe how to set a breakpoint Running the executable under GDB Printing Variable Values Stepping into a subroutineExamining the Stack Setting Variable Values During a Session Listing Source Code Gdb c Continuing Definebaz,defnQUOTEfooUNQUOTE Baz Page Getting In and Out of GDB Invoking GDB Choosing files Files Processed. See Command files Choosing modes GNU Emacs sets this option when it runs GDB as a Line number in a standard, recognizable fashion eachTime a stack frame is displayed which includes each Like two `\032 characters, followed by the file name Emacs Interface Quitting GDBRedirecting WDB input and output to a file Shell commands Page Command completion GDB CommandsCommand syntax GDB sounds bell press TAB again, to see Help , h Short list of named classes of commandsGetting help Apropos reload ResultsComplete This is intended for use by GNU Emacs Getting help Page Running Programs Under GDB Compiling for debuggingStarting your program Arguments, so that you may use normal Directory See Arguments To Your ProgramYour program. SeeProgram Environment Program. See Program Input and Output Arguments To Your ProgramProgram Environment For example, this command Display the list of search paths for executablesPath environment variable Do not supply varname, print the names Working directory Program Input and Output Debugging a Running Process Killing the child process Debugging programs with multiple threads New process 35 thread Here are commands to get more information about threads Thread apply command allows you toWith the command argument threadno Display a summary of all threads currently Debugging programs with multiple processes New process. The mode can be Unimpeded. This is the defaultSet the debugger response to a program call Fork. The child process runs Stopping and Continuing Breakpoints Setting breakpoints See Break conditions page 59, for more Breakpoints Breakpoint CatchpointWhether Breakpoint is When hit EnabledMarked to be Breakpoints are Setting catchpoints Call to vfork. This is currently only Is currently only available for HP-UXUnloading of any dynamically loaded Shared library, or the unloading Selecting a frame page 73 . When Deleting breakpointsDisabling breakpoints Break conditions Breakpoint, GDB prints an error message No symbol foo in current contextStops your program only if the value Use condition, GDB checks expression Breakpoint command lists Breakpoint menus Cannot insert breakpoints Continuing and stepping Conditions Function Setting breakpoints page 52. This form of the command Signals Stops. See Automatic display Info handle is an alias for info signals Stopping and starting multi-thread programs Stopping and Continuing Examining the Stack Stack frames Backtraces Commands for Examining the StackStacks Without frames Selecting a frame Have existed longer. n defaults to one When used without any argument, this command does notWith an argument, this command is used to select a stack Information about a frame Setting catchpoints Page Examining Source Files Printing source linesList Show listsize Searching source files Specifying source directories Contains Source and machine codeShow directories Set disassembly-flavor Disassemble or x/i commandsSelect the instruction set to use when Disassembling the program viaPage Following forms of print command are supported Examining DataExpressions To See Artificial arrays page 85, for more information Where it is defined. See Program variables Program variablesType addr Normally supposed to reside at addr You can print the contents of array with Artificial arrays Output formats Machine instruction. The default is Examining memoryPrint, s null-terminated string, or Time you use either x or print However, the count n must come first wx4 does not work Automatic display For fmt specifying only a display format and not a size orSee Output formats For fmt i or s, or including a unit-size or a number Print settings A symbol. This is the default File name and line number of a symbolSymbolic form of an address Address Default is off Strings. When GDB starts, this limit is set toSetting number-of-elementsto zero Short strings. The default is off This is the default format Show which format GDB is using to printPrint using only seven-bit characters if this Default These settings are of interest when debugging C++ programs Default is onShow whether C++ names in assembly listings Would print Value history Convenience variables Command, in which case it is a pointer to the type of $ Format in which the data was printed$exitcode Program being debugged terminates Registers Info registers Info all-registers Info registers regnameOr print the instruction to be executed next with Or add four to the stack pointer3 with3with Printing Floating Point Values Floating point hardwareTo get the bit pattern, try the following macro This is what the macro produces 100 Using GDB with Different Languages Switching between source languagesList of filename extensions and languages Cpp Setting the working language Not skip over function prologues when steppingHaving GDB infer the source language Files An overview of type checking Displaying the languageType and range checking An overview of range checking Supported languages C++ Expressions is 0 for false and non-zero for true Non-zero for trueLeft shift, and right shift. Defined on integral types Types and pointer types Class types Double colons also represent the GDB scope operator seeExpressions page 83. Same precedence as , above C++ constants 1.3 C++ expressions GDB expression handling can interpret most C++ expressions C++ type and range checks C++ defaultsPrinting the variable or class returns GDB features for C++ GDB and CBreakpoint menus See Breakpoint menus Fortran types supported FortranFortran types Less than Less than or equal toGreater than Greater than or equal to Block Fortran special issuesCommonblockname Examining the Symbol Table Two commands give this output As with whatis, using ptype without anSymbols will be read when needed For example, for this variable declaration Allow GDB to reload the symbols for Replace symbol definitionsDo not replace symbol Once. This is the default Setting Is in another source file. The default is onTell GDB to resolve opaque types. An opaque Class, or union―for example, struct Altering Execution Assignment to variables Continuing at a different address Stores the value 4 into that memory location Returning from a function Giving your program a signalYou can use the following command to return from a function Calling program functions Patching programsReturn , return Is used as the return value from the function value Patching programs 124 Commands to specify files GDB Files See Optional warnings and messages Option with any of the commands that load GDB has the entire symbol table availableWrite the symbols for your program into a Map in symbol information from this auxiliary Section Symbols were loaded. Both the commands list To display or set the threshold, use the commandsIf threshold is nonzero, symbols from all New library has been loaded, until the symbol Names where the desired shared libraries reside. GDB Searching the default system directoriesSpecifying shared library locations Megabytes Messages Errors reading symbol filesVerbose on. See Optional warnings Symbol scope block as starting on the previous Is the symbol type of the uncomprehendedGDB circumvents the error by ignoring this Debug your program, though certain symbols Active targets Commands for managing targetsSpecifying a Debugging Target See Commands to specify files Choosing target byte order Instruct GDB to assume the target is big-endian Instruct GDB to assume the target is little-endianExecutable Display GDBs current idea of the target byte order HP-UX Configuration-Specific Information Summary of HP Enhancements to GDB Implementation of ask mode for set follow-fork-mode Support for setting breakpoints using shared library name Command watchtarget Dependent Standard Library Routines for Run Time Checking HP-UX dependenciesLinker Dependencies Abort Unlink Atoi Getpid Close Srand Strchr Supported Platforms and Modes HP-UX targets Support for Alternate rootWDB Location GDB location Specifying object file directories Librtc.sl location $WDBROOT/bin Opt/langtools/ n/aNone Bin $WDBROOT/bin Fix and continue debugging Fix and Continue compiler dependencies Fix and Continue restrictions Using Fix and Continue Run the program Example Fix and Continue sessionCompile the program Gdb b main Gdb runGdb edit Make the necessary changes. In this case, add return total Gdb q Inline SupportInline Debugging in HP 9000 Systems Breakpoint info frame disassembly Following options available for the set inline-debugcommandInline Debugging in Integrity Systems Step next list backtrace frame n info locals info args Limitations Debugging Inline Functions in Integrity Systems Viewing and Evaluating Macro Definitions Info frame disassemblyDebugging Macros Debug=none Compiler Options to Enable Macro DebuggingEvaluating Macros Examples for Macro Debugging HP-UX Configuration-Specific Information Debugging Memory Problems Memory Debugging Methodologies When to suspect a memory leakMemory debugging restrictions Debugging Memory in Interactive Mode Displays all current settings for memory This command are ignored from report. IfHeap growth. The default value is 100. Every Command discards the data existing in the file Debugging Memory Problems Debugging when the string option is set for Have occurred and WDB reports the problemSpecific pattern when it is allocated or Such as attempting to access space that is freed Use the info command to show list of memory leaks If the user specifies a value less than 16 forNumber of bytes, the debugger ignores it User-specified value Gdb info leak Debugging Memory in Batch ModeSetting Configuration Options for Batch Mode Framecount=noframes or set heap-check frame-count noframes Sets the number of frames to be printed for leak context For 32 bit IPF applications For 64 bit IPF applicationsFor 64 bit PA applications For 64-bit IPF applications Environment variable setting for Batch mode debugging Ldpreload Aborts execution when heap objects Aborts execution when out of memoryLog file for batch mode must be Stderr error message goes to stderr Example for Batch Mode RTC Complete one of the following steps Run the program as follows Rtcconfig file should contain entries such as the followingPreload the librtc library as follows For 32 bit PA applications Configuring memory debugging settings Run the program Start a debugging session as followsSpecifying the stack depth Specifying minimum leak size Stop when freeing unallocated or deallocated blocks Scenarios in memory debuggingFor example, if you use Specifying minimum block size Scramble previous memory contents at malloc/free calls Interactive debugging mode set heap-check scramble on offSyntax Detect dangling pointers and dangling blocks Detect in-block corruption of freed blocks Memory Debugging Commands in Interactive and Batch Mode Off Commands for heap profiling Point you use the info heap commandHeap Profiling As the start of the heap, end of the heap, heap This example shows how to use this feature on HP-UX Set a breakpoint Commands to track the change in data segment value Changes for a given run Thread Debugging Support Support for Enabling and Disabling Specific Threads Backtrace Support for Thread Debugging Advanced Thread Debugging Support Enabling and Disabling Advanced Thread Debugging Features Pre-requisites for Advanced Thread Debugging Onoff command checks if an application Unlock-not-own onoff The set thread-check unlock-not-ownMixed-sched-policy onoff The set thread-check Cv-multiple-mxs onoff The set thread-check cv-multiple-mxs This returns an Einval error to User and prints a warning message when thisCommand checks if any thread has terminated Different mutexes. The debugger transfers When this condition is detected. This situation Command checks if a thread has terminatedException or a cancel without joining or Created with the detach attribute. When an Provided, the command displays extended Is provided, the command displays extendedCondvar-id is provided, the command displays Rwlock-id is provided, the command displays For 64-bit PA applications Thread Debugging in Batch Mode For 64-bit PA applications, set Pre-requisites for Batch mode of Thread DebuggingFor 64 bit IPF applications, set And/Or Set the environment variable Batchrtc to on as Opt/langtools/lib/hpux64/librtc.so Limitations in Batch mode of thread debugging Thread Debugging in +check ModeWhere Pid is the process id Debugging MPI Programs Where pid is the process identifierIssue Ask mode for set follow-fork-mode Serial mode for set follow-fork-modeSupport for showing unwind info Debugger response to a program call to fork or vfork is ask Command to Search for a Pattern in the Memory Address Space Printing CFM and PFS registers Parameter is mandatory when end-addressis not Specifies the length of the memory address range. ThisString value. The character pattern must be enclosed Within double quotes. This parameter is mandatory Example 14-1 Sample Output for the find command Using the /max-countparameter Using the /size-charparameterStr0 Specifies the starting address Specifies the pattern expr1 Debugging Core Files Generating core files with packcore /unpackcore/getcore Support for the info target Command Support for the dumpcore command When starting from the HP WDB command lineWhen starting from the shell prompt Enhancements to the dumpcore command When starting from shell prompt Support for display of run time type informationInfo rtti address Sample Output Exec-path updownpathindex aliased to ep Info exec-path summaryInfo global-exec-path summary Sample Debugging Session Example Illustrating Execution Path RecoverySample Program Command to Unwind Beyond 10000 Frames Aborting a Command Line Call Invoking GDB Before a Program Aborts Instruction Level Stepping Enhanced support for watchpoints and breakpointsDeferred watchpoints Hardware watchpoints Support for procedural breakpoints Support for template breakpointsRbp Rdp Using shared library as main program Debugging support for shared libraries Privately mapping shared libraries Setting Deferred Breakpoints in Shared LibraryUsing catch load Selectively Mapping Shared Libraries As Private Opt/langtools/bin/pxdb -s on executable-name Setting breakpoints in shared library Enhancement to the info shared CommandDebugging support for Decimal Floating Point data type Printing Decimal Floating point data types Following are sample commands to print NaT registers Printing NaT RegistersHandling Decimal Floating Point Data types Evaluating Decimal Floating Point data types Assignment of Decimal floating point value to variable Arithmetic OperationsComparison Operations Printing type of Decimal Floating Point variable Additional Support for binary floating point data type Support for Binary Floating Point constants f, lThis prints the binary floating point value as oat This prints the binary floating point value as double Enhanced Java Debugging Support Java Stack Unwind FeaturesLanguage support Gdb Subcommands for Java VM Debugging Gdb help java Frame command of GDB has been enhanced to interpret a Java Java and native stack framesInfo frame Stack frame Java attach mode debugging support Java corefile debugging support Enhanced support for C++ templates Syntax Support for debugging namespaces Support for fpreg data type on IPFSupport for Complex variables in HP C This is equivalent to executing Command for evaluating the address of an expressionViewing Wide Character Strings Support for output logging Support for dumping array in an Ascii file Support for steplast command for C and C++ Support for Fortran array slicesDisplaying enumerators Support for debugging typedefs Getting information from a non-debug executable Break Call Cond Jump Return Print Set var Watch Whatis Debugging optimized codeBreak Call Clear Disassem List HP-UX Configuration-Specific Information 14.29.1.2 +O2/+O3/+O4/-ipo Debugging Optimized Code at Various Optimization Levels14.29.1.1 +O0 and +O1 +O2 or -O Following limitations apply when debugging optimized codeDebugging with Aries Debugging the application using GDB under Aries Limitations of GDB Support under Aries Detecting memory leaks using GDB under Aries Attaching GDB to an already running emulated process Visual Interface for WDB Starting and stopping Visual Interface for WDB Navigating the Visual Interface for WDB display Visual Interface for WDB GUI display Using the X-window graphical interface Specifying foreground and background colors For dterm, use the following Using the TUI modeChanging the size of the source or debugger pane Using commands to browse through source files Editing the command line and command-line historySaving the contents of a debugging session to a file Loading source files Support for XDB commands GNU GDB Logging CommandsSupport for command line calls in a stripped executable Stop in/at dbx commands Execute the chatr -B immediate executable command For 32-bit applications Command line calls to non-stripped library Support for debugging stripped binariesFor 64-bit applications Printing of locals and globals in a stripped module Syntax Displaying the current block scope informationLinux support 242 Invoke the debugger using a command like the following HP-UX Terminal User InterfaceStarting the TUI Main Automatically running a program at startup Screen Layouts Disassembly pane Disassembly pane appears when you issue the commandSource pane Pane looks like this Source/Disassembly pane appears when you issue the command Source/Disassembly paneDisassembly/Register pane Source/Register pane appears when you issue the command Source/Register pane Use the commands Toggle split-screen modeCycling through the panes Changing pane focus Fs regs Foc next Scrolling panes Changing the register display Changing the pane size Refreshing and updating the window By-function lists of XDB commands and HP WDB equivalents XDB to WDB Transition Guide Invocation commands Window mode commandsInvocation commands Window mode commands File viewing commands File viewing commands Source directory mapping commands Data Viewing and modification commands Data viewing and modification commands Ll string Lm string Stack viewing commands Stack viewing commands Status-viewing command Job control commandsStatus viewing commands Job control commands Overall breakpoint commands Overall breakpoint commandsAuxiliary breakpoint commands 10 Breakpoint creation commands Breakpoint creation commandsAuxillary breakpoint commands Breakpoint status commands 11 Overall breakpoint commands All-procedures breakpoint commands Global breakpoint commands12 Global breakpoint commands Bp bpt bpx dp Dpt Dpx Macro facility commands Assertion control commandsRecord and playback commands Signal control commands Miscellaneous commands13 Macro facility commands 14 Signal control commands XDB data formats and HP WDB equivalents Format of the print command is different in XDB and GDB16 Data format commands Decimal integer XDB special language operators and HP WDB equivalents 17 Macro facility commandsXDB location syntax and HP WDB equivalents 19 Special variables XDB special variables and HP WDB equivalents18 Special language operators Alphabetical lists of XDB commands and HP WDB equivalents XDB variable identifiers and HP WDB equivalents16.8.1 a 20 Variable Identifiers 16.8.2 B 22 B Through D 23 C through D Through K 16.8.5 L24 F through K 25 L Through P 26 M through P Through S 16.8.8 T27 Q through S 28 T Through Z 29 U through Z Symbols 30 Symbols Any string Control-C # text 280 Setting the GDB Prompt Setting Command Editing Options in GDBSetting Command History Feature in GDB Controlling GDB Control the settings To fname. This is the file where GDB reads anExits. You can access this list through history Expansion or through the history command Setting the GDB Screen Size Supported Number Formats Optional warnings and messages Show confirm Displays state of confirmation requests Optional messages about internal happeningsSet confirm on Show debug varobj Object debugging info Canned Sequences of Commands User-defined commands User-defined command hooks Command files To add source directories or Commands for controlled output Expressions Output formats 292 Using GDB under gnu Emacs Calls, like the GDB next command. Then update the display Execute to next instruction, using the GDB nexti commandUpdate display window accordingly GDB up command 295 296 Server prefix What is an annotation?GDB Annotations When printing a structure, GDB annotates it as follows Values Frame annotation begins with When printing an array, GDB annotates it as followsFrames Then comes Displays Annotation for GDB input Errors Information on breakpoints Invalidation notices Running the program Displaying source Annotations We Might Want in the Future Target-invalid 306 21.1 GDB/MI Command Syntax GDB/MI Interface Pragmatics Done running connected error exit21.1.2 GDB/MI Output syntax Value Const tuple list String Tuple → Here is what happens if you pass a bad command 21.2 GDB/MI compatibility with CLISimple examples of GDB/MI interaction Here is an example to evaluate an expression 21.4 GDB/MI command description format 21.3 GDB/MI output records21.3.1 GDB/MI result records 21.3.2 GDB/MI stream records 21.5 GDB/MI breakpoint table commands -break-after Command -break-condition command Corresponding GDB command is condition -break-delete command -break-disable commandCorresponding GDB command is delete Corresponding GDB command is disable -break-enable command -break-info Command -break-insert command Result -break-list command Setting a watchpoint on a variable in the main function -break-watch commandCorresponding GDB commands are watch, awatch, and rwatch Exec-continue running gdb -data-disassemble command 21.6 GDB/MI Data manipulation Disassemble 3 instructions from the start of main There is no direct mapping from this command to the CLIDisassemble from the current value of $pc to $pc + -data-evaluate-expression command -data-list-changed-registers Command -data-list-register-names commandDisplay a list of the registers that have changed On a PPC MBX board -data-list-register-values command To be read. Complex expressions containing embedded white -data-read-memory commandSpace should be quoted using the C convention Word-format Word-sizenr-rowsnr-cols aschar -display-delete command -display-disable Command -display-enable command -display-insert Command-display-list command -environment-cd command -environment-directory command -environment-path command -environment-pwd command Corresponding GDB command is pwd21.7 GDB/MI program control Show the current working directory -exec-continue command -exec-abort command-exec-arguments command -exec-finish command -exec-interrupt commandCorresponding GDB command is finish Corresponding GDB command is interrupt -exec-nextcommand Synopsis -exec-next-instruction commandCorresponding GDB command is next Corresponding GDB command is nexti -exec-return command -exec-runcommand SynopsisCorresponding GDB command is return Corresponding GDB command is run -exec-show-arguments command Example -exec-stepCommand Synopsis -exec-step-instruction command -exec-until commandCorresponding GDB command is stepi Regular stepping -file-exec-and-symbols command -file-exec-file commandCorresponding GDB command is until Corresponding GDB command is file -file-list-shared-libraries command -file-list-exec-sections command-file-list-exec-source-files command Miscellaneous GDB commands in GDB/MI -file-list-symbol-files command-file-symbol-file command -gdb-exitcommand Synopsis -gdb-version command -gdb-setcommand Synopsis-gdb-showcommand Synopsis -stack-info-depth command 21.9 GDB/MI Stack Manipulation Commands-stack-info-frame command -stack-list-arguments command Synopsis For a stack with frame levels 0 through -stack-list-frames command Corresponding GDB commands are backtrace and where Full stack backtraceShow frames between lowframe and highframe Show a single frame Info locals in GDB, gdbgetlocals in gdbtk -stack-list-locals command-stack-select-frame command 21.10 GDB/MI Symbol query commands -symbol-info-address command-symbol-info-file command -symbol-info-function command -symbol-info-line command -symbol-info-symbol command-symbol-list-functions command -symbol-list-types command -symbol-type command -symbol-list-variables command-symbol-locate command 21.11 GDB/MI Target Manipulation Commands -target-attach command-target-compare-sections command -target-detach command -target-download command Corresponding GDB command is loadName of the section At the end, a summary is printed -target-exec-status command -target-list-parameters command -target-list-available-targets command-target-list-current-targets command 21.12 GDB/MI thread commands -target-select command-thread-info command -thread-list-all-threads command -thread-list-ids command -thread-select command 21.14 GDB/MI variable objects 21.13 GDB/MI tracepoint commandsTracepoint commands are not yet implemented Description and use of operations on variable objects -var-create commandGDB/MI Operations -var-delete command -var-set-format command-var-show-format command -var-info-num-children command -var-list-children command -var-info-type command-var-info-expression command -var-show-attributes command -var-assign command -var-update command 360 Have you found a bug? How to report bugsReporting Bugs in GDB Reporting Bugs in GDB How to report bugs 364 Installing GDB Package Compiling GDB in another directoryGdb-gdb-199991101/mmalloc Specifying names for hosts and targets Configure options Separate directories. configure writes configurationTo use the source in the directory dirname. configure Srcdir= dirname Target=target All available targets