Lab 6: Debuggers GDB Breakpoints Inspection TUI mode - - PowerPoint PPT Presentation

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Lab 6: Debuggers GDB Breakpoints Inspection TUI mode - - PowerPoint PPT Presentation

Oct 10, 2023 369 likes •552 views

Debuggers Lab 6: Debuggers GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous Comp Sci 1585 Data Structures Lab: Tools for Computer Scientists Outline Debuggers GDB Breakpoints Inspection TUI

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Lab 6: Debuggers

Comp Sci 1585 Data Structures Lab: Tools for Computer Scientists

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

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Debuggers

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GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Debuggers

  • Step through code one line at a time
  • Inspect variables, including structs and classes
  • View disassembly
  • Check the call stack
  • $ gdb Command-line debugger
  • $ kdbg GUI frontend for gdb
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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

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Debuggers

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GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Using $ gdb

  • $ gdb your-program launches the debugger
  • Note: You will want to compile with $ g++ -g
  • (gdb) run arg1 arg2 ... runs the command with

command line arguments

  • (gdb) backtrace or (gdb) bt shows the call stack
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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

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Debuggers

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GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Setting breakpoints with $ gdb

  • (gdb) break filename.cpp:10 will stop execution

whenever line 10 in ‘filename.cpp’ is reached.

  • (gdb) continue resumes running as normal.
  • (gdb) step runs one more line of code.
  • (gdb) next runs until execution is on the next line.
  • (gdb) finish runs until the current function returns.
  • (gdb) delete removes all breakpoints.
  • More on breakpoints
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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

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Debuggers

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GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Looking at variables with $ gdb

  • (gdb) p variable prints the contents of ‘variable’.
  • (gdb) p also works with expressions of just about any

sort.

  • (gdb) x address examines one word memory at a

given address.

  • (gdb) x/2 address examines two words of memory.
  • More on examining memory
  • (gdb) info registers lists all register values.
  • (gdb) p $regname prints the value of a register.
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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

1

Debuggers

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GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Text User Interface (TUI) mode

  • $ gdb a.out -tui
  • r
  • (gdb) tui enable
  • (gdb) help layout
  • (gdb) layout

Most useful: (gdb) start followed by (gdb) layout src

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

1

Debuggers

2

GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Code::Blocks plugin

1 make a project, accepting defaults for debug target 2 add your files 3 use the debug menu to run/start/step 4 right click on variables to watch them

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

1

Debuggers

2

GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

KDevelop and KDbg

Both good options for another graphical interface

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Outline

1

Debuggers

2

GDB Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

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Debuggers GDB

Breakpoints Inspection TUI mode Code::Blocks plugin KDevelop and KDbg Miscellaneous

Miscellaneous

Conditional Breakpoints: (gdb) condition breakpoint number expression Editing variables with $ gdb :

  • (gdb) set var VARIABLE NAME = value assigns

‘value’ to ‘VARIABLE NAME’

  • (gdb) set {int}0x1234 = 4 writes 4 as an integer to

the memory address 0x1234 Disassembling code: (gdb) disassemble function prints the assembly for a function.