Debugging [GDB]

GDB Debugging

To allow gdb access to the source code (Provides debug symbols - Do not share publicly as it contains the source code).

gcc -g <file>

First, initialize gdb with the executable to debug.

gdb ./<executable> --tui

After gdb is ready, we can use the following commands:

Command	Description
`lay next`	Switch to the next layout (Enables TUI mode if disabled - Allows for reading the code while debugging both in `C` and `ASM`).
`ref`	Refresh (if a program prints to the terminal, it can break `gdb`’s interface).`
`q`	Quit `gdb`.

`b main`	Add a breakpoint at the main function.
`b`	Place a breakpoint at the current line.
`b <N>`	Place a breakpoint at line `N`.
`b +<N>`	Place a breakpoint N lines down.
`b <fn>`	Place a breakpoint at `fn` function.
`d`	Delete all breakpoints.
`d <N>`	Delete breakpoint number `N`.
`clear <fn>`	Clear the breakpoint set to `fn` function.

`n`	Execute up to the next line in `C`. If a function call is found, execute the function completely.
`s`	Execute up to the next line in `C`. (Jump over)
`s <N>`	Run `N` lines.
`u`	Same as `n`, but if in a loop, execute until the loop exits.
`nexti`	Execute up to the next instruction (line in `ASM`).
`r`	Run the program until a breakpoint or error is reached.
`c`	Continue running the program until a breakpoint or error is reached.

`x/i $pc`	Examine the previous instruction (View memory).
`info registers`	Read the CPU registers used by the program.
`bt`	See the call stack up to the current line. (How we got here, so to speak)
`print sizeof(<variable>)`	Check the size of a struct/variable/pointer.
`p <var>`	Print variable `var` value.
`info break`	List breakpoints.

Use valgrind to check for lost memory.

valgrind --leak-check=full ./<executable>