# GDB

## 1. Bắt đầu GDB

`gdb [program]`

`gdb [program] [argments]`

## 2. Disassembly (hiện thị function/frame disassembly

`(gdb) disassemble [address/symbol]`

`(gdb) disass main`

## 3. View Disassembly During Exection

`(gdb) display/[# of instructions]i $pc [± offset]`

* `display` hiển thị data with each step
* `/[#]i` - hiện thị bao nhiêu dòng instruction
* `$pc` - program counter - bộ đếm chương trình (đại ý là chỉ địa chỉ hiện tại chương trình)
* `[± offset]` - cho bạn muốn xem các câu lệnh ở vị bù từ địa chỉ hiện tại

#### Xóa chế xem:

* `(gdb) info display` - để hiện thị xem có bao nhiêu chế độ được set
* `(gdb) delete display 1` - để xóa chế độ 1

## Registers

* `info registers` - display the state of all the registers (`info r`)
* x/x $\[register] - xem nội dung của thanh ghi duy nhất (x/x hiển thị dưới dạng hex)

## Breakpoints

`(gdb) b*[Address/Symbol]` - Setting Breakpoints

`(gdb) info breakpoints` - hiện thị các breakpoints hiện có

`(gdb) delete 1` - xóa breakpoints Num = 1

`(gdb) continue [# of breakpoints]` - tiếp tục chương trình cho đến khi kết thúc hoặc gặp 1 breakpoint tiếp theo.

`(gdb) step[# of instructions]` - step into default =1

`(gdb) next instruction [# of instructions]` - step over (shorthand `ni`)

`(gdb) finish` - kết thúc 1 hàm hoặc dừng lại sau khi gặp return (shorthand `fin`)

## Kiểm tra giá trị, data

`(gdb) x/[#][size][format] [Address/Symbol/Register][± offset]`

* `x/` - câu lệnh xem giá trị, kiểm tra
* `[#]` bao nhiêu
* `[size]` means what size the data should be such as a word *w* (2 bytes), double word *d* (4 bytes), or giant word *g* (8 bytes)
* `[format]` means how the data should be interpreted such as an instruction *i*, a string *s*, hex bytes *x*
* `[Address/Symbol][± offset]` means where to start interpreting the data

## Setting Data

`set [Address/Register]=[Hex Data]`

## Process Mapping

`info proc map` - dùng để hiện thị không gian địa chỉ được ánh xạ của quy trình

## Attaching Processes <a href="#attaching-processes" id="attaching-processes"></a>

`attch [pid]`

## Bảng câu lệnh

<table><thead><tr><th width="144">Câu lệnh</th><th>Cú pháp</th></tr></thead><tbody><tr><td>gcc</td><td><strong>gcc &#x3C;file.c or file.cpp> -o namefile_bin</strong></td></tr><tr><td>gdb</td><td><strong>gdb --quiet &#x3C;name_file_bin></strong> || <strong>gdb -q</strong> and <strong>file &#x3C;name_file_bin></strong></td></tr><tr><td>b</td><td><strong>b main</strong> or <strong>break &#x3C;name_funtion or *address></strong></td></tr><tr><td>disassemble</td><td>Dump of assembler code for function current</td></tr><tr><td>info b</td><td><strong>info b (info breakpoints)</strong> – <em>show information breakpoints</em></td></tr><tr><td>clear</td><td><strong>clear &#x3C;*address></strong> – <em>can be remove a breakpoint at the address</em></td></tr><tr><td>del</td><td><strong>del &#x3C;Num_breackpoint></strong> – <em>delete breakpoint at the Num in list breakpoints</em></td></tr><tr><td>disable</td><td><strong>disable &#x3C;Num_breakpoint></strong> – <em>disable a breakpoint</em></td></tr><tr><td>enable</td><td><strong>enable &#x3C;Num_breakpoint></strong> – <em>enable a breakpoint</em></td></tr><tr><td>p ...</td><td><strong>[print,p]/[x,d,u,o,t,a,c,f,s,z,r] [$register,*address]</strong> – <em>print value</em></td></tr><tr><td>info r</td><td><strong>info [r,registers]</strong> – <em>print information registers</em></td></tr><tr><td>info r ...</td><td><strong>info r [rax,rbx, ...] [] [] ...</strong> – <em>print infor specific register</em></td></tr><tr><td>set</td><td><strong>set $register = value</strong> <em>– modifying registers</em></td></tr><tr><td>x</td><td><strong>x/nfu [$register, *address]</strong> – <em>viewing memory, for examine memory</em><br><em>/> n – the repeat count</em><br><em>/> f – the display format :x,d,u,o,t,a,c,f,s,i,m</em><br><em>/> u – the unit size is any of: b,h,w,g</em></td></tr><tr><td>set</td><td><strong>set {C-style type}$register = value</strong> – <em>modifying memory</em><br><em>> char, short, long long</em></td></tr><tr><td>bt</td><td><strong>bt</strong> – <em>provides a call stack <strong>b</strong>ack<strong>t</strong>race.</em></td></tr><tr><td>n</td><td><strong>[next, n, nexti, ni]</strong> – <em>step over</em></td></tr><tr><td>si</td><td><strong>[step, s, stepi, si]</strong> – <em>step into</em></td></tr><tr><td>fin</td><td><strong>[finish, fin]</strong> – <em>step out</em></td></tr><tr><td>u</td><td><strong>[until, u] *address</strong> – <em>run until address</em></td></tr><tr><td>set intel</td><td><strong>set disassembly-flavor intel</strong> <em>– changing disassembly to Intel</em></td></tr><tr><td>set att</td><td><strong>set disassembly-flavor att</strong> – <em>changing disassembly sytax to ATT&#x26;T</em></td></tr><tr><td>p $flag</td><td><strong>p $eflags –</strong> <em>print flags is open 1</em></td></tr><tr><td>kill</td><td>kill the running program</td></tr></tbody></table>

## Chú thích

* *x – hexadecimal*
* *d – decimal*
* *u – decimal, as if it were unsigned*
* *o – octal*
* *t – binary*
* *a – address*
* *c – for ASCII characters*
* *s – for a full (presumed-null-terminated) ASCII string*
* *…*[*link*](https://sourceware.org/gdb/onlinedocs/gdb/Output-Formats.html)
* *The unit sizes for u are*
  * *b for bytes*
  * *h for half-words (2 bytes)*
  * *w for words (4 bytes)*
  * *g for giant-words (8 bytes)*


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