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-rw-r--r--src/tools/gdb.md108
1 files changed, 103 insertions, 5 deletions
diff --git a/src/tools/gdb.md b/src/tools/gdb.md
index 7a43ca1..2318e0e 100644
--- a/src/tools/gdb.md
+++ b/src/tools/gdb.md
@@ -15,6 +15,7 @@
# Interactive usage
+## Misc
```markdown
tty <tty>
Set <tty> as tty for debugee.
@@ -22,19 +23,44 @@
and run following in target tty:
> while true; do sleep 1024; done
- set follow-fork-mode <child | parent>
- Specify which process to follow when debuggee makes a fork(2)
- syscall.
-
sharedlibrary [<regex>]
Load symbols of shared libs loaded by debugee. Optionally use <regex>
to filter libs for symbol loading.
+ display [/FMT] <expr>
+ Print <expr> every time debugee stops. Eg print next instr, see
+ examples below.
+
+ undisplay [<num>]
+ Delete display expressions either all or one referenced by <num>.
+
+ info display
+ List display expressions.
+```
+
+## Breakpoints
+```markdown
break [-qualified] <sym> thread <tnum>
Set a breakpoint only for a specific thread.
- -qualified: Tred <sym> as fully qualified symbol (quiet handy to set
+ -qualified: Treat <sym> as fully qualified symbol (quiet handy to set
breakpoints on C symbols in C++ contexts)
+ break <sym> if <cond>
+ Set conditional breakpoint (see examples below).
+
+ delete [<num>]
+ Delete breakpoint either all or one referenced by <num>.
+
+ info break
+ List breakpoints.
+
+ cond <bp> <cond>
+ Make existing breakpoint <bp> conditional with <cond>.
+
+ tbreak
+ Set temporary breakpoint, will be deleted when hit.
+ Same syntax as `break`.
+
rbreak <regex>
Set breakpoints matching <regex>, where matching internally is done
on: .*<regex>.*
@@ -46,7 +72,10 @@
<bp_list>: Space separates list, eg 'command 2 5-8' to run command
for breakpoints: 2,5,6,7,8.
+```
+## Inspection
+```markdown
info functions [<regex>]
List functions matching <regex>. List all functions if no <regex>
provided.
@@ -54,7 +83,10 @@
info variables [<regex>]
List variables matching <regex>. List all variables if no <regex>
provided.
+```
+## Signal handling
+```markdown
info handle [<signal>]
Print how to handle <signal>. If no <signal> specified print for all
signals.
@@ -70,6 +102,50 @@
Create a catchpoint for <signal>.
```
+## Source file locations
+```markdown
+ dir <path>
+ Add <path> to the beginning of the searh path for source files.
+
+ show dir
+ Show current search path.
+
+ set substitute-path <from> <to>
+ Add substitution rule checked during source file lookup.
+
+ show substitute-path
+ Show current substitution rules.
+```
+
+## Configuration
+
+```markdown
+ set follow-fork-mode <child | parent>
+ Specify which process to follow when debuggee makes a fork(2)
+ syscall.
+
+ set pagination <on | off>
+ Turn on/off gdb's pagination.
+
+ set breakpoint pending <on | off | auto>
+ on: always set pending breakpoints.
+ off: error when trying to set pending breakpoints.
+ auto: interatively query user to set breakpoint.
+
+ set print pretty <on | off>
+ Turn on/off pertty printing of structures.
+
+ set logging <on | off>
+ Enable output logging to file (default gdb.txt).
+
+ set logging file <fname>
+ Change output log file to <fname>
+
+ set logging redirect <on/off>
+ on: only log to file.
+ off: log to file and tty.
+```
+
# User commands (macros)
Gdb allows to create & document user commands as follows:
@@ -106,6 +182,28 @@ Gdb allows to create two types of command `hooks`
# Examples
+## Automatically print next instr
+When ever the debugee stops automatically print the memory at the current
+instruction pointer (`$rip` x86) and format as instruction `/i`.
+```markdown
+ # rip - x86
+ display /i $rip
+
+ # step instruction, after the step the next instruction is automatically printed
+ si
+```
+
+## Conditional breakpoints
+Create conditional breakpoints for a function `void foo(int i)` in the debugee.
+```markdown
+ # Create conditional breakpoint
+ b foo if i == 42
+
+ b foo # would create bp 2
+ # Make existing breakpoint conditional
+ cond 2 if i == 7
+```
+
## Catch SIGSEGV and execute commands
This creates a `catchpoint` for the `SIGSEGV` signal and attached the `command`
to it.