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devel-docs: add more debugging tips.

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This commit is contained in:
Jehan
2022-03-27 15:02:10 +02:00
parent 3d983728b0
commit 0225e36e9f
1 changed files with 53 additions and 3 deletions
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56
devel-docs/debugging-tips.md
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@ -125,6 +125,8 @@ Then just run your older GIMP!
## Debugging on flatpak
### Generic flatpak abilities
If you want to inspect the sandbox environment, you can do so by
specifying a custom shell instead of the GIMP binary with the following
command:
@ -149,9 +151,11 @@ flatpak install flathub org.gimp.GIMP.Debug
flatpak install flathub org.gnome.Sdk.Debug
```
Finally even with reporter trace without debug symbols (yet debug
symbols installed on your side), if you make sure you use exactly the
same flatpak commit as the reporter (see `Testing older GIMP versions`
### Getting accurate traces from reported inaccurate traces
Even with reporter trace without debug symbols (yet debug symbols
installed on your side), if you make sure you use exactly the same
flatpak commit as the reporter (see `Testing older GIMP versions`
section), you are ensured to use the same binaries. Hence you can trace
back the code line from an offset.
@ -173,6 +177,52 @@ $ flatpak run --devel --command=bash org.gimp.GIMP
Line 216 of "file-open.c" starts at address 0x4d5738 <file_open_image+1256> and ends at 0x4d5747 <file_open_image+1271>.
```
### Debugging though gdbserver
In some cases, when GIMP grabs the pointer and/or keyboard, i.e. when
you debug something happening on canvas in particular, it might be very
hard to get back to your debugger, since your system won't be responding
to your keyboard or click events.
To work around this, you can debug remotely, or simply from a TTY (while
the desktop doesn't answer properly):
In your desktop, run GIMP through a debugger server:
```
$ flatpak run --devel --command=bash org.gimp.GIMP//beta
$ gdbserver :9999 /app/bin/gimp-2.99
```
Go to a TTY and run
```
$ gdb /app/bin/gimp-2.99
(gdb) target remote localhost:9999
(gdb) continue
```
Of course, before the `continue`, you may add whatever break points or
other commands necessary for your specific issue. GIMP will start in the
desktop when you hit `continue` (it will likely be a slower start).
Then do your issue reproduction steps on GIMP. When you need to debug,
you can go to the TTY whenever you want, not bothering about any
keyboard/pointer grabs.
Note that since copy-pasting is harder in a TTY, you might want to
redirect your output to a file, especially if you need to upload it or
read it slowly next to GIMP code. For instance here are commands to
output a full backtrace into a file from the gdb prompt and exit (to
force the device ungrab by killing GIMP and go work on desktop again):
```
(gdb) set logging file gimp-issue-1234.txt
(gdb) set logging on
(gdb) thread apply all backtrace full
(gdb) quit
```
## Debugging icons ##
See file `devel-docs/icons.txt` to learn more about our icons, and in