| *dev_tools.txt* Nvim | |
| NVIM REFERENCE MANUAL | |
| Tools and techniques for developing Nvim *dev-tools* | |
| The following advice is helpful when working on or debugging issues with Nvim | |
| itself. | |
| TODO: merge |debug.txt| into here. | |
| Type |gO| to see the table of contents. | |
| ============================================================================== | |
| Backtraces *dev-tools-backtrace* | |
| LINUX | |
| Core dumps are disabled by default on Ubuntu, CentOS and others. | |
| To enable core dumps: | |
| >bash | |
| ulimit -c unlimited | |
| < | |
| On systemd-based systems getting a backtrace is as easy as: | |
| >bash | |
| coredumpctl -1 gdb | |
| < | |
| `coredumpctl` is an optional tool, so you may need to install it: | |
| >bash | |
| sudo apt install systemd-coredump | |
| < | |
| The full backtrace is most useful; please send us the `backtrace.txt` file | |
| when reporting a bug related to a crash: | |
| >bash | |
| 2>&1 coredumpctl -1 gdb | tee -a backtrace.txt | |
| (gdb) thread apply all bt full | |
| < | |
| On systems without `coredumpctl`, you may find a `core` dump file appearing | |
| in the current directory or in other locations. On Linux systems where | |
| `apport` is installed (such as Ubuntu), the directory where core dump files | |
| are saved can be `/var/lib/apport/coredump` or elsewhere, depending on the | |
| system configuration (see `/proc/sys/kernel/core_pattern`). See also: | |
| https://stackoverflow.com/a/18368068 | |
| To get a backtrace from the `./core` dump file: | |
| >bash | |
| gdb build/bin/nvim ./core 2>&1 | tee backtrace.txt | |
| (gdb) thread apply all bt full | |
| < | |
| MACOS | |
| If `nvim` crashes, you can see the backtrace in `Console.app` (under "Crash | |
| Reports" or "User Diagnostic Reports" for older macOS versions). | |
| >bash | |
| open -a Console | |
| < | |
| You may also want to enable core dumps on macOS. To do this, first make sure | |
| the `/cores/` directory exists and is writable: | |
| >bash | |
| sudo mkdir /cores | |
| sudo chown root:admin /cores | |
| sudo chmod 1775 /cores | |
| < | |
| Then set the core size limit to `unlimited`: | |
| >bash | |
| ulimit -c unlimited | |
| < | |
| Note that this is done per shell process. If you want to make this the default | |
| for all shells, add the above line to your shell's init file (e.g. `~/.bashrc` | |
| or similar). | |
| You can then open the core file in `lldb`: | |
| >bash | |
| lldb -c /cores/core.12345 | |
| < | |
| Apple's documentation archive has some other useful information | |
| https://developer.apple.com/library/archive/technotes/tn2124/_index.html#//apple_ref/doc/uid/DTS10003391-CH1-SECCOREDUMPS, | |
| but note that some of the things on this page are out of date (such as enabling | |
| core dumps with `/etc/launchd.conf`). | |
| ============================================================================== | |
| Gdb *dev-tools-gdb* | |
| USING GDB TO STEP THROUGH FUNCTIONAL TESTS | |
| Use `TEST_TAG` to run tests matching busted tags (of the form `#foo` e.g. | |
| `it("test #foo ...", ...)`): | |
| >bash | |
| GDB=1 TEST_TAG=foo make functionaltest | |
| < | |
| Then, in another terminal: | |
| >bash | |
| gdb build/bin/nvim | |
| (gdb) target remote localhost:7777 | |
| -- See `nvim_argv` in https://github.com/neovim/neovim/blob/master/test/functional/testnvim.lua. | |
| USING LLDB TO STEP THROUGH UNIT TESTS | |
| > | |
| lldb .deps/usr/bin/luajit -- .deps/usr/bin/busted --lpath="./build/?.lua" test/unit/ | |
| < | |
| USING GDB | |
| To attach to a running `nvim` process with a pid of 1234 (Tip: the pid of a | |
| running Nvim instance can be obtained by calling |getpid()|), for instance: | |
| >bash | |
| gdb -tui -p 1234 build/bin/nvim | |
| < | |
| The `gdb` interactive prompt will appear. At any time you can: | |
| - `break foo` to set a breakpoint on the `foo()` function | |
| - `n` to step over the next statement | |
| - `<Enter>` to repeat the last command | |
| - `s` to step into the next statement | |
| - `c` to continue | |
| - `finish` to step out of the current function | |
| - `p zub` to print the value of `zub` | |
| - `bt` to see a backtrace (callstack) from the current location | |
| - `CTRL-x CTRL-a` or `tui enable` to show a TUI view of the source file in the | |
| current debugging context. This can be extremely useful as it avoids the | |
| need for a gdb "frontend". | |
| - `<up>` and `<down>` to scroll the source file view | |
| GDB REVERSE DEBUGGING | |
| - `set record full insn-number-max unlimited` | |
| - `continue` for a bit (at least until `main()` is executed | |
| - `record` | |
| - provoke the bug, then use `revert-next`, `reverse-step`, etc. to rewind the | |
| debugger | |
| USING GDBSERVER | |
| You may want to connect multiple `gdb` clients to the same running `nvim` | |
| process, or you may want to connect to a remote `nvim` process with a local | |
| `gdb`. Using `gdbserver`, you can attach to a single process and control it | |
| from multiple `gdb` clients. | |
| Open a terminal and start `gdbserver` attached to `nvim` like this: | |
| >bash | |
| gdbserver :6666 build/bin/nvim 2> gdbserver.log | |
| < | |
| `gdbserver` is now listening on port 6666. You then need to attach to this | |
| debugging session in another terminal: | |
| >bash | |
| gdb build/bin/nvim | |
| < | |
| Once you've entered `gdb`, you need to attach to the remote session: | |
| > | |
| (gdb) target remote localhost:6666 | |
| < | |
| In case gdbserver puts the TUI as a background process, the TUI can become | |
| unable to read input from pty (and receives SIGTTIN signal) and/or output data | |
| (SIGTTOU signal). To force the TUI as the foreground process, you can add | |
| >c | |
| signal (SIGTTOU, SIG_IGN); | |
| if (!tcsetpgrp(data->input.in_fd, getpid())) { | |
| perror("tcsetpgrp failed"); | |
| } | |
| < | |
| to `tui.c:terminfo_start`. | |
| USING GDBSERVER IN TMUX | |
| Consider using a custom makefile | |
| https://github.com/neovim/neovim/blob/master/BUILD.md#custom-makefile to | |
| quickly start debugging sessions using the `gdbserver` method mentioned above. | |
| This example `local.mk` will create the debugging session when you type `make | |
| debug`. | |
| >make | |
| .PHONY: dbg-start dbg-attach debug build | |
| build: | |
| @$(MAKE) nvim | |
| dbg-start: build | |
| @tmux new-window -n 'dbg-neovim' 'gdbserver :6666 ./build/bin/nvim -D' | |
| dbg-attach: | |
| @tmux new-window -n 'dbg-cgdb' 'cgdb -x gdb_start.sh ./build/bin/nvim' | |
| debug: dbg-start dbg-attach | |
| < | |
| Here `gdb_start.sh` includes `gdb` commands to be called when the debugger | |
| starts. It needs to attach to the server started by the `dbg-start` rule. For | |
| example: | |
| > | |
| (gdb) target remote localhost:6666 | |
| (gdb) br main | |
| < | |
| vim:tw=78:ts=8:et:ft=help:norl: | |