events: add "Signal" event #9564

..which gets triggered when SIGUSR1 is sent to the nvim process.

Closes #9562

runtime/doc/autocmd.txt

@@ -353,6 +353,8 @@ Name			triggered by ~
 |CompleteDone|		after Insert mode completion is done
 
 |User|			to be used in combination with ":doautocmd"
+|Signal|		after the nvim process received a signal
+
 
 
 The alphabetical list of autocommand events:		*autocmd-events-abc*
@@ -914,6 +916,10 @@ ShellCmdPost			After executing a shell command with |:!cmd|,
 				any changed files.
 				For non-blocking shell commands, see
 				|job-control|.
+							*Signal*
+Signal				After the nvim process received a signal.
+				The pattern is matched against the name of the
+				received signal. Only "SIGUSR1" is supported.
 							*ShellFilterPost*
 ShellFilterPost			After executing a shell command with
 				":{range}!cmd", ":w !cmd" or ":r !cmd".

runtime/doc/vim_diff.txt

@@ -142,6 +142,7 @@ Commands:
 
 Events:
   |DirChanged|
+  |Signal|
   |TabNewEntered|
   |TermClose|
   |TermOpen|

src/nvim/auevents.lua

@@ -74,6 +74,7 @@ return {
     'SessionLoadPost',        -- after loading a session file
     'ShellCmdPost',           -- after ":!cmd"
     'ShellFilterPost',        -- after ":1,2!cmd", ":w !cmd", ":r !cmd".
+    'Signal',                 -- after nvim process received a signal
     'SourceCmd',              -- sourcing a Vim script using command
     'SourcePre',              -- before sourcing a Vim script
     'SpellFileMissing',       -- spell file missing
@@ -115,6 +116,7 @@ return {
   -- syntax file
   nvim_specific = {
     DirChanged=true,
+    Signal=true,
     TabClosed=true,
     TabNew=true,
     TabNewEntered=true,

src/nvim/fileio.c

@@ -6917,6 +6917,7 @@ static bool apply_autocmds_group(event_T event, char_u *fname, char_u *fname_io,
         || event == EVENT_REMOTEREPLY
         || event == EVENT_SPELLFILEMISSING
         || event == EVENT_SYNTAX
+        || event == EVENT_SIGNAL
         || event == EVENT_TABCLOSED) {
       fname = vim_strsave(fname);
     } else {

src/nvim/os/signal.c

@@ -15,6 +15,7 @@
 #include "nvim/globals.h"
 #include "nvim/memline.h"
 #include "nvim/eval.h"
+#include "nvim/fileio.h"
 #include "nvim/main.h"
 #include "nvim/memory.h"
 #include "nvim/misc1.h"
@@ -22,7 +23,7 @@
 #include "nvim/os/signal.h"
 #include "nvim/event/loop.h"
 
-static SignalWatcher spipe, shup, squit, sterm;
+static SignalWatcher spipe, shup, squit, sterm, susr1;
 #ifdef SIGPWR
 static SignalWatcher spwr;
 #endif
@@ -61,6 +62,10 @@ void signal_init(void)
   signal_watcher_init(&main_loop, &spwr, NULL);
   signal_watcher_start(&spwr, on_signal, SIGPWR);
 #endif
+#ifdef SIGUSR1
+  signal_watcher_init(&main_loop, &susr1, NULL);
+  signal_watcher_start(&susr1, on_signal, SIGUSR1);
+#endif
 }
 
 void signal_teardown(void)
@@ -73,6 +78,9 @@ void signal_teardown(void)
 #ifdef SIGPWR
   signal_watcher_close(&spwr, NULL);
 #endif
+#ifdef SIGUSR1
+  signal_watcher_close(&susr1, NULL);
+#endif
 }
 
 void signal_stop(void)
@@ -84,6 +92,9 @@ void signal_stop(void)
 #ifdef SIGPWR
   signal_watcher_stop(&spwr);
 #endif
+#ifdef SIGUSR1
+  signal_watcher_stop(&susr1);
+#endif
 }
 
 void signal_reject_deadly(void)
@@ -115,6 +126,10 @@ static char * signal_name(int signum)
 #endif
     case SIGHUP:
       return "SIGHUP";
+#ifdef SIGUSR1
+    case SIGUSR1:
+      return "SIGUSR1";
+#endif
     default:
       return "Unknown";
   }
@@ -162,6 +177,12 @@ static void on_signal(SignalWatcher *handle, int signum, void *data)
         deadly_signal(signum);
       }
       break;
+#ifdef SIGUSR1
+    case SIGUSR1:
+      apply_autocmds(EVENT_SIGNAL, (char_u *)"SIGUSR1", curbuf->b_fname, true,
+                     curbuf);
+      break;
+#endif
     default:
       ELOG("invalid signal: %d", signum);
       break;

test/functional/autocmd/signal_spec.lua

@@ -0,0 +1,38 @@
+local helpers = require('test.functional.helpers')(after_each)
+
+local clear = helpers.clear
+local command = helpers.command
+local eq = helpers.eq
+local funcs = helpers.funcs
+local next_msg = helpers.next_msg
+
+if helpers.pending_win32(pending) then
+  -- Only applies to POSIX systems.
+  return
+end
+
+local function posix_kill(signame, pid)
+  os.execute('kill -s '..signame..' -- '..pid..' >/dev/null')
+end
+
+describe('autocmd Signal', function()
+  before_each(clear)
+
+  it('matches *', function()
+    command('autocmd Signal * call rpcnotify(1, "foo")')
+    posix_kill('USR1', funcs.getpid())
+    eq({'notification', 'foo', {}}, next_msg())
+  end)
+
+  it('matches SIGUSR1', function()
+    command('autocmd Signal SIGUSR1 call rpcnotify(1, "foo")')
+    posix_kill('USR1', funcs.getpid())
+    eq({'notification', 'foo', {}}, next_msg())
+  end)
+
+  it('does not match unknown patterns', function()
+    command('autocmd Signal SIGUSR2 call rpcnotify(1, "foo")')
+    posix_kill('USR1', funcs.getpid())
+    eq(nil, next_msg(500))
+  end)
+end)