Support System.Signal for node backend (#2556)

* first pass at signal support for node backend

* change signal values to int's

* implements defaultSignal

* return -1 as expected by calling API if any error is raised by nodejs runtime

* finishes signal support for nodejs

* extract repetitive foreign import identifiers

* fix comments

libs/base/System/Signal.idr

@@ -16,37 +16,50 @@ import System.Errno
 signalFFI : String -> String
 signalFFI fn = "C:" ++ fn ++ ", libidris2_support, idris_signal.h"
 
+signalFFINode : String -> String
+signalFFINode fn = "node:support:" ++ fn ++ ",support_system_signal"
+
 --
 -- Signals
 --
 %foreign signalFFI "sighup"
+         signalFFINode "sighup"
 prim__sighup : Int
 
 %foreign signalFFI "sigint"
+         signalFFINode "sigint"
 prim__sigint : Int
 
 %foreign signalFFI "sigabrt"
+         signalFFINode "sigabrt"
 prim__sigabrt : Int
 
 %foreign signalFFI "sigquit"
+         signalFFINode "sigquit"
 prim__sigquit : Int
 
 %foreign signalFFI "sigill"
+         signalFFINode "sigill"
 prim__sigill : Int
 
 %foreign signalFFI "sigsegv"
+         signalFFINode "sigsegv"
 prim__sigsegv : Int
 
 %foreign signalFFI "sigtrap"
+         signalFFINode "sigtrap"
 prim__sigtrap : Int
 
 %foreign signalFFI "sigfpe"
+         signalFFINode "sigfpe"
 prim__sigfpe : Int
 
 %foreign signalFFI "sigusr1"
+         signalFFINode "sigusr1"
 prim__sigusr1 : Int
 
 %foreign signalFFI "sigusr2"
+         signalFFINode "sigusr2"
 prim__sigusr2 : Int
 
 public export
@@ -126,21 +139,27 @@ toSignal x    = lookup x codes
 -- Signal Handling
 --
 %foreign signalFFI "ignore_signal"
+         signalFFINode "ignoreSignal"
 prim__ignoreSignal : Int -> PrimIO Int
 
 %foreign signalFFI "default_signal"
+         signalFFINode "defaultSignal"
 prim__defaultSignal : Int -> PrimIO Int
 
 %foreign signalFFI "collect_signal"
+         signalFFINode "collectSignal"
 prim__collectSignal : Int -> PrimIO Int
 
 %foreign signalFFI "handle_next_collected_signal"
+         signalFFINode "handleNextCollectedSignal"
 prim__handleNextCollectedSignal : PrimIO Int
 
 %foreign signalFFI "send_signal"
+         signalFFINode "sendSignal"
 prim__sendSignal : Int -> Int -> PrimIO Int
 
 %foreign signalFFI "raise_signal"
+         signalFFINode "raiseSignal"
 prim__raiseSignal : Int -> PrimIO Int
 
 ||| An Error represented by a code. See

support/js/support_system_signal.js

@@ -0,0 +1,106 @@
+const support_system_signal_process = require('process')
+
+// https://en.wikipedia.org/wiki/Signal_(IPC)#Default_action
+const support_system_signal_sighup = 1
+const support_system_signal_sigint = 2
+const support_system_signal_sigquit = 3
+const support_system_signal_sigill = 4
+const support_system_signal_sigtrap = 5
+const support_system_signal_sigabrt = 6
+const support_system_signal_sigfpe = 8
+const support_system_signal_sigusr1 = 10
+const support_system_signal_sigsegv = 11
+const support_system_signal_sigusr2 = 12
+
+function signal_int_to_string(signal) {
+    switch (signal) {
+        case 1:
+            return 'SIGHUP'
+        case 2:
+            return 'SIGINT'
+        case 3:
+            return 'SIGQUIT'
+        case 4:
+            return 'SIGILL'
+        case 5:
+            return 'SIGTRAP'
+        case 6:
+            return 'SIGABRT'
+        case 8:
+            return 'SIGFPE'
+        case 10:
+            return 'SIGUSR1'
+        case 11:
+            return 'SIGSEGV'
+        case 12:
+            return 'SIGUSR2'
+        default:
+            // https://nodejs.org/api/process.html#signal-events
+            // 0 can be sent to test for the existence of a process, it has no effect if the process exists, but will throw an error if the process does not exist.
+            return 0
+    }
+}
+
+function support_system_signal_ignoreSignal(signal) {
+    let signal_string = signal_int_to_string(signal)
+    try {
+        support_system_signal_process.on(signal_string, sig => {})
+        return 0
+    } catch (e) {
+        return -1
+    }
+}
+
+function support_system_signal_sendSignal(pid, signal) {
+    let signal_string = signal_int_to_string(signal)
+    try {
+        support_system_signal_process.kill(pid, signal_string)
+        return 0
+    } catch (e) {
+        return -1
+    }
+}
+
+function support_system_signal_raiseSignal(signal) {
+    let signal_string = signal_int_to_string(signal)
+    try {
+        support_system_signal_process.kill(support_system_signal_process.pid, signal_string)
+        return 0
+    } catch (e) {
+        return -1
+    }
+}
+
+function support_system_signal_defaultSignal(signal) {
+    let signal_string = signal_int_to_string(signal)
+    try {
+        support_system_signal_process.removeAllListeners(signal_string)
+        return 0
+    } catch (e) {
+        return -1
+    }
+}
+
+// this implementation deduplicates signals and leaves handle ordering up to details of the Map impl
+var pending_signals = new Map();
+
+function support_system_signal_collectSignal(signal) {
+    let signal_string = system_signal_int_to_string(signal)
+    try {
+        support_system_signal_process.on(signal_string, x => { pending_signals.set(signal) })
+        return 0
+    } catch (e) {
+        return -1
+    }
+}
+
+function support_system_signal_handleNextCollectedSignal() {
+    let next = pending_signals.keys().next()
+    if (next.done) {
+        return -1
+    } else {
+        let val = next.value
+        pending_signals.delete(val)
+        return val
+    }
+}