Userland: Make killall accept signal names as well

Use getsignalbyname() to support killall -HUP foo, and such things.

Userland/killall.cpp

@@ -26,6 +26,7 @@
 
 #include <AK/String.h>
 #include <LibCore/ProcessStatisticsReader.h>
+#include <ctype.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -66,9 +67,19 @@ int main(int argc, char** argv)
  if (argv[1][0] != '-')
  print_usage_and_exit();
 
- auto number = String(&argv[1][1]).to_uint();
+ Optional<unsigned> number;
+
+ if (isalpha(argv[1][1])) {
+ int value = getsignalbyname(&argv[1][1]);
+ if (value >= 0 && value < NSIG)
+ number = value;
+ }
+
+ if (!number.has_value())
+ number = String(&argv[1][1]).to_uint();
+
  if (!number.has_value()) {
- printf("'%s' is not a valid signal number\n", &argv[1][1]);
+ printf("'%s' is not a valid signal name or number\n", &argv[1][1]);
  return 2;
  }
  signum = number.value();