Kernel+LibC+UE: Introduce SIGINFO (generated with ^T)

This signal is ignored by default, but can be caught to implement state
reporting a la BSD. :^)

DevTools/UserspaceEmulator/Emulator.cpp

@@ -1109,11 +1109,11 @@ static DefaultSignalAction default_signal_action(int signal)
     case SIGIO:
     case SIGPROF:
     case SIGTERM:
-    case SIGPWR:
         return DefaultSignalAction::Terminate;
     case SIGCHLD:
     case SIGURG:
     case SIGWINCH:
+    case SIGINFO:
         return DefaultSignalAction::Ignore;
     case SIGQUIT:
     case SIGILL:

Kernel/TTY/TTY.cpp

@@ -48,7 +48,7 @@ void TTY::set_default_termios()
 {
     memset(&m_termios, 0, sizeof(m_termios));
     m_termios.c_lflag |= ISIG | ECHO | ICANON;
-    static const char default_cc[32] = "\003\034\010\025\004\0\1\0\021\023\032\0\022\017\027\026\0";
+    static const char default_cc[32] = "\003\034\010\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024";
     memcpy(m_termios.c_cc, default_cc, sizeof(default_cc));
 }
 
@@ -141,6 +141,11 @@ bool TTY::is_werase(u8 ch) const
 void TTY::emit(u8 ch)
 {
     if (should_generate_signals()) {
+        if (ch == m_termios.c_cc[VINFO]) {
+            dbg() << tty_name() << ": VINFO pressed!";
+            generate_signal(SIGINFO);
+            return;
+        }
         if (ch == m_termios.c_cc[VINTR]) {
             dbg() << tty_name() << ": VINTR pressed!";
             generate_signal(SIGINT);

Kernel/Thread.cpp

@@ -433,11 +433,11 @@ static DefaultSignalAction default_signal_action(u8 signal)
     case SIGIO:
     case SIGPROF:
     case SIGTERM:
-    case SIGPWR:
         return DefaultSignalAction::Terminate;
     case SIGCHLD:
     case SIGURG:
     case SIGWINCH:
+    case SIGINFO:
         return DefaultSignalAction::Ignore;
     case SIGQUIT:
     case SIGILL:

Kernel/UnixTypes.h

@@ -155,6 +155,7 @@ enum {
 #define VWERASE 14
 #define VLNEXT 15
 #define VEOL2 16
+#define VINFO 17
 
 /* c_iflag bits */
 #define IGNBRK 0000001

Libraries/LibC/signal_numbers.h

@@ -56,6 +56,6 @@
 #define SIGPROF 27
 #define SIGWINCH 28
 #define SIGIO 29
-#define SIGPWR 30
+#define SIGINFO 30
 #define SIGSYS 31
 #define NSIG 32