feat(userland): cleaned up the shell's Ctrl+C and signal-death reporting

userland/apps/shell/src/line_edit.c

@@ -513,6 +513,18 @@ char* line_edit_read(line_edit_state* s, const char* prompt) {
             continue;
         }
 
+        if (c == 0x03) { // Ctrl-C: discard the line, start fresh
+            s->cursor_pos = s->line_len;
+            redraw(s, prompt); /* park the cursor at end of line */
+            write(1, "^C\r\n", 4);
+            s->line_buf[0] = '\0';
+            s->line_len = 0;
+            s->cursor_pos = 0;
+            s->history_index = s->history_count < HISTORY_MAX ? s->history_count : HISTORY_MAX;
+            write_str(prompt);
+            continue;
+        }
+
         if (c == '\r' || c == '\n') {
             write(1, "\r\n", 2);
             s->line_buf[s->line_len] = '\0';

userland/apps/shell/src/shell.c

@@ -51,15 +51,21 @@ static int reap_status(int status) {
         int sig = STLX_WTERMSIG(status);
         const char* name;
         switch (sig) {
+            case 2:  /* SIGINT: the terminal's ^C echo already told the story */
+            case 13: /* SIGPIPE: routine death for pipeline members */
+                     name = NULL;                        break;
             case 4:  name = "Illegal instruction";       break;
             case 7:  name = "Bus error";                 break;
             case 8:  name = "Floating point exception"; break;
             case 9:  name = "Killed";                    break;
             case 11: name = "Segmentation fault";        break;
+            case 15: name = "Terminated";                break;
             default: name = "Terminated by signal";      break;
         }
-        shell_err(name);
-        shell_err("\r\n");
+        if (name) {
+            shell_err(name);
+            shell_err("\r\n");
+        }
         return 128 + sig;
     }
     return status;