Kernel: Implement very basic escape sequences for TextRenderer

apps/src/sh.c

@@ -113,9 +113,14 @@ int command_match_builtins(command* cmd)
 {
     if (command_matches(cmd, "exit ")) { exit(atoi(cmd->buffer + 5)); }
     if (command_matches_exactly(cmd, "exit")) { exit(0); }
-    if (command_matches_exactly(cmd, "pid"))
+    if (command_matches_exactly(cmd, "id"))
     {
-        printf("pid %ld, ppid %ld\n", getpid(), getppid());
+        printf("pid %ld, ppid %ld, uid %d (%s), gid %d\n", getpid(), getppid(), getuid(), username, getgid());
+        return 1;
+    }
+    if (command_matches_exactly(cmd, "clear"))
+    {
+        fputs("\033@", stdout); // clear screen. for now, escape sequences in luna are non-standard.
         return 1;
     }
     return 0;

kernel/src/render/TextRenderer.cpp

@@ -30,7 +30,7 @@ void TextRenderer::reset()
 #pragma GCC optimize("O0")
 
 static void putchar_at_offset(
-    char c, [[maybe_unused]] uint32_t cx, [[maybe_unused]] uint32_t cy, [[maybe_unused]] Color& fg,
+    char c, uint32_t cx, uint32_t cy, [[maybe_unused]] Color& fg,
     [[maybe_unused]] Color& bg) // FIXME: Rewrite this function to actually work with foreground and background colors.
 {
     uint8_t* glyph = &font[c * 16];
@@ -46,9 +46,25 @@ static void putchar_at_offset(
     }
 }
 
+static bool g_escape_sequence = false;
+
 #pragma GCC pop_options
 
 void TextRenderer::putchar(char chr)
+{
+    if (g_escape_sequence)
+    {
+        g_escape_sequence = false;
+        switch (chr)
+        {
+        case '@':
+            reset();
+            framebuffer0.clear(Color::Black);
+            break;
+        default: break;
+        }
+    }
+    else
     {
         switch (chr)
         {
@@ -72,6 +88,7 @@ void TextRenderer::putchar(char chr)
                 framebuffer0.paint_rect(xpos, ypos, FONT_WIDTH, FONT_HEIGHT, Color::Black);
             }
             break;
+        case '\033': g_escape_sequence = true; break;
         default: {
             putchar_at_offset(chr, xpos, ypos, fgColor, bgColor);
             xpos += FONT_WIDTH;
@@ -91,6 +108,7 @@ void TextRenderer::putchar(char chr)
         }
         }
     }
+}
 
 void TextRenderer::write(const char* str, size_t size)
 {