efi_loader: console support for color attributes

Shell.efi uses this, and supporting color attributes makes things look
nicer.  Map the EFI fg/bg color attributes to ANSI escape sequences.
Not all colors have a perfect match, but spec just says "Devices
supporting a different number of text colors are required to emulate the
above colors to the best of the device’s capabilities".

Signed-off-by: Rob Clark <robdclark@gmail.com>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Alexander Graf <agraf@suse.de>
[agraf: s/unsigned/unsigned int/]
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
index 1bdf36b..01732aa 100644
--- a/lib/efi_loader/efi_console.c
+++ b/lib/efi_loader/efi_console.c
@@ -307,14 +307,37 @@
 	return EFI_EXIT(EFI_SUCCESS);
 }
 
+static const struct {
+	unsigned int fg;
+	unsigned int bg;
+} color[] = {
+	{ 30, 40 },     /* 0: black */
+	{ 34, 44 },     /* 1: blue */
+	{ 32, 42 },     /* 2: green */
+	{ 36, 46 },     /* 3: cyan */
+	{ 31, 41 },     /* 4: red */
+	{ 35, 45 },     /* 5: magenta */
+	{ 33, 43 },     /* 6: brown, map to yellow as edk2 does*/
+	{ 37, 47 },     /* 7: light grey, map to white */
+};
+
+/* See EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.SetAttribute(). */
 static efi_status_t EFIAPI efi_cout_set_attribute(
 			struct efi_simple_text_output_protocol *this,
 			unsigned long attribute)
 {
+	unsigned int bold = EFI_ATTR_BOLD(attribute);
+	unsigned int fg = EFI_ATTR_FG(attribute);
+	unsigned int bg = EFI_ATTR_BG(attribute);
+
 	EFI_ENTRY("%p, %lx", this, attribute);
 
-	/* Just ignore attributes (colors) for now */
-	return EFI_EXIT(EFI_UNSUPPORTED);
+	if (attribute)
+		printf(ESC"[%u;%u;%um", bold, color[fg].fg, color[bg].bg);
+	else
+		printf(ESC"[0;37;40m");
+
+	return EFI_EXIT(EFI_SUCCESS);
 }
 
 static efi_status_t EFIAPI efi_cout_clear_screen(