[image] Detect image type when image is first registered

The current usage pattern of image_probe() is a legacy from the time
before commit 34b6ecb ("[image] Simplify image management") when
loading an image to its executable location in memory was a separate
action from actually executing the image.

Call image_probe() as soon as an image is registered.  This allows
"imgstat" to display image type information for all images and allows
image-consuming code to assume that image->type is already set
correctly.

Ignore failures if image_probe() does not recognise the image, since
we do expect to handle unrecognised images (initrds, modules, etc).
Unrecognised images will be left with a NULL image->type, which
image-consuming code can easily check.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/image.c

@@ -157,6 +157,32 @@ int image_set_cmdline ( struct image *image, const char *cmdline ) {
 	return 0;
 }
 
+/**
+ * Determine image type
+ *
+ * @v image		Executable image
+ * @ret rc		Return status code
+ */
+static int image_probe ( struct image *image ) {
+	struct image_type *type;
+	int rc;
+
+	/* Try each type in turn */
+	for_each_table_entry ( type, IMAGE_TYPES ) {
+		if ( ( rc = type->probe ( image ) ) == 0 ) {
+			image->type = type;
+			DBGC ( image, "IMAGE %s is %s\n",
+			       image->name, type->name );
+			break;
+		}
+		DBGC ( image, "IMAGE %s is not %s: %s\n", image->name,
+		       type->name, strerror ( rc ) );
+	}
+
+	DBGC ( image, "IMAGE %s format not recognised\n", image->name );
+	return -ENOTSUP;
+}
+
 /**
  * Register executable image
  *
@@ -189,6 +215,14 @@ int register_image ( struct image *image ) {
 	       image->name, user_to_phys ( image->data, 0 ),
 	       user_to_phys ( image->data, image->len ) );
 
+	/* Try to detect image type, if applicable.  Ignore failures,
+	 * since we expect to handle some unrecognised images
+	 * (e.g. kernel initrds, multiboot modules, random files
+	 * provided via our EFI virtual filesystem, etc).
+	 */
+	if ( ! image->type )
+		image_probe ( image );
+
 	return 0;
 }
 
@@ -226,36 +260,6 @@ struct image * find_image ( const char *name ) {
 	return NULL;
 }
 
-/**
- * Determine image type
- *
- * @v image		Executable image
- * @ret rc		Return status code
- */
-int image_probe ( struct image *image ) {
-	struct image_type *type;
-	int rc;
-
-	/* Succeed if we already have a type */
-	if ( image->type )
-		return 0;
-
-	/* Try each type in turn */
-	for_each_table_entry ( type, IMAGE_TYPES ) {
-		if ( ( rc = type->probe ( image ) ) == 0 ) {
-			image->type = type;
-			DBGC ( image, "IMAGE %s is %s\n",
-			       image->name, type->name );
-			return 0;
-		}
-		DBGC ( image, "IMAGE %s is not %s: %s\n", image->name,
-		       type->name, strerror ( rc ) );
-	}
-
-	DBGC ( image, "IMAGE %s format not recognised\n", image->name );
-	return -ENOEXEC;
-}
-
 /**
  * Execute image
  *
@@ -288,9 +292,11 @@ int image_exec ( struct image *image ) {
 	 */
 	current_image = image_get ( image );
 
-	/* Check that this image can be selected for execution */
-	if ( ( rc = image_select ( image ) ) != 0 )
+	/* Check that this image can be executed */
+	if ( ! ( image->type && image->type->exec ) ) {
+		rc = -ENOEXEC;
 		goto err;
+	}
 
 	/* Check that image is trusted (if applicable) */
 	if ( require_trusted_images && ! ( image->flags & IMAGE_TRUSTED ) ) {
@@ -382,8 +388,8 @@ int image_replace ( struct image *replacement ) {
 	}
 
 	/* Check that the replacement image can be executed */
-	if ( ( rc = image_probe ( replacement ) ) != 0 )
-		return rc;
+	if ( ! ( replacement->type && replacement->type->exec ) )
+		return -ENOEXEC;
 
 	/* Clear any existing replacement */
 	image_put ( image->replacement );
@@ -404,16 +410,13 @@ int image_replace ( struct image *replacement ) {
  */
 int image_select ( struct image *image ) {
 	struct image *tmp;
-	int rc;
 
 	/* Unselect all other images */
 	for_each_image ( tmp )
 		tmp->flags &= ~IMAGE_SELECTED;
 
 	/* Check that this image can be executed */
-	if ( ( rc = image_probe ( image ) ) != 0 )
-		return rc;
-	if ( ! image->type->exec )
+	if ( ! ( image->type && image->type->exec ) )
 		return -ENOEXEC;
 
 	/* Mark image as selected */
@@ -472,9 +475,7 @@ int image_pixbuf ( struct image *image, struct pixel_buffer **pixbuf ) {
 	int rc;
 
 	/* Check that this image can be used to create a pixel buffer */
-	if ( ( rc = image_probe ( image ) ) != 0 )
-		return rc;
-	if ( ! image->type->pixbuf )
+	if ( ! ( image->type && image->type->pixbuf ) )
 		return -ENOTSUP;
 
 	/* Try creating pixel buffer */

src/include/ipxe/image.h

@@ -163,7 +163,6 @@ extern int image_set_cmdline ( struct image *image, const char *cmdline );
 extern int register_image ( struct image *image );
 extern void unregister_image ( struct image *image );
 struct image * find_image ( const char *name );
-extern int image_probe ( struct image *image );
 extern int image_exec ( struct image *image );
 extern int image_replace ( struct image *replacement );
 extern int image_select ( struct image *image );

src/tests/pixbuf_test.c

@@ -57,8 +57,8 @@ void pixbuf_okx ( struct pixel_buffer_test *test, const char *file,
 	/* Correct image data pointer */
 	test->image->data = virt_to_user ( ( void * ) test->image->data );
 
-	/* Check that image is detected as PNM */
-	okx ( image_probe ( test->image ) == 0, file, line );
+	/* Check that image is detected as correct type */
+	okx ( register_image ( test->image ) == 0, file, line );
 	okx ( test->image->type == test->type, file, line );
 
 	/* Check that a pixel buffer can be created from the image */
@@ -77,4 +77,7 @@ void pixbuf_okx ( struct pixel_buffer_test *test, const char *file,
 
 		pixbuf_put ( pixbuf );
 	}
+
+	/* Unregister image */
+	unregister_image ( test->image );
 }