[image] Add the concept of a static image

Not all images are allocated via alloc_image().  For example: embedded
images, the static images created to hold a runtime command line, and
the images used by unit tests are all static structures.

Using image_set_cmdline() (via e.g. the "imgargs" command) to set the
command-line arguments of a static image will succeed but will leak
memory, since nothing will ever free the allocated command line.
There are no code paths that can lead to calling image_set_len() on a
static image, but there is no safety check against future code paths
attempting this.

Define a flag IMAGE_STATIC to mark an image as statically allocated,
generalise free_image() to also handle freeing dynamically allocated
portions of static images (such as the command line), and expose
free_image() for use by static images.

Define a related flag IMAGE_STATIC_NAME to mark the name as statically
allocated.  Allow a statically allocated name to be replaced with a
dynamically allocated name since this is a potentially valid use case
(e.g. if "imgdecrypt --name <name>" is used on an embedded image).

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

1 files changed, 17 insertions, 2 deletions

diff --git a/src/include/ipxe/image.h b/src/include/ipxe/image.h
index bf2d77626..8ff938a17 100644
--- a/src/include/ipxe/image.h
+++ b/src/include/ipxe/image.h
@@ -30,14 +30,22 @@ struct image {
 
 	/** URI of image */
 	struct uri *uri;
-	/** Name */
+	/** Name
+	 *
+	 * If the @c IMAGE_STATIC_NAME flag is set, then this is a
+	 * statically allocated string.
+	 */
 	char *name;
 	/** Flags */
 	unsigned int flags;
 
 	/** Command line to pass to image */
 	char *cmdline;
-	/** Raw file image */
+	/** Raw file image
+	 *
+	 * If the @c IMAGE_STATIC flag is set, then this is a
+	 * statically allocated image.
+	 */
 	void *data;
 	/** Length of raw file image */
 	size_t len;
@@ -72,6 +80,12 @@ struct image {
 /** Image will be hidden from enumeration */
 #define IMAGE_HIDDEN 0x0008
 
+/** Image is statically allocated */
+#define IMAGE_STATIC 0x0010
+
+/** Image name is statically allocated */
+#define IMAGE_STATIC_NAME 0x0020
+
 /** An executable image type */
 struct image_type {
 	/** Name of this image type */
@@ -185,6 +199,7 @@ static inline struct image * first_image ( void ) {
 	return list_first_entry ( &images, struct image, list );
 }
 
+extern void free_image ( struct refcnt *refcnt );
 extern struct image * alloc_image ( struct uri *uri );
 extern int image_set_uri ( struct image *image, struct uri *uri );
 extern int image_set_name ( struct image *image, const char *name );