image.h

Go to the documentation of this file.

#ifndef _IPXE_IMAGE_H
#define _IPXE_IMAGE_H

/**
 * @file
 *
 * Executable images
 *
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <ipxe/tables.h>
#include <ipxe/list.h>
#include <ipxe/refcnt.h>

struct uri;
struct pixel_buffer;
struct asn1_cursor;
struct image_type;

/** An executable image */
struct image {
        /** Reference count */
        struct refcnt refcnt;

        /** List of registered images */
        struct list_head list;

        /** URI of image */
        struct uri *uri;
        /** 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
         *
         * If the @c IMAGE_STATIC flag is set, then this is a
         * statically allocated image.
         */
        union {
                /** Read-only data */
                const void *data;
                /** Writable data */
                void *rwdata;
        };
        /** Length of raw file image */
        size_t len;

        /** Image type, if known */
        struct image_type *type;

        /** Replacement image
         *
         * An image wishing to replace itself with another image (in a
         * style similar to a Unix exec() call) should return from its
         * exec() method with the replacement image set to point to
         * the new image.
         *
         * If an image unregisters itself as a result of being
         * executed, it must make sure that its replacement image (if
         * any) is registered, otherwise the replacement is likely to
         * be freed before it can be executed.
         */
        struct image *replacement;
};

/** Image is registered */
#define IMAGE_REGISTERED 0x0001

/** Image is trusted */
#define IMAGE_TRUSTED 0x0002

/** Image will be automatically unregistered after execution */
#define IMAGE_AUTO_UNREGISTER 0x0004

/** 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 */
        char *name;
        /**
         * Probe image
         *
         * @v image             Image
         * @ret rc              Return status code
         *
         * Return success if the image is of this image type.
         */
        int ( * probe ) ( struct image *image );
        /**
         * Execute image
         *
         * @v image             Image
         * @ret rc              Return status code
         */
        int ( * exec ) ( struct image *image );
        /**
         * Create pixel buffer from image
         *
         * @v image             Image
         * @v pixbuf            Pixel buffer to fill in
         * @ret rc              Return status code
         */
        int ( * pixbuf ) ( struct image *image, struct pixel_buffer **pixbuf );
        /**
         * Extract ASN.1 object from image
         *
         * @v image             Image
         * @v offset            Offset within image
         * @v cursor            ASN.1 cursor to fill in
         * @ret next            Offset to next image, or negative error
         *
         * The caller is responsible for eventually calling free() on
         * the allocated ASN.1 cursor.
         */
        int ( * asn1 ) ( struct image *image, size_t offset,
                         struct asn1_cursor **cursor );
        /**
         * Extract archive image
         *
         * @v image             Image
         * @v extracted         Extracted image
         * @ret rc              Return status code
         */
        int ( * extract ) ( struct image *image, struct image *extracted );
};

/**
 * Multiboot image probe priority
 *
 * Multiboot images are also valid executables in another format
 * (e.g. ELF), so we must perform the multiboot probe first.
 */
#define PROBE_MULTIBOOT 01

/**
 * Normal image probe priority
 */
#define PROBE_NORMAL 02

/**
 * PXE image probe priority
 *
 * PXE images have no signature checks, so will claim all image files.
 * They must therefore be tried last in the probe order list.
 */
#define PROBE_PXE 03

/** Executable image type table */
#define IMAGE_TYPES __table ( struct image_type, "image_types" )

/** An executable image type */
#define __image_type( probe_order ) __table_entry ( IMAGE_TYPES, probe_order )

/** An image tag */
struct image_tag {
        /** Name */
        const char *name;
        /** Image (weak reference, nullified when image is freed) */
        struct image *image;
};

/** Image tag table */
#define IMAGE_TAGS __table ( struct image_tag, "image_tags" )

/** An image tag */
#define __image_tag __table_entry ( IMAGE_TAGS, 01 )

extern struct list_head images;
extern struct image_tag current_image;
extern struct image_tag selected_image;

/** Iterate over all registered images */
#define for_each_image( image ) \
        list_for_each_entry ( (image), &images, list )

/** Iterate over all registered images, safe against deletion */
#define for_each_image_safe( image, tmp ) \
        list_for_each_entry_safe ( (image), (tmp), &images, list )

/**
 * Retrieve first image
 *
 * @ret image           Image, or NULL
 */
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 );
extern char * image_strip_suffix ( struct image *image );
extern int image_set_cmdline ( struct image *image, const char *cmdline );
extern int image_set_len ( struct image *image, size_t len );
extern int image_set_data ( struct image *image, const void *data,
                            size_t len );
extern int register_image ( struct image *image );
extern void unregister_image ( struct image *image );
extern struct image * find_image ( const char *name );
extern struct image * find_image_tag ( struct image_tag *tag );
extern int image_exec ( struct image *image );
extern int image_replace ( struct image *replacement );
extern int image_select ( struct image *image );
extern int image_set_trust ( int require_trusted, int permanent );
extern struct image * image_memory ( const char *name, const void *data,
                                     size_t len );
extern const char * image_argument ( struct image *image, const char *key );
extern int image_pixbuf ( struct image *image, struct pixel_buffer **pixbuf );
extern int image_asn1 ( struct image *image, size_t offset,
                        struct asn1_cursor **cursor );
extern int image_extract ( struct image *image, const char *name,
                           struct image **extracted );
extern int image_extract_exec ( struct image *image );

/**
 * Increment reference count on an image
 *
 * @v image             Image
 * @ret image           Image
 */
static inline struct image * image_get ( struct image *image ) {
        ref_get ( &image->refcnt );
        return image;
}

/**
 * Decrement reference count on an image
 *
 * @v image             Image
 */
static inline void image_put ( struct image *image ) {
        ref_put ( &image->refcnt );
}

/**
 * Clear image command line
 *
 * @v image             Image
 */
static inline void image_clear_cmdline ( struct image *image ) {
        image_set_cmdline ( image, NULL );
}

/**
 * Set image as trusted
 *
 * @v image             Image
 */
static inline void image_trust ( struct image *image ) {
        image->flags |= IMAGE_TRUSTED;
}

/**
 * Set image as untrusted
 *
 * @v image             Image
 */
static inline void image_untrust ( struct image *image ) {
        image->flags &= ~IMAGE_TRUSTED;
}

/**
 * Mark image as hidden
 *
 * @v image             Image
 */
static inline void image_hide ( struct image *image ) {
        image->flags |= IMAGE_HIDDEN;
}

/**
 * Tag image
 *
 * @v image             Image
 * @v tag               Image tag
 * @ret prev            Previous tagged image (if any)
 */
static inline struct image * image_tag ( struct image *image,
                                         struct image_tag *tag ) {
        struct image *prev = tag->image;

        tag->image = image;
        return prev;
}

#endif /* _IPXE_IMAGE_H */