[gzip] Add support for gzip archive images

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

src/image/gzip.c

@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdlib.h>
+#include <errno.h>
+#include <assert.h>
+#include <ipxe/deflate.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/image.h>
+#include <ipxe/zlib.h>
+#include <ipxe/gzip.h>
+
+/** @file
+ *
+ * gzip compressed images
+ *
+ */
+
+/**
+ * Extract gzip image
+ *
+ * @v image		Image
+ * @v extracted		Extracted image
+ * @ret rc		Return status code
+ */
+static int gzip_extract ( struct image *image, struct image *extracted ) {
+	struct gzip_header header;
+	struct gzip_extra_header extra;
+	struct gzip_crc_header crc;
+	struct gzip_footer footer;
+	struct deflate_chunk in;
+	unsigned int strings;
+	size_t offset;
+	size_t len;
+	off_t nul;
+	int rc;
+
+	/* Sanity check */
+	assert ( image->len >= ( sizeof ( header ) + sizeof ( footer ) ) );
+
+	/* Extract footer */
+	len = ( image->len - sizeof ( footer ) );
+	copy_from_user ( &footer, image->data, len, sizeof ( footer ) );
+
+	/* Extract fixed header */
+	copy_from_user ( &header, image->data, 0, sizeof ( header ) );
+	offset = sizeof ( header );
+	assert ( offset <= ( image->len - sizeof ( footer ) ) );
+
+	/* Skip extra header, if present */
+	if ( header.flags & GZIP_FL_EXTRA ) {
+		copy_from_user ( &extra, image->data, offset,
+				 sizeof ( extra ) );
+		offset += sizeof ( extra );
+		offset += le16_to_cpu ( extra.len );
+		if ( offset > len ) {
+			DBGC ( image, "GZIP %p overlength extra header\n",
+			       image );
+			return -EINVAL;
+		}
+	}
+	assert ( offset <= ( image->len - sizeof ( footer ) ) );
+
+	/* Skip name and/or comment, if present */
+	strings = 0;
+	if ( header.flags & GZIP_FL_NAME )
+		strings++;
+	if ( header.flags & GZIP_FL_COMMENT )
+		strings++;
+	while ( strings-- ) {
+		nul = memchr_user ( image->data, offset, 0, ( len - offset ) );
+		if ( nul < 0 ) {
+			DBGC ( image, "GZIP %p overlength name/comment\n",
+			       image );
+			return -EINVAL;
+		}
+		offset = ( nul + 1 /* NUL */ );
+	}
+	assert ( offset <= ( image->len - sizeof ( footer ) ) );
+
+	/* Skip CRC, if present */
+	if ( header.flags & GZIP_FL_HCRC ) {
+		offset += sizeof ( crc );
+		if ( offset > len ) {
+			DBGC ( image, "GZIP %p overlength CRC header\n",
+			       image );
+			return -EINVAL;
+		}
+	}
+
+	/* Initialise input chunk */
+	deflate_chunk_init ( &in, userptr_add ( image->data, offset ), 0, len );
+
+	/* Presize extracted image */
+	if ( ( rc = image_set_len ( extracted,
+				    le32_to_cpu ( footer.len ) ) ) != 0 ) {
+		DBGC ( image, "GZIP %p could not presize: %s\n",
+		       image, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Decompress image (expanding if necessary) */
+	if ( ( rc = zlib_deflate ( DEFLATE_RAW, &in, extracted ) ) != 0 ) {
+		DBGC ( image, "GZIP %p could not decompress: %s\n",
+		       image, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Probe gzip image
+ *
+ * @v image		gzip image
+ * @ret rc		Return status code
+ */
+static int gzip_probe ( struct image *image ) {
+	struct gzip_header header;
+	struct gzip_footer footer;
+
+	/* Sanity check */
+	if ( image->len < ( sizeof ( header ) + sizeof ( footer ) ) ) {
+		DBGC ( image, "GZIP %p image too short\n", image );
+		return -ENOEXEC;
+	}
+
+	/* Check magic header */
+	copy_from_user ( &header.magic, image->data, 0,
+			 sizeof ( header.magic ) );
+	if ( header.magic != cpu_to_be16 ( GZIP_MAGIC ) ) {
+		DBGC ( image, "GZIP %p invalid magic\n", image );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
+
+/** gzip image type */
+struct image_type gzip_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "gzip",
+	.probe = gzip_probe,
+	.extract = gzip_extract,
+};