diff options
Diffstat (limited to 'src/image/gzip.c')
| -rw-r--r-- | src/image/gzip.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/src/image/gzip.c b/src/image/gzip.c new file mode 100644 index 0000000..4072813 --- /dev/null +++ b/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, +}; |