New bit1 of iso_write_opts_set_system_area() options.
New inner call make_isolinux_mbr() produces a bootable System Area from an ISOLINUX mbr/isohdp[fp]x*.bin file and an ISOLINUX El Torito bootable image (isolinux.bin).
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@ -2162,7 +2162,7 @@ int iso_write_opts_set_system_area(IsoWriteOpts *opts, char data[32768],
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}
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memcpy(opts->system_area_data, data, 32768);
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}
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opts->system_area_options = options & 1;
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opts->system_area_options = options & 3;
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return ISO_SUCCESS;
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}
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@ -465,6 +465,9 @@ struct ecma119_image
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* end of the ISO image. Assumed are 63 secs/hed, 255 head/cyl.
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* (GRUB protective msdos label.)
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* This works with and without system_area_data.
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* bit1= apply isohybrid MBR patching to the system area.
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* This works only with system_area_data plus ISOLINUX boot image
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* and only if not bit0 is set.
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*/
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int system_area_options;
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@ -1697,6 +1697,11 @@ int iso_write_opts_set_fifo_size(IsoWriteOpts *opts, size_t fifo_size);
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* This means to patch bytes 446 to 512 of the system area so
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* that one partition is defined which begins at the second
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* 512-byte block of the image and ends where the image ends.
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* This works with and without system_area_data.
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* bit1= apply isohybrid MBR patching to the system area.
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* This works only with system area data from SYSLINUX plus an
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* ISOLINUX boot image (see iso_image_set_boot_image()) and
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* only if not bit0 is set.
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* @param flag
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* bit0 = invalidate any attached system area data. Same as data == NULL
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* @return
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@ -10,6 +10,7 @@
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/* for gettimeofday() */
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#include <sys/time.h>
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/* This code stems from syslinux-3.72/utils/isohybrid, a perl script
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under GPL which is Copyright 2002-2008 H. Peter Anvin.
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@ -31,7 +32,7 @@ license from above stem licenses, typically from LGPL.
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In case its generosity is needed, here is the 2-clause BSD license:
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make_isohybrid_mbr.c is copyright 2002-2008 H. Peter Anvin
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and 2008-2009 Thomas Schmitt
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and 2008-2010 Thomas Schmitt
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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@ -51,8 +52,9 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* A helper function. One could replace it by one or two macros. */
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static int lsb_to_buf(char **wpt, int value, int bits, int flag)
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static int lsb_to_buf(char **wpt, uint32_t value, int bits, int flag)
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{
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int b;
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@ -61,6 +63,11 @@ static int lsb_to_buf(char **wpt, int value, int bits, int flag)
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return (1);
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}
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/* ====================================================================== */
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/* Deprecated Function */
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/* ====================================================================== */
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/*
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* Create a MBR for an isohybrid enabled ISOLINUX boot image.
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*
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@ -228,3 +235,215 @@ int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag)
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return (1);
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}
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/* ====================================================================== */
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/* The New MBR Producer */
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/* ====================================================================== */
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/* The following prescription by H.Peter Anvin is actually a slightly
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generalized version of the algorithm in deprecated function
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make_isohybrid_mbr(). To be applied to externally provided System Area
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data.
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So provisorily i consider the functions lba512chs_to_buf() and
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make_isolinux_mbr() as our further contribution the existing code base
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under the existing license. This would yield:
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copyright 2002-2010 H. Peter Anvin
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and 2008-2010 Thomas Schmitt
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under "either the LGPL or the MIT/ISC/2-clause BSD licenses"
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Before release i will ask hpa for his explicit ok.
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*/
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/*
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From hpa@zytor.com Thu Apr 1 08:32:52 2010
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Date: Wed, 31 Mar 2010 14:53:51 -0700
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From: H. Peter Anvin <hpa@zytor.com>
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To: For discussion of Syslinux and tftp-hpa <syslinux@zytor.com>
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Cc: Thomas Schmitt <scdbackup@gmx.net>
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Subject: Re: [syslinux] port syslinux isohybrid perl script to C
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[...]
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> Currently i lack of blob and prescriptions.
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The blobs are available in the Syslinux build tree under the names:
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mbr/isohdp[fp]x*.bin
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The default probably should be mbr/isohdppx.bin, but it's ultimately up
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to the user.
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User definable parameters:
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-> MBR ID (default random 32-bit number,
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or preserved from previous instance)
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-> Sector count (default 32, range 1-63)
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-> Head count (default 64, range 1-256)
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-> Partition offset (default 0, range 0-64)
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-> Partition number (default 1, range 1-4)
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-> Filesystem type (default 0x17, range 1-255)
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Note: the filesystem type is largely arbitrary, in theory it can be any
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value other than 0x00, 0x05, 0x0f, 0x85, 0xee, or 0xef. 0x17 ("Windows
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IFS Hidden") seems safeish, some people believe 0x83 (Linux) is better.
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Here is the prescriptions for how to install it:
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All numbers are littleendian. "word" means 16 bits, "dword" means 32
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bits, "qword" means 64 bits.
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Common subroutine LBA_to_CHS():
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s = (lba % sector_count) + 1
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t = (lba / sector_count)
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h = (t % head_count)
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c = (t / head_count)
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if (c >= 1024):
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c = 1023
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h = head_count
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s = sector_count
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s = s | ((c & 0x300) >> 2)
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c = c & 0xff
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write byte h
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write byte s
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write byte c
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Main:
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Pad image_size to a multiple of sector_count*head_count
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Use the input file unmodified for bytes 0..431
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write qword boot_lba # Offset 432
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write dword mbr_id # Offset 440
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write word 0 # Offset 444
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# Offset 446
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For each partition entry 1..4:
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if this_partition != partition_number:
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write 16 zero bytes
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else:
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write byte 0x80
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write LBA_to_CHS(partition_offset)
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write byte filesystem_type
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write LBA_to_CHS(image_size-1)
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write dword partition_offset
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write dword image_size
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# Offset 510
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write word 0xaa55
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Use the input file unmodified for bytes 512..32767
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(pad with zero as necessary)
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[...]
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-hpa
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*/
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static
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int lba512chs_to_buf(char **wpt, off_t lba, int head_count, int sector_count)
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{
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int s, t, h, c;
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s = (lba % sector_count) + 1;
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t = (lba / sector_count);
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h = (t % head_count);
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c = (t / head_count);
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if (c >= 1024) {
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c = 1023;
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h = head_count; /* >>> not -1 ? Limits head_count to 255 */
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s = sector_count;
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}
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s = s | ((c & 0x300) >> 2);
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c = c & 0xff;
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(*((unsigned char **) wpt))[0] = h;
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(*((unsigned char **) wpt))[1] = s;
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(*((unsigned char **) wpt))[2] = c;
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(*wpt)+= 3;
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return(1);
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}
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/*
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* @param flag bit0= make own random MBR Id from current time
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*/
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int make_isolinux_mbr(int32_t *img_blocks, uint32_t boot_lba,
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uint32_t mbr_id, int head_count, int sector_count,
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int part_offset, int part_number, int fs_type,
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uint8_t *buf, int flag)
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{
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uint32_t spc, id, part, nominal_part_size;
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off_t hd_img_blocks, hd_boot_lba;
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char *wpt;
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/* For generating a weak random number */
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struct timeval tv;
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struct timezone tz;
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/* Pad image_size to a multiple of sector_count*head_count
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*/
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spc = head_count * sector_count;
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hd_img_blocks = ((off_t) *img_blocks) * (off_t) 4;
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if (hd_img_blocks % spc) {
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hd_img_blocks += spc - (hd_img_blocks % spc);
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*img_blocks = hd_img_blocks / 4 + !!(hd_img_blocks % 4);
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}
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wpt = (char *) buf + 432;
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/* write qword boot_lba # Offset 432
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*/
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hd_boot_lba = ((off_t) boot_lba) * (off_t) 4;
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lsb_to_buf(&wpt, hd_boot_lba & 0xffffffff, 32, 0);
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lsb_to_buf(&wpt, hd_boot_lba >> 32, 32, 0);
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/* write dword mbr_id # Offset 440
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(here some 32-bit random value with no crypto strength)
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*/
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if (flag & 1) {
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gettimeofday(&tv, &tz);
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id = 0xffffffff & (tv.tv_sec ^ (tv.tv_usec * 2000));
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lsb_to_buf(&wpt, id, 32, 0);
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}
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/* write word 0 # Offset 444
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*/
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lsb_to_buf(&wpt, 0, 16, 0);
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/* # Offset 446
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*/
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for (part = 1 ; part <= 4; part++) {
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if (part != part_number) {
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/* if this_partition != partition_number: write 16 zero bytes */
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memset(wpt, 0, 16);
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wpt+= 16;
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continue;
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}
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/* write byte 0x80
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write LBA_to_CHS(partition_offset)
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write byte filesystem_type
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write LBA_to_CHS(image_size-1)
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write dword partition_offset
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write dword image_size
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*/
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lsb_to_buf(&wpt, 0x80, 8, 0);
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lba512chs_to_buf(&wpt, part_offset, head_count, sector_count);
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lsb_to_buf(&wpt, fs_type, 8, 0);
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lba512chs_to_buf(&wpt, hd_img_blocks - 1, head_count, sector_count);
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lsb_to_buf(&wpt, part_offset, 32, 0);
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if (hd_img_blocks - (off_t) part_offset > (off_t) 0xffffffff)
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nominal_part_size = 0xffffffff;
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else
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nominal_part_size = hd_img_blocks - (off_t) part_offset;
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lsb_to_buf(&wpt, nominal_part_size, 32, 0);
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}
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/* write word 0xaa55 # Offset 510
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*/
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lsb_to_buf(&wpt, 0xaa55, 16, 0);
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return(1);
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}
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@ -23,6 +23,15 @@
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*/
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int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag);
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/*
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* The New ISOLINUX MBR Producer.
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* Be cautious with changing parameters. Only few combinations are tested.
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*
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*/
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int make_isolinux_mbr(int32_t *img_blocks, uint32_t boot_lba,
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uint32_t mbr_id, int head_count, int sector_count,
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int part_offset, int part_number, int fs_type,
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uint8_t *buf, int flag);
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/* This is the gesture of grub-mkisofs --protective-msdos-label as explained by
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@ -41,6 +50,7 @@ int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag);
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same number.
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See also http://en.wikipedia.org/wiki/Master_boot_record
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*/
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static
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int make_grub_msdos_label(int img_blocks, uint8_t *buf, int flag)
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{
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uint8_t *wpt;
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@ -141,6 +151,18 @@ int iso_write_system_area(Ecma119Image *t, uint8_t *buf)
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ret = make_grub_msdos_label(img_blocks, buf, 0);
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if (ret != 1) /* error should never happen */
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return ISO_ASSERT_FAILURE;
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} else if(t->system_area_options & 2) {
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/* Patch externally provided system area as isohybrid MBR */
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if (t->catalog == NULL || t->system_area_data == NULL) {
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/* isohybrid makes only sense together with ISOLINUX boot image
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and externally provided System Area.
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*/
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return ISO_ISOLINUX_CANT_PATCH;
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}
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ret = make_isolinux_mbr(&img_blocks, t->bootimg->sections[0].block,
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(uint32_t) 0, 64, 32, 0, 1, 0x17, buf, 1);
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if (ret != 1)
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return ret;
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}
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return ISO_SUCCESS;
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}
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