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).
This commit is contained in:
Thomas Schmitt 2010-04-10 18:50:59 +02:00
parent c3d5ab7bc7
commit b089f2e978
5 changed files with 252 additions and 3 deletions

View File

@ -2162,7 +2162,7 @@ int iso_write_opts_set_system_area(IsoWriteOpts *opts, char data[32768],
}
memcpy(opts->system_area_data, data, 32768);
}
opts->system_area_options = options & 1;
opts->system_area_options = options & 3;
return ISO_SUCCESS;
}

View File

@ -465,6 +465,9 @@ struct ecma119_image
* end of the ISO image. Assumed are 63 secs/hed, 255 head/cyl.
* (GRUB protective msdos label.)
* This works with and without system_area_data.
* bit1= apply isohybrid MBR patching to the system area.
* This works only with system_area_data plus ISOLINUX boot image
* and only if not bit0 is set.
*/
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);
* This means to patch bytes 446 to 512 of the system area so
* that one partition is defined which begins at the second
* 512-byte block of the image and ends where the image ends.
* This works with and without system_area_data.
* bit1= apply isohybrid MBR patching to the system area.
* This works only with system area data from SYSLINUX plus an
* ISOLINUX boot image (see iso_image_set_boot_image()) and
* only if not bit0 is set.
* @param flag
* bit0 = invalidate any attached system area data. Same as data == NULL
* @return

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@ -10,6 +10,7 @@
/* for gettimeofday() */
#include <sys/time.h>
/* This code stems from syslinux-3.72/utils/isohybrid, a perl script
under GPL which is Copyright 2002-2008 H. Peter Anvin.
@ -31,7 +32,7 @@ license from above stem licenses, typically from LGPL.
In case its generosity is needed, here is the 2-clause BSD license:
make_isohybrid_mbr.c is copyright 2002-2008 H. Peter Anvin
and 2008-2009 Thomas Schmitt
and 2008-2010 Thomas Schmitt
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
@ -51,8 +52,9 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* A helper function. One could replace it by one or two macros. */
static int lsb_to_buf(char **wpt, int value, int bits, int flag)
static int lsb_to_buf(char **wpt, uint32_t value, int bits, int flag)
{
int b;
@ -61,6 +63,11 @@ static int lsb_to_buf(char **wpt, int value, int bits, int flag)
return (1);
}
/* ====================================================================== */
/* Deprecated Function */
/* ====================================================================== */
/*
* Create a MBR for an isohybrid enabled ISOLINUX boot image.
*
@ -228,3 +235,215 @@ int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag)
return (1);
}
/* ====================================================================== */
/* The New MBR Producer */
/* ====================================================================== */
/* The following prescription by H.Peter Anvin is actually a slightly
generalized version of the algorithm in deprecated function
make_isohybrid_mbr(). To be applied to externally provided System Area
data.
So provisorily i consider the functions lba512chs_to_buf() and
make_isolinux_mbr() as our further contribution the existing code base
under the existing license. This would yield:
copyright 2002-2010 H. Peter Anvin
and 2008-2010 Thomas Schmitt
under "either the LGPL or the MIT/ISC/2-clause BSD licenses"
Before release i will ask hpa for his explicit ok.
*/
/*
From hpa@zytor.com Thu Apr 1 08:32:52 2010
Date: Wed, 31 Mar 2010 14:53:51 -0700
From: H. Peter Anvin <hpa@zytor.com>
To: For discussion of Syslinux and tftp-hpa <syslinux@zytor.com>
Cc: Thomas Schmitt <scdbackup@gmx.net>
Subject: Re: [syslinux] port syslinux isohybrid perl script to C
[...]
> Currently i lack of blob and prescriptions.
The blobs are available in the Syslinux build tree under the names:
mbr/isohdp[fp]x*.bin
The default probably should be mbr/isohdppx.bin, but it's ultimately up
to the user.
User definable parameters:
-> MBR ID (default random 32-bit number,
or preserved from previous instance)
-> Sector count (default 32, range 1-63)
-> Head count (default 64, range 1-256)
-> Partition offset (default 0, range 0-64)
-> Partition number (default 1, range 1-4)
-> Filesystem type (default 0x17, range 1-255)
Note: the filesystem type is largely arbitrary, in theory it can be any
value other than 0x00, 0x05, 0x0f, 0x85, 0xee, or 0xef. 0x17 ("Windows
IFS Hidden") seems safeish, some people believe 0x83 (Linux) is better.
Here is the prescriptions for how to install it:
All numbers are littleendian. "word" means 16 bits, "dword" means 32
bits, "qword" means 64 bits.
Common subroutine LBA_to_CHS():
s = (lba % sector_count) + 1
t = (lba / sector_count)
h = (t % head_count)
c = (t / head_count)
if (c >= 1024):
c = 1023
h = head_count
s = sector_count
s = s | ((c & 0x300) >> 2)
c = c & 0xff
write byte h
write byte s
write byte c
Main:
Pad image_size to a multiple of sector_count*head_count
Use the input file unmodified for bytes 0..431
write qword boot_lba # Offset 432
write dword mbr_id # Offset 440
write word 0 # Offset 444
# Offset 446
For each partition entry 1..4:
if this_partition != partition_number:
write 16 zero bytes
else:
write byte 0x80
write LBA_to_CHS(partition_offset)
write byte filesystem_type
write LBA_to_CHS(image_size-1)
write dword partition_offset
write dword image_size
# Offset 510
write word 0xaa55
Use the input file unmodified for bytes 512..32767
(pad with zero as necessary)
[...]
-hpa
*/
static
int lba512chs_to_buf(char **wpt, off_t lba, int head_count, int sector_count)
{
int s, t, h, c;
s = (lba % sector_count) + 1;
t = (lba / sector_count);
h = (t % head_count);
c = (t / head_count);
if (c >= 1024) {
c = 1023;
h = head_count; /* >>> not -1 ? Limits head_count to 255 */
s = sector_count;
}
s = s | ((c & 0x300) >> 2);
c = c & 0xff;
(*((unsigned char **) wpt))[0] = h;
(*((unsigned char **) wpt))[1] = s;
(*((unsigned char **) wpt))[2] = c;
(*wpt)+= 3;
return(1);
}
/*
* @param flag bit0= make own random MBR Id from current time
*/
int make_isolinux_mbr(int32_t *img_blocks, uint32_t boot_lba,
uint32_t mbr_id, int head_count, int sector_count,
int part_offset, int part_number, int fs_type,
uint8_t *buf, int flag)
{
uint32_t spc, id, part, nominal_part_size;
off_t hd_img_blocks, hd_boot_lba;
char *wpt;
/* For generating a weak random number */
struct timeval tv;
struct timezone tz;
/* Pad image_size to a multiple of sector_count*head_count
*/
spc = head_count * sector_count;
hd_img_blocks = ((off_t) *img_blocks) * (off_t) 4;
if (hd_img_blocks % spc) {
hd_img_blocks += spc - (hd_img_blocks % spc);
*img_blocks = hd_img_blocks / 4 + !!(hd_img_blocks % 4);
}
wpt = (char *) buf + 432;
/* write qword boot_lba # Offset 432
*/
hd_boot_lba = ((off_t) boot_lba) * (off_t) 4;
lsb_to_buf(&wpt, hd_boot_lba & 0xffffffff, 32, 0);
lsb_to_buf(&wpt, hd_boot_lba >> 32, 32, 0);
/* write dword mbr_id # Offset 440
(here some 32-bit random value with no crypto strength)
*/
if (flag & 1) {
gettimeofday(&tv, &tz);
id = 0xffffffff & (tv.tv_sec ^ (tv.tv_usec * 2000));
lsb_to_buf(&wpt, id, 32, 0);
}
/* write word 0 # Offset 444
*/
lsb_to_buf(&wpt, 0, 16, 0);
/* # Offset 446
*/
for (part = 1 ; part <= 4; part++) {
if (part != part_number) {
/* if this_partition != partition_number: write 16 zero bytes */
memset(wpt, 0, 16);
wpt+= 16;
continue;
}
/* write byte 0x80
write LBA_to_CHS(partition_offset)
write byte filesystem_type
write LBA_to_CHS(image_size-1)
write dword partition_offset
write dword image_size
*/
lsb_to_buf(&wpt, 0x80, 8, 0);
lba512chs_to_buf(&wpt, part_offset, head_count, sector_count);
lsb_to_buf(&wpt, fs_type, 8, 0);
lba512chs_to_buf(&wpt, hd_img_blocks - 1, head_count, sector_count);
lsb_to_buf(&wpt, part_offset, 32, 0);
if (hd_img_blocks - (off_t) part_offset > (off_t) 0xffffffff)
nominal_part_size = 0xffffffff;
else
nominal_part_size = hd_img_blocks - (off_t) part_offset;
lsb_to_buf(&wpt, nominal_part_size, 32, 0);
}
/* write word 0xaa55 # Offset 510
*/
lsb_to_buf(&wpt, 0xaa55, 16, 0);
return(1);
}

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@ -23,6 +23,15 @@
*/
int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag);
/*
* The New ISOLINUX MBR Producer.
* Be cautious with changing parameters. Only few combinations are tested.
*
*/
int make_isolinux_mbr(int32_t *img_blocks, uint32_t boot_lba,
uint32_t mbr_id, int head_count, int sector_count,
int part_offset, int part_number, int fs_type,
uint8_t *buf, int flag);
/* This is the gesture of grub-mkisofs --protective-msdos-label as explained by
@ -41,6 +50,7 @@ int make_isohybrid_mbr(int bin_lba, int *img_blocks, char *mbr, int flag);
same number.
See also http://en.wikipedia.org/wiki/Master_boot_record
*/
static
int make_grub_msdos_label(int img_blocks, uint8_t *buf, int flag)
{
uint8_t *wpt;
@ -141,6 +151,18 @@ int iso_write_system_area(Ecma119Image *t, uint8_t *buf)
ret = make_grub_msdos_label(img_blocks, buf, 0);
if (ret != 1) /* error should never happen */
return ISO_ASSERT_FAILURE;
} else if(t->system_area_options & 2) {
/* Patch externally provided system area as isohybrid MBR */
if (t->catalog == NULL || t->system_area_data == NULL) {
/* isohybrid makes only sense together with ISOLINUX boot image
and externally provided System Area.
*/
return ISO_ISOLINUX_CANT_PATCH;
}
ret = make_isolinux_mbr(&img_blocks, t->bootimg->sections[0].block,
(uint32_t) 0, 64, 32, 0, 1, 0x17, buf, 1);
if (ret != 1)
return ret;
}
return ISO_SUCCESS;
}