1 /* ----------------------------------------------------------------------- *
3 * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
4 * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9 * Boston MA 02111-1307, USA; either version 2 of the License, or
10 * (at your option) any later version; incorporated herein by reference.
12 * ----------------------------------------------------------------------- */
15 * syslxmod.c - Code to provide a SYSLINUX code set to an installer.
18 #define _XOPEN_SOURCE 500 /* Required on glibc 2.x */
20 /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */
21 #define _DEFAULT_SOURCE 1
33 * Generate sector extents
35 static void generate_extents(struct syslinux_extent _slimg
*ex
, int nptrs
,
36 const sector_t
*sectp
, int nsect
)
38 uint32_t addr
= 0x8000; /* ldlinux.sys starts loading here */
47 memset_sl(ex
, 0, nptrs
* sizeof *ex
);
53 uint32_t xbytes
= (len
+ 1) * SECTOR_SIZE
;
55 if (sect
== lba
+ len
&& xbytes
< 65536 &&
56 ((addr
^ (base
+ xbytes
- 1)) & 0xffff0000) == 0) {
57 /* We can add to the current extent */
62 set_64_sl(&ex
->lba
, lba
);
63 set_16_sl(&ex
->len
, len
);
77 set_64_sl(&ex
->lba
, lba
);
78 set_16_sl(&ex
->len
, len
);
84 * Form a pointer based on a 16-bit patcharea/epa field
86 static inline void *ptr(void *img
, const uint16_t _slimg
*offset_p
)
88 return (char *)img
+ get_16_sl(offset_p
);
90 static inline void _slimg
*slptr(void _slimg
*img
,
91 const uint16_t _slimg
*offset_p
)
93 return (char _slimg
*)img
+ get_16_sl(offset_p
);
97 * This patches the boot sector and the beginning of ldlinux.sys
98 * based on an ldlinux.sys sector map passed in. Typically this is
99 * handled by writing ldlinux.sys, mapping it, and then overwrite it
100 * with the patched version. If this isn't safe to do because of
101 * an OS which does block reallocation, then overwrite it with
102 * direct access since the location is known.
104 * Returns the number of modified bytes in ldlinux.sys if successful,
107 int syslinux_patch(const sector_t
*sectp
, int nsectors
,
108 int stupid
, int raid_mode
,
109 const char *subdir
, const char *subvol
)
111 struct patch_area _slimg
*patcharea
;
112 struct ext_patch_area _slimg
*epa
;
113 struct syslinux_extent _slimg
*ex
;
114 const uint32_t _slimg
*wp
;
115 int nsect
= ((boot_image_len
+ SECTOR_SIZE
- 1) >> SECTOR_SHIFT
) + 2;
118 struct fat_boot_sector
*sbs
= (struct fat_boot_sector
*)boot_sector
;
119 uint64_t _slimg
*advptrs
;
121 if (nsectors
< nsect
)
122 return -1; /* The actual file is too small for content */
124 /* Search for LDLINUX_MAGIC to find the patch area */
125 for (wp
= (const uint32_t _slimg
*)boot_image
;
126 get_32_sl(wp
) != LDLINUX_MAGIC
;
129 patcharea
= (struct patch_area _slimg
*)wp
;
130 epa
= slptr(boot_image
, &patcharea
->epaoffset
);
132 /* First sector need pointer in boot sector */
133 set_32(ptr(sbs
, &epa
->sect1ptr0
), sectp
[0]);
134 set_32(ptr(sbs
, &epa
->sect1ptr1
), sectp
[0] >> 32);
137 /* Handle RAID mode */
139 /* Patch in INT 18h = CD 18 */
140 set_16(ptr(sbs
, &epa
->raidpatch
), 0x18CD);
143 /* Set up the totals */
144 dw
= boot_image_len
>> 2; /* COMPLETE dwords, excluding ADV */
145 set_16_sl(&patcharea
->data_sectors
, nsect
- 2); /* Not including ADVs */
146 set_16_sl(&patcharea
->adv_sectors
, 2); /* ADVs need 2 sectors */
147 set_32_sl(&patcharea
->dwords
, dw
);
149 /* Handle Stupid mode */
151 /* Access only one sector at a time */
152 set_16_sl(&patcharea
->maxtransfer
, 1);
155 /* Set the sector extents */
156 ex
= slptr(boot_image
, &epa
->secptroffset
);
157 nptrs
= get_16_sl(&epa
->secptrcnt
);
161 /* Not necessarily an error in this case, but a general problem */
162 fprintf(stderr
, "Insufficient extent space, build error!\n");
167 /* -1 for the pointer in the boot sector, -2 for the two ADVs */
168 generate_extents(ex
, nptrs
, sectp
, nsect
-1-2);
171 advptrs
= slptr(boot_image
, &epa
->advptroffset
);
172 set_64_sl(&advptrs
[0], sectp
[nsect
-1-2]);
173 set_64_sl(&advptrs
[1], sectp
[nsect
-1-1]);
175 /* Poke in the base directory path */
177 int sublen
= strlen(subdir
) + 1;
178 if (get_16_sl(&epa
->dirlen
) < sublen
) {
179 fprintf(stderr
, "Subdirectory path too long... aborting install!\n");
182 memcpy_to_sl(slptr(boot_image
, &epa
->diroffset
), subdir
, sublen
);
185 /* Poke in the subvolume information */
187 int sublen
= strlen(subvol
) + 1;
188 if (get_16_sl(&epa
->subvollen
) < sublen
) {
189 fprintf(stderr
, "Subvol name too long... aborting install!\n");
192 memcpy_to_sl(slptr(boot_image
, &epa
->subvoloffset
), subvol
, sublen
);
195 /* Now produce a checksum */
196 set_32_sl(&patcharea
->checksum
, 0);
198 csum
= LDLINUX_MAGIC
;
199 for (i
= 0, wp
= (const uint32_t _slimg
*)boot_image
; i
< dw
; i
++, wp
++)
200 csum
-= get_32_sl(wp
); /* Negative checksum */
202 set_32_sl(&patcharea
->checksum
, csum
);
205 * Assume all bytes modified. This can be optimized at the expense
206 * of keeping track of what the highest modified address ever was.