1 /* ----------------------------------------------------------------------- *
3 * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
4 * Copyright 2009-2010 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 */
31 * Generate sector extents
33 static void generate_extents(struct syslinux_extent *ex, int nptrs,
34 const sector_t *sectp, int nsect)
36 uint32_t addr = 0x7c00 + 2*SECTOR_SIZE;
43 memset(ex, 0, nptrs * sizeof *ex);
48 if (len && sect == lba + len &&
49 ((addr ^ (base + len * SECTOR_SIZE)) & 0xffff0000) == 0) {
50 /* We can add to the current extent */
56 set_64_sl(&ex->lba, lba);
57 set_16_sl(&ex->len, len);
71 set_64_sl(&ex->lba, lba);
72 set_16_sl(&ex->len, len);
78 * Form a pointer based on a 16-bit patcharea/epa field
80 static inline void *ptr(void *img, uint16_t *offset_p)
82 return (char *)img + get_16_sl(offset_p);
86 * This patches the boot sector and the beginning of ldlinux.sys
87 * based on an ldlinux.sys sector map passed in. Typically this is
88 * handled by writing ldlinux.sys, mapping it, and then overwrite it
89 * with the patched version. If this isn't safe to do because of
90 * an OS which does block reallocation, then overwrite it with
91 * direct access since the location is known.
93 * Returns the number of modified bytes in ldlinux.sys if successful,
98 int syslinux_patch(const sector_t *sectp, int nsectors,
99 int stupid, int raid_mode,
100 const char *subdir, const char *subvol)
102 struct patch_area *patcharea;
103 struct ext_patch_area *epa;
104 struct syslinux_extent *ex;
106 int nsect = ((boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + 2;
109 struct boot_sector *sbs = (struct boot_sector *)boot_sector;
112 if (nsectors < nsect)
113 return -1; /* The actual file is too small for content */
115 /* Search for LDLINUX_MAGIC to find the patch area */
116 for (wp = (uint32_t *)boot_image; get_32_sl(wp) != LDLINUX_MAGIC;
119 patcharea = (struct patch_area *)wp;
120 epa = ptr(boot_image, &patcharea->epaoffset);
122 /* First sector need pointer in boot sector */
123 set_32(ptr(sbs, &epa->sect1ptr0), sectp[0]);
124 set_32(ptr(sbs, &epa->sect1ptr1), sectp[0] >> 32);
127 /* Handle RAID mode */
129 /* Patch in INT 18h = CD 18 */
130 set_16(ptr(sbs, &epa->raidpatch), 0x18CD);
133 /* Set up the totals */
134 dw = boot_image_len >> 2; /* COMPLETE dwords, excluding ADV */
135 set_16_sl(&patcharea->data_sectors, nsect - 2); /* Not including ADVs */
136 set_16_sl(&patcharea->adv_sectors, 2); /* ADVs need 2 sectors */
137 set_32_sl(&patcharea->dwords, dw);
139 /* Handle Stupid mode */
141 /* Access only one sector at a time */
142 set_16_sl(&patcharea->maxtransfer, 1);
145 /* Set the sector extents */
146 ex = ptr(boot_image, &epa->secptroffset);
147 nptrs = get_16_sl(&epa->secptrcnt);
150 /* Not necessarily an error in this case, but a general problem */
151 fprintf(stderr, "Insufficient extent space, build error!\n");
155 /* -1 for the pointer in the boot sector, -2 for the two ADVs */
156 generate_extents(ex, nptrs, sectp, nsect-1-2);
159 advptrs = ptr(boot_image, &epa->advptroffset);
160 set_64_sl(&advptrs[0], sectp[nsect-1-2]);
161 set_64_sl(&advptrs[1], sectp[nsect-1-1]);
163 /* Poke in the base directory path */
165 int sublen = strlen(subdir) + 1;
166 if (get_16_sl(&epa->dirlen) < sublen) {
167 fprintf(stderr, "Subdirectory path too long... aborting install!\n");
170 memcpy_to_sl(ptr(boot_image, &epa->diroffset), subdir, sublen);
173 /* Poke in the subvolume information */
175 int sublen = strlen(subvol) + 1;
176 if (get_16_sl(&epa->subvollen) < sublen) {
177 fprintf(stderr, "Subvol name too long... aborting install!\n");
180 memcpy_to_sl(ptr(boot_image, &epa->subvoloffset), subvol, sublen);
183 /* Now produce a checksum */
184 set_32_sl(&patcharea->checksum, 0);
186 csum = LDLINUX_MAGIC;
187 for (i = 0, wp = (uint32_t *)boot_image; i < dw; i++, wp++)
188 csum -= get_32_sl(wp); /* Negative checksum */
190 set_32_sl(&patcharea->checksum, csum);
193 * Assume all bytes modified. This can be optimized at the expense
194 * of keeping track of what the highest modified address ever was.