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 = 0x8000; /* ldlinux.sys starts loading here */
44 memset(ex, 0, nptrs * sizeof *ex);
50 uint32_t xbytes = (len + 1) * SECTOR_SIZE;
52 if (sect == lba + len && xbytes < 65536 &&
53 ((addr ^ (base + xbytes - 1)) & 0xffff0000) == 0) {
54 /* We can add to the current extent */
59 set_64_sl(&ex->lba, lba);
60 set_16_sl(&ex->len, len);
74 set_64_sl(&ex->lba, lba);
75 set_16_sl(&ex->len, len);
81 * Form a pointer based on a 16-bit patcharea/epa field
83 static inline void *ptr(void *img, uint16_t *offset_p)
85 return (char *)img + get_16_sl(offset_p);
89 * This patches the boot sector and the beginning of ldlinux.sys
90 * based on an ldlinux.sys sector map passed in. Typically this is
91 * handled by writing ldlinux.sys, mapping it, and then overwrite it
92 * with the patched version. If this isn't safe to do because of
93 * an OS which does block reallocation, then overwrite it with
94 * direct access since the location is known.
96 * Returns the number of modified bytes in ldlinux.sys if successful,
99 int syslinux_patch(const sector_t *sectp, int nsectors,
100 int stupid, int raid_mode,
101 const char *subdir, const char *subvol)
103 struct patch_area *patcharea;
104 struct ext_patch_area *epa;
105 struct syslinux_extent *ex;
107 int nsect = ((boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + 2;
110 struct fat_boot_sector *sbs = (struct fat_boot_sector *)boot_sector;
113 if (nsectors < nsect)
114 return -1; /* The actual file is too small for content */
116 /* Search for LDLINUX_MAGIC to find the patch area */
117 for (wp = (uint32_t *)boot_image; get_32_sl(wp) != LDLINUX_MAGIC;
120 patcharea = (struct patch_area *)wp;
121 epa = ptr(boot_image, &patcharea->epaoffset);
123 /* First sector need pointer in boot sector */
124 set_32(ptr(sbs, &epa->sect1ptr0), sectp[0]);
125 set_32(ptr(sbs, &epa->sect1ptr1), sectp[0] >> 32);
128 /* Handle RAID mode */
130 /* Patch in INT 18h = CD 18 */
131 set_16(ptr(sbs, &epa->raidpatch), 0x18CD);
134 /* Set up the totals */
135 dw = boot_image_len >> 2; /* COMPLETE dwords, excluding ADV */
136 set_16_sl(&patcharea->data_sectors, nsect - 2); /* Not including ADVs */
137 set_16_sl(&patcharea->adv_sectors, 2); /* ADVs need 2 sectors */
138 set_32_sl(&patcharea->dwords, dw);
140 /* Handle Stupid mode */
142 /* Access only one sector at a time */
143 set_16_sl(&patcharea->maxtransfer, 1);
146 /* Set the sector extents */
147 ex = ptr(boot_image, &epa->secptroffset);
148 nptrs = get_16_sl(&epa->secptrcnt);
151 /* Not necessarily an error in this case, but a general problem */
152 fprintf(stderr, "Insufficient extent space, build error!\n");
156 /* -1 for the pointer in the boot sector, -2 for the two ADVs */
157 generate_extents(ex, nptrs, sectp, nsect-1-2);
160 advptrs = ptr(boot_image, &epa->advptroffset);
161 set_64_sl(&advptrs[0], sectp[nsect-1-2]);
162 set_64_sl(&advptrs[1], sectp[nsect-1-1]);
164 /* Poke in the base directory path */
166 int sublen = strlen(subdir) + 1;
167 if (get_16_sl(&epa->dirlen) < sublen) {
168 fprintf(stderr, "Subdirectory path too long... aborting install!\n");
171 memcpy_to_sl(ptr(boot_image, &epa->diroffset), subdir, sublen);
174 /* Poke in the subvolume information */
176 int sublen = strlen(subvol) + 1;
177 if (get_16_sl(&epa->subvollen) < sublen) {
178 fprintf(stderr, "Subvol name too long... aborting install!\n");
181 memcpy_to_sl(ptr(boot_image, &epa->subvoloffset), subvol, sublen);
184 /* Now produce a checksum */
185 set_32_sl(&patcharea->checksum, 0);
187 csum = LDLINUX_MAGIC;
188 for (i = 0, wp = (uint32_t *)boot_image; i < dw; i++, wp++)
189 csum -= get_32_sl(wp); /* Negative checksum */
191 set_32_sl(&patcharea->checksum, csum);
194 * Assume all bytes modified. This can be optimized at the expense
195 * of keeping track of what the highest modified address ever was.