static void cleanup_adv(unsigned char *advbuf) { int i; uint32_t csum; /* Make sure both copies agree, and update the checksum */ set_32((uint32_t *) advbuf, ADV_MAGIC1); csum = ADV_MAGIC2; for (i = 8; i < ADV_SIZE - 4; i += 4) csum -= get_32((uint32_t *) (advbuf + i)); set_32((uint32_t *) (advbuf + 4), csum); set_32((uint32_t *) (advbuf + ADV_SIZE - 4), ADV_MAGIC3); memcpy(advbuf + ADV_SIZE, advbuf, ADV_SIZE); }
/* * This patches the boot sector and the beginning of ldlinux.sys * based on an ldlinux.sys sector map passed in. Typically this is * handled by writing ldlinux.sys, mapping it, and then overwrite it * with the patched version. If this isn't safe to do because of * an OS which does block reallocation, then overwrite it with * direct access since the location is known. * * Returns the number of modified bytes in ldlinux.sys if successful, * otherwise -1. */ int syslinux_patch(const sector_t *sectp, int nsectors, int stupid, int raid_mode, const char *subdir, const char *subvol) { struct patch_area *patcharea; struct ext_patch_area *epa; struct syslinux_extent *ex; uint32_t *wp; int nsect = ((boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + 2; uint32_t csum; int i, dw, nptrs; struct fat_boot_sector *sbs = (struct fat_boot_sector *)boot_sector; uint64_t *advptrs; if (nsectors < nsect) return -1; /* The actual file is too small for content */ /* Search for LDLINUX_MAGIC to find the patch area */ for (wp = (uint32_t *)boot_image; get_32_sl(wp) != LDLINUX_MAGIC; wp++) ; patcharea = (struct patch_area *)wp; epa = ptr(boot_image, &patcharea->epaoffset); /* First sector need pointer in boot sector */ set_32(ptr(sbs, &epa->sect1ptr0), sectp[0]); set_32(ptr(sbs, &epa->sect1ptr1), sectp[0] >> 32); sectp++; /* Handle RAID mode */ if (raid_mode) { /* Patch in INT 18h = CD 18 */ set_16(ptr(sbs, &epa->raidpatch), 0x18CD); } /* Set up the totals */ dw = boot_image_len >> 2; /* COMPLETE dwords, excluding ADV */ set_16_sl(&patcharea->data_sectors, nsect - 2); /* Not including ADVs */ set_16_sl(&patcharea->adv_sectors, 2); /* ADVs need 2 sectors */ set_32_sl(&patcharea->dwords, dw); /* Handle Stupid mode */ if (stupid) { /* Access only one sector at a time */ set_16_sl(&patcharea->maxtransfer, 1); } /* Set the sector extents */ ex = ptr(boot_image, &epa->secptroffset); nptrs = get_16_sl(&epa->secptrcnt); if (nsect > nptrs) { /* Not necessarily an error in this case, but a general problem */ fprintf(stderr, "Insufficient extent space, build error!\n"); exit(1); } /* -1 for the pointer in the boot sector, -2 for the two ADVs */ generate_extents(ex, nptrs, sectp, nsect-1-2); /* ADV pointers */ advptrs = ptr(boot_image, &epa->advptroffset); set_64_sl(&advptrs[0], sectp[nsect-1-2]); set_64_sl(&advptrs[1], sectp[nsect-1-1]); /* Poke in the base directory path */ if (subdir) { int sublen = strlen(subdir) + 1; if (get_16_sl(&epa->dirlen) < sublen) { fprintf(stderr, "Subdirectory path too long... aborting install!\n"); exit(1); } memcpy_to_sl(ptr(boot_image, &epa->diroffset), subdir, sublen); } /* Poke in the subvolume information */ if (subvol) { int sublen = strlen(subvol) + 1; if (get_16_sl(&epa->subvollen) < sublen) { fprintf(stderr, "Subvol name too long... aborting install!\n"); exit(1); } memcpy_to_sl(ptr(boot_image, &epa->subvoloffset), subvol, sublen); } /* Now produce a checksum */ set_32_sl(&patcharea->checksum, 0); csum = LDLINUX_MAGIC; for (i = 0, wp = (uint32_t *)boot_image; i < dw; i++, wp++) csum -= get_32_sl(wp); /* Negative checksum */ set_32_sl(&patcharea->checksum, csum); /* * Assume all bytes modified. This can be optimized at the expense * of keeping track of what the highest modified address ever was. */ return dw << 2; }