diff options
Diffstat (limited to 'contrib/syslinux-4.02/libinstaller/fat.c')
| -rw-r--r-- | contrib/syslinux-4.02/libinstaller/fat.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/libinstaller/fat.c b/contrib/syslinux-4.02/libinstaller/fat.c new file mode 100644 index 0000000..e210135 --- /dev/null +++ b/contrib/syslinux-4.02/libinstaller/fat.c @@ -0,0 +1,129 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved + * Copyright 2009-2010 Intel Corporation; author H. Peter Anvin + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 53 Temple Place Ste 330, + * Boston MA 02111-1307, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * fat.c - Initial sanity check for FAT-based installers + */ + +#define _XOPEN_SOURCE 500 /* Required on glibc 2.x */ +#define _BSD_SOURCE +#include <stdio.h> +#include <inttypes.h> +#include <string.h> +#include <stddef.h> +#include <stdlib.h> + +#include "syslinux.h" +#include "syslxint.h" + +void syslinux_make_bootsect(void *bs) +{ + struct boot_sector *bootsect = bs; + const struct boot_sector *sbs = + (const struct boot_sector *)boot_sector; + + memcpy(&bootsect->bsHead, &sbs->bsHead, bsHeadLen); + memcpy(&bootsect->bsCode, &sbs->bsCode, bsCodeLen); +} + +/* + * Check to see that what we got was indeed an MS-DOS boot sector/superblock; + * Return NULL if OK and otherwise an error message; + */ +const char *syslinux_check_bootsect(const void *bs) +{ + int veryold; + int sectorsize; + long long sectors, fatsectors, dsectors; + long long clusters; + int rootdirents, clustersize; + const struct boot_sector *sectbuf = bs; + + veryold = 0; + + /* Must be 0xF0 or 0xF8..0xFF */ + if (get_8(§buf->bsMedia) != 0xF0 && get_8(§buf->bsMedia) < 0xF8) + return "invalid media signature (not a FAT filesystem?)"; + + sectorsize = get_16(§buf->bsBytesPerSec); + if (sectorsize == SECTOR_SIZE) + ; /* ok */ + else if (sectorsize >= 512 && sectorsize <= 4096 && + (sectorsize & (sectorsize - 1)) == 0) + return "unsupported sectors size"; + else + return "impossible sector size"; + + clustersize = get_8(§buf->bsSecPerClust); + if (clustersize == 0 || (clustersize & (clustersize - 1))) + return "impossible cluster size"; + + sectors = get_16(§buf->bsSectors); + sectors = sectors ? sectors : get_32(§buf->bsHugeSectors); + + dsectors = sectors - get_16(§buf->bsResSectors); + + fatsectors = get_16(§buf->bsFATsecs); + fatsectors = fatsectors ? fatsectors : get_32(§buf->bs32.FATSz32); + fatsectors *= get_8(§buf->bsFATs); + dsectors -= fatsectors; + + rootdirents = get_16(§buf->bsRootDirEnts); + dsectors -= (rootdirents + sectorsize / 32 - 1) / sectorsize; + + if (dsectors < 0) + return "negative number of data sectors"; + + if (fatsectors == 0) + return "zero FAT sectors"; + + clusters = dsectors / clustersize; + + if (clusters < 0xFFF5) { + /* FAT12 or FAT16 */ + + if (!get_16(§buf->bsFATsecs)) + return "zero FAT sectors (FAT12/16)"; + + if (get_8(§buf->bs16.BootSignature) == 0x29) { + if (!memcmp(§buf->bs16.FileSysType, "FAT12 ", 8)) { + if (clusters >= 0xFF5) + return "more than 4084 clusters but claims FAT12"; + } else if (!memcmp(§buf->bs16.FileSysType, "FAT16 ", 8)) { + if (clusters < 0xFF5) + return "less than 4084 clusters but claims FAT16"; + } else if (!memcmp(§buf->bs16.FileSysType, "FAT32 ", 8)) { + return "less than 65525 clusters but claims FAT32"; + } else if (memcmp(§buf->bs16.FileSysType, "FAT ", 8)) { + static char fserr[] = + "filesystem type \"????????\" not supported"; + memcpy(fserr + 17, §buf->bs16.FileSysType, 8); + return fserr; + } + } + } else if (clusters < 0x0FFFFFF5) { + /* + * FAT32... + * + * Moving the FileSysType and BootSignature was a lovely stroke + * of M$ idiocy... + */ + if (get_8(§buf->bs32.BootSignature) != 0x29 || + memcmp(§buf->bs32.FileSysType, "FAT32 ", 8)) + return "missing FAT32 signature"; + } else { + return "impossibly large number of clusters"; + } + + return NULL; +} |