--- /dev/null
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#ifdef FSYS_FAT
+
+#include "shared.h"
+#include "filesys.h"
+#include "fat.h"
+
+struct fat_superblock
+{
+ int fat_offset;
+ int fat_length;
+ int fat_size;
+ int root_offset;
+ int root_max;
+ int data_offset;
+
+ int num_sectors;
+ int num_clust;
+ int clust_eof_marker;
+ int sects_per_clust;
+ int sectsize_bits;
+ int clustsize_bits;
+ int root_cluster;
+
+ int cached_fat;
+ int file_cluster;
+ int current_cluster_num;
+ int current_cluster;
+};
+
+/* pointer(s) into filesystem info buffer for DOS stuff */
+#define FAT_SUPER ( (struct fat_superblock *) \
+ ( FSYS_BUF + 32256) )/* 512 bytes long */
+#define FAT_BUF ( FSYS_BUF + 30208 ) /* 4 sector FAT buffer */
+#define NAME_BUF ( FSYS_BUF + 29184 ) /* Filename buffer (833 bytes) */
+
+#define FAT_CACHE_SIZE 2048
+
+int
+fat_mount (void)
+{
+ struct fat_bpb bpb;
+ __u32 magic, first_fat;
+
+ /* Check partition type for harddisk */
+ if (((current_drive & 0x80) || (current_slice != 0))
+ && ! IS_PC_SLICE_TYPE_FAT (current_slice)
+ && (! IS_PC_SLICE_TYPE_BSD_WITH_FS (current_slice, FS_MSDOS)))
+ return 0;
+
+ /* Read bpb */
+ if (! devread (0, 0, sizeof (bpb), (char *) &bpb))
+ return 0;
+
+ /* Check if the number of sectors per cluster is zero here, to avoid
+ zero division. */
+ if (bpb.sects_per_clust == 0)
+ return 0;
+
+ FAT_SUPER->sectsize_bits = log2 (bpb.bytes_per_sect);
+ FAT_SUPER->clustsize_bits
+ = FAT_SUPER->sectsize_bits + log2 (bpb.sects_per_clust);
+
+ /* Fill in info about super block */
+ FAT_SUPER->num_sectors = bpb.short_sectors
+ ? bpb.short_sectors : bpb.long_sectors;
+
+ /* FAT offset and length */
+ FAT_SUPER->fat_offset = bpb.reserved_sects;
+ FAT_SUPER->fat_length =
+ bpb.fat_length ? bpb.fat_length : bpb.fat32_length;
+
+ /* Rootdir offset and length for FAT12/16 */
+ FAT_SUPER->root_offset =
+ FAT_SUPER->fat_offset + bpb.num_fats * FAT_SUPER->fat_length;
+ FAT_SUPER->root_max = FAT_DIRENTRY_LENGTH * bpb.dir_entries;
+
+ /* Data offset and number of clusters */
+ FAT_SUPER->data_offset =
+ FAT_SUPER->root_offset
+ + ((FAT_SUPER->root_max - 1) >> FAT_SUPER->sectsize_bits) + 1;
+ FAT_SUPER->num_clust =
+ 2 + ((FAT_SUPER->num_sectors - FAT_SUPER->data_offset)
+ / bpb.sects_per_clust);
+ FAT_SUPER->sects_per_clust = bpb.sects_per_clust;
+
+ if (!bpb.fat_length)
+ {
+ /* This is a FAT32 */
+ if (bpb.dir_entries)
+ return 0;
+
+ if (bpb.flags & 0x0080)
+ {
+ /* FAT mirroring is disabled, get active FAT */
+ int active_fat = bpb.flags & 0x000f;
+ if (active_fat >= bpb.num_fats)
+ return 0;
+ FAT_SUPER->fat_offset += active_fat * FAT_SUPER->fat_length;
+ }
+
+ FAT_SUPER->fat_size = 8;
+ FAT_SUPER->root_cluster = bpb.root_cluster;
+
+ /* Yes the following is correct. FAT32 should be called FAT28 :) */
+ FAT_SUPER->clust_eof_marker = 0xffffff8;
+ }
+ else
+ {
+ if (!FAT_SUPER->root_max)
+ return 0;
+
+ FAT_SUPER->root_cluster = -1;
+ if (FAT_SUPER->num_clust > FAT_MAX_12BIT_CLUST)
+ {
+ FAT_SUPER->fat_size = 4;
+ FAT_SUPER->clust_eof_marker = 0xfff8;
+ }
+ else
+ {
+ FAT_SUPER->fat_size = 3;
+ FAT_SUPER->clust_eof_marker = 0xff8;
+ }
+ }
+
+
+ /* Now do some sanity checks */
+
+ if (bpb.bytes_per_sect != (1 << FAT_SUPER->sectsize_bits)
+ || bpb.bytes_per_sect != SECTOR_SIZE
+ || bpb.sects_per_clust != (1 << (FAT_SUPER->clustsize_bits
+ - FAT_SUPER->sectsize_bits))
+ || FAT_SUPER->num_clust <= 2
+ || (FAT_SUPER->fat_size * FAT_SUPER->num_clust / (2 * SECTOR_SIZE)
+ > FAT_SUPER->fat_length))
+ return 0;
+
+ /* kbs: Media check on first FAT entry [ported from PUPA] */
+
+ if (!devread(FAT_SUPER->fat_offset, 0,
+ sizeof(first_fat), (char *)&first_fat))
+ return 0;
+
+ if (FAT_SUPER->fat_size == 8)
+ {
+ first_fat &= 0x0fffffff;
+ magic = 0x0fffff00;
+ }
+ else if (FAT_SUPER->fat_size == 4)
+ {
+ first_fat &= 0x0000ffff;
+ magic = 0xff00;
+ }
+ else
+ {
+ first_fat &= 0x00000fff;
+ magic = 0x0f00;
+ }
+
+ if (first_fat != (magic | bpb.media))
+ return 0;
+
+ FAT_SUPER->cached_fat = - 2 * FAT_CACHE_SIZE;
+ return 1;
+}
+
+int
+fat_read (char *buf, int len)
+{
+ int logical_clust;
+ int offset;
+ int ret = 0;
+ int size;
+
+ if (FAT_SUPER->file_cluster < 0)
+ {
+ /* root directory for fat16 */
+ size = FAT_SUPER->root_max - filepos;
+ if (size > len)
+ size = len;
+ if (!devread(FAT_SUPER->root_offset, filepos, size, buf))
+ return 0;
+ filepos += size;
+ return size;
+ }
+
+ logical_clust = filepos >> FAT_SUPER->clustsize_bits;
+ offset = (filepos & ((1 << FAT_SUPER->clustsize_bits) - 1));
+ if (logical_clust < FAT_SUPER->current_cluster_num)
+ {
+ FAT_SUPER->current_cluster_num = 0;
+ FAT_SUPER->current_cluster = FAT_SUPER->file_cluster;
+ }
+
+ while (len > 0)
+ {
+ int sector;
+ while (logical_clust > FAT_SUPER->current_cluster_num)
+ {
+ /* calculate next cluster */
+ int fat_entry =
+ FAT_SUPER->current_cluster * FAT_SUPER->fat_size;
+ int next_cluster;
+ int cached_pos = (fat_entry - FAT_SUPER->cached_fat);
+
+ if (cached_pos < 0 ||
+ (cached_pos + FAT_SUPER->fat_size) > 2*FAT_CACHE_SIZE)
+ {
+ FAT_SUPER->cached_fat = (fat_entry & ~(2*SECTOR_SIZE - 1));
+ cached_pos = (fat_entry - FAT_SUPER->cached_fat);
+ sector = FAT_SUPER->fat_offset
+ + FAT_SUPER->cached_fat / (2*SECTOR_SIZE);
+ if (!devread (sector, 0, FAT_CACHE_SIZE, (char*) FAT_BUF))
+ return 0;
+ }
+ next_cluster = * (unsigned long *) (FAT_BUF + (cached_pos >> 1));
+ if (FAT_SUPER->fat_size == 3)
+ {
+ if (cached_pos & 1)
+ next_cluster >>= 4;
+ next_cluster &= 0xFFF;
+ }
+ else if (FAT_SUPER->fat_size == 4)
+ next_cluster &= 0xFFFF;
+
+ if (next_cluster >= FAT_SUPER->clust_eof_marker)
+ return ret;
+ if (next_cluster < 2 || next_cluster >= FAT_SUPER->num_clust)
+ {
+ errnum = ERR_FSYS_CORRUPT;
+ return 0;
+ }
+
+ FAT_SUPER->current_cluster = next_cluster;
+ FAT_SUPER->current_cluster_num++;
+ }
+
+ sector = FAT_SUPER->data_offset +
+ ((FAT_SUPER->current_cluster - 2) << (FAT_SUPER->clustsize_bits
+ - FAT_SUPER->sectsize_bits));
+ size = (1 << FAT_SUPER->clustsize_bits) - offset;
+ if (size > len)
+ size = len;
+
+ disk_read_func = disk_read_hook;
+
+ devread(sector, offset, size, buf);
+
+ disk_read_func = NULL;
+
+ len -= size;
+ buf += size;
+ ret += size;
+ filepos += size;
+ logical_clust++;
+ offset = 0;
+ }
+ return errnum ? 0 : ret;
+}
+
+int
+fat_dir (char *dirname)
+{
+ char *rest, ch, dir_buf[FAT_DIRENTRY_LENGTH];
+ char *filename = (char *) NAME_BUF;
+ int attrib = FAT_ATTRIB_DIR;
+#ifndef STAGE1_5
+ int do_possibilities = 0;
+#endif
+
+ /* XXX I18N:
+ * the positions 2,4,6 etc are high bytes of a 16 bit unicode char
+ */
+ static unsigned char longdir_pos[] =
+ { 1, 3, 5, 7, 9, 14, 16, 18, 20, 22, 24, 28, 30 };
+ int slot = -2;
+ int alias_checksum = -1;
+
+ FAT_SUPER->file_cluster = FAT_SUPER->root_cluster;
+ filepos = 0;
+ FAT_SUPER->current_cluster_num = MAXINT;
+
+ /* main loop to find desired directory entry */
+ loop:
+
+ /* if we have a real file (and we're not just printing possibilities),
+ then this is where we want to exit */
+
+ if (!*dirname || isspace (*dirname))
+ {
+ if (attrib & FAT_ATTRIB_DIR)
+ {
+ errnum = ERR_BAD_FILETYPE;
+ return 0;
+ }
+
+ return 1;
+ }
+
+ /* continue with the file/directory name interpretation */
+
+ while (*dirname == '/')
+ dirname++;
+
+ if (!(attrib & FAT_ATTRIB_DIR))
+ {
+ errnum = ERR_BAD_FILETYPE;
+ return 0;
+ }
+ /* Directories don't have a file size */
+ filemax = MAXINT;
+
+ for (rest = dirname; (ch = *rest) && !isspace (ch) && ch != '/'; rest++);
+
+ *rest = 0;
+
+# ifndef STAGE1_5
+ if (print_possibilities && ch != '/')
+ do_possibilities = 1;
+# endif
+
+ while (1)
+ {
+ if (fat_read (dir_buf, FAT_DIRENTRY_LENGTH) != FAT_DIRENTRY_LENGTH
+ || dir_buf[0] == 0)
+ {
+ if (!errnum)
+ {
+# ifndef STAGE1_5
+ if (print_possibilities < 0)
+ {
+#if 0
+ putchar ('\n');
+#endif
+ return 1;
+ }
+# endif /* STAGE1_5 */
+
+ errnum = ERR_FILE_NOT_FOUND;
+ *rest = ch;
+ }
+
+ return 0;
+ }
+
+ if (FAT_DIRENTRY_ATTRIB (dir_buf) == FAT_ATTRIB_LONGNAME)
+ {
+ /* This is a long filename. The filename is build from back
+ * to front and may span multiple entries. To bind these
+ * entries together they all contain the same checksum over
+ * the short alias.
+ *
+ * The id field tells if this is the first entry (the last
+ * part) of the long filename, and also at which offset this
+ * belongs.
+ *
+ * We just write the part of the long filename this entry
+ * describes and continue with the next dir entry.
+ */
+ int i, offset;
+ unsigned char id = FAT_LONGDIR_ID(dir_buf);
+
+ if ((id & 0x40))
+ {
+ id &= 0x3f;
+ slot = id;
+ filename[slot * 13] = 0;
+ alias_checksum = FAT_LONGDIR_ALIASCHECKSUM(dir_buf);
+ }
+
+ if (id != slot || slot == 0
+ || alias_checksum != FAT_LONGDIR_ALIASCHECKSUM(dir_buf))
+ {
+ alias_checksum = -1;
+ continue;
+ }
+
+ slot--;
+ offset = slot * 13;
+
+ for (i=0; i < 13; i++)
+ filename[offset+i] = dir_buf[longdir_pos[i]];
+ continue;
+ }
+
+ if (!FAT_DIRENTRY_VALID (dir_buf))
+ continue;
+
+ if (alias_checksum != -1 && slot == 0)
+ {
+ int i;
+ unsigned char sum;
+
+ slot = -2;
+ for (sum = 0, i = 0; i< 11; i++)
+ sum = ((sum >> 1) | (sum << 7)) + dir_buf[i];
+
+ if (sum == alias_checksum)
+ {
+# ifndef STAGE1_5
+ if (do_possibilities)
+ goto print_filename;
+# endif /* STAGE1_5 */
+
+ if (substring (dirname, filename) == 0)
+ break;
+ }
+ }
+
+ /* XXX convert to 8.3 filename format here */
+ {
+ int i, j, c;
+
+ for (i = 0; i < 8 && (c = filename[i] = tolower (dir_buf[i]))
+ && !isspace (c); i++);
+
+ filename[i++] = '.';
+
+ for (j = 0; j < 3 && (c = filename[i + j] = tolower (dir_buf[8 + j]))
+ && !isspace (c); j++);
+
+ if (j == 0)
+ i--;
+
+ filename[i + j] = 0;
+ }
+
+# ifndef STAGE1_5
+ if (do_possibilities)
+ {
+ print_filename:
+ if (substring (dirname, filename) <= 0)
+ {
+ if (print_possibilities > 0)
+ print_possibilities = -print_possibilities;
+ print_a_completion (filename);
+ }
+ continue;
+ }
+# endif /* STAGE1_5 */
+
+ if (substring (dirname, filename) == 0)
+ break;
+ }
+
+ *(dirname = rest) = ch;
+
+ attrib = FAT_DIRENTRY_ATTRIB (dir_buf);
+ filemax = FAT_DIRENTRY_FILELENGTH (dir_buf);
+ filepos = 0;
+ FAT_SUPER->file_cluster = FAT_DIRENTRY_FIRST_CLUSTER (dir_buf);
+ FAT_SUPER->current_cluster_num = MAXINT;
+
+ /* go back to main loop at top of function */
+ goto loop;
+}
+
+#endif /* FSYS_FAT */
Code Review / kvmfornfv.git / blobdiff