- 根目录:
- fs
- adfs
- dir_f.c
/*
* linux/fs/adfs/dir_f.c
*
* Copyright (C) 1997-1999 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* E and F format directory handling
*/
#include <linux/buffer_head.h>
#include "adfs.h"
#include "dir_f.h"
static void adfs_f_free(struct adfs_dir *dir);
/*
* Read an (unaligned) value of length 1..4 bytes
*/
static inline unsigned int adfs_readval(unsigned char *p, int len)
{
unsigned int val = 0;
switch (len) {
case 4: val |= p[3] << 24;
case 3: val |= p[2] << 16;
case 2: val |= p[1] << 8;
default: val |= p[0];
}
return val;
}
static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
{
switch (len) {
case 4: p[3] = val >> 24;
case 3: p[2] = val >> 16;
case 2: p[1] = val >> 8;
default: p[0] = val;
}
}
static inline int adfs_readname(char *buf, char *ptr, int maxlen)
{
char *old_buf = buf;
while ((unsigned char)*ptr >= ' ' && maxlen--) {
if (*ptr == '/')
*buf++ = '.';
else
*buf++ = *ptr;
ptr++;
}
return buf - old_buf;
}
#define ror13(v) ((v >> 13) | (v << 19))
#define dir_u8(idx) \
({ int _buf = idx >> blocksize_bits; \
int _off = idx - (_buf << blocksize_bits);\
*(u8 *)(bh[_buf]->b_data + _off); \
})
#define dir_u32(idx) \
({ int _buf = idx >> blocksize_bits; \
int _off = idx - (_buf << blocksize_bits);\
*(__le32 *)(bh[_buf]->b_data + _off); \
})
#define bufoff(_bh,_idx) \
({ int _buf = _idx >> blocksize_bits; \
int _off = _idx - (_buf << blocksize_bits);\
(u8 *)(_bh[_buf]->b_data + _off); \
})
/*
* There are some algorithms that are nice in
* assembler, but a bitch in C... This is one
* of them.
*/
static u8
adfs_dir_checkbyte(const struct adfs_dir *dir)
{
struct buffer_head * const *bh = dir->bh;
const int blocksize_bits = dir->sb->s_blocksize_bits;
union { __le32 *ptr32; u8 *ptr8; } ptr, end;
u32 dircheck = 0;
int last = 5 - 26;
int i = 0;
/*
* Accumulate each word up to the last whole
* word of the last directory entry. This
* can spread across several buffer heads.
*/
do {
last += 26;
do {
dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
i += sizeof(u32);
} while (i < (last & ~3));
} while (dir_u8(last) != 0);
/*
* Accumulate the last few bytes. These
* bytes will be within the same bh.
*/
if (i != last) {
ptr.ptr8 = bufoff(bh, i);
end.ptr8 = ptr.ptr8 + last - i;
do {
dircheck = *ptr.ptr8++ ^ ror13(dircheck);
} while (ptr.ptr8 < end.ptr8);
}
/*
* The directory tail is in the final bh
* Note that contary to the RISC OS PRMs,
* the first few bytes are NOT included
* in the check. All bytes are in the
* same bh.
*/
ptr.ptr8 = bufoff(bh, 2008);
end.ptr8 = ptr.ptr8 + 36;
do {
__le32 v = *ptr.ptr32++;
dircheck = le32_to_cpu(v) ^ ror13(dircheck);
} while (ptr.ptr32 < end.ptr32);
return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
}
/*
* Read and check that a directory is valid
*/
static int
adfs_dir_read(struct super_block *sb, unsigned long object_id,
unsigned int size, struct adfs_dir *dir)
{
const unsigned int blocksize_bits = sb->s_blocksize_bits;
int blk = 0;
/*
* Directories which are not a multiple of 2048 bytes
* are considered bad v2 [3.6]
*/
if (size & 2047)
goto bad_dir;
size >>= blocksize_bits;
dir->nr_buffers = 0;
dir->sb = sb;
for (blk = 0; blk < size; blk++) {
int phys;
phys = __adfs_block_map(sb, object_id, blk);
if (!phys) {
adfs_error(sb, "dir object %lX has a hole at offset %d",
object_id, blk);
goto release_buffers;
}
dir->bh[blk] = sb_bread(sb, phys);
if (!dir->bh[blk])
goto release_buffers;
}
memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
goto bad_dir;
if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
memcmp(&dir->dirhead.startname, "Hugo", 4))
goto bad_dir;
if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
goto bad_dir;
dir->nr_buffers = blk;
return 0;
bad_dir:
adfs_error(sb, "corrupted directory fragment %lX",
object_id);
release_buffers:
for (blk -= 1; blk >= 0; blk -= 1)
brelse(dir->bh[blk]);
dir->sb = NULL;
return -EIO;
}
/*
* convert a disk-based directory entry to a Linux ADFS directory entry
*/
static inline void
adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
struct adfs_direntry *de)
{
obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
obj->file_id = adfs_readval(de->dirinddiscadd, 3);
obj->loadaddr = adfs_readval(de->dirload, 4);
obj->execaddr = adfs_readval(de->direxec, 4);
obj->size = adfs_readval(de->dirlen, 4);
obj->attr = de->newdiratts;
obj->filetype = -1;
/*
* object is a file and is filetyped and timestamped?
* RISC OS 12-bit filetype is stored in load_address[19:8]
*/
if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
(0xfff00000 == (0xfff00000 & obj->loadaddr))) {
obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
/* optionally append the ,xyz hex filetype suffix */
if (ADFS_SB(dir->sb)->s_ftsuffix)
obj->name_len +=
append_filetype_suffix(
&obj->name[obj->name_len],
obj->filetype);
}
}
/*
* convert a Linux ADFS directory entry to a disk-based directory entry
*/
static inline void
adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
{
adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
adfs_writeval(de->dirload, 4, obj->loadaddr);
adfs_writeval(de->direxec, 4, obj->execaddr);
adfs_writeval(de->dirlen, 4, obj->size);
de->newdiratts = obj->attr;
}
/*
* get a directory entry. Note that the caller is responsible
* for holding the relevant locks.
*/
static int
__adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
{
struct super_block *sb = dir->sb;
struct adfs_direntry de;
int thissize, buffer, offset;
buffer = pos >> sb->s_blocksize_bits;
if (buffer > dir->nr_buffers)
return -EINVAL;
offset = pos & (sb->s_blocksize - 1);
thissize = sb->s_blocksize - offset;
if (thissize > 26)
thissize = 26;
memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
if (thissize != 26)
memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
26 - thissize);
if (!de.dirobname[0])
return -ENOENT;
adfs_dir2obj(dir, obj, &de);
return 0;
}
static int
__adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
{
struct super_block *sb = dir->sb;
struct adfs_direntry de;
int thissize, buffer, offset;
buffer = pos >> sb->s_blocksize_bits;
if (buffer > dir->nr_buffers)
return -EINVAL;
offset = pos & (sb->s_blocksize - 1);
thissize = sb->s_blocksize - offset;
if (thissize > 26)
thissize = 26;
/*
* Get the entry in total
*/
memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
if (thissize != 26)
memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
26 - thissize);
/*
* update it
*/
adfs_obj2dir(&de, obj);
/*
* Put the new entry back
*/
memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
if (thissize != 26)
memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
26 - thissize);
return 0;
}
/*
* the caller is responsible for holding the necessary
* locks.
*/
static int
adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
{
int pos, ret;
ret = -ENOENT;
for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
struct object_info obj;
if (!__adfs_dir_get(dir, pos, &obj))
break;
if (obj.file_id == object_id) {
ret = pos;
break;
}
}
return ret;
}
static int
adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
{
int ret;
if (sz != ADFS_NEWDIR_SIZE)
return -EIO;
ret = adfs_dir_read(sb, id, sz, dir);
if (ret)
adfs_error(sb, "unable to read directory");
else
dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
return ret;
}
static int
adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
{
if (fpos >= ADFS_NUM_DIR_ENTRIES)
return -ENOENT;
dir->pos = 5 + fpos * 26;
return 0;
}
static int
adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
{
unsigned int ret;
ret = __adfs_dir_get(dir, dir->pos, obj);
if (ret == 0)
dir->pos += 26;
return ret;
}
static int
adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
{
struct super_block *sb = dir->sb;
int ret, i;
ret = adfs_dir_find_entry(dir, obj->file_id);
if (ret < 0) {
adfs_error(dir->sb, "unable to locate entry to update");
goto out;
}
__adfs_dir_put(dir, ret, obj);
/*
* Increment directory sequence number
*/
dir->bh[0]->b_data[0] += 1;
dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
ret = adfs_dir_checkbyte(dir);
/*
* Update directory check byte
*/
dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
#if 1
{
const unsigned int blocksize_bits = sb->s_blocksize_bits;
memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
goto bad_dir;
if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
memcmp(&dir->dirhead.startname, "Hugo", 4))
goto bad_dir;
if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
goto bad_dir;
}
#endif
for (i = dir->nr_buffers - 1; i >= 0; i--)
mark_buffer_dirty(dir->bh[i]);
ret = 0;
out:
return ret;
#if 1
bad_dir:
adfs_error(dir->sb, "whoops! I broke a directory!");
return -EIO;
#endif
}
static int
adfs_f_sync(struct adfs_dir *dir)
{
int err = 0;
int i;
for (i = dir->nr_buffers - 1; i >= 0; i--) {
struct buffer_head *bh = dir->bh[i];
sync_dirty_buffer(bh);
if (buffer_req(bh) && !buffer_uptodate(bh))
err = -EIO;
}
return err;
}
static void
adfs_f_free(struct adfs_dir *dir)
{
int i;
for (i = dir->nr_buffers - 1; i >= 0; i--) {
brelse(dir->bh[i]);
dir->bh[i] = NULL;
}
dir->nr_buffers = 0;
dir->sb = NULL;
}
struct adfs_dir_ops adfs_f_dir_ops = {
.read = adfs_f_read,
.setpos = adfs_f_setpos,
.getnext = adfs_f_getnext,
.update = adfs_f_update,
.sync = adfs_f_sync,
.free = adfs_f_free
};