patch-2.2.18 linux/fs/adfs/dir_f.c

• Lines: 476
• Date: Fri Sep 15 23:24:41 2000
• Orig file: v2.2.17/fs/adfs/dir_f.c
• Orig date: Thu Jan 1 01:00:00 1970

diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/fs/adfs/dir_f.c linux/fs/adfs/dir_f.c
@@ -0,0 +1,475 @@
+/*
+ *  linux/fs/adfs/dir_f.c
+ *
+ * Copyright (C) 1997-1999 Russell King
+ *
+ * E and F format directory handling
+ */
+#include <linux/version.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/adfs_fs.h>
+#include <linux/sched.h>
+#include <linux/stat.h>
+
+#include <asm/spinlock.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 (*ptr >= ' ' && maxlen--) {
+		if (*ptr == '/')
+			*buf++ = '.';
+		else
+			*buf++ = *ptr;
+		ptr++;
+	}
+	*buf = '\0';
+
+	return buf - old_buf;
+}
+
+static inline void adfs_writename(char *to, char *from, int maxlen)
+{
+	int i;
+
+	for (i = 0; i < maxlen; i++) {
+		if (from[i] == '\0')
+			break;
+		if (from[i] == '.')
+			to[i] = '/';
+		else
+			to[i] = from[i];
+	}
+
+	for (; i < maxlen; i++)
+		to[i] = '\0';
+}
+
+#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);\
+	  *(u32 *)(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 { u32 *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 = cpu_to_le32(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 {
+		unsigned int v = *ptr.ptr32++;
+		dircheck = cpu_to_le32(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
+ */
+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] = bread(sb->s_dev, phys, sb->s_blocksize);
+		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 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;
+}
+
+/*
+ * 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 relevent locks.
+ */
+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(obj, &de);
+
+	return 0;
+}
+
+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], 1);
+
+	ret = 0;
+out:
+	return ret;
+#if 1
+bad_dir:
+	adfs_error(dir->sb, "whoops!  I broke a directory!");
+	return -EIO;
+#endif
+}
+
+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 = {
+	adfs_f_read,
+	adfs_f_setpos,
+	adfs_f_getnext,
+	adfs_f_update,
+	NULL,
+	NULL,
+	adfs_f_free
+};