463 lines
9.7 KiB
C
463 lines
9.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/adfs/dir_f.c
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*
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* Copyright (C) 1997-1999 Russell King
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*
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* E and F format directory handling
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*/
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#include "adfs.h"
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#include "dir_f.h"
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static void adfs_f_free(struct adfs_dir *dir);
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/*
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* Read an (unaligned) value of length 1..4 bytes
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*/
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static inline unsigned int adfs_readval(unsigned char *p, int len)
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{
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unsigned int val = 0;
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switch (len) {
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case 4: val |= p[3] << 24;
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/* fall through */
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case 3: val |= p[2] << 16;
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/* fall through */
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case 2: val |= p[1] << 8;
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/* fall through */
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default: val |= p[0];
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}
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return val;
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}
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static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
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{
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switch (len) {
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case 4: p[3] = val >> 24;
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/* fall through */
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case 3: p[2] = val >> 16;
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/* fall through */
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case 2: p[1] = val >> 8;
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/* fall through */
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default: p[0] = val;
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}
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}
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#define ror13(v) ((v >> 13) | (v << 19))
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#define dir_u8(idx) \
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({ int _buf = idx >> blocksize_bits; \
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int _off = idx - (_buf << blocksize_bits);\
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*(u8 *)(bh[_buf]->b_data + _off); \
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})
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#define dir_u32(idx) \
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({ int _buf = idx >> blocksize_bits; \
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int _off = idx - (_buf << blocksize_bits);\
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*(__le32 *)(bh[_buf]->b_data + _off); \
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})
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#define bufoff(_bh,_idx) \
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({ int _buf = _idx >> blocksize_bits; \
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int _off = _idx - (_buf << blocksize_bits);\
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(u8 *)(_bh[_buf]->b_data + _off); \
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})
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/*
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* There are some algorithms that are nice in
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* assembler, but a bitch in C... This is one
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* of them.
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*/
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static u8
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adfs_dir_checkbyte(const struct adfs_dir *dir)
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{
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struct buffer_head * const *bh = dir->bh;
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const int blocksize_bits = dir->sb->s_blocksize_bits;
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union { __le32 *ptr32; u8 *ptr8; } ptr, end;
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u32 dircheck = 0;
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int last = 5 - 26;
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int i = 0;
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/*
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* Accumulate each word up to the last whole
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* word of the last directory entry. This
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* can spread across several buffer heads.
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*/
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do {
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last += 26;
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do {
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dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
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i += sizeof(u32);
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} while (i < (last & ~3));
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} while (dir_u8(last) != 0);
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/*
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* Accumulate the last few bytes. These
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* bytes will be within the same bh.
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*/
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if (i != last) {
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ptr.ptr8 = bufoff(bh, i);
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end.ptr8 = ptr.ptr8 + last - i;
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do {
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dircheck = *ptr.ptr8++ ^ ror13(dircheck);
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} while (ptr.ptr8 < end.ptr8);
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}
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/*
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* The directory tail is in the final bh
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* Note that contary to the RISC OS PRMs,
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* the first few bytes are NOT included
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* in the check. All bytes are in the
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* same bh.
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*/
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ptr.ptr8 = bufoff(bh, 2008);
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end.ptr8 = ptr.ptr8 + 36;
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do {
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__le32 v = *ptr.ptr32++;
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dircheck = le32_to_cpu(v) ^ ror13(dircheck);
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} while (ptr.ptr32 < end.ptr32);
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return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
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}
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/* Read and check that a directory is valid */
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static int adfs_dir_read(struct super_block *sb, u32 indaddr,
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unsigned int size, struct adfs_dir *dir)
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{
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const unsigned int blocksize_bits = sb->s_blocksize_bits;
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int blk = 0;
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/*
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* Directories which are not a multiple of 2048 bytes
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* are considered bad v2 [3.6]
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*/
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if (size & 2047)
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goto bad_dir;
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size >>= blocksize_bits;
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dir->nr_buffers = 0;
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dir->sb = sb;
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for (blk = 0; blk < size; blk++) {
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int phys;
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phys = __adfs_block_map(sb, indaddr, blk);
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if (!phys) {
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adfs_error(sb, "dir %06x has a hole at offset %d",
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indaddr, blk);
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goto release_buffers;
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}
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dir->bh[blk] = sb_bread(sb, phys);
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if (!dir->bh[blk])
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goto release_buffers;
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}
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memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
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memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
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if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
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memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
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goto bad_dir;
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if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
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memcmp(&dir->dirhead.startname, "Hugo", 4))
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goto bad_dir;
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if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
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goto bad_dir;
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dir->nr_buffers = blk;
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return 0;
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bad_dir:
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adfs_error(sb, "dir %06x is corrupted", indaddr);
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release_buffers:
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for (blk -= 1; blk >= 0; blk -= 1)
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brelse(dir->bh[blk]);
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dir->sb = NULL;
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return -EIO;
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}
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/*
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* convert a disk-based directory entry to a Linux ADFS directory entry
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*/
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static inline void
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adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
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struct adfs_direntry *de)
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{
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unsigned int name_len;
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for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) {
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if (de->dirobname[name_len] < ' ')
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break;
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obj->name[name_len] = de->dirobname[name_len];
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}
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obj->name_len = name_len;
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obj->indaddr = adfs_readval(de->dirinddiscadd, 3);
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obj->loadaddr = adfs_readval(de->dirload, 4);
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obj->execaddr = adfs_readval(de->direxec, 4);
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obj->size = adfs_readval(de->dirlen, 4);
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obj->attr = de->newdiratts;
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adfs_object_fixup(dir, obj);
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}
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/*
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* convert a Linux ADFS directory entry to a disk-based directory entry
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*/
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static inline void
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adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
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{
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adfs_writeval(de->dirinddiscadd, 3, obj->indaddr);
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adfs_writeval(de->dirload, 4, obj->loadaddr);
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adfs_writeval(de->direxec, 4, obj->execaddr);
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adfs_writeval(de->dirlen, 4, obj->size);
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de->newdiratts = obj->attr;
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}
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/*
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* get a directory entry. Note that the caller is responsible
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* for holding the relevant locks.
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*/
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static int
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__adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
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{
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struct super_block *sb = dir->sb;
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struct adfs_direntry de;
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int thissize, buffer, offset;
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buffer = pos >> sb->s_blocksize_bits;
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if (buffer > dir->nr_buffers)
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return -EINVAL;
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offset = pos & (sb->s_blocksize - 1);
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thissize = sb->s_blocksize - offset;
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if (thissize > 26)
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thissize = 26;
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memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
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if (thissize != 26)
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memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
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26 - thissize);
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if (!de.dirobname[0])
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return -ENOENT;
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adfs_dir2obj(dir, obj, &de);
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return 0;
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}
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static int
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__adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
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{
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struct super_block *sb = dir->sb;
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struct adfs_direntry de;
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int thissize, buffer, offset;
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buffer = pos >> sb->s_blocksize_bits;
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if (buffer > dir->nr_buffers)
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return -EINVAL;
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offset = pos & (sb->s_blocksize - 1);
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thissize = sb->s_blocksize - offset;
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if (thissize > 26)
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thissize = 26;
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/*
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* Get the entry in total
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*/
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memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
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if (thissize != 26)
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memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
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26 - thissize);
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/*
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* update it
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*/
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adfs_obj2dir(&de, obj);
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/*
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* Put the new entry back
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*/
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memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
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if (thissize != 26)
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memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
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26 - thissize);
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return 0;
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}
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/*
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* the caller is responsible for holding the necessary
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* locks.
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*/
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static int adfs_dir_find_entry(struct adfs_dir *dir, u32 indaddr)
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{
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int pos, ret;
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ret = -ENOENT;
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for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
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struct object_info obj;
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if (!__adfs_dir_get(dir, pos, &obj))
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break;
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if (obj.indaddr == indaddr) {
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ret = pos;
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break;
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}
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}
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return ret;
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}
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static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size,
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struct adfs_dir *dir)
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{
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int ret;
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if (size != ADFS_NEWDIR_SIZE)
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return -EIO;
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ret = adfs_dir_read(sb, indaddr, size, dir);
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if (ret)
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adfs_error(sb, "unable to read directory");
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else
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dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
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return ret;
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}
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static int
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adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
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{
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if (fpos >= ADFS_NUM_DIR_ENTRIES)
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return -ENOENT;
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dir->pos = 5 + fpos * 26;
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return 0;
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}
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static int
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adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
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{
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unsigned int ret;
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ret = __adfs_dir_get(dir, dir->pos, obj);
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if (ret == 0)
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dir->pos += 26;
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return ret;
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}
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static int
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adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
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{
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struct super_block *sb = dir->sb;
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int ret, i;
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ret = adfs_dir_find_entry(dir, obj->indaddr);
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if (ret < 0) {
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adfs_error(dir->sb, "unable to locate entry to update");
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goto out;
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}
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__adfs_dir_put(dir, ret, obj);
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/*
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* Increment directory sequence number
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*/
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dir->bh[0]->b_data[0] += 1;
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dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
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ret = adfs_dir_checkbyte(dir);
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/*
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* Update directory check byte
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*/
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dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
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#if 1
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{
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const unsigned int blocksize_bits = sb->s_blocksize_bits;
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memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
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memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
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if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
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memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
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goto bad_dir;
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if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
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memcmp(&dir->dirhead.startname, "Hugo", 4))
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goto bad_dir;
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if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
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goto bad_dir;
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}
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#endif
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for (i = dir->nr_buffers - 1; i >= 0; i--)
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mark_buffer_dirty(dir->bh[i]);
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ret = 0;
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out:
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return ret;
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#if 1
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bad_dir:
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adfs_error(dir->sb, "whoops! I broke a directory!");
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return -EIO;
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#endif
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}
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static int
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adfs_f_sync(struct adfs_dir *dir)
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{
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int err = 0;
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int i;
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for (i = dir->nr_buffers - 1; i >= 0; i--) {
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struct buffer_head *bh = dir->bh[i];
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sync_dirty_buffer(bh);
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if (buffer_req(bh) && !buffer_uptodate(bh))
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err = -EIO;
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}
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return err;
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}
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static void
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adfs_f_free(struct adfs_dir *dir)
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{
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int i;
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for (i = dir->nr_buffers - 1; i >= 0; i--) {
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brelse(dir->bh[i]);
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dir->bh[i] = NULL;
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}
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dir->nr_buffers = 0;
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dir->sb = NULL;
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}
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const struct adfs_dir_ops adfs_f_dir_ops = {
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.read = adfs_f_read,
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.setpos = adfs_f_setpos,
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.getnext = adfs_f_getnext,
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.update = adfs_f_update,
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.sync = adfs_f_sync,
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.free = adfs_f_free
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};
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