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-rw-r--r--fs/adfs/dir_f.c324
1 files changed, 324 insertions, 0 deletions
diff --git a/fs/adfs/dir_f.c b/fs/adfs/dir_f.c
new file mode 100644
index 000000000..05e963402
--- /dev/null
+++ b/fs/adfs/dir_f.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/adfs/dir_f.c
+ *
+ * Copyright (C) 1997-1999 Russell King
+ *
+ * E and F format directory handling
+ */
+#include "adfs.h"
+#include "dir_f.h"
+
+/*
+ * 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;
+ fallthrough;
+ case 3: val |= p[2] << 16;
+ fallthrough;
+ case 2: val |= p[1] << 8;
+ fallthrough;
+ 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;
+ fallthrough;
+ case 3: p[2] = val >> 16;
+ fallthrough;
+ case 2: p[1] = val >> 8;
+ fallthrough;
+ default: p[0] = val;
+ }
+}
+
+#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);\
+ (void *)(_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;
+}
+
+static int adfs_f_validate(struct adfs_dir *dir)
+{
+ struct adfs_dirheader *head = dir->dirhead;
+ struct adfs_newdirtail *tail = dir->newtail;
+
+ if (head->startmasseq != tail->endmasseq ||
+ tail->dirlastmask || tail->reserved[0] || tail->reserved[1] ||
+ (memcmp(&head->startname, "Nick", 4) &&
+ memcmp(&head->startname, "Hugo", 4)) ||
+ memcmp(&head->startname, &tail->endname, 4) ||
+ adfs_dir_checkbyte(dir) != tail->dircheckbyte)
+ return -EIO;
+
+ return 0;
+}
+
+/* Read and check that a directory is valid */
+static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size,
+ struct adfs_dir *dir)
+{
+ const unsigned int blocksize_bits = sb->s_blocksize_bits;
+ int ret;
+
+ if (size && size != ADFS_NEWDIR_SIZE)
+ return -EIO;
+
+ ret = adfs_dir_read_buffers(sb, indaddr, ADFS_NEWDIR_SIZE, dir);
+ if (ret)
+ return ret;
+
+ dir->dirhead = bufoff(dir->bh, 0);
+ dir->newtail = bufoff(dir->bh, 2007);
+
+ if (adfs_f_validate(dir))
+ goto bad_dir;
+
+ dir->parent_id = adfs_readval(dir->newtail->dirparent, 3);
+
+ return 0;
+
+bad_dir:
+ adfs_error(sb, "dir %06x is corrupted", indaddr);
+ adfs_dir_relse(dir);
+
+ 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)
+{
+ unsigned int name_len;
+
+ for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) {
+ if (de->dirobname[name_len] < ' ')
+ break;
+
+ obj->name[name_len] = de->dirobname[name_len];
+ }
+
+ obj->name_len = name_len;
+ obj->indaddr = 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;
+
+ adfs_object_fixup(dir, obj);
+}
+
+/*
+ * 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->indaddr);
+ 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 adfs_direntry de;
+ int ret;
+
+ ret = adfs_dir_copyfrom(&de, dir, pos, 26);
+ if (ret)
+ return ret;
+
+ if (!de.dirobname[0])
+ return -ENOENT;
+
+ adfs_dir2obj(dir, obj, &de);
+
+ return 0;
+}
+
+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_iterate(struct adfs_dir *dir, struct dir_context *ctx)
+{
+ struct object_info obj;
+ int pos = 5 + (ctx->pos - 2) * 26;
+
+ while (ctx->pos < 2 + ADFS_NUM_DIR_ENTRIES) {
+ if (__adfs_dir_get(dir, pos, &obj))
+ break;
+ if (!dir_emit(ctx, obj.name, obj.name_len,
+ obj.indaddr, DT_UNKNOWN))
+ break;
+ pos += 26;
+ ctx->pos++;
+ }
+ return 0;
+}
+
+static int adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
+{
+ struct adfs_direntry de;
+ int offset, ret;
+
+ offset = 5 - (int)sizeof(de);
+
+ do {
+ offset += sizeof(de);
+ ret = adfs_dir_copyfrom(&de, dir, offset, sizeof(de));
+ if (ret) {
+ adfs_error(dir->sb, "error reading directory entry");
+ return -ENOENT;
+ }
+ if (!de.dirobname[0]) {
+ adfs_error(dir->sb, "unable to locate entry to update");
+ return -ENOENT;
+ }
+ } while (adfs_readval(de.dirinddiscadd, 3) != obj->indaddr);
+
+ /* Update the directory entry with the new object state */
+ adfs_obj2dir(&de, obj);
+
+ /* Write the directory entry back to the directory */
+ return adfs_dir_copyto(dir, offset, &de, 26);
+}
+
+static int adfs_f_commit(struct adfs_dir *dir)
+{
+ int ret;
+
+ /* Increment directory sequence number */
+ dir->dirhead->startmasseq += 1;
+ dir->newtail->endmasseq += 1;
+
+ /* Update directory check byte */
+ dir->newtail->dircheckbyte = adfs_dir_checkbyte(dir);
+
+ /* Make sure the directory still validates correctly */
+ ret = adfs_f_validate(dir);
+ if (ret)
+ adfs_msg(dir->sb, KERN_ERR, "error: update broke directory");
+
+ return ret;
+}
+
+const struct adfs_dir_ops adfs_f_dir_ops = {
+ .read = adfs_f_read,
+ .iterate = adfs_f_iterate,
+ .setpos = adfs_f_setpos,
+ .getnext = adfs_f_getnext,
+ .update = adfs_f_update,
+ .commit = adfs_f_commit,
+};