This I/O manager saves the contents of the location being overwritten
to a tdb database. This helps in undoing the changes done to the
file system.
The call sequence involve
set_undo_io_backing_manager(unix_io_manager);
set_undo_io_backup_file("/tmp/test.tdb");
retval = ext2fs_open2(dev_name, 0, flags,
superblock, block_size, undo_io_manager,
¤t_fs);
Signed-off-by: Aneesh Kumar K.V <[EMAIL PROTECTED]>
---
lib/ext2fs/Makefile.in | 10 +-
lib/ext2fs/ext2_io.h | 5 +
lib/ext2fs/undo_io.c | 533 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 546 insertions(+), 2 deletions(-)
create mode 100644 lib/ext2fs/undo_io.c
diff --git a/lib/ext2fs/Makefile.in b/lib/ext2fs/Makefile.in
index 799659e..6b49a13 100644
--- a/lib/ext2fs/Makefile.in
+++ b/lib/ext2fs/Makefile.in
@@ -66,7 +66,8 @@ OBJS= $(DEBUGFS_LIB_OBJS) $(RESIZE_LIB_OBJS)
$(E2IMAGE_LIB_OBJS) \
unix_io.o \
unlink.o \
valid_blk.o \
- version.o
+ version.o \
+ undo_io.o
SRCS= ext2_err.c \
$(srcdir)/alloc.c \
@@ -134,7 +135,8 @@ SRCS= ext2_err.c \
$(srcdir)/tst_bitops.c \
$(srcdir)/tst_byteswap.c \
$(srcdir)/tst_getsize.c \
- $(srcdir)/tst_iscan.c
+ $(srcdir)/tst_iscan.c \
+ $(srcdir)/undo_io.c
HFILES= bitops.h ext2fs.h ext2_io.h ext2_fs.h ext2_ext_attr.h ext3_extents.h
HFILES_IN= ext2_err.h ext2_types.h
@@ -550,3 +552,7 @@ tst_iscan.o: $(srcdir)/tst_iscan.c $(srcdir)/ext2_fs.h \
$(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \
$(srcdir)/ext2_fs.h $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \
$(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/bitops.h
+undo_io.o: $(srcdir)/undo_io.c $(srcdir)/ext2_fs.h \
+ $(top_builddir)/lib/ext2fs/ext2_types.h $(srcdir)/ext2fs.h \
+ $(srcdir)/ext2_fs.h $(top_srcdir)/lib/et/com_err.h $(srcdir)/ext2_io.h \
+ $(top_builddir)/lib/ext2fs/ext2_err.h $(srcdir)/bitops.h
diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index eada278..476eb4d 100644
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -96,6 +96,11 @@ extern errcode_t io_channel_write_byte(io_channel channel,
/* unix_io.c */
extern io_manager unix_io_manager;
+/* undo_io.c */
+extern io_manager undo_io_manager;
+extern errcode_t set_undo_io_backing_manager(io_manager manager);
+extern errcode_t set_undo_io_backup_file(char *file_name);
+
/* test_io.c */
extern io_manager test_io_manager, test_io_backing_manager;
extern void (*test_io_cb_read_blk)
diff --git a/lib/ext2fs/undo_io.c b/lib/ext2fs/undo_io.c
new file mode 100644
index 0000000..2c8f6d8
--- /dev/null
+++ b/lib/ext2fs/undo_io.c
@@ -0,0 +1,533 @@
+/*
+ * undo_io.c --- This is the undo io manager that copies the old data that
+ * copies the old data being overwritten into a tdb database
+ *
+ * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
+ * 2002 by Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#define _LARGEFILE_SOURCE
+#define _LARGEFILE64_SOURCE
+
+#include <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <fcntl.h>
+#include <time.h>
+#ifdef __linux__
+#include <sys/utsname.h>
+#endif
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#if HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
+#include <tdb.h>
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+/*
+ * For checking structure magic numbers...
+ */
+
+#define EXT2_CHECK_MAGIC(struct, code) \
+ if ((struct)->magic != (code)) return (code)
+
+
+struct undo_private_data {
+ int magic;
+ TDB_CONTEXT *tdb;
+ char *tdb_file;
+
+ /* The backing io channel */
+ io_channel real;
+
+ /* device from from which data should be read */
+ int dev;
+
+ /* to support offset in unix I/O manager */
+ ext2_loff_t offset;
+};
+
+static errcode_t undo_open(const char *name, int flags, io_channel *channel);
+static errcode_t undo_close(io_channel channel);
+static errcode_t undo_set_blksize(io_channel channel, int blksize);
+static errcode_t undo_read_blk(io_channel channel, unsigned long block,
+ int count, void *data);
+static errcode_t undo_write_blk(io_channel channel, unsigned long block,
+ int count, const void *data);
+static errcode_t undo_flush(io_channel channel);
+static errcode_t undo_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *data);
+static errcode_t undo_set_option(io_channel channel, const char *option,
+ const char *arg);
+
+static struct struct_io_manager struct_undo_manager = {
+ EXT2_ET_MAGIC_IO_MANAGER,
+ "Undo I/O Manager",
+ undo_open,
+ undo_close,
+ undo_set_blksize,
+ undo_read_blk,
+ undo_write_blk,
+ undo_flush,
+ undo_write_byte,
+ undo_set_option
+};
+
+io_manager undo_io_manager = &struct_undo_manager;
+static io_manager undo_io_backing_manager ;
+static char *tdb_file ;
+
+errcode_t set_undo_io_backing_manager(io_manager manager)
+{
+ /*
+ * We may want to do some validation later
+ */
+ undo_io_backing_manager = manager;
+ return 0;
+}
+
+errcode_t set_undo_io_backup_file(char *file_name)
+{
+ tdb_file = strdup(file_name);
+
+ if (tdb_file == NULL) {
+ return EXT2_ET_NO_MEMORY;
+ }
+
+ return 0;
+}
+
+static errcode_t is_trans_overlapping(TDB_CONTEXT *tdb,
+ ext2_loff_t *location, int *size)
+{
+
+ ext2_loff_t req_loc, cur_loc;
+ int req_size, cur_size;
+ TDB_DATA key, data;
+
+restart:
+ req_loc = *location;
+ req_size = *size;
+
+ /* loop through the existing entries and find if they overlap */
+ for (key = tdb_firstkey(tdb); key.dptr; key = tdb_nextkey(tdb, key)) {
+ data = tdb_fetch(tdb, key);
+ /*
+ * we are not interested in the data
+ */
+ free(data.dptr);
+
+ cur_loc = *(ext2_loff_t *)key.dptr;
+ cur_size = data.dsize;
+
+ if (req_loc < cur_loc) {
+ if (req_loc+req_size > cur_loc) {
+ /* ------------------
+ * | | | |
+ * ------------------
+ * rl cl rs cs
+ */
+ *size = cur_loc - req_loc;
+ goto restart;
+ }
+ continue;
+ }
+
+ if(req_loc >= cur_loc + cur_size)
+ continue;
+
+ if (req_loc + req_size <= cur_loc + cur_size) {
+
+ /* ------------------
+ * | | | |
+ * ------------------
+ * cl rl rs cs
+ */
+ /*
+ * The old entry completely overlap
+ * with the new entry. So no need
+ * to add new entries
+ */
+ return 1;
+ }
+
+ /* ------------------
+ * | | | |
+ * ------------------
+ * cl rl cs rs
+ */
+ /*
+ * We have partial overlapping entry
+ * update location and new size
+ */
+
+ *location = cur_loc + cur_size;
+ *size = req_loc + req_size - (*location);
+ /*
+ * Now we need to check whether the new value of
+ * location and size are overlapping
+ */
+ goto restart;
+ }
+
+ /* Not a overlapping entry */
+ return 0;
+
+}
+
+static errcode_t undo_write_tdb(struct undo_private_data * data,
+ ext2_loff_t location, int size)
+
+{
+ TDB_DATA tdb_key, tdb_data;
+ errcode_t retval = 0;
+ int actual = 0;
+ ext2_loff_t cur_loc ;
+
+ if (data->tdb == NULL) {
+ /*
+ * Transaction database not initialized
+ */
+ return 0;
+ }
+
+ if (is_trans_overlapping(data->tdb, &location, &size)) {
+ /*
+ * Already we have the original contents
+ * in the database. So skip this write
+ */
+ return 0;
+ }
+
+ tdb_key.dptr = (unsigned char *)&location;
+ tdb_key.dsize = sizeof(location);
+
+ retval = ext2fs_get_mem(size, &(tdb_data.dptr));
+ if (retval) {
+ return retval;
+ }
+
+ if ((cur_loc = ext2fs_llseek(data->dev, 0, SEEK_CUR)) == -1) {
+ retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
+ goto error_out_lseek;
+ }
+
+ if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
+ retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
+ goto error_out_lseek;
+ }
+
+ actual = read(data->dev, tdb_data.dptr, size);
+ if (actual != size) {
+ /*
+ * eventhough it is read we still are doing a write
+ * so return error that is related to write
+ */
+ retval = EXT2_ET_SHORT_WRITE;
+ goto error_out;
+ }
+
+ tdb_data.dsize = size;
+
+#ifdef DEBUG
+ printf("Printing with key %lld data %x and size %d\n", location,
tdb_data.dptr, size);
+#endif
+ // I have libtdb1. Enable after rebasing to latest e2fsprogs that has
this API
+ //tdb_transaction_start(data->tdb);
+
+ retval = tdb_store(data->tdb, tdb_key, tdb_data, TDB_INSERT);
+ if (retval == -1) {
+ /*
+ * TDB_ERR_EXISTS cannot happen because we have already
+ * verified it doesn't exist
+ */
+
+ /* FIXME!! Not sure what should be the error */
+ //tdb_transaction_cancel(data->tdb);
+ retval = EXT2_ET_SHORT_WRITE;
+ goto error_out;
+
+ }
+ //tdb_transaction_commit(data->tdb);
+
+error_out:
+ /* Move the location back */
+ if (ext2fs_llseek(data->dev, cur_loc, SEEK_SET) != cur_loc) {
+ retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
+ goto error_out;
+ }
+
+error_out_lseek:
+ free(tdb_data.dptr);
+ return retval;
+
+}
+
+static TDB_CONTEXT *undo_setup_tdb(char *tdb_file,
+ struct undo_private_data *data)
+{
+ errcode_t retval;
+
+ data->tdb = tdb_open(tdb_file, 0, TDB_CLEAR_IF_FIRST,
+ O_RDWR | O_CREAT | O_TRUNC, 0600);
+ return data->tdb;
+
+}
+static errcode_t undo_open(const char *name, int flags, io_channel *channel)
+{
+ io_channel io = NULL;
+ struct undo_private_data *data = NULL;
+ errcode_t retval;
+ int open_flags;
+ struct stat st;
+
+ if (name == 0)
+ return EXT2_ET_BAD_DEVICE_NAME;
+ retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
+ if (retval)
+ return retval;
+ memset(io, 0, sizeof(struct struct_io_channel));
+ io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
+ retval = ext2fs_get_mem(sizeof(struct undo_private_data), &data);
+ if (retval)
+ goto cleanup;
+
+ io->manager = undo_io_manager;
+ retval = ext2fs_get_mem(strlen(name)+1, &io->name);
+ if (retval)
+ goto cleanup;
+
+ strcpy(io->name, name);
+ io->private_data = data;
+ io->block_size = 1024;
+ io->read_error = 0;
+ io->write_error = 0;
+ io->refcount = 1;
+
+ memset(data, 0, sizeof(struct undo_private_data));
+ data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
+
+ if (undo_io_backing_manager) {
+ retval = undo_io_backing_manager->open(name, flags,
+ &data->real);
+ if (retval)
+ goto cleanup;
+ } else {
+ data->real = 0;
+ }
+
+ /* setup the tdb file */
+ if (undo_setup_tdb(tdb_file, data) == NULL )
+ goto cleanup;
+
+#ifdef HAVE_OPEN64
+ data->dev = open64(io->name, O_RDONLY);
+#else
+ data->dev = open(io->name, O_RDONLY);
+#endif
+ if (data->dev < 0) {
+ retval = errno;
+ goto cleanup;
+ }
+
+ *channel = io;
+ return 0;
+
+cleanup:
+ if (data->real)
+ io_channel_close(data->real);
+
+ if (data)
+ ext2fs_free_mem(&data);
+
+ if (io)
+ ext2fs_free_mem(&io);
+
+ return retval;
+}
+
+static errcode_t undo_close(io_channel channel)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (--channel->refcount > 0)
+ return 0;
+
+ if (data->real)
+ retval = io_channel_close(data->real);
+
+ if (data->tdb)
+ tdb_close(data->tdb);
+
+ close(data->dev);
+
+ ext2fs_free_mem(&channel->private_data);
+ if (channel->name)
+ ext2fs_free_mem(&channel->name);
+ ext2fs_free_mem(&channel);
+
+ return retval;
+}
+
+static errcode_t undo_set_blksize(io_channel channel, int blksize)
+{
+ struct undo_private_data *data;
+ errcode_t retval;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_set_blksize(data->real, blksize);
+
+ channel->block_size = blksize;
+ return 0;
+}
+
+
+static errcode_t undo_read_blk(io_channel channel, unsigned long block,
+ int count, void *buf)
+{
+ errcode_t retval;
+ struct undo_private_data *data;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_read_blk(data->real, block, count, buf);
+
+ return retval;
+}
+
+static errcode_t undo_write_blk(io_channel channel, unsigned long block,
+ int count, const void *buf)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+ ssize_t size;
+ ext2_loff_t location;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+
+ if (count == 1)
+ size = channel->block_size;
+ else {
+ if (count < 0)
+ size = -count;
+ else
+ size = count * channel->block_size;
+ }
+
+ location = ((ext2_loff_t) block * channel->block_size) + data->offset;
+
+ /*
+ * First write the existing content into database
+ */
+ retval = undo_write_tdb(data, location, size);
+ if (retval)
+ return retval;
+
+
+ if (data->real)
+ retval = io_channel_write_blk(data->real, block, count, buf);
+
+ return retval;
+
+}
+
+static errcode_t undo_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *buf)
+{
+ struct undo_private_data *data;
+ errcode_t retval = 0;
+ ssize_t actual;
+ ext2_loff_t location;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ location = offset + data->offset;
+ retval = undo_write_tdb(data, location, size);
+ if (retval)
+ return retval;
+
+ if (data->real && data->real->manager->write_byte)
+ retval = io_channel_write_byte(data->real, offset, size, buf);
+
+ return retval;
+}
+
+/*
+ * Flush data buffers to disk.
+ */
+static errcode_t undo_flush(io_channel channel)
+{
+ errcode_t retval = 0;
+ struct undo_private_data *data;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ if (data->real)
+ retval = io_channel_flush(data->real);
+
+ return retval;
+}
+
+static errcode_t undo_set_option(io_channel channel, const char *option,
+ const char *arg)
+{
+ struct undo_private_data *data;
+ unsigned long tmp;
+ char *end;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct undo_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ /*
+ * Need to support offset option to work with
+ * Unix I/O manager
+ */
+ if (!strcmp(option, "offset")) {
+ if (!arg)
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ tmp = strtoul(arg, &end, 0);
+ if (*end)
+ return EXT2_ET_INVALID_ARGUMENT;
+ data->offset = tmp;
+ return 0;
+ }
+}
--
1.5.2.14.g45bde-dirty
-
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
