Re: [PATCH v2 01/28] libext2fs: support modifying arbitrary extended attributes

[Zheng Liu <gnehzuil.liu@gmail.com>]

On Tue, Dec 03, 2013 at 11:54:57AM -0800, Darrick J. Wong wrote:
> On Tue, Dec 03, 2013 at 08:11:28PM +0800, Zheng Liu wrote:
> > From: "Darrick J. Wong" <darrick.wong@oracle.com>
> > 
> > Add functions to allow clients to get, set, and remove extended
> > attributes from any file.  It also supports modifying EAs living in
> > i_file_acl.
> > 
> > v2: Put the header declarations in the correct part of ext2fs.h,
> > provide a function to release an EA block from an inode, and check
> > i_extra_isize to make sure we actually have space for in-inode EAs.
> > 
> > [Modified by Zheng]
> > Ext_attr feature check in ext2fs_xattrs_read/write() is removed because
> > inline_data feature can be enabled without ext_attr.
> 
> Ok, so inline_data implies ext_attr.

No.  I try this command to create a ext4 filesystem with inline_data:

  % sudo mke2fs -t ext4 -O inline_data,^ext_attr ${DEV}

Then I mount it and create/delete/modify some files.  Everything is
fine.  So that means that we can use inline_data even without ext_attr.
That is why I modify the sanity check in mke2fs and tune2fs.  Now we
only check the inode size to ensure that we have enough space to store a
xattr entry in inode extended attribute space.  I will explain why we
must ensure the inode has a 'system.data' xattr entry.

> I think we should change the test to
> check for either feature flag, because with no test, we could accidentally
> read/write EAs on a FS with ^ext_attr,^inline_data.  Or maybe provide a helper
> predicate to hide those details.

Agree.  I will add a sanity check for inline_data feature.

> 
> Also, I'd ask you to send broken out changes to my patches... but I haven't
> posted my monster patchset recently. :)

No problem.  I will split this patch and send them out.

Thanks,
                                                - Zheng

> 
> (I think I might work up the courage to patchbomb the mailing list tonight.)
> 
> --D
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
> > ---
> >  lib/ext2fs/ext2_err.et.in |   18 ++
> >  lib/ext2fs/ext2fs.h       |   28 ++
> >  lib/ext2fs/ext_attr.c     |  754 +++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 800 insertions(+)
> > 
> > diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
> > index 9cc1bd1..b819a90 100644
> > --- a/lib/ext2fs/ext2_err.et.in
> > +++ b/lib/ext2fs/ext2_err.et.in
> > @@ -482,4 +482,22 @@ ec	EXT2_ET_BLOCK_BITMAP_CSUM_INVALID,
> >  ec	EXT2_ET_INLINE_DATA_CANT_ITERATE,
> >  	"Cannot block iterate on an inode containing inline data"
> >  
> > +ec	EXT2_ET_EA_BAD_NAME_LEN,
> > +	"Extended attribute has an invalid name length"
> > +
> > +ec	EXT2_ET_EA_BAD_VALUE_SIZE,
> > +	"Extended attribute has an invalid value length"
> > +
> > +ec	EXT2_ET_BAD_EA_HASH,
> > +	"Extended attribute has an incorrect hash"
> > +
> > +ec	EXT2_ET_BAD_EA_HEADER,
> > +	"Extended attribute block has a bad header"
> > +
> > +ec	EXT2_ET_EA_KEY_NOT_FOUND,
> > +	"Extended attribute key not found"
> > +
> > +ec	EXT2_ET_EA_NO_SPACE,
> > +	"Insufficient space to store extended attribute data"
> > +
> >  	end
> > diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> > index 67876ad..30bd4cf 100644
> > --- a/lib/ext2fs/ext2fs.h
> > +++ b/lib/ext2fs/ext2fs.h
> > @@ -637,6 +637,13 @@ typedef struct stat ext2fs_struct_stat;
> >  #define EXT2_FLAG_FLUSH_NO_SYNC          1
> >  
> >  /*
> > + * Modify and iterate extended attributes
> > + */
> > +struct ext2_xattr_handle;
> > +#define XATTR_ABORT	1
> > +#define XATTR_CHANGED	2
> > +
> > +/*
> >   * function prototypes
> >   */
> >  static inline int ext2fs_has_group_desc_csum(ext2_filsys fs)
> > @@ -1142,6 +1149,27 @@ extern errcode_t ext2fs_adjust_ea_refcount3(ext2_filsys fs, blk64_t blk,
> >  					   char *block_buf,
> >  					   int adjust, __u32 *newcount,
> >  					   ext2_ino_t inum);
> > +errcode_t ext2fs_xattrs_expand(struct ext2_xattr_handle *h,
> > +			       unsigned int expandby);
> > +errcode_t ext2fs_xattrs_write(struct ext2_xattr_handle *handle);
> > +errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle);
> > +errcode_t ext2fs_xattrs_iterate(struct ext2_xattr_handle *h,
> > +				int (*func)(char *name, char *value,
> > +					    void *data),
> > +				void *data);
> > +errcode_t ext2fs_xattr_get(struct ext2_xattr_handle *h, const char *key,
> > +			   void **value, unsigned int *value_len);
> > +errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
> > +			   const char *key,
> > +			   const void *value,
> > +			   unsigned int value_len);
> > +errcode_t ext2fs_xattr_remove(struct ext2_xattr_handle *handle,
> > +			      const char *key);
> > +errcode_t ext2fs_xattrs_open(ext2_filsys fs, ext2_ino_t ino,
> > +			     struct ext2_xattr_handle **handle);
> > +errcode_t ext2fs_xattrs_close(struct ext2_xattr_handle **handle);
> > +errcode_t ext2fs_free_ext_attr(ext2_filsys fs, ext2_ino_t ino,
> > +			       struct ext2_inode_large *inode);
> >  
> >  /* extent.c */
> >  extern errcode_t ext2fs_extent_header_verify(void *ptr, int size);
> > diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
> > index 9649a14..4d40149 100644
> > --- a/lib/ext2fs/ext_attr.c
> > +++ b/lib/ext2fs/ext_attr.c
> > @@ -186,3 +186,757 @@ errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
> >  	return ext2fs_adjust_ea_refcount2(fs, blk, block_buf, adjust,
> >  					  newcount);
> >  }
> > +
> > +/* Manipulate the contents of extended attribute regions */
> > +struct ext2_xattr {
> > +	char *name;
> > +	void *value;
> > +	unsigned int value_len;
> > +};
> > +
> > +struct ext2_xattr_handle {
> > +	ext2_filsys fs;
> > +	struct ext2_xattr *attrs;
> > +	unsigned int length;
> > +	ext2_ino_t ino;
> > +	int dirty;
> > +};
> > +
> > +errcode_t ext2fs_xattrs_expand(struct ext2_xattr_handle *h,
> > +			       unsigned int expandby)
> > +{
> > +	struct ext2_xattr *new_attrs;
> > +	errcode_t err;
> > +
> > +	err = ext2fs_get_arrayzero(h->length + expandby,
> > +				   sizeof(struct ext2_xattr), &new_attrs);
> > +	if (err)
> > +		return err;
> > +
> > +	memcpy(new_attrs, h->attrs, h->length * sizeof(struct ext2_xattr));
> > +	ext2fs_free_mem(&h->attrs);
> > +	h->length += expandby;
> > +	h->attrs = new_attrs;
> > +
> > +	return 0;
> > +}
> > +
> > +struct ea_name_index {
> > +	int index;
> > +	const char *name;
> > +};
> > +
> > +static struct ea_name_index ea_names[] = {
> > +	{1, "user."},
> > +	{2, "system.posix_acl_access"},
> > +	{3, "system.posix_acl_default"},
> > +	{4, "trusted."},
> > +	{6, "security."},
> > +	{7, "system."},
> > +	{0, NULL},
> > +};
> > +
> > +static const char *find_ea_prefix(int index)
> > +{
> > +	struct ea_name_index *e;
> > +
> > +	for (e = ea_names; e->name; e++)
> > +		if (e->index == index)
> > +			return e->name;
> > +
> > +	return NULL;
> > +}
> > +
> > +static int find_ea_index(const char *fullname, char **name, int *index)
> > +{
> > +	struct ea_name_index *e;
> > +
> > +	for (e = ea_names; e->name; e++) {
> > +		if (memcmp(fullname, e->name, strlen(e->name)) == 0) {
> > +			*name = (char *)fullname + strlen(e->name);
> > +			*index = e->index;
> > +			return 1;
> > +		}
> > +	}
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_free_ext_attr(ext2_filsys fs, ext2_ino_t ino,
> > +			       struct ext2_inode_large *inode)
> > +{
> > +	struct ext2_ext_attr_header *header;
> > +	void *block_buf = NULL;
> > +	dgrp_t grp;
> > +	blk64_t blk, goal;
> > +	errcode_t err;
> > +	struct ext2_inode_large i;
> > +
> > +	/* Read inode? */
> > +	if (inode == NULL) {
> > +		err = ext2fs_read_inode_full(fs, ino, (struct ext2_inode *)&i,
> > +					     sizeof(struct ext2_inode_large));
> > +		if (err)
> > +			return err;
> > +		inode = &i;
> > +	}
> > +
> > +	/* Do we already have an EA block? */
> > +	blk = ext2fs_file_acl_block(fs, (struct ext2_inode *)inode);
> > +	if (blk == 0)
> > +		return 0;
> > +
> > +	/* Find block, zero it, write back */
> > +	if ((blk < fs->super->s_first_data_block) ||
> > +	    (blk >= ext2fs_blocks_count(fs->super))) {
> > +		err = EXT2_ET_BAD_EA_BLOCK_NUM;
> > +		goto out;
> > +	}
> > +
> > +	err = ext2fs_get_mem(fs->blocksize, &block_buf);
> > +	if (err)
> > +		goto out;
> > +
> > +	err = ext2fs_read_ext_attr3(fs, blk, block_buf, ino);
> > +	if (err)
> > +		goto out2;
> > +
> > +	header = (struct ext2_ext_attr_header *) block_buf;
> > +	if (header->h_magic != EXT2_EXT_ATTR_MAGIC) {
> > +		err = EXT2_ET_BAD_EA_HEADER;
> > +		goto out2;
> > +	}
> > +
> > +	header->h_refcount--;
> > +	err = ext2fs_write_ext_attr3(fs, blk, block_buf, ino);
> > +	if (err)
> > +		goto out2;
> > +
> > +	/* Erase link to block */
> > +	ext2fs_file_acl_block_set(fs, (struct ext2_inode *)inode, 0);
> > +	if (header->h_refcount == 0)
> > +		ext2fs_block_alloc_stats2(fs, blk, -1);
> > +
> > +	/* Write inode? */
> > +	if (inode == &i) {
> > +		err = ext2fs_write_inode_full(fs, ino, (struct ext2_inode *)&i,
> > +					      sizeof(struct ext2_inode_large));
> > +		if (err)
> > +			goto out2;
> > +	}
> > +
> > +out2:
> > +	ext2fs_free_mem(&block_buf);
> > +out:
> > +	return err;
> > +}
> > +
> > +static errcode_t prep_ea_block_for_write(ext2_filsys fs, ext2_ino_t ino,
> > +					 struct ext2_inode_large *inode)
> > +{
> > +	struct ext2_ext_attr_header *header;
> > +	void *block_buf = NULL;
> > +	dgrp_t grp;
> > +	blk64_t blk, goal;
> > +	errcode_t err;
> > +
> > +	/* Do we already have an EA block? */
> > +	blk = ext2fs_file_acl_block(fs, (struct ext2_inode *)inode);
> > +	if (blk != 0) {
> > +		if ((blk < fs->super->s_first_data_block) ||
> > +		    (blk >= ext2fs_blocks_count(fs->super))) {
> > +			err = EXT2_ET_BAD_EA_BLOCK_NUM;
> > +			goto out;
> > +		}
> > +
> > +		err = ext2fs_get_mem(fs->blocksize, &block_buf);
> > +		if (err)
> > +			goto out;
> > +
> > +		err = ext2fs_read_ext_attr3(fs, blk, block_buf, ino);
> > +		if (err)
> > +			goto out2;
> > +
> > +		header = (struct ext2_ext_attr_header *) block_buf;
> > +		if (header->h_magic != EXT2_EXT_ATTR_MAGIC) {
> > +			err = EXT2_ET_BAD_EA_HEADER;
> > +			goto out2;
> > +		}
> > +
> > +		/* Single-user block.  We're done here. */
> > +		if (header->h_refcount == 1)
> > +			return 0;
> > +
> > +		/* We need to CoW the block. */
> > +		header->h_refcount--;
> > +		err = ext2fs_write_ext_attr3(fs, blk, block_buf, ino);
> > +		if (err)
> > +			goto out2;
> > +	} else {
> > +		/* No block, we must increment i_blocks */
> > +		err = ext2fs_iblk_add_blocks(fs, (struct ext2_inode *)inode,
> > +					     1);
> > +		if (err)
> > +			goto out;
> > +	}
> > +
> > +	/* Allocate a block */
> > +	grp = ext2fs_group_of_ino(fs, ino);
> > +	goal = ext2fs_inode_table_loc(fs, grp);
> > +	err = ext2fs_alloc_block2(fs, goal, NULL, &blk);
> > +	if (err)
> > +		return err;
> > +	ext2fs_file_acl_block_set(fs, (struct ext2_inode *)inode, blk);
> > +out2:
> > +	ext2fs_free_mem(&block_buf);
> > +out:
> > +	return err;
> > +}
> > +
> > +
> > +static errcode_t write_xattrs_to_buffer(struct ext2_xattr_handle *handle,
> > +					struct ext2_xattr **pos,
> > +					void *entries_start,
> > +					unsigned int storage_size,
> > +					unsigned int value_offset_correction)
> > +{
> > +	struct ext2_xattr *x = *pos;
> > +	struct ext2_ext_attr_entry *e = entries_start;
> > +	void *end = entries_start + storage_size;
> > +	char *shortname;
> > +	unsigned int entry_size, value_size;
> > +	int idx, ret;
> > +
> > +	/* For all remaining x...  */
> > +	for (; x < handle->attrs + handle->length; x++) {
> > +		if (!x->name)
> > +			continue;
> > +
> > +		/* Calculate index and shortname position */
> > +		shortname = x->name;
> > +		ret = find_ea_index(x->name, &shortname, &idx);
> > +
> > +		/* Calculate entry and value size */
> > +		entry_size = (sizeof(*e) + strlen(shortname) +
> > +			      EXT2_EXT_ATTR_PAD - 1) &
> > +			     ~(EXT2_EXT_ATTR_PAD - 1);
> > +		value_size = ((x->value_len + EXT2_EXT_ATTR_PAD - 1) /
> > +			      EXT2_EXT_ATTR_PAD) * EXT2_EXT_ATTR_PAD;
> > +
> > +		/*
> > +		 * Would entry collide with value?
> > +		 * Note that we must leave sufficient room for a (u32)0 to
> > +		 * mark the end of the entries.
> > +		 */
> > +		if ((void *)e + entry_size + sizeof(__u32) > end - value_size)
> > +			break;
> > +
> > +		/* Fill out e appropriately */
> > +		e->e_name_len = strlen(shortname);
> > +		e->e_name_index = (ret ? idx : 0);
> > +		e->e_value_offs = end - value_size - (void *)entries_start +
> > +				value_offset_correction;
> > +		e->e_value_block = 0;
> > +		e->e_value_size = x->value_len;
> > +
> > +		/* Store name and value */
> > +		end -= value_size;
> > +		memcpy((void *)e + sizeof(*e), shortname, e->e_name_len);
> > +		memcpy(end, x->value, e->e_value_size);
> > +
> > +		e->e_hash = ext2fs_ext_attr_hash_entry(e, end);
> > +
> > +		e = EXT2_EXT_ATTR_NEXT(e);
> > +		*(__u32 *)e = 0;
> > +	}
> > +	*pos = x;
> > +
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_xattrs_write(struct ext2_xattr_handle *handle)
> > +{
> > +	struct ext2_xattr *x;
> > +	struct ext2_inode_large *inode;
> > +	void *start, *block_buf = NULL;
> > +	struct ext2_ext_attr_header *header;
> > +	__u32 ea_inode_magic;
> > +	blk64_t blk;
> > +	unsigned int storage_size;
> > +	unsigned int i, written;
> > +	errcode_t err;
> > +
> > +	i = EXT2_INODE_SIZE(handle->fs->super);
> > +	if (i < sizeof(*inode))
> > +		i = sizeof(*inode);
> > +	err = ext2fs_get_memzero(i, &inode);
> > +	if (err)
> > +		return err;
> > +
> > +	err = ext2fs_read_inode_full(handle->fs, handle->ino,
> > +				     (struct ext2_inode *)inode,
> > +				     EXT2_INODE_SIZE(handle->fs->super));
> > +	if (err)
> > +		goto out;
> > +
> > +	x = handle->attrs;
> > +	/* Does the inode have size for EA? */
> > +	if (EXT2_INODE_SIZE(handle->fs->super) <= EXT2_GOOD_OLD_INODE_SIZE +
> > +						  inode->i_extra_isize +
> > +						  sizeof(__u32))
> > +		goto write_ea_block;
> > +
> > +	/* Write the inode EA */
> > +	ea_inode_magic = EXT2_EXT_ATTR_MAGIC;
> > +	memcpy(((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> > +	       inode->i_extra_isize, &ea_inode_magic, sizeof(__u32));
> > +	storage_size = EXT2_INODE_SIZE(handle->fs->super) -
> > +		EXT2_GOOD_OLD_INODE_SIZE - inode->i_extra_isize -
> > +		sizeof(__u32);
> > +	start = ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> > +		inode->i_extra_isize + sizeof(__u32);
> > +
> > +	err = write_xattrs_to_buffer(handle, &x, start, storage_size, 0);
> > +	if (err)
> > +		goto out;
> > +
> > +	/* Are we done? */
> > +	if (x == handle->attrs + handle->length)
> > +		goto skip_ea_block;
> > +
> > +write_ea_block:
> > +	/* Write the EA block */
> > +	err = ext2fs_get_mem(handle->fs->blocksize, &block_buf);
> > +	if (err)
> > +		goto out;
> > +
> > +	storage_size = handle->fs->blocksize -
> > +		sizeof(struct ext2_ext_attr_header);
> > +	start = block_buf + sizeof(struct ext2_ext_attr_header);
> > +
> > +	err = write_xattrs_to_buffer(handle, &x, start, storage_size,
> > +				     (void *)start - block_buf);
> > +	if (err)
> > +		goto out2;
> > +
> > +	if (x < handle->attrs + handle->length) {
> > +		err = EXT2_ET_EA_NO_SPACE;
> > +		goto out2;
> > +	}
> > +
> > +	if (block_buf) {
> > +		/* Write a header on the EA block */
> > +		header = block_buf;
> > +		header->h_magic = EXT2_EXT_ATTR_MAGIC;
> > +		header->h_refcount = 1;
> > +		header->h_blocks = 1;
> > +
> > +		/* Get a new block for writing */
> > +		err = prep_ea_block_for_write(handle->fs, handle->ino, inode);
> > +		if (err)
> > +			goto out2;
> > +
> > +		/* Finally, write the new EA block */
> > +		blk = ext2fs_file_acl_block(handle->fs,
> > +					    (struct ext2_inode *)inode);
> > +		err = ext2fs_write_ext_attr3(handle->fs, blk, block_buf,
> > +					     handle->ino);
> > +		if (err)
> > +			goto out2;
> > +	}
> > +
> > +skip_ea_block:
> > +	blk = ext2fs_file_acl_block(handle->fs, (struct ext2_inode *)inode);
> > +	if (!block_buf && blk) {
> > +		/* xattrs shrunk, free the block */
> > +		ext2fs_file_acl_block_set(handle->fs,
> > +					  (struct ext2_inode *)inode, 0);
> > +		err = ext2fs_iblk_sub_blocks(handle->fs,
> > +					     (struct ext2_inode *)inode, 1);
> > +		if (err)
> > +			goto out;
> > +		ext2fs_block_alloc_stats2(handle->fs, blk, -1);
> > +	}
> > +
> > +	/* Write the inode */
> > +	err = ext2fs_write_inode_full(handle->fs, handle->ino,
> > +				      (struct ext2_inode *)inode,
> > +				      EXT2_INODE_SIZE(handle->fs->super));
> > +	if (err)
> > +		goto out2;
> > +
> > +out2:
> > +	ext2fs_free_mem(&block_buf);
> > +out:
> > +	ext2fs_free_mem(&inode);
> > +	handle->dirty = 0;
> > +	return err;
> > +}
> > +
> > +static errcode_t read_xattrs_from_buffer(struct ext2_xattr_handle *handle,
> > +					 struct ext2_ext_attr_entry *entries,
> > +					 unsigned int storage_size,
> > +					 void *value_start)
> > +{
> > +	struct ext2_xattr *x;
> > +	struct ext2_ext_attr_entry *entry;
> > +	const char *prefix;
> > +	void *ptr;
> > +	unsigned int remain, prefix_len;
> > +	errcode_t err;
> > +
> > +	x = handle->attrs;
> > +	while (x->name)
> > +		x++;
> > +
> > +	entry = entries;
> > +	while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
> > +		__u32 hash;
> > +
> > +		/* header eats this space */
> > +		remain -= sizeof(struct ext2_ext_attr_entry);
> > +
> > +		/* is attribute name valid? */
> > +		if (EXT2_EXT_ATTR_SIZE(entry->e_name_len) > remain)
> > +			return EXT2_ET_EA_BAD_NAME_LEN;
> > +
> > +		/* attribute len eats this space */
> > +		remain -= EXT2_EXT_ATTR_SIZE(entry->e_name_len);
> > +
> > +		/* check value size */
> > +		if (entry->e_value_size > remain)
> > +			return EXT2_ET_EA_BAD_VALUE_SIZE;
> > +
> > +		/* e_value_block must be 0 in inode's ea */
> > +		if (entry->e_value_block != 0)
> > +			return EXT2_ET_BAD_EA_BLOCK_NUM;
> > +
> > +		hash = ext2fs_ext_attr_hash_entry(entry, value_start +
> > +							 entry->e_value_offs);
> > +
> > +		/* e_hash may be 0 in older inode's ea */
> > +		if (entry->e_hash != 0 && entry->e_hash != hash)
> > +			return EXT2_ET_BAD_EA_HASH;
> > +
> > +		remain -= entry->e_value_size;
> > +
> > +		/* Allocate space for more attrs? */
> > +		if (x == handle->attrs + handle->length) {
> > +			err = ext2fs_xattrs_expand(handle, 4);
> > +			if (err)
> > +				return err;
> > +			x = handle->attrs + handle->length - 4;
> > +		}
> > +
> > +		/* Extract name/value */
> > +		prefix = find_ea_prefix(entry->e_name_index);
> > +		prefix_len = (prefix ? strlen(prefix) : 0);
> > +		err = ext2fs_get_memzero(entry->e_name_len + prefix_len + 1,
> > +					 &x->name);
> > +		if (err)
> > +			return err;
> > +		if (prefix)
> > +			memcpy(x->name, prefix, prefix_len);
> > +		if (entry->e_name_len)
> > +			memcpy(x->name + prefix_len,
> > +			       (void *)entry + sizeof(*entry),
> > +			       entry->e_name_len);
> > +
> > +		err = ext2fs_get_mem(entry->e_value_size, &x->value);
> > +		if (err)
> > +			return err;
> > +		x->value_len = entry->e_value_size;
> > +		memcpy(x->value, value_start + entry->e_value_offs,
> > +		       entry->e_value_size);
> > +		x++;
> > +		entry = EXT2_EXT_ATTR_NEXT(entry);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle)
> > +{
> > +	struct ext2_xattr *attrs = NULL, *x;
> > +	unsigned int attrs_len;
> > +	struct ext2_inode_large *inode;
> > +	struct ext2_ext_attr_header *header;
> > +	__u32 ea_inode_magic;
> > +	unsigned int storage_size;
> > +	void *start, *block_buf = NULL;
> > +	blk64_t blk;
> > +	int i;
> > +	errcode_t err;
> > +
> > +	i = EXT2_INODE_SIZE(handle->fs->super);
> > +	if (i < sizeof(*inode))
> > +		i = sizeof(*inode);
> > +	err = ext2fs_get_memzero(i, &inode);
> > +	if (err)
> > +		return err;
> > +
> > +	err = ext2fs_read_inode_full(handle->fs, handle->ino,
> > +				     (struct ext2_inode *)inode,
> > +				     EXT2_INODE_SIZE(handle->fs->super));
> > +	if (err)
> > +		goto out;
> > +
> > +	/* Does the inode have size for EA? */
> > +	if (EXT2_INODE_SIZE(handle->fs->super) <= EXT2_GOOD_OLD_INODE_SIZE +
> > +						  inode->i_extra_isize +
> > +						  sizeof(__u32))
> > +		goto read_ea_block;
> > +
> > +	/* Look for EA in the inode */
> > +	memcpy(&ea_inode_magic, ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> > +	       inode->i_extra_isize, sizeof(__u32));
> > +	if (ea_inode_magic == EXT2_EXT_ATTR_MAGIC) {
> > +		storage_size = EXT2_INODE_SIZE(handle->fs->super) -
> > +			EXT2_GOOD_OLD_INODE_SIZE - inode->i_extra_isize -
> > +			sizeof(__u32);
> > +		start = ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> > +			inode->i_extra_isize + sizeof(__u32);
> > +
> > +		err = read_xattrs_from_buffer(handle, start, storage_size,
> > +					      start);
> > +		if (err)
> > +			goto out;
> > +	}
> > +
> > +read_ea_block:
> > +	/* Look for EA in a separate EA block */
> > +	blk = ext2fs_file_acl_block(handle->fs, (struct ext2_inode *)inode);
> > +	if (blk != 0) {
> > +		if ((blk < handle->fs->super->s_first_data_block) ||
> > +		    (blk >= ext2fs_blocks_count(handle->fs->super))) {
> > +			err = EXT2_ET_BAD_EA_BLOCK_NUM;
> > +			goto out;
> > +		}
> > +
> > +		err = ext2fs_get_mem(handle->fs->blocksize, &block_buf);
> > +		if (err)
> > +			goto out;
> > +
> > +		err = ext2fs_read_ext_attr3(handle->fs, blk, block_buf,
> > +					    handle->ino);
> > +		if (err)
> > +			goto out3;
> > +
> > +		header = (struct ext2_ext_attr_header *) block_buf;
> > +		if (header->h_magic != EXT2_EXT_ATTR_MAGIC) {
> > +			err = EXT2_ET_BAD_EA_HEADER;
> > +			goto out3;
> > +		}
> > +
> > +		if (header->h_blocks != 1) {
> > +			err = EXT2_ET_BAD_EA_HEADER;
> > +			goto out3;
> > +		}
> > +
> > +		/* Read EAs */
> > +		storage_size = handle->fs->blocksize -
> > +			sizeof(struct ext2_ext_attr_header);
> > +		start = block_buf + sizeof(struct ext2_ext_attr_header);
> > +		err = read_xattrs_from_buffer(handle, start, storage_size,
> > +					      block_buf);
> > +		if (err)
> > +			goto out3;
> > +
> > +		ext2fs_free_mem(&block_buf);
> > +	}
> > +
> > +	ext2fs_free_mem(&block_buf);
> > +	ext2fs_free_mem(&inode);
> > +	return 0;
> > +
> > +out3:
> > +	ext2fs_free_mem(&block_buf);
> > +out:
> > +	ext2fs_free_mem(&inode);
> > +	return err;
> > +}
> > +
> > +#define XATTR_ABORT	1
> > +#define XATTR_CHANGED	2
> > +errcode_t ext2fs_xattrs_iterate(struct ext2_xattr_handle *h,
> > +				int (*func)(char *name, char *value,
> > +					    void *data),
> > +				void *data)
> > +{
> > +	struct ext2_xattr *x;
> > +	errcode_t err;
> > +	int ret;
> > +
> > +	for (x = h->attrs; x < h->attrs + h->length; x++) {
> > +		if (!x->name)
> > +			continue;
> > +
> > +		ret = func(x->name, x->value, data);
> > +		if (ret & XATTR_CHANGED)
> > +			h->dirty = 1;
> > +		if (ret & XATTR_ABORT)
> > +			return 0;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_xattr_get(struct ext2_xattr_handle *h, const char *key,
> > +			   void **value, unsigned int *value_len)
> > +{
> > +	struct ext2_xattr *x;
> > +	void *val;
> > +	errcode_t err;
> > +
> > +	for (x = h->attrs; x < h->attrs + h->length; x++) {
> > +		if (!x->name)
> > +			continue;
> > +
> > +		if (strcmp(x->name, key) == 0) {
> > +			err = ext2fs_get_mem(x->value_len, &val);
> > +			if (err)
> > +				return err;
> > +			memcpy(val, x->value, x->value_len);
> > +			*value = val;
> > +			*value_len = x->value_len;
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	return EXT2_ET_EA_KEY_NOT_FOUND;
> > +}
> > +
> > +errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
> > +			   const char *key,
> > +			   const void *value,
> > +			   unsigned int value_len)
> > +{
> > +	struct ext2_xattr *x, *last_empty;
> > +	char *new_value;
> > +	errcode_t err;
> > +
> > +	last_empty = NULL;
> > +	for (x = handle->attrs; x < handle->attrs + handle->length; x++) {
> > +		if (!x->name) {
> > +			last_empty = x;
> > +			continue;
> > +		}
> > +
> > +		/* Replace xattr */
> > +		if (strcmp(x->name, key) == 0) {
> > +			err = ext2fs_get_mem(value_len, &new_value);
> > +			if (err)
> > +				return err;
> > +			memcpy(new_value, value, value_len);
> > +			ext2fs_free_mem(&x->value);
> > +			x->value = new_value;
> > +			x->value_len = value_len;
> > +			handle->dirty = 1;
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	/* Add attr to empty slot */
> > +	if (last_empty) {
> > +		err = ext2fs_get_mem(strlen(key) + 1, &last_empty->name);
> > +		if (err)
> > +			return err;
> > +		strcpy(last_empty->name, key);
> > +
> > +		err = ext2fs_get_mem(value_len, &last_empty->value);
> > +		if (err)
> > +			return err;
> > +		memcpy(last_empty->value, value, value_len);
> > +		last_empty->value_len = value_len;
> > +		handle->dirty = 1;
> > +		return 0;
> > +	}
> > +
> > +	/* Expand array, append slot */
> > +	err = ext2fs_xattrs_expand(handle, 4);
> > +	if (err)
> > +		return err;
> > +
> > +	x = handle->attrs + handle->length - 4;
> > +	err = ext2fs_get_mem(strlen(key) + 1, &x->name);
> > +	if (err)
> > +		return err;
> > +	strcpy(x->name, key);
> > +
> > +	err = ext2fs_get_mem(value_len, &x->value);
> > +	if (err)
> > +		return err;
> > +	memcpy(x->value, value, value_len);
> > +	x->value_len = value_len;
> > +	handle->dirty = 1;
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_xattr_remove(struct ext2_xattr_handle *handle,
> > +			      const char *key)
> > +{
> > +	struct ext2_xattr *x;
> > +	errcode_t err;
> > +
> > +	for (x = handle->attrs; x < handle->attrs + handle->length; x++) {
> > +		if (!x->name)
> > +			continue;
> > +
> > +		if (strcmp(x->name, key) == 0) {
> > +			ext2fs_free_mem(&x->name);
> > +			ext2fs_free_mem(&x->value);
> > +			x->value_len = 0;
> > +			handle->dirty = 1;
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	return EXT2_ET_EA_KEY_NOT_FOUND;
> > +}
> > +
> > +errcode_t ext2fs_xattrs_open(ext2_filsys fs, ext2_ino_t ino,
> > +			     struct ext2_xattr_handle **handle)
> > +{
> > +	struct ext2_xattr_handle *h;
> > +	errcode_t err;
> > +
> > +	err = ext2fs_get_memzero(sizeof(*h), &h);
> > +	if (err)
> > +		return err;
> > +
> > +	h->length = 4;
> > +	err = ext2fs_get_arrayzero(h->length, sizeof(struct ext2_xattr),
> > +				   &h->attrs);
> > +	if (err) {
> > +		ext2fs_free_mem(&h);
> > +		return err;
> > +	}
> > +	h->ino = ino;
> > +	h->fs = fs;
> > +	*handle = h;
> > +	return 0;
> > +}
> > +
> > +errcode_t ext2fs_xattrs_close(struct ext2_xattr_handle **handle)
> > +{
> > +	unsigned int i;
> > +	struct ext2_xattr_handle *h = *handle;
> > +	struct ext2_xattr *a = h->attrs;
> > +	errcode_t err;
> > +
> > +	if (h->dirty) {
> > +		err = ext2fs_xattrs_write(h);
> > +		if (err)
> > +			return err;
> > +	}
> > +
> > +	for (i = 0; i < h->length; i++) {
> > +		if (a[i].name)
> > +			ext2fs_free_mem(&a[i].name);
> > +		if (a[i].value)
> > +			ext2fs_free_mem(&a[i].value);
> > +	}
> > +
> > +	ext2fs_free_mem(&h->attrs);
> > +	ext2fs_free_mem(handle);
> > +	return 0;
> > +}
> > -- 
> > 1.7.9.7
> > 
> > --
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