vfs_streams_xattr module

Store streams in posix xattrs. A kludge, as xattrs are limited in many ways,
but it might be a help for some situations.
(This used to be commit 83a805220e52742119546c76a054d50582e33a24)

1 files changed, 672 insertions, 0 deletions

diff --git a/source3/modules/vfs_streams_xattr.c b/source3/modules/vfs_streams_xattr.c
new file mode 100644
index 00000000000..3701cddfb51
--- /dev/null
+++ b/source3/modules/vfs_streams_xattr.c
@@ -0,0 +1,672 @@
+/*
+ * Store streams in xattrs
+ *
+ * Copyright (C) Volker Lendecke, 2008
+ *
+ * Partly based on James Peach's Darwin module, which is
+ *
+ * Copyright (C) James Peach 2006-2007
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "includes.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_VFS
+
+#define XATTR_DOSSTREAM_PREFIX "user.DosStream."
+
+struct stream_io {
+	char *base;
+	char *xattr_name;
+};
+
+static SMB_INO_T stream_inode(const SMB_STRUCT_STAT *sbuf, const char *sname)
+{
+	struct MD5Context ctx;
+        unsigned char hash[16];
+	SMB_INO_T result;
+	char *upper_sname;
+
+	DEBUG(10, ("stream_inode called for %lu/%lu [%s]\n",
+		   (unsigned long)sbuf->st_dev,
+		   (unsigned long)sbuf->st_ino, sname));
+
+	upper_sname = talloc_strdup_upper(talloc_tos(), sname);
+	SMB_ASSERT(upper_sname != NULL);
+
+        MD5Init(&ctx);
+        MD5Update(&ctx, (unsigned char *)&(sbuf->st_dev),
+		  sizeof(sbuf->st_dev));
+        MD5Update(&ctx, (unsigned char *)&(sbuf->st_ino),
+		  sizeof(sbuf->st_ino));
+        MD5Update(&ctx, (unsigned char *)upper_sname,
+		  talloc_get_size(upper_sname)-1);
+        MD5Final(hash, &ctx);
+
+	TALLOC_FREE(upper_sname);
+
+        /* Hopefully all the variation is in the lower 4 (or 8) bytes! */
+	memcpy(&result, hash, sizeof(result));
+
+	DEBUG(10, ("stream_inode returns %lu\n", (unsigned long)result));
+
+	return result;
+}
+
+static ssize_t get_xattr_size(connection_struct *conn, const char *fname,
+			      const char *xattr_name)
+{
+	NTSTATUS status;
+	struct ea_struct ea;
+	ssize_t result;
+
+	status = get_ea_value(talloc_tos(), conn, NULL, fname,
+			      xattr_name, &ea);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		return -1;
+	}
+
+	result = ea.value.length-1;
+	TALLOC_FREE(ea.value.data);
+	return result;
+}
+
+
+static int streams_xattr_fstat(vfs_handle_struct *handle, files_struct *fsp,
+			       SMB_STRUCT_STAT *sbuf)
+{
+	struct stream_io *io = (struct stream_io *)
+		VFS_FETCH_FSP_EXTENSION(handle, fsp);
+
+	if (io == NULL) {
+		return SMB_VFS_NEXT_FSTAT(handle, fsp, sbuf);
+	}
+
+	if (SMB_VFS_NEXT_FSTAT(handle, fsp, sbuf) == -1) {
+		return -1;
+	}
+
+	sbuf->st_size = get_xattr_size(handle->conn, io->base, io->xattr_name);
+	if (sbuf->st_size == -1) {
+		return -1;
+	}
+
+	sbuf->st_ino = stream_inode(sbuf, io->xattr_name);
+	sbuf->st_mode &= ~S_IFMT;
+        sbuf->st_mode |= S_IFREG;
+        sbuf->st_blocks = sbuf->st_size % STAT_ST_BLOCKSIZE + 1;
+
+	return 0;
+}
+
+static int streams_xattr_stat(vfs_handle_struct *handle, const char *fname,
+			      SMB_STRUCT_STAT *sbuf)
+{
+	NTSTATUS status;
+	char *base, *sname;
+	int result = -1;
+	char *xattr_name;
+
+	if (!is_ntfs_stream_name(fname)) {
+		return SMB_VFS_NEXT_STAT(handle, fname, sbuf);
+	}
+
+	status = split_ntfs_stream_name(talloc_tos(), fname, &base, &sname);
+	if (!NT_STATUS_IS_OK(status)) {
+		errno = EINVAL;
+		goto fail;
+	}
+
+	if (SMB_VFS_NEXT_STAT(handle, base, sbuf) == -1) {
+		goto fail;
+	}
+
+	xattr_name = talloc_asprintf(talloc_tos(), "%s%s",
+				     XATTR_DOSSTREAM_PREFIX, sname);
+	if (xattr_name == NULL) {
+		errno = ENOMEM;
+		goto fail;
+	}
+
+	sbuf->st_size = get_xattr_size(handle->conn, base, xattr_name);
+	if (sbuf->st_size == -1) {
+		errno = ENOENT;
+		goto fail;
+	}
+
+	sbuf->st_ino = stream_inode(sbuf, xattr_name);
+	sbuf->st_mode &= ~S_IFMT;
+        sbuf->st_mode |= S_IFREG;
+        sbuf->st_blocks = sbuf->st_size % STAT_ST_BLOCKSIZE + 1;
+
+	result = 0;
+ fail:
+	TALLOC_FREE(base);
+	TALLOC_FREE(sname);
+	return result;
+}
+
+static int streams_xattr_lstat(vfs_handle_struct *handle, const char *fname,
+			       SMB_STRUCT_STAT *sbuf)
+{
+	NTSTATUS status;
+	char *base, *sname;
+	int result = -1;
+	char *xattr_name;
+
+	if (!is_ntfs_stream_name(fname)) {
+		return SMB_VFS_NEXT_LSTAT(handle, fname, sbuf);
+	}
+
+	status = split_ntfs_stream_name(talloc_tos(), fname, &base, &sname);
+	if (!NT_STATUS_IS_OK(status)) {
+		errno = EINVAL;
+		goto fail;
+	}
+
+	if (SMB_VFS_NEXT_LSTAT(handle, base, sbuf) == -1) {
+		goto fail;
+	}
+
+	xattr_name = talloc_asprintf(talloc_tos(), "%s%s",
+				     XATTR_DOSSTREAM_PREFIX, sname);
+	if (xattr_name == NULL) {
+		errno = ENOMEM;
+		goto fail;
+	}
+
+	sbuf->st_size = get_xattr_size(handle->conn, base, xattr_name);
+	if (sbuf->st_size == -1) {
+		errno = ENOENT;
+		goto fail;
+	}
+
+	sbuf->st_ino = stream_inode(sbuf, xattr_name);
+	sbuf->st_mode &= ~S_IFMT;
+        sbuf->st_mode |= S_IFREG;
+        sbuf->st_blocks = sbuf->st_size % STAT_ST_BLOCKSIZE + 1;
+
+	result = 0;
+ fail:
+	TALLOC_FREE(base);
+	TALLOC_FREE(sname);
+	return result;
+}
+
+static int streams_xattr_open(vfs_handle_struct *handle,  const char *fname,
+			      files_struct *fsp, int flags, mode_t mode)
+{
+	TALLOC_CTX *frame;
+	NTSTATUS status;
+	struct stream_io *sio;
+	char *base, *sname;
+	struct ea_struct ea;
+	char *xattr_name;
+	int baseflags;
+	int hostfd = -1;
+
+	if (!is_ntfs_stream_name(fname)) {
+		return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
+	}
+
+	frame = talloc_stackframe();
+
+	status = split_ntfs_stream_name(talloc_tos(), fname,
+					&base, &sname);
+	if (!NT_STATUS_IS_OK(status)) {
+		errno = EINVAL;
+		goto fail;
+	}
+
+	xattr_name = talloc_asprintf(talloc_tos(), "%s%s",
+				     XATTR_DOSSTREAM_PREFIX, sname);
+	if (xattr_name == NULL) {
+		errno = ENOMEM;
+		goto fail;
+	}
+
+	/*
+	 * We use baseflags to turn off nasty side-effects when opening the
+	 * underlying file.
+         */
+        baseflags = flags;
+        baseflags &= ~O_TRUNC;
+        baseflags &= ~O_EXCL;
+        baseflags &= ~O_CREAT;
+
+        hostfd = SMB_VFS_NEXT_OPEN(handle, base, fsp, baseflags, mode);
+
+        /* It is legit to open a stream on a directory, but the base
+         * fd has to be read-only.
+         */
+        if ((hostfd == -1) && (errno == EISDIR)) {
+                baseflags &= ~O_ACCMODE;
+                baseflags |= O_RDONLY;
+                hostfd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, baseflags,
+					   mode);
+        }
+
+        if (hostfd == -1) {
+		goto fail;
+        }
+
+	status = get_ea_value(talloc_tos(), handle->conn, fsp, base,
+			      xattr_name, &ea);
+
+	if (!NT_STATUS_IS_OK(status)
+	    && !NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
+		/*
+		 * The base file is not there. This is an error even if we got
+		 * O_CREAT, the higher levels should have created the base
+		 * file for us.
+		 */
+		errno = ENOENT;
+		goto fail;
+	}
+
+	if (!NT_STATUS_IS_OK(status)) {
+		/*
+		 * The attribute does not exist
+		 */
+
+                if (flags & O_CREAT) {
+			/*
+			 * Darn, xattrs need at least 1 byte
+			 */
+                        char null = '\0';
+
+                        if (SMB_VFS_NEXT_SETXATTR(
+				handle, base, xattr_name, &null, sizeof(null),
+				flags & O_EXCL ? XATTR_CREATE : 0) == -1) {
+				goto fail;
+			}
+		}
+	}
+
+	if (flags & O_TRUNC) {
+		char null = '\0';
+		if (SMB_VFS_NEXT_SETXATTR(
+			    handle, base, xattr_name, &null, sizeof(null),
+			    flags & O_EXCL ? XATTR_CREATE : 0) == -1) {
+			goto fail;
+		}
+	}
+
+        sio = (struct stream_io *)VFS_ADD_FSP_EXTENSION(handle, fsp,
+							struct stream_io);
+        if (sio == NULL) {
+                errno = ENOMEM;
+                goto fail;
+        }
+
+        sio->xattr_name = talloc_strdup(VFS_MEMCTX_FSP_EXTENSION(handle, fsp),
+					xattr_name);
+        sio->base = talloc_strdup(VFS_MEMCTX_FSP_EXTENSION(handle, fsp),
+				  base);
+
+	if ((sio->xattr_name == NULL) || (sio->base == NULL)) {
+		errno = ENOMEM;
+		goto fail;
+	}
+
+	TALLOC_FREE(frame);
+	return hostfd;
+
+ fail:
+	if (hostfd >= 0) {
+		/*
+		 * BUGBUGBUG -- we would need to call fd_close_posix here, but
+		 * we don't have a full fsp yet
+		 */
+		SMB_VFS_NEXT_CLOSE(handle, fsp, hostfd);
+	}
+
+	TALLOC_FREE(frame);
+	return -1;
+}
+
+static int streams_xattr_unlink(vfs_handle_struct *handle,  const char *fname)
+{
+	NTSTATUS status;
+	char *base = NULL;
+	char *sname = NULL;
+	int ret = -1;
+	char *xattr_name;
+
+	if (!is_ntfs_stream_name(fname)) {
+		return SMB_VFS_NEXT_UNLINK(handle, fname);
+	}
+
+	status = split_ntfs_stream_name(talloc_tos(), fname, &base, &sname);
+	if (!NT_STATUS_IS_OK(status)) {
+		errno = EINVAL;
+		goto fail;
+	}
+
+	xattr_name = talloc_asprintf(talloc_tos(), "%s%s",
+				     XATTR_DOSSTREAM_PREFIX, sname);
+	if (xattr_name == NULL) {
+		errno = ENOMEM;
+		goto fail;
+	}
+
+	ret = SMB_VFS_NEXT_REMOVEXATTR(handle, base, xattr_name);
+
+	if ((ret == -1) && (errno == ENOATTR)) {
+		errno = ENOENT;
+		goto fail;
+	}
+
+	ret = 0;
+
+ fail:
+	TALLOC_FREE(base);
+	TALLOC_FREE(sname);
+	return ret;
+}
+
+static NTSTATUS walk_xattr_streams(connection_struct *conn, files_struct *fsp,
+				   const char *fname,
+				   bool (*fn)(struct ea_struct *ea,
+					      void *private_data),
+				   void *private_data)
+{
+	NTSTATUS status;
+	char **names;
+	size_t i, num_names;
+	size_t prefix_len = strlen(XATTR_DOSSTREAM_PREFIX);
+
+	status = get_ea_names_from_file(talloc_tos(), conn, fsp, fname,
+					&names, &num_names);
+	if (!NT_STATUS_IS_OK(status)) {
+		return status;
+	}
+
+	for (i=0; i<num_names; i++) {
+		struct ea_struct ea;
+
+		if (strncmp(names[i], XATTR_DOSSTREAM_PREFIX,
+			    prefix_len) != 0) {
+			continue;
+		}
+
+		status = get_ea_value(names, conn, fsp, fname, names[i], &ea);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(10, ("Could not get ea %s for file %s: %s\n",
+				   names[i], fname, nt_errstr(status)));
+			continue;
+		}
+
+		ea.name = talloc_asprintf(ea.value.data, ":%s",
+					  names[i] + prefix_len);
+		if (ea.name == NULL) {
+			DEBUG(0, ("talloc failed\n"));
+			continue;
+		}
+
+		if (!fn(&ea, private_data)) {
+			TALLOC_FREE(ea.value.data);
+			return NT_STATUS_OK;
+		}
+
+		TALLOC_FREE(ea.value.data);
+	}
+
+	TALLOC_FREE(names);
+	return NT_STATUS_OK;
+}
+
+static bool add_one_stream(TALLOC_CTX *mem_ctx, unsigned int *num_streams,
+			   struct stream_struct **streams,
+			   const char *name, SMB_OFF_T size,
+			   SMB_OFF_T alloc_size)
+{
+	struct stream_struct *tmp;
+
+	tmp = TALLOC_REALLOC_ARRAY(mem_ctx, *streams, struct stream_struct,
+				   (*num_streams)+1);
+	if (tmp == NULL) {
+		return false;
+	}
+
+	tmp[*num_streams].name = talloc_strdup(tmp, name);
+	if (tmp[*num_streams].name == NULL) {
+		return false;
+	}
+
+	tmp[*num_streams].size = size;
+	tmp[*num_streams].alloc_size = alloc_size;
+
+	*streams = tmp;
+	*num_streams += 1;
+	return true;
+}
+
+struct streaminfo_state {
+	TALLOC_CTX *mem_ctx;
+	vfs_handle_struct *handle;
+	unsigned int num_streams;
+	struct stream_struct *streams;
+	NTSTATUS status;
+};
+
+static bool collect_one_stream(struct ea_struct *ea, void *private_data)
+{
+	struct streaminfo_state *state =
+		(struct streaminfo_state *)private_data;
+
+	if (!add_one_stream(state->mem_ctx,
+			    &state->num_streams, &state->streams,
+			    ea->name, ea->value.length-1,
+			    smb_roundup(state->handle->conn,
+					ea->value.length-1))) {
+		state->status = NT_STATUS_NO_MEMORY;
+		return false;
+	}
+
+	return true;
+}
+
+static NTSTATUS streams_xattr_streaminfo(vfs_handle_struct *handle,
+					 struct files_struct *fsp,
+					 const char *fname,
+					 TALLOC_CTX *mem_ctx,
+					 unsigned int *pnum_streams,
+					 struct stream_struct **pstreams)
+{
+	SMB_STRUCT_STAT sbuf;
+	int ret;
+	NTSTATUS status;
+	struct streaminfo_state state;
+
+	if ((fsp != NULL) && (fsp->fh->fd != -1)) {
+		if (is_ntfs_stream_name(fsp->fsp_name)) {
+			return NT_STATUS_INVALID_PARAMETER;
+		}
+		ret = SMB_VFS_NEXT_FSTAT(handle, fsp, &sbuf);
+	}
+	else {
+		if (is_ntfs_stream_name(fname)) {
+			return NT_STATUS_INVALID_PARAMETER;
+		}
+		ret = SMB_VFS_NEXT_STAT(handle, fname, &sbuf);
+	}
+
+	if (ret == -1) {
+		return map_nt_error_from_unix(errno);
+	}
+
+	state.streams = NULL;
+	state.num_streams = 0;
+
+	if (!S_ISDIR(sbuf.st_mode)) {
+		if (!add_one_stream(mem_ctx,
+				    &state.num_streams, &state.streams,
+				    "::$DATA", sbuf.st_size,
+				    get_allocation_size(handle->conn, fsp,
+							&sbuf))) {
+			return NT_STATUS_NO_MEMORY;
+		}
+	}
+
+	state.mem_ctx = mem_ctx;
+	state.handle = handle;
+	state.status = NT_STATUS_OK;
+
+	status = walk_xattr_streams(handle->conn, fsp, fname,
+				    collect_one_stream, &state);
+
+	if (!NT_STATUS_IS_OK(status)) {
+		TALLOC_FREE(state.streams);
+		return status;
+	}
+
+	if (!NT_STATUS_IS_OK(state.status)) {
+		TALLOC_FREE(state.streams);
+		return state.status;
+	}
+
+	*pnum_streams = state.num_streams;
+	*pstreams = state.streams;
+	return NT_STATUS_OK;
+}
+
+static int streams_xattr_statvfs(struct vfs_handle_struct *handle,
+				 const char *path,
+				 struct vfs_statvfs_struct *statbuf)
+{
+	int ret;
+
+	ret = SMB_VFS_NEXT_STATVFS(handle, path, statbuf);
+	statbuf->FsCapabilities |= FILE_NAMED_STREAMS;
+	return ret;
+
+}
+
+static ssize_t streams_xattr_pwrite(vfs_handle_struct *handle,
+				    files_struct *fsp, const void *data,
+				    size_t n, SMB_OFF_T offset)
+{
+        struct stream_io *sio =
+		(struct stream_io *)VFS_FETCH_FSP_EXTENSION(handle, fsp);
+	struct ea_struct ea;
+	NTSTATUS status;
+	int ret;
+
+	if (sio == NULL) {
+		return SMB_VFS_NEXT_PWRITE(handle, fsp, data, n, offset);
+	}
+
+	status = get_ea_value(talloc_tos(), handle->conn, fsp, sio->base,
+			      sio->xattr_name, &ea);
+	if (!NT_STATUS_IS_OK(status)) {
+		return -1;
+	}
+
+        if ((offset + n) > ea.value.length-1) {
+		uint8 *tmp;
+
+		tmp = TALLOC_REALLOC_ARRAY(talloc_tos(), ea.value.data, uint8,
+					   offset + n + 1);
+
+		if (tmp == NULL) {
+			TALLOC_FREE(ea.value.data);
+                        errno = ENOMEM;
+                        return -1;
+                }
+		ea.value.data = tmp;
+		ea.value.length = offset + n + 1;
+		ea.value.data[offset+n] = 0;
+        }
+
+        memcpy(ea.value.data + offset, data, n);
+
+	ret = SMB_VFS_NEXT_FSETXATTR(handle, fsp, sio->xattr_name,
+				     ea.value.data, ea.value.length, 0);
+
+	TALLOC_FREE(ea.value.data);
+
+	return n;
+}
+
+static ssize_t streams_xattr_pread(vfs_handle_struct *handle,
+				   files_struct *fsp, void *data,
+				   size_t n, SMB_OFF_T offset)
+{
+        struct stream_io *sio =
+		(struct stream_io *)VFS_FETCH_FSP_EXTENSION(handle, fsp);
+	struct ea_struct ea;
+	NTSTATUS status;
+        size_t length, overlap;
+
+	if (sio == NULL) {
+		return SMB_VFS_NEXT_PREAD(handle, fsp, data, n, offset);
+	}
+
+	status = get_ea_value(talloc_tos(), handle->conn, fsp, sio->base,
+			      sio->xattr_name, &ea);
+	if (!NT_STATUS_IS_OK(status)) {
+		return -1;
+	}
+
+	length = ea.value.length-1;
+
+        /* Attempt to read past EOF. */
+        if (length <= offset) {
+                errno = EINVAL;
+                return -1;
+        }
+
+        overlap = (offset + n) > length ? (length - offset) : n;
+        memcpy(data, ea.value.data + offset, overlap);
+
+	TALLOC_FREE(ea.value.data);
+        return overlap;
+}
+
+/* VFS operations structure */
+
+static vfs_op_tuple streams_xattr_ops[] = {
+	{SMB_VFS_OP(streams_xattr_statvfs), SMB_VFS_OP_STATVFS,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_open), SMB_VFS_OP_OPEN,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_stat), SMB_VFS_OP_STAT,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_fstat), SMB_VFS_OP_FSTAT,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_lstat), SMB_VFS_OP_LSTAT,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_pread), SMB_VFS_OP_PREAD,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_pwrite), SMB_VFS_OP_PWRITE,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_lstat), SMB_VFS_OP_LSTAT,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_unlink), SMB_VFS_OP_UNLINK,
+	 SMB_VFS_LAYER_TRANSPARENT},
+	{SMB_VFS_OP(streams_xattr_streaminfo), SMB_VFS_OP_STREAMINFO,
+	 SMB_VFS_LAYER_OPAQUE},
+	{SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
+};
+
+NTSTATUS vfs_streams_xattr_init(void);
+NTSTATUS vfs_streams_xattr_init(void)
+{
+	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "streams_xattr",
+				streams_xattr_ops);
+}