export_image.c

/*
 * export_image.c
 */

/*
 * Copyright (C) 2012-2016 Eric Biggers
 *
 * This file is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option) any
 * later version.
 *
 * This file 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 Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this file; if not, see https://www.gnu.org/licenses/.
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "wimlib.h"
#include "wimlib/blob_table.h"
#include "wimlib/error.h"
#include "wimlib/inode.h"
#include "wimlib/metadata.h"
#include "wimlib/xml.h"

static int
blob_set_not_exported(struct blob_descriptor *blob, void *_ignore)
{
	blob->out_refcnt = 0;
	blob->was_exported = 0;
	return 0;
}

static int
blob_rollback_export(struct blob_descriptor *blob, void *_blob_table)
{
	struct blob_table *blob_table = _blob_table;

	blob->refcnt -= blob->out_refcnt;
	if (blob->was_exported) {
		blob_table_unlink(blob_table, blob);
		free_blob_descriptor(blob);
	}
	return 0;
}

static int
inode_export_blobs(struct wim_inode *inode, struct blob_table *src_blob_table,
		   struct blob_table *dest_blob_table, bool gift)
{
	unsigned i;
	const u8 *hash;
	struct blob_descriptor *src_blob, *dest_blob;

	for (i = 0; i < inode->i_num_streams; i++) {

		/* Retrieve SHA-1 message digest of blob to export.  */
		hash = stream_hash(&inode->i_streams[i]);
		if (is_zero_hash(hash))  /* Empty stream?  */
			continue;

		/* Search for the blob (via SHA-1 message digest) in the
		 * destination WIM.  */
		dest_blob = lookup_blob(dest_blob_table, hash);
		if (!dest_blob) {
			/* Blob not yet present in destination WIM.  Search for
			 * it in the source WIM, then export it into the
			 * destination WIM.  */
			src_blob = stream_blob(&inode->i_streams[i],
					       src_blob_table);
			if (!src_blob)
				return blob_not_found_error(inode, hash);

			if (gift) {
				dest_blob = src_blob;
				blob_table_unlink(src_blob_table, src_blob);
			} else {
				dest_blob = clone_blob_descriptor(src_blob);
				if (!dest_blob)
					return WIMLIB_ERR_NOMEM;
			}
			dest_blob->refcnt = 0;
			dest_blob->out_refcnt = 0;
			dest_blob->was_exported = 1;
			blob_table_insert(dest_blob_table, dest_blob);
		}

		/* Blob is present in destination WIM (either pre-existing,
		 * already exported, or just exported above).  Increment its
		 * reference count appropriately.   Note: we use 'refcnt' for
		 * the raw reference count, but 'out_refcnt' for references
		 * arising just from the export operation; this is used to roll
		 * back a failed export if needed.  */
		dest_blob->refcnt += inode->i_nlink;
		dest_blob->out_refcnt += inode->i_nlink;
	}
	return 0;
}

/* API function documented in wimlib.h  */
WIMLIBAPI int
wimlib_export_image(WIMStruct *src_wim,
		    int src_image,
		    WIMStruct *dest_wim,
		    const tchar *dest_name,
		    const tchar *dest_description,
		    int export_flags)
{
	int ret;
	int start_src_image;
	int end_src_image;
	int orig_dest_image_count;
	int image;
	bool all_images = (src_image == WIMLIB_ALL_IMAGES);

	/* Check for sane parameters.  */
	if (export_flags & ~(WIMLIB_EXPORT_FLAG_BOOT |
			     WIMLIB_EXPORT_FLAG_NO_NAMES |
			     WIMLIB_EXPORT_FLAG_NO_DESCRIPTIONS |
			     WIMLIB_EXPORT_FLAG_GIFT |
			     WIMLIB_EXPORT_FLAG_WIMBOOT))
		return WIMLIB_ERR_INVALID_PARAM;

	if (!src_wim || !dest_wim)
		return WIMLIB_ERR_INVALID_PARAM;

	if (!wim_has_metadata(src_wim) || !wim_has_metadata(dest_wim))
		return WIMLIB_ERR_METADATA_NOT_FOUND;

	if (all_images) {
		/* Multi-image export.  */
		if ((!(export_flags & WIMLIB_EXPORT_FLAG_NO_NAMES) &&
			dest_name) ||
		    (!(export_flags & WIMLIB_EXPORT_FLAG_NO_DESCRIPTIONS) &&
			dest_description))
		{
			ERROR("Image name and description must be "
			      "left NULL for multi-image export");
			return WIMLIB_ERR_INVALID_PARAM;
		}
		start_src_image = 1;
		end_src_image = src_wim->hdr.image_count;
	} else {
		start_src_image = src_image;
		end_src_image = src_image;
	}
	orig_dest_image_count = dest_wim->hdr.image_count;

	/* We don't yet support having a single WIMStruct contain duplicate
	 * 'image_metadata' structures, so we must forbid this from happening.
	 * A duplication is possible if 'src_wim == dest_wim', if the same image
	 * is exported to the same destination WIMStruct multiple times, or if
	 * an image is exported in an A => B => A manner.  */
	for (src_image = start_src_image;
	     src_image <= end_src_image; src_image++)
	{
		const struct wim_image_metadata *src_imd =
				src_wim->image_metadata[src_image - 1];
		for (int i = 0; i < dest_wim->hdr.image_count; i++)
			if (dest_wim->image_metadata[i] == src_imd)
				return WIMLIB_ERR_DUPLICATE_EXPORTED_IMAGE;
	}

	/* Blob checksums must be known before proceeding.  */
	ret = wim_checksum_unhashed_blobs(src_wim);
	if (ret)
		return ret;
	ret = wim_checksum_unhashed_blobs(dest_wim);
	if (ret)
		return ret;

	/* Enable rollbacks  */
	for_blob_in_table(dest_wim->blob_table, blob_set_not_exported, NULL);

	/* Forbid exports where the destination WIM already contains image(s)
	 * with the requested name(s).  However, allow multi-image exports where
	 * there is a duplication among the source names only.  */
	if (!(export_flags & WIMLIB_EXPORT_FLAG_NO_NAMES)) {
		for (src_image = start_src_image;
		     src_image <= end_src_image;
		     src_image++)
		{
			const tchar *name = dest_name ? dest_name :
				wimlib_get_image_name(src_wim, src_image);

			if (wimlib_image_name_in_use(dest_wim, name)) {
				ERROR("There is already an image named \"%"TS"\" "
				      "in the destination WIM", name);
				ret = WIMLIB_ERR_IMAGE_NAME_COLLISION;
				goto out_rollback;
			}
		}
	}

	/* Export each requested image.  */
	for (src_image = start_src_image;
	     src_image <= end_src_image;
	     src_image++)
	{
		const tchar *next_dest_name, *next_dest_description;
		struct wim_image_metadata *src_imd;
		struct wim_inode *inode;

		/* Determine destination image name and description.  */

		if (export_flags & WIMLIB_EXPORT_FLAG_NO_NAMES)
			next_dest_name = NULL;
		else if (dest_name)
			next_dest_name = dest_name;
		else
			next_dest_name = wimlib_get_image_name(src_wim, src_image);

		if (export_flags & WIMLIB_EXPORT_FLAG_NO_DESCRIPTIONS)
			next_dest_description = NULL;
		else if (dest_description)
			next_dest_description = dest_description;
		else
			next_dest_description = wimlib_get_image_description(src_wim, src_image);

		/* Load metadata for source image into memory.  */
		ret = select_wim_image(src_wim, src_image);
		if (ret)
			goto out_rollback;

		src_imd = wim_get_current_image_metadata(src_wim);

		/* Iterate through inodes in the source image and export their
		 * blobs into the destination WIM.  */
		image_for_each_inode(inode, src_imd) {
			ret = inode_export_blobs(inode,
						 src_wim->blob_table,
						 dest_wim->blob_table,
						 export_flags & WIMLIB_EXPORT_FLAG_GIFT);
			if (ret)
				goto out_rollback;
		}

		/* Export XML information into the destination WIM.  */
		ret = xml_export_image(src_wim->xml_info, src_image,
				       dest_wim->xml_info, next_dest_name,
				       next_dest_description,
				       export_flags & WIMLIB_EXPORT_FLAG_WIMBOOT);
		if (ret)
			goto out_rollback;

		/* Reference the source image metadata from the destination WIM.
		 */
		ret = append_image_metadata(dest_wim, src_imd);
		if (ret)
			goto out_rollback;
		src_imd->refcnt++;
	}

	/* Image export complete.  Finish by setting any needed special metadata
	 * on the destination WIM.  */

	if (src_wim->hdr.flags & WIM_HDR_FLAG_RP_FIX)
		dest_wim->hdr.flags |= WIM_HDR_FLAG_RP_FIX;

	for (src_image = start_src_image;
	     src_image <= end_src_image;
	     src_image++)
	{
		int dst_image = orig_dest_image_count + 1 +
				(src_image - start_src_image);

		if ((export_flags & WIMLIB_EXPORT_FLAG_BOOT) &&
		    (!all_images || src_image == src_wim->hdr.boot_idx))
			dest_wim->hdr.boot_idx = dst_image;
	}

	return 0;

out_rollback:
	while ((image = xml_get_image_count(dest_wim->xml_info))
	       > orig_dest_image_count)
	{
		xml_delete_image(dest_wim->xml_info, image);
	}
	while (dest_wim->hdr.image_count > orig_dest_image_count)
	{
		put_image_metadata(dest_wim->image_metadata[
					--dest_wim->hdr.image_count]);
	}
	for_blob_in_table(dest_wim->blob_table, blob_rollback_export,
			  dest_wim->blob_table);
	return ret;
}