svn_repos.h

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/**
 * @copyright
 * ====================================================================
 * Copyright (c) 2000-2006 CollabNet.  All rights reserved.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution.  The terms
 * are also available at http://subversion.tigris.org/license-1.html.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 *
 * This software consists of voluntary contributions made by many
 * individuals.  For exact contribution history, see the revision
 * history and logs, available at http://subversion.tigris.org/.
 * ====================================================================
 * @endcopyright
 *
 * @file svn_repos.h
 * @brief tools built on top of the filesystem.
 */


#ifndef SVN_REPOS_H
#define SVN_REPOS_H

#include <apr_pools.h>
#include <apr_hash.h>
#include "svn_fs.h"
#include "svn_delta.h"
#include "svn_types.h"
#include "svn_error.h"
#include "svn_version.h"


#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/* ---------------------------------------------------------------*/

/**
 * Get libsvn_repos version information.
 *
 * @since New in 1.1.
 */
const svn_version_t *svn_repos_version(void);



/** Callback type for checking authorization on paths produced by (at
 * least) svn_repos_dir_delta().
 *
 * Set @a *allowed to TRUE to indicate that some operation is
 * authorized for @a path in @a root, or set it to FALSE to indicate
 * unauthorized (presumably according to state stored in @a baton).
 * 
 * Do not assume @a pool has any lifetime beyond this call.
 *
 * The exact operation being authorized depends on the callback
 * implementation.  For read authorization, for example, the caller
 * would implement an instance that does read checking, and pass it as
 * a parameter named [perhaps] 'authz_read_func'.  The receiver of
 * that parameter might also take another parameter named
 * 'authz_write_func', which although sharing this type, would be a
 * different implementation.
 *
 * @note If someday we want more sophisticated authorization states
 * than just yes/no, @a allowed can become an enum type.
 */
typedef svn_error_t *(*svn_repos_authz_func_t)(svn_boolean_t *allowed,
                                               svn_fs_root_t *root,
                                               const char *path,
                                               void *baton,
                                               apr_pool_t *pool);


/** An enum defining the kinds of access authz looks up.
 *
 * @since New in 1.3.
 */
typedef enum
{
  /** No access. */
  svn_authz_none = 0,

  /** Path can be read. */
  svn_authz_read = 1,

  /** Path can be altered. */
  svn_authz_write = 2,

  /** The other access credentials are recursive. */
  svn_authz_recursive = 4
} svn_repos_authz_access_t;


/** Callback type for checking authorization on paths produced by
 * the repository commit editor.
 *
 * Set @a *allowed to TRUE to indicate that the @a required access on
 * @a path in @a root is authorized, or set it to FALSE to indicate
 * unauthorized (presumable according to state stored in @a baton).
 *
 * If @a path is NULL, the callback should perform a global authz
 * lookup for the @a required access.  That is, the lookup should
 * check if the @a required access is granted for at least one path of
 * the repository, and set @a *allowed to TRUE if so.  @a root may
 * also be NULL if @a path is NULL.
 *
 * This callback is very similar to svn_repos_authz_func_t, with the
 * exception of the addition of the @a required parameter.
 * This is due to historical reasons: when authz was first implemented
 * for svn_repos_dir_delta(), it seemed there would need only checks
 * for read and write operations, hence the svn_repos_authz_func_t
 * callback prototype and usage scenario.  But it was then realized
 * that lookups due to copying needed to be recursive, and that
 * brute-force recursive lookups didn't square with the O(1)
 * performances a copy operation should have.
 *
 * So a special way to ask for a recursive lookup was introduced.  The
 * commit editor needs this capability to retain acceptable
 * performance.  Instead of revving the existing callback, causing
 * unnecessary revving of functions that don't actually need the
 * extended functionality, this second, more complete callback was
 * introduced, for use by the commit editor.
 *
 * Some day, it would be nice to reunite these two callbacks and do
 * the necessary revving anyway, but for the time being, this dual
 * callback mechanism will do.
 */
typedef svn_error_t *(*svn_repos_authz_callback_t)
  (svn_repos_authz_access_t required,
   svn_boolean_t *allowed,
   svn_fs_root_t *root,
   const char *path,
   void *baton,
   apr_pool_t *pool);

/**
 * A callback function type for use in svn_repos_get_file_revs().
 * @a baton is provided by the caller, @a path is the pathname of the file
 * in revision @a rev and @a rev_props are the revision properties.
 * If @a delta_handler and @a delta_baton are non-NULL, they may be set to a
 * handler/baton which will be called with the delta between the previous
 * revision and this one after the return of this callback.  They may be
 * left as NULL/NULL.
 * @a prop_diffs is an array of svn_prop_t elements indicating the property
 * delta for this and the previous revision.
 * @a pool may be used for temporary allocations, but you can't rely
 * on objects allocated to live outside of this particular call and the
 * immediately following calls to @a *delta_handler if any.
 *
 * @since New in 1.1.
 */
typedef svn_error_t *(*svn_repos_file_rev_handler_t)
  (void *baton,
   const char *path,
   svn_revnum_t rev,
   apr_hash_t *rev_props,
   svn_txdelta_window_handler_t *delta_handler,
   void **delta_baton,
   apr_array_header_t *prop_diffs,
   apr_pool_t *pool);


/** The repository object. */
typedef struct svn_repos_t svn_repos_t;

/* Opening and creating repositories. */


/** Find the root path of the repository that contains @a path.
 *
 * If a repository was found, the path to the root of the repository
 * is returned, else @c NULL. The pointer to the returned path may be
 * equal to @a path.
 */
const char *svn_repos_find_root_path(const char *path,
                                     apr_pool_t *pool);

/** Set @a *repos_p to a repository object for the repository at @a path.
 *
 * Allocate @a *repos_p in @a pool.
 *
 * Acquires a shared lock on the repository, and attaches a cleanup
 * function to @a pool to remove the lock.  If no lock can be acquired,
 * returns error, with undefined effect on @a *repos_p.  If an exclusive
 * lock is present, this blocks until it's gone.
 */
svn_error_t *svn_repos_open(svn_repos_t **repos_p,
                            const char *path,
                            apr_pool_t *pool);

/** Create a new Subversion repository at @a path, building the necessary
 * directory structure, creating the filesystem, and so on.
 * Return the repository object in @a *repos_p, allocated in @a pool.
 *
 * @a config is a client configuration hash of @c svn_config_t * items
 * keyed on config category names, and may be NULL.
 *
 * @a fs_config is passed to the filesystem, and may be NULL.
 *
 * @a unused_1 and @a unused_2 are not used and should be NULL.
 */
svn_error_t *svn_repos_create(svn_repos_t **repos_p, 
                              const char *path,
                              const char *unused_1,
                              const char *unused_2,
                              apr_hash_t *config,
                              apr_hash_t *fs_config,
                              apr_pool_t *pool);

/** Destroy the Subversion repository found at @a path, using @a pool for any
 * necessary allocations.
 */
svn_error_t *svn_repos_delete(const char *path, apr_pool_t *pool);

/** Return the filesystem associated with repository object @a repos. */
svn_fs_t *svn_repos_fs(svn_repos_t *repos);


/** Make a hot copy of the Subversion repository found at @a src_path 
 * to @a dst_path. 
 *
 * Copy a possibly live Subversion repository from @a src_path to
 * @a dst_path.  If @a clean_logs is @c TRUE, perform cleanup on the
 * source filesystem as part of the copy operation; currently, this
 * means deleting copied, unused logfiles for a Berkeley DB source
 * repository.
 */
svn_error_t * svn_repos_hotcopy(const char *src_path,
                                const char *dst_path,
                                svn_boolean_t clean_logs,
                                apr_pool_t *pool);

/**
 * Run database recovery procedures on the repository at @a path,
 * returning the database to a consistent state.  Use @a pool for all
 * allocation.
 *
 * Acquires an exclusive lock on the repository, recovers the
 * database, and releases the lock.  If an exclusive lock can't be
 * acquired, returns error.
 *
 * @deprecated Provided for backward compatibility with the 1.0 API.
 */
svn_error_t *svn_repos_recover(const char *path, apr_pool_t *pool);

/**
 * Run database recovery procedures on the repository at @a path,
 * returning the database to a consistent state.  Use @a pool for all
 * allocation.
 *
 * Acquires an exclusive lock on the repository, recovers the
 * database, and releases the lock.  If an exclusive lock can't be
 * acquired, returns error.
 *
 * If @a nonblocking is TRUE, an error of type EWOULDBLOCK is
 * returned if the lock is not immediately available.
 *
 * If @a start_callback is not NULL, it will be called with @a
 * start_callback_baton as argument before the recovery starts, but
 * after the exclusive lock has been acquired.
 *
 * @since New in 1.1.
 */
svn_error_t *svn_repos_recover2(const char *path,
                                svn_boolean_t nonblocking,
                                svn_error_t *(*start_callback)(void *baton),
                                void *start_callback_baton,
                                apr_pool_t *pool);

/** This function is a wrapper around svn_fs_berkeley_logfiles(),
 * returning log file paths relative to the root of the repository.
 *
 * @copydoc svn_fs_berkeley_logfiles()
 */
svn_error_t *svn_repos_db_logfiles(apr_array_header_t **logfiles,
                                   const char *path,
                                   svn_boolean_t only_unused,
                                   apr_pool_t *pool);



/* Repository Paths */

/** Return the top-level repository path allocated in @a pool. */
const char *svn_repos_path(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's filesystem directory, allocated in
 * @a pool.
 */
const char *svn_repos_db_env(svn_repos_t *repos, apr_pool_t *pool);

/** Return path to @a repos's config directory, allocated in @a pool. */
const char *svn_repos_conf_dir(svn_repos_t *repos, apr_pool_t *pool);

/** Return path to @a repos's svnserve.conf, allocated in @a pool. */
const char *svn_repos_svnserve_conf(svn_repos_t *repos, apr_pool_t *pool);

/** Return path to @a repos's lock directory, allocated in @a pool. */
const char *svn_repos_lock_dir(svn_repos_t *repos, apr_pool_t *pool);

/** Return path to @a repos's db lockfile, allocated in @a pool. */
const char *svn_repos_db_lockfile(svn_repos_t *repos, apr_pool_t *pool);

/** Return path to @a repos's db logs lockfile, allocated in @a pool. */
const char *svn_repos_db_logs_lockfile(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's hook directory, allocated in @a pool. */
const char *svn_repos_hook_dir(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's start-commit hook, allocated in @a pool. */
const char *svn_repos_start_commit_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's pre-commit hook, allocated in @a pool. */
const char *svn_repos_pre_commit_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's post-commit hook, allocated in @a pool. */
const char *svn_repos_post_commit_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's pre-revprop-change hook, allocated in 
 * @a pool.
 */
const char *svn_repos_pre_revprop_change_hook(svn_repos_t *repos,
                                              apr_pool_t *pool);

/** Return the path to @a repos's post-revprop-change hook, allocated in 
 * @a pool.
 */
const char *svn_repos_post_revprop_change_hook(svn_repos_t *repos,
                                               apr_pool_t *pool);


/** @defgroup svn_repos_lock_hooks paths to lock hooks
 * @{ 
 * @since New in 1.2. */

/** Return the path to @a repos's pre-lock hook, allocated in @a pool. */
const char *svn_repos_pre_lock_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's post-lock hook, allocated in @a pool. */
const char *svn_repos_post_lock_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's pre-unlock hook, allocated in @a pool. */
const char *svn_repos_pre_unlock_hook(svn_repos_t *repos, apr_pool_t *pool);

/** Return the path to @a repos's post-unlock hook, allocated in @a pool. */
const char *svn_repos_post_unlock_hook(svn_repos_t *repos, apr_pool_t *pool);

/** @} */

/* ---------------------------------------------------------------*/

/* Reporting the state of a working copy, for updates. */


/**
 * Construct and return a @a report_baton that will be passed to the
 * other functions in this section to describe the state of a pre-existing
 * tree (typically, a working copy).  When the report is finished,
 * @a editor/@a edit_baton will be driven in such a way as to transform the
 * existing tree to @a revnum and, if @a tgt_path is non-NULL, switch the
 * reported hierarchy to @a tgt_path.
 *
 * @a fs_base is the absolute path of the node in the filesystem at which
 * the comparison should be rooted.  @a target is a single path component,
 * used to limit the scope of the report to a single entry of @a fs_base,
 * or "" if all of @a fs_base itself is the main subject of the report.
 *
 * @a tgt_path and @a revnum is the fs path/revision pair that is the
 * "target" of the delta.  @a tgt_path should be provided only when
 * the source and target paths of the report differ.  That is, @a tgt_path
 * should *only* be specified when specifying that the resultant editor
 * drive be one that transforms the reported hierarchy into a pristine tree
 * of @a tgt_path at revision @a revnum.  A @c NULL value for @a tgt_path
 * will indicate that the editor should be driven in such a way as to
 * transform the reported hierarchy to revision @a revnum, preserving the
 * reported hierarchy.
 *
 * @a text_deltas instructs the driver of the @a editor to enable
 * the generation of text deltas.
 *
 * @a recurse instructs the driver of the @a editor to send a recursive
 * delta (or not.)
 *
 * @a ignore_ancestry instructs the driver to ignore node ancestry
 * when determining how to transmit differences.
 *
 * The @a authz_read_func and @a authz_read_baton are passed along to
 * svn_repos_dir_delta(); see that function for how they are used.
 *
 * All allocation for the context and collected state will occur in
 * @a pool.
 *
 * @note @a username isn't used and should be removed if this function is
 * revised.
 */
svn_error_t *
svn_repos_begin_report(void **report_baton,
                       svn_revnum_t revnum,
                       const char *username,
                       svn_repos_t *repos,
                       const char *fs_base,
                       const char *target,
                       const char *tgt_path,
                       svn_boolean_t text_deltas,
                       svn_boolean_t recurse,
                       svn_boolean_t ignore_ancestry,
                       const svn_delta_editor_t *editor,
                       void *edit_baton,
                       svn_repos_authz_func_t authz_read_func,
                       void *authz_read_baton,
                       apr_pool_t *pool);

/**
 * Given a @a report_baton constructed by svn_repos_begin_report(),
 * record the presence of @a path at @a revision in the current tree.
 *
 * @a path is relative to the anchor/target used in the creation of the
 * @a report_baton.
 *
 * @a revision may be SVN_INVALID_REVNUM if (for example) @a path represents
 * a locally-added path with no revision number.
 *
 * The first call of this in a given report usually passes an empty
 * @a path; this is used to set up the correct root revision for the editor
 * drive.
 *
 * If @a start_empty is true and @a path is a directory, then require the
 * caller to explicitly provide all the children of @path - do not assume
 * that the tree also contains all the children of @a path at @a revision.
 * This is for 'low confidence' client reporting.
 * 
 * If the caller has a lock token for @a path, then @a lock_token should
 * be set to that token.  Else, @a lock_token should be NULL.
 *
 * All temporary allocations are done in @a pool.
 *
 * @since New in 1.2.
 */
svn_error_t *svn_repos_set_path2(void *report_baton,
                                 const char *path,
                                 svn_revnum_t revision,
                                 svn_boolean_t start_empty,
                                 const char *lock_token,
                                 apr_pool_t *pool);

/**
 * Similar to svn_repos_set_path2(), but with @a lock_token set to @c NULL.
 *
 * @deprecated Provided for backward compatibility with the 1.1 API.
 */
svn_error_t *svn_repos_set_path(void *report_baton,
                                const char *path,
                                svn_revnum_t revision,
                                svn_boolean_t start_empty,
                                apr_pool_t *pool);

/**
 * Given a @a report_baton constructed by svn_repos_begin_report(), 
 * record the presence of @path in the current tree, containing the contents
 * of @a link_path at @a revision.
 *
 * Note that while @a path is relative to the anchor/target used in the
 * creation of the @a report_baton, @a link_path is an absolute filesystem
 * path!
 *
 * If @a start_empty is true and @a path is a directory, then require the
 * caller to explicitly provide all the children of @path - do not assume
 * that the tree also contains all the children of @a link_path at
 * @a revision.  This is for 'low confidence' client reporting.
 *
 * If the caller has a lock token for @a link_path, then @a lock_token
 * should be set to that token.  Else, @a lock_token should be NULL.
 *
 * All temporary allocations are done in @a pool.
 *
 * @since New in 1.2.
 */
svn_error_t *svn_repos_link_path2(void *report_baton,
                                  const char *path,
                                  const char *link_path,
                                  svn_revnum_t revision,
                                  svn_boolean_t start_empty,
                                  const char *lock_token,
                                  apr_pool_t *pool);

/**
 * Similar to svn_repos_link_path2(), but with @a lock_token set to @c NULL.
 *
 * @deprecated Provided for backward compatibility with the 1.1 API.
 */
svn_error_t *svn_repos_link_path(void *report_baton,
                                 const char *path,
                                 const char *link_path,
                                 svn_revnum_t revision,
                                 svn_boolean_t start_empty,
                                 apr_pool_t *pool);

/** Given a @a report_baton constructed by svn_repos_begin_report(), 
 * record the non-existence of @a path in the current tree.
 *
 * (This allows the reporter's driver to describe missing pieces of a
 * working copy, so that 'svn up' can recreate them.)
 *
 * All temporary allocations are done in @a pool.
 */
svn_error_t *svn_repos_delete_path(void *report_baton,
                                   const char *path,
                                   apr_pool_t *pool);

/** Given a @a report_baton constructed by svn_repos_begin_report(),
 * finish the report and drive the editor as specified when the report
 * baton was constructed.
 *
 * If an error occurs during the driving of the editor, do NOT abort the
 * edit; that responsibility belongs to the caller of this function, if
 * it happens at all.
 *
 * After the call to this function, @a report_baton is no longer valid;
 * it should not be passed to any other reporting functions, including
 * svn_repos_abort_report().
 */
svn_error_t *svn_repos_finish_report(void *report_baton,
                                     apr_pool_t *pool);


/** Given a @a report_baton constructed by svn_repos_begin_report(),
 * abort the report.  This function can be called anytime before
 * svn_repos_finish_report() is called.
 *
 * After the call to this function, @a report_baton is no longer valid;
 * it should not be passed to any other reporting functions.
 */
svn_error_t *svn_repos_abort_report(void *report_baton,
                                    apr_pool_t *pool);


/* ---------------------------------------------------------------*/

/* The magical dir_delta update routines. */

/** Use the provided @a editor and @a edit_baton to describe the changes
 * necessary for making a given node (and its descendants, if it is a
 * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry is the node to update.  If @a src_entry
 * is empty, then compute the difference between the entire tree
 * anchored at @a src_parent_dir under @a src_root and @a tgt_path
 * under @a target_root.  Else, describe the changes needed to update
 * only that entry in @a src_parent_dir.  Typically, callers of this
 * function will use a @a tgt_path that is the concatenation of @a
 * src_parent_dir and @a src_entry.
 *
 * @a src_root and @a tgt_root can both be either revision or transaction
 * roots.  If @a tgt_root is a revision, @a editor's set_target_revision()
 * will be called with the @a tgt_root's revision number, else it will
 * not be called at all.
 *
 * If @a authz_read_func is non-null, invoke it before any call to
 *
 *    @a editor->open_root
 *    @a editor->add_directory
 *    @a editor->open_directory
 *    @a editor->add_file
 *    @a editor->open_file
 *
 * passing @a tgt_root, the same path that would be passed to the
 * editor function in question, and @a authz_read_baton.  If the
 * @a *allowed parameter comes back TRUE, then proceed with the planned
 * editor call; else if FALSE, then invoke @a editor->absent_file or
 * @a editor->absent_directory as appropriate, except if the planned
 * editor call was open_root, throw SVN_ERR_AUTHZ_ROOT_UNREADABLE.
 *
 * If @a text_deltas is @c FALSE, send a single @c NULL txdelta window to 
 * the window handler returned by @a editor->apply_textdelta().
 *
 * If @a entry_props is @c TRUE, accompany each opened/added entry with
 * propchange editor calls that relay special "entry props" (this
 * is typically used only for working copy updates).
 *
 * @a ignore_ancestry instructs the function to ignore node ancestry
 * when determining how to transmit differences.
 *
 * Before completing successfully, this function calls @a editor's
 * close_edit(), so the caller should expect its @a edit_baton to be
 * invalid after its use with this function.
 *
 * Do any allocation necessary for the delta computation in @a pool.
 * This function's maximum memory consumption is at most roughly
 * proportional to the greatest depth of the tree under @a tgt_root, not
 * the total size of the delta.
 */
svn_error_t *
svn_repos_dir_delta(svn_fs_root_t *src_root,
                    const char *src_parent_dir,
                    const char *src_entry,
                    svn_fs_root_t *tgt_root,
                    const char *tgt_path,
                    const svn_delta_editor_t *editor,
                    void *edit_baton,
                    svn_repos_authz_func_t authz_read_func,
                    void *authz_read_baton,
                    svn_boolean_t text_deltas,
                    svn_boolean_t recurse,
                    svn_boolean_t entry_props,
                    svn_boolean_t ignore_ancestry,
                    apr_pool_t *pool);

/** Use the provided @a editor and @a edit_baton to describe the
 * skeletal changes made in a particular filesystem @a root
 * (revision or transaction).
 *
 * Changes will be limited to those within @a base_dir, and if 
 * @a low_water_mark is set to something other than @c SVN_INVALID_REVNUM
 * it is assumed that the client has no knowledge of revisions prior to
 * @a low_water_mark.  Together, these two arguments define the portion of
 * the tree that the client is assumed to have knowledge of, and thus any
 * copies of data fro * directory) under @a src_root look exactly like @a tgt_path under
 * @a tgt_root.  @a src_entry i