source: valtobtest/subversion-1.6.2/subversion/libsvn_repos/dump.c @ 3

/* dump.c --- writing filesystem contents into a portable 'dumpfile' format.
 *
 * ====================================================================
 * 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/.
 * ====================================================================
 */


#include "svn_private_config.h"
#include "svn_pools.h"
#include "svn_error.h"
#include "svn_fs.h"
#include "svn_iter.h"
#include "svn_repos.h"
#include "svn_string.h"
#include "svn_path.h"
#include "svn_time.h"
#include "svn_checksum.h"
#include "svn_props.h"


#define ARE_VALID_COPY_ARGS(p,r) ((p) && SVN_IS_VALID_REVNUM(r))

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

/** A variant of our hash-writing routine in libsvn_subr;  this one
    writes to a stringbuf instead of a file, and outputs PROPS-END
    instead of END.  If OLDHASH is not NULL, then only properties
    which vary from OLDHASH will be written, and properties which
    exist only in OLDHASH will be written out with "D" entries
    (like "K" entries but with no corresponding value). **/

static void
write_hash_to_stringbuf(apr_hash_t *hash,
                        apr_hash_t *oldhash,
                        svn_stringbuf_t **strbuf,
                        apr_pool_t *pool)
{
  apr_hash_index_t *this;      /* current hash entry */

  *strbuf = svn_stringbuf_create("", pool);

  for (this = apr_hash_first(pool, hash); this; this = apr_hash_next(this))
    {
      const void *key;
      void *val;
      apr_ssize_t keylen;
      svn_string_t *value;

      /* Get this key and val. */
      apr_hash_this(this, &key, &keylen, &val);
      value = val;

      /* Don't output properties equal to the ones in oldhash, if present. */
      if (oldhash)
        {
          svn_string_t *oldvalue = apr_hash_get(oldhash, key, keylen);

          if (oldvalue && svn_string_compare(value, oldvalue))
            continue;
        }

      /* Output name length, then name. */

      svn_stringbuf_appendcstr(*strbuf,
                               apr_psprintf(pool, "K %" APR_SSIZE_T_FMT "\n",
                                            keylen));

      svn_stringbuf_appendbytes(*strbuf, (const char *) key, keylen);
      svn_stringbuf_appendbytes(*strbuf, "\n", 1);

      /* Output value length, then value. */

      svn_stringbuf_appendcstr(*strbuf,
                               apr_psprintf(pool, "V %" APR_SIZE_T_FMT "\n",
                                            value->len));

      svn_stringbuf_appendbytes(*strbuf, value->data, value->len);
      svn_stringbuf_appendbytes(*strbuf, "\n", 1);
    }

  if (oldhash)
    {
      /* Output a "D " entry for each property in oldhash but not hash. */
      for (this = apr_hash_first(pool, oldhash); this;
           this = apr_hash_next(this))
        {
          const void *key;
          apr_ssize_t keylen;

          /* Get this key. */
          apr_hash_this(this, &key, &keylen, NULL);

          /* Only output values deleted in hash. */
          if (apr_hash_get(hash, key, keylen))
            continue;

          /* Output name length, then name. */

          svn_stringbuf_appendcstr(*strbuf,
                                   apr_psprintf(pool,
                                                "D %" APR_SSIZE_T_FMT "\n",
                                                keylen));

          svn_stringbuf_appendbytes(*strbuf, (const char *) key, keylen);
          svn_stringbuf_appendbytes(*strbuf, "\n", 1);
        }
    }
  svn_stringbuf_appendbytes(*strbuf, "PROPS-END\n", 10);
}


/* Compute the delta between OLDROOT/OLDPATH and NEWROOT/NEWPATH and
   store it into a new temporary file *TEMPFILE.  OLDROOT may be NULL,
   in which case the delta will be computed against an empty file, as
   per the svn_fs_get_file_delta_stream docstring.  Record the length
   of the temporary file in *LEN, and rewind the file before
   returning. */
static svn_error_t *
store_delta(apr_file_t **tempfile, svn_filesize_t *len,
            svn_fs_root_t *oldroot, const char *oldpath,
            svn_fs_root_t *newroot, const char *newpath, apr_pool_t *pool)
{
  svn_stream_t *temp_stream;
  apr_off_t offset = 0;
  svn_txdelta_stream_t *delta_stream;
  svn_txdelta_window_handler_t wh;
  void *whb;

  /* Create a temporary file and open a stream to it. Note that we need
     the file handle in order to rewind it. */
  SVN_ERR(svn_io_open_unique_file3(tempfile, NULL, NULL,
                                   svn_io_file_del_on_pool_cleanup,
                                   pool, pool));
  temp_stream = svn_stream_from_aprfile2(*tempfile, TRUE, pool);

  /* Compute the delta and send it to the temporary file. */
  SVN_ERR(svn_fs_get_file_delta_stream(&delta_stream, oldroot, oldpath,
                                       newroot, newpath, pool));
  svn_txdelta_to_svndiff2(&wh, &whb, temp_stream, 0, pool);
  SVN_ERR(svn_txdelta_send_txstream(delta_stream, wh, whb, pool));

  /* Get the length of the temporary file and rewind it. */
  SVN_ERR(svn_io_file_seek(*tempfile, APR_CUR, &offset, pool));
  *len = offset;
  offset = 0;
  return svn_io_file_seek(*tempfile, APR_SET, &offset, pool);
}


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

/** An editor which dumps node-data in 'dumpfile format' to a file. **/

/* Look, mom!  No file batons! */

struct edit_baton
{
  /* The path which implicitly prepends all full paths coming into
     this editor.  This will almost always be "" or "/".  */
  const char *path;

  /* The stream to dump to. */
  svn_stream_t *stream;

  /* Send feedback here, if non-NULL */
  svn_stream_t *feedback_stream;

  /* The fs revision root, so we can read the contents of paths. */
  svn_fs_root_t *fs_root;
  svn_revnum_t current_rev;

  /* True if dumped nodes should output deltas instead of full text. */
  svn_boolean_t use_deltas;

  /* True if this "dump" is in fact a verify. */
  svn_boolean_t verify;

  /* The first revision dumped in this dumpstream. */
  svn_revnum_t oldest_dumped_rev;

  /* reusable buffer for writing file contents */
  char buffer[SVN__STREAM_CHUNK_SIZE];
  apr_size_t bufsize;
};

struct dir_baton
{
  struct edit_baton *edit_baton;
  struct dir_baton *parent_dir_baton;

  /* is this directory a new addition to this revision? */
  svn_boolean_t added;

  /* has this directory been written to the output stream? */
  svn_boolean_t written_out;

  /* the absolute path to this directory */
  const char *path;

  /* the comparison path and revision of this directory.  if both of
     these are valid, use them as a source against which to compare
     the directory instead of the default comparison source of PATH in
     the previous revision. */
  const char *cmp_path;
  svn_revnum_t cmp_rev;

  /* hash of paths that need to be deleted, though some -might- be
     replaced.  maps const char * paths to this dir_baton.  (they're
     full paths, because that's what the editor driver gives us.  but
     really, they're all within this directory.) */
  apr_hash_t *deleted_entries;

  /* pool to be used for deleting the hash items */
  apr_pool_t *pool;
};


/* Make a directory baton to represent the directory was path
   (relative to EDIT_BATON's path) is PATH.

   CMP_PATH/CMP_REV are the path/revision against which this directory
   should be compared for changes.  If either is omitted (NULL for the
   path, SVN_INVALID_REVNUM for the rev), just compare this directory
   PATH against itself in the previous revision.

   PARENT_DIR_BATON is the directory baton of this directory's parent,
   or NULL if this is the top-level directory of the edit.  ADDED
   indicated if this directory is newly added in this revision.
   Perform all allocations in POOL.  */
static struct dir_baton *
make_dir_baton(const char *path,
               const char *cmp_path,
               svn_revnum_t cmp_rev,
               void *edit_baton,
               void *parent_dir_baton,
               svn_boolean_t added,
               apr_pool_t *pool)
{
  struct edit_baton *eb = edit_baton;
  struct dir_baton *pb = parent_dir_baton;
  struct dir_baton *new_db = apr_pcalloc(pool, sizeof(*new_db));
  const char *full_path;

  /* A path relative to nothing?  I don't think so. */
  SVN_ERR_ASSERT_NO_RETURN(!path || pb);

  /* Construct the full path of this node. */
  if (pb)
    full_path = svn_path_join(eb->path, path, pool);
  else
    full_path = apr_pstrdup(pool, eb->path);

  /* Remove leading slashes from copyfrom paths. */
  if (cmp_path)
    cmp_path = ((*cmp_path == '/') ? cmp_path + 1 : cmp_path);

  new_db->edit_baton = eb;
  new_db->parent_dir_baton = pb;
  new_db->path = full_path;
  new_db->cmp_path = cmp_path ? apr_pstrdup(pool, cmp_path) : NULL;
  new_db->cmp_rev = cmp_rev;
  new_db->added = added;
  new_db->written_out = FALSE;
  new_db->deleted_entries = apr_hash_make(pool);
  new_db->pool = pool;

  return new_db;
}


/* This helper is the main "meat" of the editor -- it does all the
   work of writing a node record.

   Write out a node record for PATH of type KIND under EB->FS_ROOT.
   ACTION describes what is happening to the node (see enum svn_node_action).
   Write record to writable EB->STREAM, using EB->BUFFER to write in chunks.

   If the node was itself copied, IS_COPY is TRUE and the
   path/revision of the copy source are in CMP_PATH/CMP_REV.  If
   IS_COPY is FALSE, yet CMP_PATH/CMP_REV are valid, this node is part
   of a copied subtree.
  */
static svn_error_t *
dump_node(struct edit_baton *eb,
          const char *path,    /* an absolute path. */
          svn_node_kind_t kind,
          enum svn_node_action action,
          svn_boolean_t is_copy,
          const char *cmp_path,
          svn_revnum_t cmp_rev,
          apr_pool_t *pool)
{
  svn_stringbuf_t *propstring;
  svn_filesize_t content_length = 0;
  apr_size_t len;
  svn_boolean_t must_dump_text = FALSE, must_dump_props = FALSE;
  const char *compare_path = path;
  svn_revnum_t compare_rev = eb->current_rev - 1;
  svn_fs_root_t *compare_root = NULL;
  apr_file_t *delta_file = NULL;

  /* Write out metadata headers for this file node. */
  SVN_ERR(svn_stream_printf(eb->stream, pool,
                            SVN_REPOS_DUMPFILE_NODE_PATH ": %s\n",
                            (*path == '/') ? path + 1 : path));
  if (kind == svn_node_file)
    SVN_ERR(svn_stream_printf(eb->stream, pool,
                              SVN_REPOS_DUMPFILE_NODE_KIND ": file\n"));
  else if (kind == svn_node_dir)
    SVN_ERR(svn_stream_printf(eb->stream, pool,
                              SVN_REPOS_DUMPFILE_NODE_KIND ": dir\n"));

  /* Remove leading slashes from copyfrom paths. */
  if (cmp_path)
    cmp_path = ((*cmp_path == '/') ? cmp_path + 1 : cmp_path);

  /* Validate the comparison path/rev. */
  if (ARE_VALID_COPY_ARGS(cmp_path, cmp_rev))
    {
      compare_path = cmp_path;
      compare_rev = cmp_rev;
    }

  if (action == svn_node_action_change)
    {
      SVN_ERR(svn_stream_printf(eb->stream, pool,
                                SVN_REPOS_DUMPFILE_NODE_ACTION
                                ": change\n"));

      /* either the text or props changed, or possibly both. */
      SVN_ERR(svn_fs_revision_root(&compare_root,
                                   svn_fs_root_fs(eb->fs_root),
                                   compare_rev, pool));

      SVN_ERR(svn_fs_props_changed(&must_dump_props,
                                   compare_root, compare_path,
                                   eb->fs_root, path, pool));
      if (kind == svn_node_file)
        SVN_ERR(svn_fs_contents_changed(&must_dump_text,
                                        compare_root, compare_path,
                                        eb->fs_root, path, pool));
    }
  else if (action == svn_node_action_replace)
    {
      if (! is_copy)
        {
          /* a simple delete+add, implied by a single 'replace' action. */
          SVN_ERR(svn_stream_printf(eb->stream, pool,
                                    SVN_REPOS_DUMPFILE_NODE_ACTION
                                    ": replace\n"));

          /* definitely need to dump all content for a replace. */
          if (kind == svn_node_file)
            must_dump_text = TRUE;
          must_dump_props = TRUE;
        }
      else
        {
          /* more complex:  delete original, then add-with-history.  */

          /* the path & kind headers have already been printed;  just
             add a delete action, and end the current record.*/
          SVN_ERR(svn_stream_printf(eb->stream, pool,
                                    SVN_REPOS_DUMPFILE_NODE_ACTION
                                    ": delete\n\n"));

          /* recurse:  print an additional add-with-history record. */
          SVN_ERR(dump_node(eb, path, kind, svn_node_action_add,
                            is_copy, compare_path, compare_rev, pool));

          /* we can leave this routine quietly now, don't need to dump
             any content;  that was already done in the second record. */
          must_dump_text = FALSE;
          must_dump_props = FALSE;
        }
    }
  else if (action == svn_node_action_delete)
    {
      SVN_ERR(svn_stream_printf(eb->stream, pool,
                                SVN_REPOS_DUMPFILE_NODE_ACTION
                                ": delete\n"));

      /* we can leave this routine quietly now, don't need to dump
         any content. */
      must_dump_text = FALSE;
      must_dump_props = FALSE;
    }
  else if (action == svn_node_action_add)
    {
      SVN_ERR(svn_stream_printf(eb->stream, pool,
                                SVN_REPOS_DUMPFILE_NODE_ACTION ": add\n"));

      if (! is_copy)
        {
          /* Dump all contents for a simple 'add'. */
          if (kind == svn_node_file)
            must_dump_text = TRUE;
          must_dump_props = TRUE;
        }
      else
        {
          if (!eb->verify && cmp_rev < eb->oldest_dumped_rev)
            SVN_ERR(svn_stream_printf
                    (eb->feedback_stream, pool,
                     _("WARNING: Referencing data in revision %ld,"
                       " which is older than the oldest\n"
                       "WARNING: dumped revision (%ld).  Loading this dump"
                       " into an empty repository\n"
                       "WARNING: will fail.\n"),
                     cmp_rev, eb->oldest_dumped_rev));

          SVN_ERR(svn_stream_printf(eb->stream, pool,
                                    SVN_REPOS_DUMPFILE_NODE_COPYFROM_REV
                                    ": %ld\n"
                                    SVN_REPOS_DUMPFILE_NODE_COPYFROM_PATH
                                    ": %s\n",
                                    cmp_rev, cmp_path));

          SVN_ERR(svn_fs_revision_root(&compare_root,
                                       svn_fs_root_fs(eb->fs_root),
                                       compare_rev, pool));

          /* Need to decide if the copied node had any extra textual or
             property mods as well.  */
          SVN_ERR(svn_fs_props_changed(&must_dump_props,
                                       compare_root, compare_path,
                                       eb->fs_root, path, pool));
          if (kind == svn_node_file)
            {
              svn_checksum_t *checksum;
              const char *hex_digest;
              SVN_ERR(svn_fs_contents_changed(&must_dump_text,
                                              compare_root, compare_path,
                                              eb->fs_root, path, pool));

              SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_md5,
                                           compare_root, compare_path,
                                           TRUE, pool));
              hex_digest = svn_checksum_to_cstring(checksum, pool);
              if (hex_digest)
                SVN_ERR(svn_stream_printf(eb->stream, pool,
                                      SVN_REPOS_DUMPFILE_TEXT_COPY_SOURCE_MD5
                                      ": %s\n", hex_digest));

              SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_sha1,
                                           compare_root, compare_path,
                                           TRUE, pool));
              hex_digest = svn_checksum_to_cstring(checksum, pool);
              if (hex_digest)
                SVN_ERR(svn_stream_printf(eb->stream, pool,
                                      SVN_REPOS_DUMPFILE_TEXT_COPY_SOURCE_SHA1
                                      ": %s\n", hex_digest));
            }
        }
    }

  if ((! must_dump_text) && (! must_dump_props))
    {
      /* If we're not supposed to dump text or props, so be it, we can
         just go home.  However, if either one needs to be dumped,
         then our dumpstream format demands that at a *minimum*, we
         see a lone "PROPS-END" as a divider between text and props
         content within the content-block. */
      len = 2;
      return svn_stream_write(eb->stream, "\n\n", &len); /* ### needed? */
    }

  /*** Start prepping content to dump... ***/

  /* If we are supposed to dump properties, write out a property
     length header and generate a stringbuf that contains those
     property values here. */
  if (must_dump_props)
    {
      apr_hash_t *prophash, *oldhash = NULL;
      apr_size_t proplen;

      SVN_ERR(svn_fs_node_proplist(&prophash, eb->fs_root, path, pool));
      if (eb->use_deltas && compare_root)
        {
          /* Fetch the old property hash to diff against and output a header
             saying that our property contents are a delta. */
          SVN_ERR(svn_fs_node_proplist(&oldhash, compare_root, compare_path,
                                       pool));
          SVN_ERR(svn_stream_printf(eb->stream, pool,
                                    SVN_REPOS_DUMPFILE_PROP_DELTA
                                    ": true\n"));
        }
      write_hash_to_stringbuf(prophash, oldhash, &propstring, pool);
      proplen = propstring->len;
      content_length += proplen;
      SVN_ERR(svn_stream_printf(eb->stream, pool,
                                SVN_REPOS_DUMPFILE_PROP_CONTENT_LENGTH
                                ": %" APR_SIZE_T_FMT "\n", proplen));
    }

  /* If we are supposed to dump text, write out a text length header
     here, and an MD5 checksum (if available). */
  if (must_dump_text && (kind == svn_node_file))
    {
      svn_checksum_t *checksum;
      const char *hex_digest;
      svn_filesize_t textlen;

      if (eb->use_deltas)
        {
          /* Compute the text delta now and write it into a temporary
             file, so that we can find its length.  Output a header
             saying our text contents are a delta. */
          SVN_ERR(store_delta(&delta_file, &textlen, compare_root,
                              compare_path, eb->fs_root, path, pool));
          SVN_ERR(svn_stream_printf(eb->stream, pool,
                                    SVN_REPOS_DUMPFILE_TEXT_DELTA
                                    ": true\n"));

          if (compare_root)
            {
              SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_md5,
                                           compare_root, compare_path,
                                           TRUE, pool));
              hex_digest = svn_checksum_to_cstring(checksum, pool);
              if (hex_digest)
                SVN_ERR(svn_stream_printf(eb->stream, pool,
                                          SVN_REPOS_DUMPFILE_TEXT_DELTA_BASE_MD5
                                          ": %s\n", hex_digest));

              SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_sha1,
                                           compare_root, compare_path,
                                           TRUE, pool));
              hex_digest = svn_checksum_to_cstring(checksum, pool);
              if (hex_digest)
                SVN_ERR(svn_stream_printf(eb->stream, pool,
                                      SVN_REPOS_DUMPFILE_TEXT_DELTA_BASE_SHA1
                                      ": %s\n", hex_digest));
            }
        }
      else
        {
          /* Just fetch the length of the file. */
          SVN_ERR(svn_fs_file_length(&textlen, eb->fs_root, path, pool));
        }

      content_length += textlen;
      SVN_ERR(svn_stream_printf(eb->stream, pool,
                                SVN_REPOS_DUMPFILE_TEXT_CONTENT_LENGTH
                                ": %" SVN_FILESIZE_T_FMT "\n", textlen));

      SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_md5,
                                   eb->fs_root, path, TRUE, pool));
      hex_digest = svn_checksum_to_cstring(checksum, pool);
      if (hex_digest)
        SVN_ERR(svn_stream_printf(eb->stream, pool,
                                  SVN_REPOS_DUMPFILE_TEXT_CONTENT_MD5
                                  ": %s\n", hex_digest));

      SVN_ERR(svn_fs_file_checksum(&checksum, svn_checksum_sha1,
                                   eb->fs_root, path, TRUE, pool));
      hex_digest = svn_checksum_to_cstring(checksum, pool);
      if (hex_digest)
        SVN_ERR(svn_stream_printf(eb->stream, pool,
                                  SVN_REPOS_DUMPFILE_TEXT_CONTENT_SHA1
                                  ": %s\n", hex_digest));
    }

  /* 'Content-length:' is the last header before we dump the content,
     and is the sum of the text and prop contents lengths.  We write
     this only for the benefit of non-Subversion RFC-822 parsers. */
  SVN_ERR(svn_stream_printf(eb->stream, pool,
                            SVN_REPOS_DUMPFILE_CONTENT_LENGTH
                            ": %" SVN_FILESIZE_T_FMT "\n\n",
                            content_length));

  /* Dump property content if we're supposed to do so. */
  if (must_dump_props)
    {
      len = propstring->len;
      SVN_ERR(svn_stream_write(eb->stream, propstring->data, &len));
    }

  /* Dump text content */
  if (must_dump_text && (kind == svn_node_file))
    {
      svn_stream_t *contents;

      if (delta_file)
        {
          /* Make sure to close the underlying file when the stream is
             closed. */
          contents = svn_stream_from_aprfile2(delta_file, FALSE, pool);
        }
      else
        SVN_ERR(svn_fs_file_contents(&contents, eb->fs_root, path, pool));

      SVN_ERR(svn_stream_copy3(contents, svn_stream_disown(eb->stream, pool),
                               NULL, NULL, pool));
    }

  len = 2;
  return svn_stream_write(eb->stream, "\n\n", &len); /* ### needed? */
}


static svn_error_t *
open_root(void *edit_baton,
          svn_revnum_t base_revision,
          apr_pool_t *pool,
          void **root_baton)
{
  *root_baton = make_dir_baton(NULL, NULL, SVN_INVALID_REVNUM,
                               edit_baton, NULL, FALSE, pool);
  return SVN_NO_ERROR;
}


static svn_error_t *
delete_entry(const char *path,
             svn_revnum_t revision,
             void *parent_baton,
             apr_pool_t *pool)
{
  struct dir_baton *pb = parent_baton;
  const char *mypath = apr_pstrdup(pb->pool, path);

  /* remember this path needs to be deleted. */
  apr_hash_set(pb->deleted_entries, mypath, APR_HASH_KEY_STRING, pb);

  return SVN_NO_ERROR;
}


static svn_error_t *
add_directory(const char *path,
              void *parent_baton,
              const char *copyfrom_path,
              svn_revnum_t copyfrom_rev,
              apr_pool_t *pool,
              void **child_baton)
{
  struct dir_baton *pb = parent_baton;
  struct edit_baton *eb = pb->edit_baton;
  void *val;
  svn_boolean_t is_copy = FALSE;
  struct dir_baton *new_db
    = make_dir_baton(path, copyfrom_path, copyfrom_rev, eb, pb, TRUE, pool);

  /* This might be a replacement -- is the path already deleted? */
  val = apr_hash_get(pb->deleted_entries, path, APR_HASH_KEY_STRING);

  /* Detect an add-with-history. */
  is_copy = ARE_VALID_COPY_ARGS(copyfrom_path, copyfrom_rev);

  /* Dump the node. */
  SVN_ERR(dump_node(eb, path,
                    svn_node_dir,
                    val ? svn_node_action_replace : svn_node_action_add,
                    is_copy,
                    is_copy ? copyfrom_path : NULL,
                    is_copy ? copyfrom_rev : SVN_INVALID_REVNUM,
                    pool));

  if (val)
    /* Delete the path, it's now been dumped. */
    apr_hash_set(pb->deleted_entries, path, APR_HASH_KEY_STRING, NULL);

  new_db->written_out = TRUE;

  *child_baton = new_db;
  return SVN_NO_ERROR;
}


static svn_error_t *
open_directory(const char *path,
               void *parent_baton,
               svn_revnum_t base_revision,
               apr_pool_t *pool,
               void **child_baton)
{
  struct dir_baton *pb = parent_baton;
  struct edit_baton *eb = pb->edit_baton;
  struct dir_baton *new_db;
  const char *cmp_path = NULL;
  svn_revnum_t cmp_rev = SVN_INVALID_REVNUM;

  /* If the parent directory has explicit comparison path and rev,
     record the same for this one. */
  if (pb && ARE_VALID_COPY_ARGS(pb->cmp_path, pb->cmp_rev))
    {
      cmp_path = svn_path_join(pb->cmp_path,
                               svn_path_basename(path, pool), pool);
      cmp_rev = pb->cmp_rev;
    }

  new_db = make_dir_baton(path, cmp_path, cmp_rev, eb, pb, FALSE, pool);
  *child_baton = new_db;
  return SVN_NO_ERROR;
}


static svn_error_t *
close_directory(void *dir_baton,
                apr_pool_t *pool)
{
  struct dir_baton *db = dir_baton;
  struct edit_baton *eb = db->edit_baton;
  apr_hash_index_t *hi;
  apr_pool_t *subpool = svn_pool_create(pool);

  for (hi = apr_hash_first(pool, db->deleted_entries);
       hi;
       hi = apr_hash_next(hi))
    {
      const void *key;
      const char *path;
      apr_hash_this(hi, &key, NULL, NULL);
      path = key;

      svn_pool_clear(subpool);

      /* By sending 'svn_node_unknown', the Node-kind: header simply won't
         be written out.  No big deal at all, really.  The loader
         shouldn't care.  */
      SVN_ERR(dump_node(eb, path,
                        svn_node_unknown, svn_node_action_delete,
                        FALSE, NULL, SVN_INVALID_REVNUM, subpool));
    }

  svn_pool_destroy(subpool);
  return SVN_NO_ERROR;
}


static svn_error_t *
add_file(const char *path,
         void *parent_baton,
         const char *copyfrom_path,
         svn_revnum_t copyfrom_rev,
         apr_pool_t *pool,
         void **file_baton)
{
  struct dir_baton *pb = parent_baton;
  struct edit_baton *eb = pb->edit_baton;
  void *val;
  svn_boolean_t is_copy = FALSE;

  /* This might be a replacement -- is the path already deleted? */
  val = apr_hash_get(pb->deleted_entries, path, APR_HASH_KEY_STRING);

  /* Detect add-with-history. */
  is_copy = ARE_VALID_COPY_ARGS(copyfrom_path, copyfrom_rev);

  /* Dump the node. */
  SVN_ERR(dump_node(eb, path,
                    svn_node_file,
                    val ? svn_node_action_replace : svn_node_action_add,
                    is_copy,
                    is_copy ? copyfrom_path : NULL,
                    is_copy ? copyfrom_rev : SVN_INVALID_REVNUM,
                    pool));

  if (val)
    /* delete the path, it's now been dumped. */
    apr_hash_set(pb->deleted_entries, path, APR_HASH_KEY_STRING, NULL);

  *file_baton = NULL;  /* muhahahaha */
  return SVN_NO_ERROR;
}


static svn_error_t *
open_file(const char *path,
          void *parent_baton,
          svn_revnum_t ancestor_revision,
          apr_pool_t *pool,
          void **file_baton)
{
  struct dir_baton *pb = parent_baton;
  struct edit_baton *eb = pb->edit_baton;
  const char *cmp_path = NULL;
  svn_revnum_t cmp_rev = SVN_INVALID_REVNUM;

  /* If the parent directory has explicit comparison path and rev,
     record the same for this one. */
  if (pb && ARE_VALID_COPY_ARGS(pb->cmp_path, pb->cmp_rev))
    {
      cmp_path = svn_path_join(pb->cmp_path,
                               svn_path_basename(path, pool), pool);
      cmp_rev = pb->cmp_rev;
    }

  SVN_ERR(dump_node(eb, path,
                    svn_node_file, svn_node_action_change,
                    FALSE, cmp_path, cmp_rev, pool));

  *file_baton = NULL;  /* muhahahaha again */
  return SVN_NO_ERROR;
}


static svn_error_t *
change_dir_prop(void *parent_baton,
                const char *name,
                const svn_string_t *value,
                apr_pool_t *pool)
{
  struct dir_baton *db = parent_baton;
  struct edit_baton *eb = db->edit_baton;

  /* This function is what distinguishes between a directory that is
     opened to merely get somewhere, vs. one that is opened because it
     *actually* changed by itself.  */
  if (! db->written_out)
    {
      SVN_ERR(dump_node(eb, db->path,
                        svn_node_dir, svn_node_action_change,
                        FALSE, db->cmp_path, db->cmp_rev, pool));
      db->written_out = TRUE;
    }
  return SVN_NO_ERROR;
}



static svn_error_t *
get_dump_editor(const svn_delta_editor_t **editor,
                void **edit_baton,
                svn_fs_t *fs,
                svn_revnum_t to_rev,
                const char *root_path,
                svn_stream_t *stream,
                svn_stream_t *feedback_stream,
                svn_revnum_t oldest_dumped_rev,
                svn_boolean_t use_deltas,
                svn_boolean_t verify,
                apr_pool_t *pool)
{
  /* Allocate an edit baton to be stored in every directory baton.
     Set it up for the directory baton we create here, which is the
     root baton. */
  struct edit_baton *eb = apr_pcalloc(pool, sizeof(*eb));
  svn_delta_editor_t *dump_editor = svn_delta_default_editor(pool);

  /* Set up the edit baton. */
  eb->stream = stream;
  eb->feedback_stream = feedback_stream;
  eb->oldest_dumped_rev = oldest_dumped_rev;
  eb->bufsize = sizeof(eb->buffer);
  eb->path = apr_pstrdup(pool, root_path);
  SVN_ERR(svn_fs_revision_root(&(eb->fs_root), fs, to_rev, pool));
  eb->current_rev = to_rev;
  eb->use_deltas = use_deltas;
  eb->verify = verify;

  /* Set up the editor. */
  dump_editor->open_root = open_root;
  dump_editor->delete_entry = delete_entry;
  dump_editor->add_directory = add_directory;
  dump_editor->open_directory = open_directory;
  dump_editor->close_directory = close_directory;
  dump_editor->change_dir_prop = change_dir_prop;
  dump_editor->add_file = add_file;
  dump_editor->open_file = open_file;

  *edit_baton = eb;
  *editor = dump_editor;

  return SVN_NO_ERROR;
}

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

/** The main dumping routine, svn_repos_dump_fs. **/


/* Helper for svn_repos_dump_fs.

   Write a revision record of REV in FS to writable STREAM, using POOL.
 */
static svn_error_t *
write_revision_record(svn_stream_t *stream,
                      svn_fs_t *fs,
                      svn_revnum_t rev,
                      apr_pool_t *pool)
{
  apr_size_t len;
  apr_hash_t *props;
  svn_stringbuf_t *encoded_prophash;
  apr_time_t timetemp;
  svn_string_t *datevalue;

  /* Read the revision props even if we're aren't going to dump
     them for verification purposes */
  SVN_ERR(svn_fs_revision_proplist(&props, fs, rev, pool));

  /* Run revision date properties through the time conversion to
     canonicalize them. */
  /* ### Remove this when it is no longer needed for sure. */
  datevalue = apr_hash_get(props, SVN_PROP_REVISION_DATE,
                           APR_HASH_KEY_STRING);
  if (datevalue)
    {
      SVN_ERR(svn_time_from_cstring(&timetemp, datevalue->data, pool));
      datevalue = svn_string_create(svn_time_to_cstring(timetemp, pool),
                                    pool);
      apr_hash_set(props, SVN_PROP_REVISION_DATE, APR_HASH_KEY_STRING,
                   datevalue);
    }

  write_hash_to_stringbuf(props, NULL, &encoded_prophash, pool);

  /* ### someday write a revision-content-checksum */

  SVN_ERR(svn_stream_printf(stream, pool,
                            SVN_REPOS_DUMPFILE_REVISION_NUMBER
                            ": %ld\n", rev));
  SVN_ERR(svn_stream_printf(stream, pool,
                            SVN_REPOS_DUMPFILE_PROP_CONTENT_LENGTH
                            ": %" APR_SIZE_T_FMT "\n",
                            encoded_prophash->len));

  /* Write out a regular Content-length header for the benefit of
     non-Subversion RFC-822 parsers. */
  SVN_ERR(svn_stream_printf(stream, pool,
                            SVN_REPOS_DUMPFILE_CONTENT_LENGTH
                            ": %" APR_SIZE_T_FMT "\n\n",
                            encoded_prophash->len));

  len = encoded_prophash->len;
  SVN_ERR(svn_stream_write(stream, encoded_prophash->data, &len));

  len = 1;
  return svn_stream_write(stream, "\n", &len);
}



/* The main dumper. */
svn_error_t *
svn_repos_dump_fs2(svn_repos_t *repos,
                   svn_stream_t *stream,
                   svn_stream_t *feedback_stream,
                   svn_revnum_t start_rev,
                   svn_revnum_t end_rev,
                   svn_boolean_t incremental,
                   svn_boolean_t use_deltas,
                   svn_cancel_func_t cancel_func,
                   void *cancel_baton,
                   apr_pool_t *pool)
{
  const svn_delta_editor_t *dump_editor;
  void *dump_edit_baton;
  svn_revnum_t i;
  svn_fs_t *fs = svn_repos_fs(repos);
  apr_pool_t *subpool = svn_pool_create(pool);
  svn_revnum_t youngest;
  const char *uuid;
  int version;
  svn_boolean_t dumping = (stream != NULL);

  /* Determine the current youngest revision of the filesystem. */
  SVN_ERR(svn_fs_youngest_rev(&youngest, fs, pool));

  /* Use default vals if necessary. */
  if (! SVN_IS_VALID_REVNUM(start_rev))
    start_rev = 0;
  if (! SVN_IS_VALID_REVNUM(end_rev))
    end_rev = youngest;
  if (! stream)
    stream = svn_stream_empty(pool);
  if (! feedback_stream)
    feedback_stream = svn_stream_empty(pool);

  /* Validate the revisions. */
  if (start_rev > end_rev)
    return svn_error_createf(SVN_ERR_REPOS_BAD_ARGS, NULL,
                             _("Start revision %ld"
                               " is greater than end revision %ld"),
                             start_rev, end_rev);
  if (end_rev > youngest)
    return svn_error_createf(SVN_ERR_REPOS_BAD_ARGS, NULL,
                             _("End revision %ld is invalid "
                               "(youngest revision is %ld)"),
                             end_rev, youngest);
  if ((start_rev == 0) && incremental)
    incremental = FALSE; /* revision 0 looks the same regardless of
                            whether or not this is an incremental
                            dump, so just simplify things. */

  /* Write out the UUID. */
  SVN_ERR(svn_fs_get_uuid(fs, &uuid, pool));

  /* If we're not using deltas, use the previous version, for
     compatibility with svn 1.0.x. */
  version = SVN_REPOS_DUMPFILE_FORMAT_VERSION;
  if (!use_deltas)
    version--;

  /* Write out "general" metadata for the dumpfile.  In this case, a
     magic header followed by a dumpfile format version. */
  SVN_ERR(svn_stream_printf(stream, pool,
                            SVN_REPOS_DUMPFILE_MAGIC_HEADER ": %d\n\n",
                            version));
  SVN_ERR(svn_stream_printf(stream, pool, SVN_REPOS_DUMPFILE_UUID
                            ": %s\n\n", uuid));

  /* Main loop:  we're going to dump revision i.  */
  for (i = start_rev; i <= end_rev; i++)
    {
      svn_revnum_t from_rev, to_rev;
      svn_fs_root_t *to_root;
      svn_boolean_t use_deltas_for_rev;

      svn_pool_clear(subpool);

      /* Check for cancellation. */
      if (cancel_func)
        SVN_ERR(cancel_func(cancel_baton));

      /* Special-case the initial revision dump: it needs to contain
         *all* nodes, because it's the foundation of all future
         revisions in the dumpfile. */
      if ((i == start_rev) && (! incremental))
        {
          /* Special-special-case a dump of revision 0. */
          if (i == 0)
            {
              /* Just write out the one revision 0 record and move on.
                 The parser might want to use its properties. */
              SVN_ERR(write_revision_record(stream, fs, 0, subpool));
              to_rev = 0;
              goto loop_end;
            }

          /* Compare START_REV to revision 0, so that everything
             appears to be added.  */
          from_rev = 0;
          to_rev = i;
        }
      else
        {
          /* In the normal case, we want to compare consecutive revs. */
          from_rev = i - 1;
          to_rev = i;
        }

      /* Write the revision record. */
      SVN_ERR(write_revision_record(stream, fs, to_rev, subpool));

      /* Fetch the editor which dumps nodes to a file.  Regardless of
         what we've been told, don't use deltas for the first rev of a
         non-incremental dump. */
      use_deltas_for_rev = use_deltas && (incremental || i != start_rev);
      SVN_ERR(get_dump_editor(&dump_editor, &dump_edit_baton, fs, to_rev,
                              "/", stream, feedback_stream, start_rev,
                              use_deltas_for_rev, FALSE, subpool));

      /* Drive the editor in one way or another. */
      SVN_ERR(svn_fs_revision_root(&to_root, fs, to_rev, subpool));

      /* If this is the first revision of a non-incremental dump,
         we're in for a full tree dump.  Otherwise, we want to simply
         replay the revision.  */
      if ((i == start_rev) && (! incremental))
        {
          svn_fs_root_t *from_root;
          SVN_ERR(svn_fs_revision_root(&from_root, fs, from_rev, subpool));
          SVN_ERR(svn_repos_dir_delta2(from_root, "/", "",
                                       to_root, "/",
                                       dump_editor, dump_edit_baton,
                                       NULL,
                                       NULL,
                                       FALSE, /* don't send text-deltas */
                                       svn_depth_infinity,
                                       FALSE, /* don't send entry props */
                                       FALSE, /* don't ignore ancestry */
                                       subpool));
        }
      else
        {
          SVN_ERR(svn_repos_replay2(to_root, "", SVN_INVALID_REVNUM, FALSE,
                                    dump_editor, dump_edit_baton,
                                    NULL, NULL, subpool));
        }

    loop_end:
      SVN_ERR(svn_stream_printf(feedback_stream, pool,
                                dumping
                                ? _("* Dumped revision %ld.\n")
                                : _("* Verified revision %ld.\n"),
                                to_rev));
    }

  svn_pool_destroy(subpool);

  return SVN_NO_ERROR;
}


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

/* verify, based on dump */


/* Creating a new revision that changes /A/B/E/bravo means creating new
   directory listings for /, /A, /A/B, and /A/B/E in the new revision, with
   each entry not changed in the new revision a link back to the entry in a
   previous revision.  svn_repos_replay()ing a revision does not verify that
   those links are correct.

   For paths actually changed in the revision we verify, we get directory
   contents or file length twice: once in the dump editor, and once here.
   We could create a new verify baton, store in it the changed paths, and
   skip those here, but that means building an entire wrapper editor and
   managing two levels of batons.  The impact from checking these entries
   twice should be minimal, while the code to avoid it is not.
*/

static svn_error_t *
verify_directory_entry(void *baton, const void *key, apr_ssize_t klen,
                       void *val, apr_pool_t *pool)
{
  struct dir_baton *db = baton;
  char *path = svn_path_join(db->path, (const char *)key, pool);
  svn_node_kind_t kind;
  apr_hash_t *dirents;
  svn_filesize_t len;

  SVN_ERR(svn_fs_check_path(&kind, db->edit_baton->fs_root, path, pool));
  switch (kind) {
  case svn_node_dir:
    /* Getting this directory's contents is enough to ensure that our
       link to it is correct. */
    SVN_ERR(svn_fs_dir_entries(&dirents, db->edit_baton->fs_root, path, pool));
    break;
  case svn_node_file:
    /* Getting this file's size is enough to ensure that our link to it
       is correct. */
    SVN_ERR(svn_fs_file_length(&len, db->edit_baton->fs_root, path, pool));
    break;
  default:
    return svn_error_createf(SVN_ERR_NODE_UNEXPECTED_KIND, NULL,
                             _("Unexpected node kind %d for '%s'"), kind, path);
  }

  return SVN_NO_ERROR;
}

static svn_error_t *
verify_close_directory(void *dir_baton,
                apr_pool_t *pool)
{
  struct dir_baton *db = dir_baton;
  apr_hash_t *dirents;
  SVN_ERR(svn_fs_dir_entries(&dirents, db->edit_baton->fs_root,
                             db->path, pool));
  SVN_ERR(svn_iter_apr_hash(NULL, dirents, verify_directory_entry,
                            dir_baton, pool));
  return close_directory(dir_baton, pool);
}

svn_error_t *
svn_repos_verify_fs(svn_repos_t *repos,
                    svn_stream_t *feedback_stream,
                    svn_revnum_t start_rev,
                    svn_revnum_t end_rev,
                    svn_cancel_func_t cancel_func,
                    void *cancel_baton,
                    apr_pool_t *pool)
{
  svn_fs_t *fs = svn_repos_fs(repos);
  svn_revnum_t youngest;
  svn_revnum_t rev;
  apr_pool_t *iterpool = svn_pool_create(pool);

  /* Determine the current youngest revision of the filesystem. */
  SVN_ERR(svn_fs_youngest_rev(&youngest, fs, pool));

  /* Use default vals if necessary. */
  if (! SVN_IS_VALID_REVNUM(start_rev))
    start_rev = 0;
  if (! SVN_IS_VALID_REVNUM(end_rev))
    end_rev = youngest;
  if (! feedback_stream)
    feedback_stream = svn_stream_empty(pool);

  /* Validate the revisions. */
  if (start_rev > end_rev)
    return svn_error_createf(SVN_ERR_REPOS_BAD_ARGS, NULL,
                             _("Start revision %ld"
                               " is greater than end revision %ld"),
                             start_rev, end_rev);
  if (end_rev > youngest)
    return svn_error_createf(SVN_ERR_REPOS_BAD_ARGS, NULL,
                             _("End revision %ld is invalid "
                               "(youngest revision is %ld)"),
                             end_rev, youngest);

  for (rev = start_rev; rev <= end_rev; rev++)
    {
      svn_delta_editor_t *dump_editor;
      void *dump_edit_baton;
      const svn_delta_editor_t *cancel_editor;
      void *cancel_edit_baton;
      svn_fs_root_t *to_root;

      svn_pool_clear(iterpool);

      /* Get cancellable dump editor, but with our close_directory handler. */
      SVN_ERR(get_dump_editor((const svn_delta_editor_t **)&dump_editor,
                              &dump_edit_baton, fs, rev, "",
                              svn_stream_empty(pool), feedback_stream,
                              start_rev,
                              FALSE, TRUE, /* use_deltas, verify */
                              iterpool));
      dump_editor->close_directory = verify_close_directory;
      SVN_ERR(svn_delta_get_cancellation_editor(cancel_func, cancel_baton,
                                                dump_editor, dump_edit_baton,
                                                &cancel_editor,
                                                &cancel_edit_baton,
                                                iterpool));

      SVN_ERR(svn_fs_revision_root(&to_root, fs, rev, iterpool));
      SVN_ERR(svn_repos_replay2(to_root, "", SVN_INVALID_REVNUM, FALSE,
                                cancel_editor, cancel_edit_baton,
                                NULL, NULL, iterpool));
      SVN_ERR(svn_stream_printf(feedback_stream, iterpool,
                                _("* Verified revision %ld.\n"),
                                rev));
    }

  svn_pool_destroy(iterpool);

  return SVN_NO_ERROR;
}