subversion/libsvn_fs_fs/rev_file.c - subversion - Git at Google

 /* rev_file.c --- revision file and index access functions
  *
  * ====================================================================
  *    Licensed to the Apache Software Foundation (ASF) under one
  *    or more contributor license agreements.  See the NOTICE file
  *    distributed with this work for additional information
  *    regarding copyright ownership.  The ASF licenses this file
  *    to you under the Apache License, Version 2.0 (the
  *    "License"); you may not use this file except in compliance
  *    with the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  *    Unless required by applicable law or agreed to in writing,
  *    software distributed under the License is distributed on an
  *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  *    KIND, either express or implied.  See the License for the
  *    specific language governing permissions and limitations
  *    under the License.
  * ====================================================================
  */

 #include "rev_file.h"
 #include "fs_fs.h"
 #include "index.h"
 #include "low_level.h"
 #include "util.h"

 #include "../libsvn_fs/fs-loader.h"

 #include "private/svn_io_private.h"
 #include "svn_private_config.h"

 /* Initialize the *FILE structure for REVISION in filesystem FS.  Set its
  * pool member to the provided POOL. */
 static void
 init_revision_file(svn_fs_fs__revision_file_t *file,
                    svn_fs_t *fs,
                    svn_revnum_t revision,
                    apr_pool_t *pool)
 {
   fs_fs_data_t *ffd = fs->fsap_data;

   file->is_packed = svn_fs_fs__is_packed_rev(fs, revision);
   file->start_revision = svn_fs_fs__packed_base_rev(fs, revision);

   file->file = NULL;
   file->stream = NULL;
   file->p2l_stream = NULL;
   file->l2p_stream = NULL;
   file->block_size = ffd->block_size;
   file->l2p_offset = -1;
   file->l2p_checksum = NULL;
   file->p2l_offset = -1;
   file->p2l_checksum = NULL;
   file->footer_offset = -1;
   file->pool = pool;
 }

 /* Baton type for set_read_only() */
 typedef struct set_read_only_baton_t
 {
   /* File to set to read-only. */
   const char *file_path;

   /* Scratch pool sufficient life time.
    * Ideally the pool that we registered the cleanup on. */
   apr_pool_t *pool;
 } set_read_only_baton_t;

 /* APR pool cleanup callback taking a set_read_only_baton_t baton and then
  * (trying to) set the specified file to r/o mode. */
 static apr_status_t
 set_read_only(void *baton)
 {
   set_read_only_baton_t *ro_baton = baton;
   apr_status_t status = APR_SUCCESS;
   svn_error_t *err;

   err = svn_io_set_file_read_only(ro_baton->file_path, TRUE, ro_baton->pool);
   if (err)
     {
       status = err->apr_err;
       svn_error_clear(err);
     }

   return status;
 }

 /* If the file at PATH is read-only, attempt to make it writable.  The
  * original state will be restored with RESULT_POOL gets cleaned up.
  * SCRATCH_POOL is for temporary allocations. */
 static svn_error_t *
 auto_make_writable(const char *path,
                    apr_pool_t *result_pool,
                    apr_pool_t *scratch_pool)
 {
   svn_boolean_t is_read_only;
   apr_finfo_t finfo;

   SVN_ERR(svn_io_stat(&finfo, path, SVN__APR_FINFO_READONLY, scratch_pool));
   SVN_ERR(svn_io__is_finfo_read_only(&is_read_only, &finfo, scratch_pool));

   if (is_read_only)
     {
       /* Tell the pool to restore the r/o state upon cleanup
          (assuming the file will still exist, failing silently otherwise). */
       set_read_only_baton_t *baton = apr_pcalloc(result_pool,
                                                   sizeof(*baton));
       baton->pool = result_pool;
       baton->file_path = apr_pstrdup(result_pool, path);
       apr_pool_cleanup_register(result_pool, baton,
                                 set_read_only, apr_pool_cleanup_null);

       /* Finally, allow write access (undoing it has already been scheduled
          and is idempotent). */
       SVN_ERR(svn_io_set_file_read_write(path, FALSE, scratch_pool));
     }

   return SVN_NO_ERROR;
 }

 /* Core implementation of svn_fs_fs__open_pack_or_rev_file working on an
  * existing, initialized FILE structure.  If WRITABLE is TRUE, give write
  * access to the file - temporarily resetting the r/o state if necessary.
  */
 static svn_error_t *
 open_pack_or_rev_file(svn_fs_fs__revision_file_t *file,
                       svn_fs_t *fs,
                       svn_revnum_t rev,
                       svn_boolean_t writable,
                       apr_pool_t *result_pool,
                       apr_pool_t *scratch_pool)
 {
   fs_fs_data_t *ffd = fs->fsap_data;
   svn_error_t *err;
   svn_boolean_t retry = FALSE;

   do
     {
       const char *path = svn_fs_fs__path_rev_absolute(fs, rev, scratch_pool);
       apr_file_t *apr_file;
       apr_int32_t flags = writable
                         ? APR_READ | APR_WRITE | APR_BUFFERED
                         : APR_READ | APR_BUFFERED;

       /* We may have to *temporarily* enable write access. */
       err = writable ? auto_make_writable(path, result_pool, scratch_pool)
                      : SVN_NO_ERROR;

       /* open the revision file in buffered r/o or r/w mode */
       if (!err)
         err = svn_io_file_open(&apr_file, path, flags, APR_OS_DEFAULT,
                                result_pool);

       if (!err)
         {
           file->file = apr_file;
           file->stream = svn_stream_from_aprfile2(apr_file, TRUE,
                                                   result_pool);
           file->is_packed = svn_fs_fs__is_packed_rev(fs, rev);

           return SVN_NO_ERROR;
         }

       if (err && APR_STATUS_IS_ENOENT(err->apr_err))
         {
           if (ffd->format >= SVN_FS_FS__MIN_PACKED_FORMAT)
             {
               /* Could not open the file. This may happen if the
                * file once existed but got packed later. */
               svn_error_clear(err);

               /* if that was our 2nd attempt, leave it at that. */
               if (retry)
                 return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
                                          _("No such revision %ld"), rev);

               /* We failed for the first time. Refresh cache & retry. */
               SVN_ERR(svn_fs_fs__update_min_unpacked_rev(fs, scratch_pool));
               file->start_revision = svn_fs_fs__packed_base_rev(fs, rev);

               retry = TRUE;
             }
           else
             {
               svn_error_clear(err);
               return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
                                        _("No such revision %ld"), rev);
             }
         }
       else
         {
           retry = FALSE;
         }
     }
   while (retry);

   return svn_error_trace(err);
 }

 svn_error_t *
 svn_fs_fs__open_pack_or_rev_file(svn_fs_fs__revision_file_t **file,
                                  svn_fs_t *fs,
                                  svn_revnum_t rev,
                                  apr_pool_t *result_pool,
                                  apr_pool_t *scratch_pool)
 {
   *file = apr_palloc(result_pool, sizeof(**file));
   init_revision_file(*file, fs, rev, result_pool);

   return svn_error_trace(open_pack_or_rev_file(*file, fs, rev, FALSE,
                                                result_pool, scratch_pool));
 }

 svn_error_t *
 svn_fs_fs__open_pack_or_rev_file_writable(svn_fs_fs__revision_file_t** file,
                                           svn_fs_t* fs,
                                           svn_revnum_t rev,
                                           apr_pool_t* result_pool,
                                           apr_pool_t *scratch_pool)
 {
   *file = apr_palloc(result_pool, sizeof(**file));
   init_revision_file(*file, fs, rev, result_pool);

   return svn_error_trace(open_pack_or_rev_file(*file, fs, rev, TRUE,
                                                result_pool, scratch_pool));
 }

 svn_error_t *
 svn_fs_fs__auto_read_footer(svn_fs_fs__revision_file_t *file)
 {
   if (file->l2p_offset == -1)
     {
       apr_off_t filesize = 0;
       unsigned char footer_length;
       svn_stringbuf_t *footer;

       /* Determine file size. */
       SVN_ERR(svn_io_file_seek(file->file, APR_END, &filesize, file->pool));

       /* Read last byte (containing the length of the footer). */
       SVN_ERR(svn_io_file_aligned_seek(file->file, file->block_size, NULL,
                                        filesize - 1, file->pool));
       SVN_ERR(svn_io_file_read_full2(file->file, &footer_length,
                                      sizeof(footer_length), NULL, NULL,
                                      file->pool));

       /* Read footer. */
       footer = svn_stringbuf_create_ensure(footer_length, file->pool);
       SVN_ERR(svn_io_file_aligned_seek(file->file, file->block_size, NULL,
                                        filesize - 1 - footer_length,
                                        file->pool));
       SVN_ERR(svn_io_file_read_full2(file->file, footer->data, footer_length,
                                      &footer->len, NULL, file->pool));
       footer->data[footer->len] = '\0';

       /* Extract index locations. */
       SVN_ERR(svn_fs_fs__parse_footer(&file->l2p_offset, &file->l2p_checksum,
                                       &file->p2l_offset, &file->p2l_checksum,
                                       footer, file->start_revision,
                                       filesize - footer_length - 1,
                                       file->pool));
       file->footer_offset = filesize - footer_length - 1;
     }

   return SVN_NO_ERROR;
 }

 svn_error_t *
 svn_fs_fs__open_proto_rev_file(svn_fs_fs__revision_file_t **file,
                                svn_fs_t *fs,
                                const svn_fs_fs__id_part_t *txn_id,
                                apr_pool_t* result_pool,
                                apr_pool_t *scratch_pool)
 {
   apr_file_t *apr_file;
   SVN_ERR(svn_io_file_open(&apr_file,
                            svn_fs_fs__path_txn_proto_rev(fs, txn_id,
                                                          scratch_pool),
                            APR_READ | APR_BUFFERED, APR_OS_DEFAULT,
                            result_pool));

   *file = apr_pcalloc(result_pool, sizeof(**file));
   (*file)->file = apr_file;
   (*file)->is_packed = FALSE;
   (*file)->start_revision = SVN_INVALID_REVNUM;
   (*file)->stream = svn_stream_from_aprfile2(apr_file, TRUE, result_pool);

   return SVN_NO_ERROR;
 }

 svn_error_t *
 svn_fs_fs__close_revision_file(svn_fs_fs__revision_file_t *file)
 {
   if (file->stream)
     SVN_ERR(svn_stream_close(file->stream));
   if (file->file)
     SVN_ERR(svn_io_file_close(file->file, file->pool));

   file->file = NULL;
   file->stream = NULL;
   file->l2p_stream = NULL;
   file->p2l_stream = NULL;

   return SVN_NO_ERROR;
 }
	/* rev_file.c --- revision file and index access functions
	*
	* ====================================================================
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	* ====================================================================
	*/

	#include "rev_file.h"
	#include "fs_fs.h"
	#include "index.h"
	#include "low_level.h"
	#include "util.h"

	#include "../libsvn_fs/fs-loader.h"

	#include "private/svn_io_private.h"
	#include "svn_private_config.h"

	/* Initialize the *FILE structure for REVISION in filesystem FS. Set its
	* pool member to the provided POOL. */
	static void
	init_revision_file(svn_fs_fs__revision_file_t *file,
	svn_fs_t *fs,
	svn_revnum_t revision,
	apr_pool_t *pool)
	{
	fs_fs_data_t *ffd = fs->fsap_data;

	file->is_packed = svn_fs_fs__is_packed_rev(fs, revision);
	file->start_revision = svn_fs_fs__packed_base_rev(fs, revision);

	file->file = NULL;
	file->stream = NULL;
	file->p2l_stream = NULL;
	file->l2p_stream = NULL;
	file->block_size = ffd->block_size;
	file->l2p_offset = -1;
	file->l2p_checksum = NULL;
	file->p2l_offset = -1;
	file->p2l_checksum = NULL;
	file->footer_offset = -1;
	file->pool = pool;
	}

	/* Baton type for set_read_only() */
	typedef struct set_read_only_baton_t
	{
	/* File to set to read-only. */
	const char *file_path;

	/* Scratch pool sufficient life time.
	* Ideally the pool that we registered the cleanup on. */
	apr_pool_t *pool;
	} set_read_only_baton_t;

	/* APR pool cleanup callback taking a set_read_only_baton_t baton and then
	* (trying to) set the specified file to r/o mode. */
	static apr_status_t
	set_read_only(void *baton)
	{
	set_read_only_baton_t *ro_baton = baton;
	apr_status_t status = APR_SUCCESS;
	svn_error_t *err;

	err = svn_io_set_file_read_only(ro_baton->file_path, TRUE, ro_baton->pool);
	if (err)
	{
	status = err->apr_err;
	svn_error_clear(err);
	}

	return status;
	}

	/* If the file at PATH is read-only, attempt to make it writable. The
	* original state will be restored with RESULT_POOL gets cleaned up.
	* SCRATCH_POOL is for temporary allocations. */
	static svn_error_t *
	auto_make_writable(const char *path,
	apr_pool_t *result_pool,
	apr_pool_t *scratch_pool)
	{
	svn_boolean_t is_read_only;
	apr_finfo_t finfo;

	SVN_ERR(svn_io_stat(&finfo, path, SVN__APR_FINFO_READONLY, scratch_pool));
	SVN_ERR(svn_io__is_finfo_read_only(&is_read_only, &finfo, scratch_pool));

	if (is_read_only)
	{
	/* Tell the pool to restore the r/o state upon cleanup
	(assuming the file will still exist, failing silently otherwise). */
	set_read_only_baton_t *baton = apr_pcalloc(result_pool,
	sizeof(*baton));
	baton->pool = result_pool;
	baton->file_path = apr_pstrdup(result_pool, path);
	apr_pool_cleanup_register(result_pool, baton,
	set_read_only, apr_pool_cleanup_null);

	/* Finally, allow write access (undoing it has already been scheduled
	and is idempotent). */
	SVN_ERR(svn_io_set_file_read_write(path, FALSE, scratch_pool));
	}

	return SVN_NO_ERROR;
	}

	/* Core implementation of svn_fs_fs__open_pack_or_rev_file working on an
	* existing, initialized FILE structure. If WRITABLE is TRUE, give write
	* access to the file - temporarily resetting the r/o state if necessary.
	*/
	static svn_error_t *
	open_pack_or_rev_file(svn_fs_fs__revision_file_t *file,
	svn_fs_t *fs,
	svn_revnum_t rev,
	svn_boolean_t writable,
	apr_pool_t *result_pool,
	apr_pool_t *scratch_pool)
	{
	fs_fs_data_t *ffd = fs->fsap_data;
	svn_error_t *err;
	svn_boolean_t retry = FALSE;

	do
	{
	const char *path = svn_fs_fs__path_rev_absolute(fs, rev, scratch_pool);
	apr_file_t *apr_file;
	apr_int32_t flags = writable
	? APR_READ \| APR_WRITE \| APR_BUFFERED
	: APR_READ \| APR_BUFFERED;

	/* We may have to temporarily enable write access. */
	err = writable ? auto_make_writable(path, result_pool, scratch_pool)
	: SVN_NO_ERROR;

	/* open the revision file in buffered r/o or r/w mode */
	if (!err)
	err = svn_io_file_open(&apr_file, path, flags, APR_OS_DEFAULT,
	result_pool);

	if (!err)
	{
	file->file = apr_file;
	file->stream = svn_stream_from_aprfile2(apr_file, TRUE,
	result_pool);
	file->is_packed = svn_fs_fs__is_packed_rev(fs, rev);

	return SVN_NO_ERROR;
	}

	if (err && APR_STATUS_IS_ENOENT(err->apr_err))
	{
	if (ffd->format >= SVN_FS_FS__MIN_PACKED_FORMAT)
	{
	/* Could not open the file. This may happen if the
	* file once existed but got packed later. */
	svn_error_clear(err);

	/* if that was our 2nd attempt, leave it at that. */
	if (retry)
	return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
	_("No such revision %ld"), rev);

	/* We failed for the first time. Refresh cache & retry. */
	SVN_ERR(svn_fs_fs__update_min_unpacked_rev(fs, scratch_pool));
	file->start_revision = svn_fs_fs__packed_base_rev(fs, rev);

	retry = TRUE;
	}
	else
	{
	svn_error_clear(err);
	return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
	_("No such revision %ld"), rev);
	}
	}
	else
	{
	retry = FALSE;
	}
	}
	while (retry);

	return svn_error_trace(err);
	}

	svn_error_t *
	svn_fs_fs__open_pack_or_rev_file(svn_fs_fs__revision_file_t **file,
	svn_fs_t *fs,
	svn_revnum_t rev,
	apr_pool_t *result_pool,
	apr_pool_t *scratch_pool)
	{
	file = apr_palloc(result_pool, sizeof(*file));
	init_revision_file(*file, fs, rev, result_pool);

	return svn_error_trace(open_pack_or_rev_file(*file, fs, rev, FALSE,
	result_pool, scratch_pool));
	}

	svn_error_t *
	svn_fs_fs__open_pack_or_rev_file_writable(svn_fs_fs__revision_file_t** file,
	svn_fs_t* fs,
	svn_revnum_t rev,
	apr_pool_t* result_pool,
	apr_pool_t *scratch_pool)
	{
	file = apr_palloc(result_pool, sizeof(*file));
	init_revision_file(*file, fs, rev, result_pool);

	return svn_error_trace(open_pack_or_rev_file(*file, fs, rev, TRUE,
	result_pool, scratch_pool));
	}

	svn_error_t *
	svn_fs_fs__auto_read_footer(svn_fs_fs__revision_file_t *file)
	{
	if (file->l2p_offset == -1)
	{
	apr_off_t filesize = 0;
	unsigned char footer_length;
	svn_stringbuf_t *footer;

	/* Determine file size. */
	SVN_ERR(svn_io_file_seek(file->file, APR_END, &filesize, file->pool));

	/* Read last byte (containing the length of the footer). */
	SVN_ERR(svn_io_file_aligned_seek(file->file, file->block_size, NULL,
	filesize - 1, file->pool));
	SVN_ERR(svn_io_file_read_full2(file->file, &footer_length,
	sizeof(footer_length), NULL, NULL,
	file->pool));

	/* Read footer. */
	footer = svn_stringbuf_create_ensure(footer_length, file->pool);
	SVN_ERR(svn_io_file_aligned_seek(file->file, file->block_size, NULL,
	filesize - 1 - footer_length,
	file->pool));
	SVN_ERR(svn_io_file_read_full2(file->file, footer->data, footer_length,
	&footer->len, NULL, file->pool));
	footer->data[footer->len] = '\0';

	/* Extract index locations. */
	SVN_ERR(svn_fs_fs__parse_footer(&file->l2p_offset, &file->l2p_checksum,
	&file->p2l_offset, &file->p2l_checksum,
	footer, file->start_revision,
	filesize - footer_length - 1,
	file->pool));
	file->footer_offset = filesize - footer_length - 1;
	}

	return SVN_NO_ERROR;
	}

	svn_error_t *
	svn_fs_fs__open_proto_rev_file(svn_fs_fs__revision_file_t **file,
	svn_fs_t *fs,
	const svn_fs_fs__id_part_t *txn_id,
	apr_pool_t* result_pool,
	apr_pool_t *scratch_pool)
	{
	apr_file_t *apr_file;
	SVN_ERR(svn_io_file_open(&apr_file,
	svn_fs_fs__path_txn_proto_rev(fs, txn_id,
	scratch_pool),
	APR_READ \| APR_BUFFERED, APR_OS_DEFAULT,
	result_pool));

	file = apr_pcalloc(result_pool, sizeof(*file));
	(*file)->file = apr_file;
	(*file)->is_packed = FALSE;
	(*file)->start_revision = SVN_INVALID_REVNUM;
	(*file)->stream = svn_stream_from_aprfile2(apr_file, TRUE, result_pool);

	return SVN_NO_ERROR;
	}

	svn_error_t *
	svn_fs_fs__close_revision_file(svn_fs_fs__revision_file_t *file)
	{
	if (file->stream)
	SVN_ERR(svn_stream_close(file->stream));
	if (file->file)
	SVN_ERR(svn_io_file_close(file->file, file->pool));

	file->file = NULL;
	file->stream = NULL;
	file->l2p_stream = NULL;
	file->p2l_stream = NULL;

	return SVN_NO_ERROR;
	}