3 * ====================================================================
4 * Licensed to the Apache Software Foundation (ASF) under one
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7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
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12 * http://www.apache.org/licenses/LICENSE-2.0
14 * Unless required by applicable law or agreed to in writing,
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17 * KIND, either express or implied. See the License for the
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20 * ====================================================================
24 * @brief Delta-parsing
27 /* ==================================================================== */
35 #include <apr_pools.h>
37 #include <apr_tables.h>
38 #include <apr_file_io.h> /* for apr_file_t */
40 #include "svn_types.h"
41 #include "svn_string.h"
43 #include "svn_checksum.h"
47 #endif /* __cplusplus */
51 /** This compression level effectively disables data compression.
52 * However, the data pre-processing costs may still not be zero.
56 #define SVN_DELTA_COMPRESSION_LEVEL_NONE 0
58 /** This is the maximum compression level we can pass to zlib.
62 #define SVN_DELTA_COMPRESSION_LEVEL_MAX 9
64 /** This is the default compression level we pass to zlib. It
65 * should be between 0 and 9, with higher numbers resulting in
66 * better compression rates but slower operation.
70 #define SVN_DELTA_COMPRESSION_LEVEL_DEFAULT 5
73 * Get libsvn_delta version information.
78 svn_delta_version(void);
81 * @defgroup delta_support Delta generation and handling
88 * A text delta represents the difference between two strings of
89 * bytes, the `source' string and the `target' string. Given a source
90 * string and a target string, we can compute a text delta; given a
91 * source string and a delta, we can reconstruct the target string.
92 * However, note that deltas are not reversible: you cannot always
93 * reconstruct the source string given the target string and delta.
95 * Since text deltas can be very large, the interface here allows us
96 * to produce and consume them in pieces. Each piece, represented by
97 * an #svn_txdelta_window_t structure, describes how to produce the
98 * next section of the target string.
100 * To compute a new text delta:
102 * - We call svn_txdelta() on the streams we want to compare. That
103 * returns us an #svn_txdelta_stream_t object.
105 * - We then call svn_txdelta_next_window() on the stream object
106 * repeatedly. Each call returns a new #svn_txdelta_window_t
107 * object, which describes the next portion of the target string.
108 * When svn_txdelta_next_window() returns zero, we are done building
111 * @defgroup svn_delta_txt_delta Text deltas
115 /** Action codes for text delta instructions. */
116 enum svn_delta_action {
117 /* Note: The svndiff implementation relies on the values assigned in
118 * this enumeration matching the instruction encoding values. */
120 /** Append the @a length bytes at @a offset in the source view to the
123 * It must be the case that 0 <= @a offset < @a offset +
124 * @a length <= size of source view.
128 /** Append the @a length bytes at @a offset in the target view, to the
131 * It must be the case that 0 <= @a offset < current position in the
134 * However! @a offset + @a length may be *beyond* the end of the existing
135 * target data. "Where the heck does the text come from, then?"
136 * If you start at @a offset, and append @a length bytes one at a time,
137 * it'll work out --- you're adding new bytes to the end at the
138 * same rate you're reading them from the middle. Thus, if your
139 * current target text is "abcdefgh", and you get an #svn_txdelta_target
140 * instruction whose @a offset is 6 and whose @a length is 7,
141 * the resulting string is "abcdefghghghghg". This trick is actually
142 * useful in encoding long runs of consecutive characters, long runs
143 * of CR/LF pairs, etc.
147 /** Append the @a length bytes at @a offset in the window's @a new string
150 * It must be the case that 0 <= @a offset < @a offset +
151 * @a length <= length of @a new. Windows MUST use new data in ascending
152 * order with no overlap at the moment; svn_txdelta_to_svndiff()
158 /** A single text delta instruction. */
159 typedef struct svn_txdelta_op_t
161 /** Action code of delta instruction */
162 enum svn_delta_action action_code;
163 /** Offset of delta, see #svn_delta_action for more details. */
165 /** Number of bytes of delta, see #svn_delta_action for more details. */
170 /** An #svn_txdelta_window_t object describes how to reconstruct a
171 * contiguous section of the target string (the "target view") using a
172 * specified contiguous region of the source string (the "source
173 * view"). It contains a series of instructions which assemble the
174 * new target string text by pulling together substrings from:
178 * - the previously constructed portion of the target view,
180 * - a string of new data contained within the window structure
182 * The source view must always slide forward from one window to the
183 * next; that is, neither the beginning nor the end of the source view
184 * may move to the left as we read from a window stream. This
185 * property allows us to apply deltas to non-seekable source streams
186 * without making a full copy of the source stream.
188 typedef struct svn_txdelta_window_t
191 /** The offset of the source view for this window. */
192 svn_filesize_t sview_offset;
194 /** The length of the source view for this window. */
195 apr_size_t sview_len;
197 /** The length of the target view for this window, i.e. the number of
198 * bytes which will be reconstructed by the instruction stream. */
199 apr_size_t tview_len;
201 /** The number of instructions in this window. */
204 /** The number of svn_txdelta_source instructions in this window. If
205 * this number is 0, we don't need to read the source in order to
206 * reconstruct the target view.
210 /** The instructions for this window. */
211 const svn_txdelta_op_t *ops;
213 /** New data, for use by any `svn_txdelta_new' instructions. */
214 const svn_string_t *new_data;
216 } svn_txdelta_window_t;
219 * Return a deep copy of @a window, allocated in @a pool.
223 svn_txdelta_window_t *
224 svn_txdelta_window_dup(const svn_txdelta_window_t *window,
228 * Compose two delta windows, yielding a third, allocated in @a pool.
233 svn_txdelta_window_t *
234 svn_txdelta_compose_windows(const svn_txdelta_window_t *window_A,
235 const svn_txdelta_window_t *window_B,
239 * Apply the instructions from @a window to a source view @a sbuf to
240 * produce a target view @a tbuf.
242 * @a sbuf is assumed to have @a window->sview_len bytes of data and
243 * @a tbuf is assumed to have room for @a tlen bytes of output. @a
244 * tlen may be more than @a window->tview_len, so return the actual
245 * number of bytes written. @a sbuf is not touched and may be NULL if
246 * @a window contains no source-copy operations. This is purely a
247 * memory operation; nothing can go wrong as long as we have a valid
252 * @since Since 1.9, @a tbuf may be NULL if @a *tlen is 0.
255 svn_txdelta_apply_instructions(svn_txdelta_window_t *window,
256 const char *sbuf, char *tbuf,
259 /** A typedef for functions that consume a series of delta windows, for
260 * use in caller-pushes interfaces. Such functions will typically
261 * apply the delta windows to produce some file, or save the windows
262 * somewhere. At the end of the delta window stream, you must call
263 * this function passing zero for the @a window argument.
265 typedef svn_error_t *(*svn_txdelta_window_handler_t)(
266 svn_txdelta_window_t *window, void *baton);
269 /** This function will generate delta windows that turn @a source into
270 * @a target, and pushing these windows into the @a handler window handler
271 * callback (passing @a handler_baton to each invocation).
273 * If @a checksum is not NULL, then a checksum (of kind @a checksum_kind)
274 * will be computed for the target stream, and placed into *checksum.
276 * If @a cancel_func is not NULL, then it should refer to a cancellation
277 * function (along with @a cancel_baton).
279 * Results (the checksum) will be allocated from @a result_pool, and all
280 * temporary allocations will be performed in @a scratch_pool.
282 * Note: this function replaces the combination of svn_txdelta() and
283 * svn_txdelta_send_txstream().
288 svn_txdelta_run(svn_stream_t *source,
289 svn_stream_t *target,
290 svn_txdelta_window_handler_t handler,
292 svn_checksum_kind_t checksum_kind,
293 svn_checksum_t **checksum,
294 svn_cancel_func_t cancel_func,
296 apr_pool_t *result_pool,
297 apr_pool_t *scratch_pool);
300 /** A delta stream --- this is the hat from which we pull a series of
301 * svn_txdelta_window_t objects, which, taken in order, describe the
302 * entire target string. This type is defined within libsvn_delta, and
303 * opaque outside that library.
305 typedef struct svn_txdelta_stream_t svn_txdelta_stream_t;
308 /** A typedef for a function that will set @a *window to the next
309 * window from a #svn_txdelta_stream_t object. If there are no more
310 * delta windows, NULL will be used. The returned window, if any,
311 * will be allocated in @a pool. @a baton is the baton specified
312 * when the stream was created.
316 typedef svn_error_t *
317 (*svn_txdelta_next_window_fn_t)(svn_txdelta_window_t **window,
321 /** A typedef for a function that will return the md5 checksum of the
322 * fulltext deltified by a #svn_txdelta_stream_t object. Will
323 * return NULL if the final null window hasn't yet been returned by
324 * the stream. The returned value will be allocated in the same pool
325 * as the stream. @a baton is the baton specified when the stream was
330 typedef const unsigned char *
331 (*svn_txdelta_md5_digest_fn_t)(void *baton);
333 /** Create and return a generic text delta stream with @a baton, @a
334 * next_window and @a md5_digest. Allocate the new stream in @a
339 svn_txdelta_stream_t *
340 svn_txdelta_stream_create(void *baton,
341 svn_txdelta_next_window_fn_t next_window,
342 svn_txdelta_md5_digest_fn_t md5_digest,
345 /** Set @a *window to a pointer to the next window from the delta stream
346 * @a stream. When we have completely reconstructed the target string,
347 * set @a *window to zero.
349 * The window will be allocated in @a pool.
352 svn_txdelta_next_window(svn_txdelta_window_t **window,
353 svn_txdelta_stream_t *stream,
357 /** Return the md5 digest for the complete fulltext deltified by
358 * @a stream, or @c NULL if @a stream has not yet returned its final
359 * @c NULL window. The digest is allocated in the same memory as @a
362 const unsigned char *
363 svn_txdelta_md5_digest(svn_txdelta_stream_t *stream);
365 /** Set @a *stream to a pointer to a delta stream that will turn the byte
366 * string from @a source into the byte stream from @a target.
368 * @a source and @a target are both readable generic streams. When we call
369 * svn_txdelta_next_window() on @a *stream, it will read from @a source and
370 * @a target to gather as much data as it needs. If @a calculate_checksum
371 * is set, you may call svn_txdelta_md5_digest() to get an MD5 checksum
374 * Do any necessary allocation in a sub-pool of @a pool.
379 svn_txdelta2(svn_txdelta_stream_t **stream,
380 svn_stream_t *source,
381 svn_stream_t *target,
382 svn_boolean_t calculate_checksum,
385 /** Similar to svn_txdelta2 but always calculating the target checksum.
387 * @deprecated Provided for backward compatibility with the 1.7 API.
391 svn_txdelta(svn_txdelta_stream_t **stream,
392 svn_stream_t *source,
393 svn_stream_t *target,
398 * Return a writable stream which, when fed target data, will send
399 * delta windows to @a handler/@a handler_baton which transform the
400 * data in @a source to the target data. As usual, the window handler
401 * will receive a NULL window to signify the end of the window stream.
402 * The stream handler functions will read data from @a source as
408 svn_txdelta_target_push(svn_txdelta_window_handler_t handler,
410 svn_stream_t *source,
414 /** Send the contents of @a string to window-handler @a handler/@a baton.
415 * This is effectively a 'copy' operation, resulting in delta windows that
416 * make the target equivalent to the value of @a string.
418 * All temporary allocation is performed in @a pool.
421 svn_txdelta_send_string(const svn_string_t *string,
422 svn_txdelta_window_handler_t handler,
426 /** Send the contents of @a stream to window-handler @a handler/@a baton.
427 * This is effectively a 'copy' operation, resulting in delta windows that
428 * make the target equivalent to the stream.
430 * If @a digest is non-NULL, populate it with the md5 checksum for the
431 * fulltext that was deltified (@a digest must be at least
432 * @c APR_MD5_DIGESTSIZE bytes long).
434 * All temporary allocation is performed in @a pool.
437 svn_txdelta_send_stream(svn_stream_t *stream,
438 svn_txdelta_window_handler_t handler,
440 unsigned char *digest,
443 /** Send the contents of @a txstream to window-handler @a handler/@a baton.
444 * Windows will be extracted from the stream and delivered to the handler.
446 * All temporary allocation is performed in @a pool.
449 svn_txdelta_send_txstream(svn_txdelta_stream_t *txstream,
450 svn_txdelta_window_handler_t handler,
455 /** Send the @a contents of length @a len as a txdelta against an empty
456 * source directly to window-handler @a handler/@a handler_baton.
458 * All temporary allocation is performed in @a pool.
463 svn_txdelta_send_contents(const unsigned char *contents,
465 svn_txdelta_window_handler_t handler,
469 /** Prepare to apply a text delta. @a source is a readable generic stream
470 * yielding the source data, @a target is a writable generic stream to
471 * write target data to, and allocation takes place in a sub-pool of
472 * @a pool. On return, @a *handler is set to a window handler function and
473 * @a *handler_baton is set to the value to pass as the @a baton argument to
476 * If @a result_digest is non-NULL, it points to APR_MD5_DIGESTSIZE bytes
477 * of storage, and the final call to @a handler populates it with the
478 * MD5 digest of the resulting fulltext.
480 * If @a error_info is non-NULL, it is inserted parenthetically into
481 * the error string for any error returned by svn_txdelta_apply() or
482 * @a *handler. (It is normally used to provide path information,
483 * since there's nothing else in the delta application's context to
484 * supply a path for error messages.)
486 * @note To avoid lifetime issues, @a error_info is copied into
487 * @a pool or a subpool thereof.
490 svn_txdelta_apply(svn_stream_t *source,
491 svn_stream_t *target,
492 unsigned char *result_digest,
493 const char *error_info,
495 svn_txdelta_window_handler_t *handler,
496 void **handler_baton);
501 /*** Producing and consuming svndiff-format text deltas. ***/
503 /** Prepare to produce an svndiff-format diff from text delta windows.
504 * @a output is a writable generic stream to write the svndiff data to.
505 * Allocation takes place in a sub-pool of @a pool. On return, @a *handler
506 * is set to a window handler function and @a *handler_baton is set to
507 * the value to pass as the @a baton argument to @a *handler. The svndiff
508 * version is @a svndiff_version. @a compression_level is the zlib
509 * compression level from 0 (no compression) and 9 (maximum compression).
514 svn_txdelta_to_svndiff3(svn_txdelta_window_handler_t *handler,
515 void **handler_baton,
516 svn_stream_t *output,
518 int compression_level,
521 /** Similar to svn_txdelta_to_svndiff3(), but always using the SVN default
522 * compression level (#SVN_DELTA_COMPRESSION_LEVEL_DEFAULT).
525 * @deprecated Provided for backward compatibility with the 1.6 API.
529 svn_txdelta_to_svndiff2(svn_txdelta_window_handler_t *handler,
530 void **handler_baton,
531 svn_stream_t *output,
535 /** Similar to svn_txdelta_to_svndiff2, but always using svndiff
538 * @deprecated Provided for backward compatibility with the 1.3 API.
542 svn_txdelta_to_svndiff(svn_stream_t *output,
544 svn_txdelta_window_handler_t *handler,
545 void **handler_baton);
547 /** Return a writable generic stream which will parse svndiff-format
548 * data into a text delta, invoking @a handler with @a handler_baton
549 * whenever a new window is ready.
551 * When the caller closes this stream, this will signal completion to
552 * the window handler by invoking @a handler once more, passing zero for
553 * the @c window argument.
555 * If @a error_on_early_close is @c TRUE, then attempt to avoid
556 * signaling completion to the window handler if the delta was
557 * incomplete. Specifically, attempting to close the stream will be
558 * successful only if the data written to the stream consisted of one or
559 * more complete windows of svndiff data and no extra bytes. Otherwise,
560 * closing the stream will not signal completion to the window handler,
561 * and will return a #SVN_ERR_SVNDIFF_UNEXPECTED_END error. Note that if
562 * no data at all was written, the delta is considered incomplete.
564 * If @a error_on_early_close is @c FALSE, closing the stream will
565 * signal completion to the window handler, regardless of how much data
566 * was written, and discard any pending incomplete data.
568 * Allocate the stream in @a pool.
571 svn_txdelta_parse_svndiff(svn_txdelta_window_handler_t handler,
573 svn_boolean_t error_on_early_close,
577 * Read and parse one delta window in svndiff format from the
578 * readable stream @a stream and place it in @a *window, allocating
579 * the result in @a pool. The caller must take responsibility for
580 * stripping off the four-byte 'SVN@<ver@>' header at the beginning of
581 * the svndiff document before reading the first window, and must
582 * provide the version number (the value of the fourth byte) to each
583 * invocation of this routine with the @a svndiff_version argument.
588 svn_txdelta_read_svndiff_window(svn_txdelta_window_t **window,
589 svn_stream_t *stream,
594 * Read and skip one delta window in svndiff format from the
595 * file @a file. @a pool is used for temporary allocations. The
596 * caller must take responsibility for stripping off the four-byte
597 * 'SVN@<ver@>' header at the beginning of the svndiff document before
598 * reading or skipping the first window, and must provide the version
599 * number (the value of the fourth byte) to each invocation of this
600 * routine with the @a svndiff_version argument.
605 svn_txdelta_skip_svndiff_window(apr_file_t *file,
612 /** Traversing tree deltas.
614 * In Subversion, we've got various producers and consumers of tree
617 * In processing a `commit' command:
618 * - The client examines its working copy data, and produces a tree
619 * delta describing the changes to be committed.
620 * - The client networking library consumes that delta, and sends them
621 * across the wire as an equivalent series of network requests (for
622 * example, to svnserve as an ra_svn protocol stream, or to an
623 * Apache httpd server as WebDAV commands)
624 * - The server receives those requests and produces a tree delta ---
625 * hopefully equivalent to the one the client produced above.
626 * - The Subversion server module consumes that delta and commits an
627 * appropriate transaction to the filesystem.
629 * In processing an `update' command, the process is reversed:
630 * - The Subversion server module talks to the filesystem and produces
631 * a tree delta describing the changes necessary to bring the
632 * client's working copy up to date.
633 * - The server consumes this delta, and assembles a reply
634 * representing the appropriate changes.
635 * - The client networking library receives that reply, and produces a
636 * tree delta --- hopefully equivalent to the one the Subversion
637 * server produced above.
638 * - The working copy library consumes that delta, and makes the
639 * appropriate changes to the working copy.
641 * The simplest approach would be to represent tree deltas using the
642 * obvious data structure. To do an update, the server would
643 * construct a delta structure, and the working copy library would
644 * apply that structure to the working copy; the network layer's job
645 * would simply be to get the structure across the net intact.
647 * However, we expect that these deltas will occasionally be too large
648 * to fit in a typical workstation's swap area. For example, in
649 * checking out a 200Mb source tree, the entire source tree is
650 * represented by a single tree delta. So it's important to handle
651 * deltas that are too large to fit in swap all at once.
653 * So instead of representing the tree delta explicitly, we define a
654 * standard way for a consumer to process each piece of a tree delta
655 * as soon as the producer creates it. The #svn_delta_editor_t
656 * structure is a set of callback functions to be defined by a delta
657 * consumer, and invoked by a delta producer. Each invocation of a
658 * callback function describes a piece of the delta --- a file's
659 * contents changing, something being renamed, etc.
661 * @defgroup svn_delta_tree_deltas Tree deltas
665 /** A structure full of callback functions the delta source will invoke
666 * as it produces the delta.
668 * @note Don't try to allocate one of these yourself. Instead, always
669 * use svn_delta_default_editor() or some other constructor, to ensure
670 * that unused slots are filled in with no-op functions.
672 * <h3>Function Usage</h3>
674 * Here's how to use these functions to express a tree delta.
676 * The delta consumer implements the callback functions described in
677 * this structure, and the delta producer invokes them. So the
678 * caller (producer) is pushing tree delta data at the callee
681 * At the start of traversal, the consumer provides @a edit_baton, a
682 * baton global to the entire delta edit. If there is a target
683 * revision that needs to be set for this operation, the producer
684 * should call the @c set_target_revision function at this point.
686 * Next, if there are any tree deltas to express, the producer should
687 * pass the @a edit_baton to the @c open_root function, to get a baton
688 * representing root of the tree being edited.
690 * Most of the callbacks work in the obvious way:
698 * Each of these takes a directory baton, indicating the directory
699 * in which the change takes place, and a @a path argument, giving the
700 * path of the file, subdirectory, or directory entry to change.
702 * The @a path argument to each of the callbacks is relative to the
703 * root of the edit. Editors will usually want to join this relative
704 * path with some base stored in the edit baton (e.g. a URL, or a
705 * location in the OS filesystem).
707 * Since every call requires a parent directory baton, including
708 * @c add_directory and @c open_directory, where do we ever get our
709 * initial directory baton, to get things started? The @c open_root
710 * function returns a baton for the top directory of the change. In
711 * general, the producer needs to invoke the editor's @c open_root
712 * function before it can get anything of interest done.
714 * While @c open_root provides a directory baton for the root of
715 * the tree being changed, the @c add_directory and @c open_directory
716 * callbacks provide batons for other directories. Like the
717 * callbacks above, they take a @a parent_baton and a relative path
718 * @a path, and then return a new baton for the subdirectory being
719 * created / modified --- @a child_baton. The producer can then use
720 * @a child_baton to make further changes in that subdirectory.
722 * So, if we already have subdirectories named `foo' and `foo/bar',
723 * then the producer can create a new file named `foo/bar/baz.c' by
726 * - @c open_root () --- yielding a baton @a root for the top directory
728 * - @c open_directory (@a root, "foo") --- yielding a baton @a f for `foo'
730 * - @c open_directory (@a f, "foo/bar") --- yielding a baton @a b for
733 * - @c add_file (@a b, "foo/bar/baz.c")
735 * When the producer is finished making changes to a directory, it
736 * should call @c close_directory. This lets the consumer do any
737 * necessary cleanup, and free the baton's storage.
739 * The @c add_file and @c open_file callbacks each return a baton
740 * for the file being created or changed. This baton can then be
741 * passed to @c apply_textdelta to change the file's contents, or
742 * @c change_file_prop to change the file's properties. When the
743 * producer is finished making changes to a file, it should call
744 * @c close_file, to let the consumer clean up and free the baton.
746 * The @c add_file and @c add_directory functions each take arguments
747 * @a copyfrom_path and @a copyfrom_revision. If @a copyfrom_path is
748 * non-@c NULL, then @a copyfrom_path and @a copyfrom_revision indicate where
749 * the file or directory should be copied from (to create the file
750 * or directory being added). In that case, @a copyfrom_path must be
751 * either a path relative to the root of the edit, or a URI from the
752 * repository being edited. If @a copyfrom_path is @c NULL, then @a
753 * copyfrom_revision must be #SVN_INVALID_REVNUM; it is invalid to
754 * pass a mix of valid and invalid copyfrom arguments.
757 * <h3>Function Call Ordering</h3>
759 * There are six restrictions on the order in which the producer
760 * may use the batons:
762 * 1. The producer may call @c open_directory, @c add_directory,
763 * @c open_file, @c add_file at most once on any given directory
764 * entry. @c delete_entry may be called at most once on any given
765 * directory entry and may later be followed by @c add_directory or
766 * @c add_file on the same directory entry. @c delete_entry may
767 * not be called on any directory entry after @c open_directory,
768 * @c add_directory, @c open_file or @c add_file has been called on
769 * that directory entry.
771 * 2. The producer may not close a directory baton until it has
772 * closed all batons for its subdirectories.
774 * 3. When a producer calls @c open_directory or @c add_directory,
775 * it must specify the most recently opened of the currently open
776 * directory batons. Put another way, the producer cannot have
777 * two sibling directory batons open at the same time.
779 * 4. A producer must call @c change_dir_prop on a directory either
780 * before opening any of the directory's subdirs or after closing
781 * them, but not in the middle.
783 * 5. When the producer calls @c open_file or @c add_file, either:
785 * (a) The producer must follow with any changes to the file
786 * (@c change_file_prop and/or @c apply_textdelta, as applicable),
787 * followed by a @c close_file call, before issuing any other file
788 * or directory calls, or
790 * (b) The producer must follow with a @c change_file_prop call if
791 * it is applicable, before issuing any other file or directory
792 * calls; later, after all directory batons including the root
793 * have been closed, the producer must issue @c apply_textdelta
794 * and @c close_file calls.
796 * 6. When the producer calls @c apply_textdelta, it must make all of
797 * the window handler calls (including the @c NULL window at the
798 * end) before issuing any other #svn_delta_editor_t calls.
800 * So, the producer needs to use directory and file batons as if it
801 * is doing a single depth-first traversal of the tree, with the
802 * exception that the producer may keep file batons open in order to
803 * make @c apply_textdelta calls at the end.
806 * <h3>Pool Usage</h3>
808 * Many editor functions are invoked multiple times, in a sequence
809 * determined by the editor "driver". The driver is responsible for
810 * creating a pool for use on each iteration of the editor function,
811 * and clearing that pool between each iteration. The driver passes
812 * the appropriate pool on each function invocation.
814 * Based on the requirement of calling the editor functions in a
815 * depth-first style, it is usually customary for the driver to similarly
816 * nest the pools. However, this is only a safety feature to ensure
817 * that pools associated with deeper items are always cleared when the
818 * top-level items are also cleared. The interface does not assume, nor
819 * require, any particular organization of the pools passed to these
820 * functions. In fact, if "postfix deltas" are used for files, the file
821 * pools definitely need to live outside the scope of their parent
822 * directories' pools.
824 * Note that close_directory can be called *before* a file in that
825 * directory has been closed. That is, the directory's baton is
826 * closed before the file's baton. The implication is that
827 * @c apply_textdelta and @c close_file should not refer to a parent
828 * directory baton UNLESS the editor has taken precautions to
829 * allocate it in a pool of the appropriate lifetime (the @a dir_pool
830 * passed to @c open_directory and @c add_directory definitely does not
831 * have the proper lifetime). In general, it is recommended to simply
832 * avoid keeping a parent directory baton in a file baton.
837 * At least one implementation of the editor interface is
838 * asynchronous; an error from one operation may be detected some
839 * number of operations later. As a result, an editor driver must not
840 * assume that an error from an editing function resulted from the
841 * particular operation being detected. Moreover, once an editing
842 * function (including @c close_edit) returns an error, the edit is
843 * dead; the only further operation which may be called on the editor
846 typedef struct svn_delta_editor_t
848 /** Set the target revision for this edit to @a target_revision. This
849 * call, if used, should precede all other editor calls.
851 * @note This is typically used only for server->client update-type
852 * operations. It doesn't really make much sense for commit-type
853 * operations, because the revision of a commit isn't known until
854 * the commit is finalized.
856 * Any temporary allocations may be performed in @a scratch_pool.
858 svn_error_t *(*set_target_revision)(void *edit_baton,
859 svn_revnum_t target_revision,
860 apr_pool_t *scratch_pool);
862 /** Set @a *root_baton to a baton for the top directory of the change.
863 * (This is the top of the subtree being changed, not necessarily
864 * the root of the filesystem.) As with any other directory baton, the
865 * producer should call @c close_directory on @a root_baton when done.
866 * And as with other @c open_* calls, the @a base_revision here is the
867 * current revision of the directory (before getting bumped up to the
868 * new target revision set with @c set_target_revision).
870 * Allocations for the returned @a root_baton should be performed in
871 * @a result_pool. It is also typical to (possibly) save this pool for
872 * later usage by @c close_directory.
874 svn_error_t *(*open_root)(void *edit_baton,
875 svn_revnum_t base_revision,
876 apr_pool_t *result_pool,
880 /** Remove the directory entry at @a path, a child of the directory
881 * represented by @a parent_baton. If @a revision is a valid
882 * revision number, it is used as a sanity check to ensure that you
883 * are really removing the revision of @a path that you think you are.
885 * Any temporary allocations may be performed in @a scratch_pool.
887 * @note The @a revision parameter is typically used only for
888 * client->server commit-type operations, allowing the server to
889 * verify that it is deleting what the client thinks it should be
890 * deleting. It only really makes sense in the opposite direction
891 * (during server->client update-type operations) when the trees
892 * whose delta is being described are ancestrally related (that is,
893 * one tree is an ancestor of the other).
895 svn_error_t *(*delete_entry)(const char *path,
896 svn_revnum_t revision,
898 apr_pool_t *scratch_pool);
901 /** We are going to add a new subdirectory at @a path, a child of
902 * the directory represented by @a parent_baton. We will use
903 * the value this callback stores in @a *child_baton as the
904 * parent baton for further changes in the new subdirectory.
906 * If @a copyfrom_path is non-@c NULL, this add has history (i.e., is a
907 * copy), and the origin of the copy may be recorded as
908 * @a copyfrom_path under @a copyfrom_revision.
910 * Allocations for the returned @a child_baton should be performed in
911 * @a result_pool. It is also typical to (possibly) save this pool for
912 * later usage by @c close_directory.
914 svn_error_t *(*add_directory)(const char *path,
916 const char *copyfrom_path,
917 svn_revnum_t copyfrom_revision,
918 apr_pool_t *result_pool,
921 /** We are going to make changes in the subdirectory at @a path, a
922 * child of the directory represented by @a parent_baton.
923 * The callback must store a value in @a *child_baton that
924 * should be used as the parent baton for subsequent changes in this
925 * subdirectory. If a valid revnum, @a base_revision is the current
926 * revision of the subdirectory.
928 * Allocations for the returned @a child_baton should be performed in
929 * @a result_pool. It is also typical to (possibly) save this pool for
930 * later usage by @c close_directory.
932 svn_error_t *(*open_directory)(const char *path,
934 svn_revnum_t base_revision,
935 apr_pool_t *result_pool,
938 /** Change the value of a directory's property.
939 * - @a dir_baton specifies the directory whose property should change.
940 * - @a name is the name of the property to change.
941 * - @a value is the new (final) value of the property, or @c NULL if the
942 * property should be removed altogether.
944 * The callback is guaranteed to be called exactly once for each property
945 * whose value differs between the start and the end of the edit.
947 * Any temporary allocations may be performed in @a scratch_pool.
949 svn_error_t *(*change_dir_prop)(void *dir_baton,
951 const svn_string_t *value,
952 apr_pool_t *scratch_pool);
954 /** We are done processing a subdirectory, whose baton is @a dir_baton
955 * (set by @c add_directory or @c open_directory). We won't be using
956 * the baton any more, so whatever resources it refers to may now be
959 * Any temporary allocations may be performed in @a scratch_pool.
961 svn_error_t *(*close_directory)(void *dir_baton,
962 apr_pool_t *scratch_pool);
965 /** In the directory represented by @a parent_baton, indicate that
966 * @a path is present as a subdirectory in the edit source, but
967 * cannot be conveyed to the edit consumer. Currently, this would
968 * only occur because of authorization restrictions, but may change
971 * Any temporary allocations may be performed in @a scratch_pool.
973 svn_error_t *(*absent_directory)(const char *path,
975 apr_pool_t *scratch_pool);
977 /** We are going to add a new file at @a path, a child of the
978 * directory represented by @a parent_baton. The callback can
979 * store a baton for this new file in @a **file_baton; whatever value
980 * it stores there should be passed through to @c apply_textdelta.
982 * If @a copyfrom_path is non-@c NULL, this add has history (i.e., is a
983 * copy), and the origin of the copy may be recorded as
984 * @a copyfrom_path under @a copyfrom_revision.
986 * Allocations for the returned @a file_baton should be performed in
987 * @a result_pool. It is also typical to save this pool for later usage
988 * by @c apply_textdelta and possibly @c close_file.
990 * @note Because the editor driver could be employing the "postfix
991 * deltas" paradigm, @a result_pool could potentially be relatively
992 * long-lived. Every file baton created by the editor for a given
993 * editor drive might be resident in memory similtaneously. Editor
994 * implementations should ideally keep their file batons as
995 * conservative (memory-usage-wise) as possible, and use @a result_pool
996 * only for those batons. (Consider using a subpool of @a result_pool
997 * for scratch work, destroying the subpool before exiting this
998 * function's implementation.)
1000 svn_error_t *(*add_file)(const char *path,
1002 const char *copyfrom_path,
1003 svn_revnum_t copyfrom_revision,
1004 apr_pool_t *result_pool,
1007 /** We are going to make changes to a file at @a path, a child of the
1008 * directory represented by @a parent_baton.
1010 * The callback can store a baton for this new file in @a **file_baton;
1011 * whatever value it stores there should be passed through to
1012 * @c apply_textdelta. If a valid revnum, @a base_revision is the
1013 * current revision of the file.
1015 * Allocations for the returned @a file_baton should be performed in
1016 * @a result_pool. It is also typical to save this pool for later usage
1017 * by @c apply_textdelta and possibly @c close_file.
1019 * @note See note about memory usage on @a add_file, which also
1022 svn_error_t *(*open_file)(const char *path,
1024 svn_revnum_t base_revision,
1025 apr_pool_t *result_pool,
1028 /** Apply a text delta, yielding the new revision of a file.
1030 * @a file_baton indicates the file we're creating or updating, and the
1031 * ancestor file on which it is based; it is the baton set by some
1032 * prior @c add_file or @c open_file callback.
1034 * The callback should set @a *handler to a text delta window
1035 * handler; we will then call @a *handler on successive text
1036 * delta windows as we receive them. The callback should set
1037 * @a *handler_baton to the value we should pass as the @a baton
1038 * argument to @a *handler. These values should be allocated within
1041 * @a base_checksum is the hex MD5 digest for the base text against
1042 * which the delta is being applied; it is ignored if NULL, and may
1043 * be ignored even if not NULL. If it is not ignored, it must match
1044 * the checksum of the base text against which svndiff data is being
1045 * applied; if it does not, @c apply_textdelta or the @a *handler call
1046 * which detects the mismatch will return the error
1047 * SVN_ERR_CHECKSUM_MISMATCH (if there is no base text, there may
1048 * still be an error if @a base_checksum is neither NULL nor the hex
1049 * MD5 checksum of the empty string).
1051 svn_error_t *(*apply_textdelta)(void *file_baton,
1052 const char *base_checksum,
1053 apr_pool_t *result_pool,
1054 svn_txdelta_window_handler_t *handler,
1055 void **handler_baton);
1057 /** Change the value of a file's property.
1058 * - @a file_baton specifies the file whose property should change.
1059 * - @a name is the name of the property to change.
1060 * - @a value is the new (final) value of the property, or @c NULL if the
1061 * property should be removed altogether.
1063 * The callback is guaranteed to be called exactly once for each property
1064 * whose value differs between the start and the end of the edit.
1066 * Any temporary allocations may be performed in @a scratch_pool.
1068 svn_error_t *(*change_file_prop)(void *file_baton,
1070 const svn_string_t *value,
1071 apr_pool_t *scratch_pool);
1073 /** We are done processing a file, whose baton is @a file_baton (set by
1074 * @c add_file or @c open_file). We won't be using the baton any
1075 * more, so whatever resources it refers to may now be freed.
1077 * @a text_checksum is the hex MD5 digest for the fulltext that
1078 * resulted from a delta application, see @c apply_textdelta. The
1079 * checksum is ignored if NULL. If not null, it is compared to the
1080 * checksum of the new fulltext, and the error
1081 * SVN_ERR_CHECKSUM_MISMATCH is returned if they do not match. If
1082 * there is no new fulltext, @a text_checksum is ignored.
1084 * Any temporary allocations may be performed in @a scratch_pool.
1086 svn_error_t *(*close_file)(void *file_baton,
1087 const char *text_checksum,
1088 apr_pool_t *scratch_pool);
1090 /** In the directory represented by @a parent_baton, indicate that
1091 * @a path is present as a file in the edit source, but cannot be
1092 * cannot be conveyed to the edit consumer. Currently, this would
1093 * only occur because of authorization restrictions, but may change
1096 * Any temporary allocations may be performed in @a scratch_pool.
1098 svn_error_t *(*absent_file)(const char *path,
1100 apr_pool_t *scratch_pool);
1102 /** All delta processing is done. Call this, with the @a edit_baton for
1105 * Any temporary allocations may be performed in @a scratch_pool.
1107 svn_error_t *(*close_edit)(void *edit_baton,
1108 apr_pool_t *scratch_pool);
1110 /** The editor-driver has decided to bail out. Allow the editor to
1111 * gracefully clean up things if it needs to.
1113 * Any temporary allocations may be performed in @a scratch_pool.
1115 svn_error_t *(*abort_edit)(void *edit_baton,
1116 apr_pool_t *scratch_pool);
1118 /* Be sure to update svn_delta_get_cancellation_editor() and
1119 * svn_delta_default_editor() if you add a new callback here. */
1120 } svn_delta_editor_t;
1123 /** Return a default delta editor template, allocated in @a pool.
1125 * The editor functions in the template do only the most basic
1126 * baton-swapping: each editor function that produces a baton does so
1127 * by copying its incoming baton into the outgoing baton reference.
1129 * This editor is not intended to be useful by itself, but is meant to
1130 * be the basis for a useful editor. After getting a default editor,
1131 * you substitute in your own implementations for the editor functions
1132 * you care about. The ones you don't care about, you don't have to
1133 * implement -- you can rely on the template's implementation to
1134 * safely do nothing of consequence.
1136 svn_delta_editor_t *
1137 svn_delta_default_editor(apr_pool_t *pool);
1139 /** A text-delta window handler which does nothing.
1141 * Editors can return this handler from @c apply_textdelta if they don't
1142 * care about text delta windows.
1145 svn_delta_noop_window_handler(svn_txdelta_window_t *window,
1148 /** Set @a *editor and @a *edit_baton to a cancellation editor that
1149 * wraps @a wrapped_editor and @a wrapped_baton.
1151 * The @a editor will call @a cancel_func with @a cancel_baton when each of
1152 * its functions is called, continuing on to call the corresponding wrapped
1153 * function if @a cancel_func returns #SVN_NO_ERROR.
1155 * If @a cancel_func is @c NULL, set @a *editor to @a wrapped_editor and
1156 * @a *edit_baton to @a wrapped_baton.
1159 svn_delta_get_cancellation_editor(svn_cancel_func_t cancel_func,
1161 const svn_delta_editor_t *wrapped_editor,
1162 void *wrapped_baton,
1163 const svn_delta_editor_t **editor,
1167 /** Set @a *editor and @a *edit_baton to an depth-based filtering
1168 * editor that wraps @a wrapped_editor and @a wrapped_baton.
1170 * The @a editor will track the depth of this drive against the @a
1171 * requested_depth, taking into account whether not the edit drive is
1172 * making use of a target (via @a has_target), and forward editor
1173 * calls which operate "within" the request depth range through to @a
1176 * @a requested_depth must be one of the following depth values:
1177 * #svn_depth_infinity, #svn_depth_empty, #svn_depth_files,
1178 * #svn_depth_immediates, or #svn_depth_unknown.
1180 * If filtering is deemed unnecessary (or if @a requested_depth is
1181 * #svn_depth_unknown), @a *editor and @a *edit_baton will be set to @a
1182 * wrapped_editor and @a wrapped_baton, respectively; otherwise,
1183 * they'll be set to new objects allocated from @a pool.
1185 * @note Because the svn_delta_editor_t interface's @c delete_entry()
1186 * function doesn't carry node kind information, a depth-based
1187 * filtering editor being asked to filter for #svn_depth_files but
1188 * receiving a @c delete_entry() call on an immediate child of the
1189 * editor's target is unable to know if that deletion should be
1190 * allowed or filtered out -- a delete of a top-level file is okay in
1191 * this case, a delete of a top-level subdirectory is not. As such,
1192 * this filtering editor takes a conservative approach, and ignores
1193 * top-level deletion requests when filtering for #svn_depth_files.
1194 * Fortunately, most non-depth-aware (pre-1.5) Subversion editor
1195 * drivers can be told to drive non-recursively (where non-recursive
1196 * means essentially #svn_depth_files), which means they won't
1197 * transmit out-of-scope editor commands anyway.
1199 * @since New in 1.5.
1202 svn_delta_depth_filter_editor(const svn_delta_editor_t **editor,
1204 const svn_delta_editor_t *wrapped_editor,
1205 void *wrapped_edit_baton,
1206 svn_depth_t requested_depth,
1207 svn_boolean_t has_target,
1213 /** Path-based editor drives.
1215 * @defgroup svn_delta_path_delta_drivers Path-based delta drivers
1219 /** Callback function type for svn_delta_path_driver().
1221 * The handler of this callback is given the callback baton @a
1222 * callback_baton, @a path which is a relpath relative to the
1223 * root of the edit, and the @a parent_baton which represents
1224 * path's parent directory as created by the editor passed to
1225 * svn_delta_path_driver().
1227 * If @a path represents a directory, the handler must return a @a
1228 * *dir_baton for @a path, generated from the same editor (so that the
1229 * driver can later close that directory).
1231 * If, however, @a path represents a file, the handler should NOT
1232 * return any file batons. It can close any opened or added files
1233 * immediately, or delay that close until the end of the edit when
1234 * svn_delta_path_driver() returns.
1236 * Finally, if @a parent_baton is @c NULL, then the root of the edit
1237 * is also one of the paths passed to svn_delta_path_driver(). The
1238 * handler of this callback must call the editor's open_root()
1239 * function and return the top-level root dir baton in @a *dir_baton.
1241 typedef svn_error_t *(*svn_delta_path_driver_cb_func_t)(
1244 void *callback_baton,
1249 /** Drive @a editor (with its @a edit_baton) to visit each path in @a paths.
1250 * As each path is hit as part of the editor drive, use
1251 * @a callback_func and @a callback_baton to allow the caller to handle
1252 * the portion of the editor drive related to that path.
1254 * Each path in @a paths is a (const char *) relpath, relative
1255 * to the root path of the @a edit. The editor drive will be
1256 * performed in the same order as @a paths. The paths should be sorted
1257 * using something like svn_sort_compare_paths to ensure that a depth-first
1258 * pattern is observed for directory/file baton creation. If @a sort_paths
1259 * is set, the function will sort the paths for you. Some callers may need
1260 * further customization of the order (ie. libsvn_delta/compat.c).
1262 * Use @a scratch_pool for all necessary allocations.
1264 * @since New in 1.8.
1267 svn_delta_path_driver2(const svn_delta_editor_t *editor,
1269 const apr_array_header_t *paths,
1270 svn_boolean_t sort_paths,
1271 svn_delta_path_driver_cb_func_t callback_func,
1272 void *callback_baton,
1273 apr_pool_t *scratch_pool);
1276 /** Similar to svn_delta_path_driver2, but takes an (unused) revision,
1277 * and will sort the provided @a paths using svn_sort_compare_paths.
1279 * @note In versions prior to 1.8, this function would modify the order
1280 * of elements in @a paths, despite the 'const' marker on the parameter.
1281 * This has been fixed in 1.8.
1283 * @deprecated Provided for backward compatibility with the 1.7 API.
1287 svn_delta_path_driver(const svn_delta_editor_t *editor,
1289 svn_revnum_t revision,
1290 const apr_array_header_t *paths,
1291 svn_delta_path_driver_cb_func_t callback_func,
1292 void *callback_baton,
1293 apr_pool_t *scratch_pool);
1298 /*** File revision iterator types ***/
1301 * The callback invoked by file rev loopers, such as
1302 * svn_ra_plugin_t.get_file_revs2() and svn_repos_get_file_revs2().
1304 * @a baton is provided by the caller, @a path is the pathname of the file
1305 * in revision @a rev and @a rev_props are the revision properties.
1307 * If @a delta_handler and @a delta_baton are non-NULL, they may be set to a
1308 * handler/baton which will be called with the delta between the previous
1309 * revision and this one after the return of this callback. They may be
1310 * left as NULL/NULL.
1312 * @a result_of_merge will be @c TRUE if the revision being returned was
1313 * included as the result of a merge.
1315 * @a prop_diffs is an array of svn_prop_t elements indicating the property
1316 * delta for this and the previous revision.
1318 * @a pool may be used for temporary allocations, but you can't rely
1319 * on objects allocated to live outside of this particular call and
1320 * the immediately following calls to @a *delta_handler if any. (Pass
1321 * in a pool via @a baton if need be.)
1323 * @since New in 1.5.
1325 typedef svn_error_t *(*svn_file_rev_handler_t)(
1329 apr_hash_t *rev_props,
1330 svn_boolean_t result_of_merge,
1331 svn_txdelta_window_handler_t *delta_handler,
1333 apr_array_header_t *prop_diffs,
1337 * The old file rev handler interface.
1339 * @note #svn_file_rev_handler_old_t is a placeholder type for both
1340 * #svn_repos_file_rev_handler_t and #svn_ra_file_rev_handler_t. It is
1341 * reproduced here for dependency reasons.
1343 * @deprecated This type is provided for the svn_compat_wrap_file_rev_handler()
1344 * compatibility wrapper, and should not be used for new development.
1345 * @since New in 1.5.
1347 typedef svn_error_t *(*svn_file_rev_handler_old_t)(
1351 apr_hash_t *rev_props,
1352 svn_txdelta_window_handler_t *delta_handler,
1354 apr_array_header_t *prop_diffs,
1357 /** Return, in @a *handler2 and @a *handler2_baton a function/baton that
1358 * will call @a handler/@a handler_baton, allocating the @a *handler2_baton
1361 * @note This is used by compatibility wrappers, which exist in more than
1362 * Subversion core library.
1364 * @note #svn_file_rev_handler_old_t is a placeholder type for both
1365 * #svn_repos_file_rev_handler_t and #svn_ra_file_rev_handler_t. It is
1366 * reproduced here for dependency reasons.
1368 * @since New in 1.5.
1371 svn_compat_wrap_file_rev_handler(svn_file_rev_handler_t *handler2,
1372 void **handler2_baton,
1373 svn_file_rev_handler_old_t handler,
1374 void *handler_baton,
1377 /** @} end group: delta_support */
1382 #endif /* __cplusplus */
1384 #endif /* SVN_DELTA_H */