Merge branch 'svn-fe' of git://repo.or.cz/git/jrn into jn/svn-fe

This simplifies svn-fe a great deal and fulfills a longstanding wish:
support for dumps with deltas in them, and incremental imports.

The cost is that commandline usage of the svn-fe tool becomes a little
more complicated since it no longer keeps state itself but instead reads
blobs back from fast-import in order to copy them between revisions and
apply deltas to them.

Also removes a couple of custom data structures and replaces them with
strbufs like other parts of Git.

* 'svn-fe' of git://repo.or.cz/git/jrn: (32 commits)
  vcs-svn: reset first_commit_done in fast_export_init
  vcs-svn: do not initialize report_buffer twice
  vcs-svn: avoid hangs from corrupt deltas
  vcs-svn: guard against overflow when computing preimage length
  vcs-svn: cap number of bytes read from sliding view
  test-svn-fe: split off "test-svn-fe -d" into a separate function
  vcs-svn: implement text-delta handling
  vcs-svn: let deltas use data from preimage
  vcs-svn: let deltas use data from postimage
  vcs-svn: verify that deltas consume all inline data
  vcs-svn: implement copyfrom_data delta instruction
  vcs-svn: read instructions from deltas
  vcs-svn: read inline data from deltas
  vcs-svn: read the preimage when applying deltas
  vcs-svn: parse svndiff0 window header
  vcs-svn: skeleton of an svn delta parser
  vcs-svn: make buffer_read_binary API more convenient
  vcs-svn: learn to maintain a sliding view of a file
  Makefile: list one vcs-svn/xdiff object or header per line
  vcs-svn: avoid using ls command twice
  ...

Conflicts:
	Makefile
	contrib/svn-fe/svn-fe.txt

18 files changed, 789 insertions, 938 deletions

diff --git a/vcs-svn/LICENSE b/vcs-svn/LICENSE
index 0a5e3c43a..eb91858b8 100644
--- a/vcs-svn/LICENSE
+++ b/vcs-svn/LICENSE
@@ -1,8 +1,7 @@
 Copyright (C) 2010 David Barr <david.barr@cordelta.com>.
 All rights reserved.
 
-Copyright (C) 2008 Jason Evans <jasone@canonware.com>.
-All rights reserved.
+Copyright (C) 2010 Jonathan Nieder <jrnieder@gmail.com>.
 
 Copyright (C) 2005 Stefan Hegny, hydrografix Consulting GmbH,
 Frankfurt/Main, Germany
diff --git a/vcs-svn/fast_export.c b/vcs-svn/fast_export.c
index 99ed70b88..19d7c34c2 100644
--- a/vcs-svn/fast_export.c
+++ b/vcs-svn/fast_export.c
@@ -4,34 +4,77 @@
  */
 
 #include "git-compat-util.h"
+#include "strbuf.h"
+#include "quote.h"
 #include "fast_export.h"
-#include "line_buffer.h"
 #include "repo_tree.h"
-#include "string_pool.h"
+#include "strbuf.h"
+#include "svndiff.h"
+#include "sliding_window.h"
+#include "line_buffer.h"
 
 #define MAX_GITSVN_LINE_LEN 4096
 
 static uint32_t first_commit_done;
+static struct line_buffer postimage = LINE_BUFFER_INIT;
+static struct line_buffer report_buffer = LINE_BUFFER_INIT;
+
+/* NEEDSWORK: move to fast_export_init() */
+static int init_postimage(void)
+{
+	static int postimage_initialized;
+	if (postimage_initialized)
+		return 0;
+	postimage_initialized = 1;
+	return buffer_tmpfile_init(&postimage);
+}
+
+void fast_export_init(int fd)
+{
+	first_commit_done = 0;
+	if (buffer_fdinit(&report_buffer, fd))
+		die_errno("cannot read from file descriptor %d", fd);
+}
+
+void fast_export_deinit(void)
+{
+	if (buffer_deinit(&report_buffer))
+		die_errno("error closing fast-import feedback stream");
+}
+
+void fast_export_reset(void)
+{
+	buffer_reset(&report_buffer);
+}
 
-void fast_export_delete(uint32_t depth, uint32_t *path)
+void fast_export_delete(const char *path)
 {
 	putchar('D');
 	putchar(' ');
-	pool_print_seq(depth, path, '/', stdout);
+	quote_c_style(path, NULL, stdout, 0);
 	putchar('\n');
 }
 
-void fast_export_modify(uint32_t depth, uint32_t *path, uint32_t mode,
-			uint32_t mark)
+static void fast_export_truncate(const char *path, uint32_t mode)
+{
+	fast_export_modify(path, mode, "inline");
+	printf("data 0\n\n");
+}
+
+void fast_export_modify(const char *path, uint32_t mode, const char *dataref)
 {
 	/* Mode must be 100644, 100755, 120000, or 160000. */
-	printf("M %06"PRIo32" :%"PRIu32" ", mode, mark);
-	pool_print_seq(depth, path, '/', stdout);
+	if (!dataref) {
+		fast_export_truncate(path, mode);
+		return;
+	}
+	printf("M %06"PRIo32" %s ", mode, dataref);
+	quote_c_style(path, NULL, stdout, 0);
 	putchar('\n');
 }
 
 static char gitsvnline[MAX_GITSVN_LINE_LEN];
-void fast_export_commit(uint32_t revision, const char *author,
+void fast_export_begin_commit(uint32_t revision, const char *author,
 			const struct strbuf *log,
 			const char *uuid, const char *url,
 			unsigned long timestamp)
@@ -47,6 +90,7 @@ void fast_export_commit(uint32_t revision, const char *author,
 		*gitsvnline = '\0';
 	}
 	printf("commit refs/heads/master\n");
+	printf("mark :%"PRIu32"\n", revision);
 	printf("committer %s <%s@%s> %ld +0000\n",
 		   *author ? author : "nobody",
 		   *author ? author : "nobody",
@@ -57,15 +101,44 @@ void fast_export_commit(uint32_t revision, const char *author,
 	printf("%s\n", gitsvnline);
 	if (!first_commit_done) {
 		if (revision > 1)
-			printf("from refs/heads/master^0\n");
+			printf("from :%"PRIu32"\n", revision - 1);
 		first_commit_done = 1;
 	}
-	repo_diff(revision - 1, revision);
-	fputc('\n', stdout);
+}
 
+void fast_export_end_commit(uint32_t revision)
+{
 	printf("progress Imported commit %"PRIu32".\n\n", revision);
 }
 
+static void ls_from_rev(uint32_t rev, const char *path)
+{
+	/* ls :5 path/to/old/file */
+	printf("ls :%"PRIu32" ", rev);
+	quote_c_style(path, NULL, stdout, 0);
+	putchar('\n');
+	fflush(stdout);
+}
+
+static void ls_from_active_commit(const char *path)
+{
+	/* ls "path/to/file" */
+	printf("ls \"");
+	quote_c_style(path, NULL, stdout, 1);
+	printf("\"\n");
+	fflush(stdout);
+}
+
+static const char *get_response_line(void)
+{
+	const char *line = buffer_read_line(&report_buffer);
+	if (line)
+		return line;
+	if (buffer_ferror(&report_buffer))
+		die_errno("error reading from fast-import");
+	die("unexpected end of fast-import feedback");
+}
+
 static void die_short_read(struct line_buffer *input)
 {
 	if (buffer_ferror(input))
@@ -73,7 +146,88 @@ static void die_short_read(struct line_buffer *input)
 	die("invalid dump: unexpected end of file");
 }
 
-void fast_export_blob(uint32_t mode, uint32_t mark, uint32_t len, struct line_buffer *input)
+static int ends_with(const char *s, size_t len, const char *suffix)
+{
+	const size_t suffixlen = strlen(suffix);
+	if (len < suffixlen)
+		return 0;
+	return !memcmp(s + len - suffixlen, suffix, suffixlen);
+}
+
+static int parse_cat_response_line(const char *header, off_t *len)
+{
+	size_t headerlen = strlen(header);
+	uintmax_t n;
+	const char *type;
+	const char *end;
+
+	if (ends_with(header, headerlen, " missing"))
+		return error("cat-blob reports missing blob: %s", header);
+	type = memmem(header, headerlen, " blob ", strlen(" blob "));
+	if (!type)
+		return error("cat-blob header has wrong object type: %s", header);
+	n = strtoumax(type + strlen(" blob "), (char **) &end, 10);
+	if (end == type + strlen(" blob "))
+		return error("cat-blob header does not contain length: %s", header);
+	if (memchr(type + strlen(" blob "), '-', end - type - strlen(" blob ")))
+		return error("cat-blob header contains negative length: %s", header);
+	if (n == UINTMAX_MAX || n > maximum_signed_value_of_type(off_t))
+		return error("blob too large for current definition of off_t");
+	*len = n;
+	if (*end)
+		return error("cat-blob header contains garbage after length: %s", header);
+	return 0;
+}
+
+static void check_preimage_overflow(off_t a, off_t b)
+{
+	if (signed_add_overflows(a, b))
+		die("blob too large for current definition of off_t");
+}
+
+static long apply_delta(off_t len, struct line_buffer *input,
+			const char *old_data, uint32_t old_mode)
+{
+	long ret;
+	struct sliding_view preimage = SLIDING_VIEW_INIT(&report_buffer, 0);
+	FILE *out;
+
+	if (init_postimage() || !(out = buffer_tmpfile_rewind(&postimage)))
+		die("cannot open temporary file for blob retrieval");
+	if (old_data) {
+		const char *response;
+		printf("cat-blob %s\n", old_data);
+		fflush(stdout);
+		response = get_response_line();
+		if (parse_cat_response_line(response, &preimage.max_off))
+			die("invalid cat-blob response: %s", response);
+		check_preimage_overflow(preimage.max_off, 1);
+	}
+	if (old_mode == REPO_MODE_LNK) {
+		strbuf_addstr(&preimage.buf, "link ");
+		check_preimage_overflow(preimage.max_off, strlen("link "));
+		preimage.max_off += strlen("link ");
+		check_preimage_overflow(preimage.max_off, 1);
+	}
+	if (svndiff0_apply(input, len, &preimage, out))
+		die("cannot apply delta");
+	if (old_data) {
+		/* Read the remainder of preimage and trailing newline. */
+		assert(!signed_add_overflows(preimage.max_off, 1));
+		preimage.max_off++;	/* room for newline */
+		if (move_window(&preimage, preimage.max_off - 1, 1))
+			die("cannot seek to end of input");
+		if (preimage.buf.buf[0] != '\n')
+			die("missing newline after cat-blob response");
+	}
+	ret = buffer_tmpfile_prepare_to_read(&postimage);
+	if (ret < 0)
+		die("cannot read temporary file for blob retrieval");
+	strbuf_release(&preimage.buf);
+	return ret;
+}
+
+void fast_export_data(uint32_t mode, uint32_t len, struct line_buffer *input)
 {
 	if (mode == REPO_MODE_LNK) {
 		/* svn symlink blobs start with "link " */
@@ -81,8 +235,79 @@ void fast_export_blob(uint32_t mode, uint32_t mark, uint32_t len, struct line_bu
 		if (buffer_skip_bytes(input, 5) != 5)
 			die_short_read(input);
 	}
-	printf("blob\nmark :%"PRIu32"\ndata %"PRIu32"\n", mark, len);
+	printf("data %"PRIu32"\n", len);
 	if (buffer_copy_bytes(input, len) != len)
 		die_short_read(input);
 	fputc('\n', stdout);
 }
+
+static int parse_ls_response(const char *response, uint32_t *mode,
+					struct strbuf *dataref)
+{
+	const char *tab;
+	const char *response_end;
+
+	assert(response);
+	response_end = response + strlen(response);
+
+	if (*response == 'm') {	/* Missing. */
+		errno = ENOENT;
+		return -1;
+	}
+
+	/* Mode. */
+	if (response_end - response < strlen("100644") ||
+	    response[strlen("100644")] != ' ')
+		die("invalid ls response: missing mode: %s", response);
+	*mode = 0;
+	for (; *response != ' '; response++) {
+		char ch = *response;
+		if (ch < '0' || ch > '7')
+			die("invalid ls response: mode is not octal: %s", response);
+		*mode *= 8;
+		*mode += ch - '0';
+	}
+
+	/* ' blob ' or ' tree ' */
+	if (response_end - response < strlen(" blob ") ||
+	    (response[1] != 'b' && response[1] != 't'))
+		die("unexpected ls response: not a tree or blob: %s", response);
+	response += strlen(" blob ");
+
+	/* Dataref. */
+	tab = memchr(response, '\t', response_end - response);
+	if (!tab)
+		die("invalid ls response: missing tab: %s", response);
+	strbuf_add(dataref, response, tab - response);
+	return 0;
+}
+
+int fast_export_ls_rev(uint32_t rev, const char *path,
+				uint32_t *mode, struct strbuf *dataref)
+{
+	ls_from_rev(rev, path);
+	return parse_ls_response(get_response_line(), mode, dataref);
+}
+
+int fast_export_ls(const char *path, uint32_t *mode, struct strbuf *dataref)
+{
+	ls_from_active_commit(path);
+	return parse_ls_response(get_response_line(), mode, dataref);
+}
+
+void fast_export_blob_delta(uint32_t mode,
+				uint32_t old_mode, const char *old_data,
+				uint32_t len, struct line_buffer *input)
+{
+	long postimage_len;
+	if (len > maximum_signed_value_of_type(off_t))
+		die("enormous delta");
+	postimage_len = apply_delta((off_t) len, input, old_data, old_mode);
+	if (mode == REPO_MODE_LNK) {
+		buffer_skip_bytes(&postimage, strlen("link "));
+		postimage_len -= strlen("link ");
+	}
+	printf("data %ld\n", postimage_len);
+	buffer_copy_bytes(&postimage, postimage_len);
+	fputc('\n', stdout);
+}
diff --git a/vcs-svn/fast_export.h b/vcs-svn/fast_export.h
index 33a8fe996..43d05b65e 100644
--- a/vcs-svn/fast_export.h
+++ b/vcs-svn/fast_export.h
@@ -1,16 +1,28 @@
 #ifndef FAST_EXPORT_H_
 #define FAST_EXPORT_H_
 
-#include "line_buffer.h"
 struct strbuf;
+struct line_buffer;
 
-void fast_export_delete(uint32_t depth, uint32_t *path);
-void fast_export_modify(uint32_t depth, uint32_t *path, uint32_t mode,
-			uint32_t mark);
-void fast_export_commit(uint32_t revision, const char *author,
+void fast_export_init(int fd);
+void fast_export_deinit(void);
+void fast_export_reset(void);
+
+void fast_export_delete(const char *path);
+void fast_export_modify(const char *path, uint32_t mode, const char *dataref);
+void fast_export_begin_commit(uint32_t revision, const char *author,
 			const struct strbuf *log, const char *uuid,
 			const char *url, unsigned long timestamp);
-void fast_export_blob(uint32_t mode, uint32_t mark, uint32_t len,
-		      struct line_buffer *input);
+void fast_export_end_commit(uint32_t revision);
+void fast_export_data(uint32_t mode, uint32_t len, struct line_buffer *input);
+void fast_export_blob_delta(uint32_t mode,
+			uint32_t old_mode, const char *old_data,
+			uint32_t len, struct line_buffer *input);
+
+/* If there is no such file at that rev, returns -1, errno == ENOENT. */
+int fast_export_ls_rev(uint32_t rev, const char *path,
+			uint32_t *mode_out, struct strbuf *dataref_out);
+int fast_export_ls(const char *path,
+			uint32_t *mode_out, struct strbuf *dataref_out);
 
 #endif
diff --git a/vcs-svn/line_buffer.c b/vcs-svn/line_buffer.c
index c39038723..01fcb842f 100644
--- a/vcs-svn/line_buffer.c
+++ b/vcs-svn/line_buffer.c
@@ -91,10 +91,10 @@ char *buffer_read_line(struct line_buffer *buf)
 	return buf->line_buffer;
 }
 
-void buffer_read_binary(struct line_buffer *buf,
-				struct strbuf *sb, uint32_t size)
+size_t buffer_read_binary(struct line_buffer *buf,
+				struct strbuf *sb, size_t size)
 {
-	strbuf_fread(sb, size, buf->infile);
+	return strbuf_fread(sb, size, buf->infile);
 }
 
 off_t buffer_copy_bytes(struct line_buffer *buf, off_t nbytes)
diff --git a/vcs-svn/line_buffer.h b/vcs-svn/line_buffer.h
index d0b22dda7..8901f214b 100644
--- a/vcs-svn/line_buffer.h
+++ b/vcs-svn/line_buffer.h
@@ -23,7 +23,7 @@ long buffer_tmpfile_prepare_to_read(struct line_buffer *buf);
 int buffer_ferror(struct line_buffer *buf);
 char *buffer_read_line(struct line_buffer *buf);
 int buffer_read_char(struct line_buffer *buf);
-void buffer_read_binary(struct line_buffer *buf, struct strbuf *sb, uint32_t len);
+size_t buffer_read_binary(struct line_buffer *buf, struct strbuf *sb, size_t len);
 /* Returns number of bytes read (not necessarily written). */
 off_t buffer_copy_bytes(struct line_buffer *buf, off_t len);
 off_t buffer_skip_bytes(struct line_buffer *buf, off_t len);
diff --git a/vcs-svn/obj_pool.h b/vcs-svn/obj_pool.h
deleted file mode 100644
index deb6eb813..000000000
--- a/vcs-svn/obj_pool.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Licensed under a two-clause BSD-style license.
- * See LICENSE for details.
- */
-
-#ifndef OBJ_POOL_H_
-#define OBJ_POOL_H_
-
-#include "git-compat-util.h"
-
-#define MAYBE_UNUSED __attribute__((__unused__))
-
-#define obj_pool_gen(pre, obj_t, initial_capacity) \
-static struct { \
-	uint32_t committed; \
-	uint32_t size; \
-	uint32_t capacity; \
-	obj_t *base; \
-} pre##_pool = {0, 0, 0, NULL}; \
-static MAYBE_UNUSED uint32_t pre##_alloc(uint32_t count) \
-{ \
-	uint32_t offset; \
-	if (pre##_pool.size + count > pre##_pool.capacity) { \
-		while (pre##_pool.size + count > pre##_pool.capacity) \
-			if (pre##_pool.capacity) \
-				pre##_pool.capacity *= 2; \
-			else \
-				pre##_pool.capacity = initial_capacity; \
-		pre##_pool.base = realloc(pre##_pool.base, \
-					pre##_pool.capacity * sizeof(obj_t)); \
-	} \
-	offset = pre##_pool.size; \
-	pre##_pool.size += count; \
-	return offset; \
-} \
-static MAYBE_UNUSED void pre##_free(uint32_t count) \
-{ \
-	pre##_pool.size -= count; \
-} \
-static MAYBE_UNUSED uint32_t pre##_offset(obj_t *obj) \
-{ \
-	return obj == NULL ? ~0 : obj - pre##_pool.base; \
-} \
-static MAYBE_UNUSED obj_t *pre##_pointer(uint32_t offset) \
-{ \
-	return offset >= pre##_pool.size ? NULL : &pre##_pool.base[offset]; \
-} \
-static MAYBE_UNUSED void pre##_commit(void) \
-{ \
-	pre##_pool.committed = pre##_pool.size; \
-} \
-static MAYBE_UNUSED void pre##_reset(void) \
-{ \
-	free(pre##_pool.base); \
-	pre##_pool.base = NULL; \
-	pre##_pool.size = 0; \
-	pre##_pool.capacity = 0; \
-	pre##_pool.committed = 0; \
-}
-
-#endif
diff --git a/vcs-svn/repo_tree.c b/vcs-svn/repo_tree.c
index c3f198d29..67d27f0b6 100644
--- a/vcs-svn/repo_tree.c
+++ b/vcs-svn/repo_tree.c
@@ -4,323 +4,45 @@
  */
 
 #include "git-compat-util.h"
-
-#include "string_pool.h"
+#include "strbuf.h"
 #include "repo_tree.h"
-#include "obj_pool.h"
 #include "fast_export.h"
 
-#include "trp.h"
-
-struct repo_dirent {
-	uint32_t name_offset;
-	struct trp_node children;
-	uint32_t mode;
-	uint32_t content_offset;
-};
-
-struct repo_dir {
-	struct trp_root entries;
-};
-
-struct repo_commit {
-	uint32_t root_dir_offset;
-};
-
-/* Memory pools for commit, dir and dirent */
-obj_pool_gen(commit, struct repo_commit, 4096)
-obj_pool_gen(dir, struct repo_dir, 4096)
-obj_pool_gen(dent, struct repo_dirent, 4096)
-
-static uint32_t active_commit;
-static uint32_t mark;
-
-static int repo_dirent_name_cmp(const void *a, const void *b);
-
-/* Treap for directory entries */
-trp_gen(static, dent_, struct repo_dirent, children, dent, repo_dirent_name_cmp)
-
-uint32_t next_blob_mark(void)
+const char *repo_read_path(const char *path, uint32_t *mode_out)
 {
-	return mark++;
-}
+	int err;
+	static struct strbuf buf = STRBUF_INIT;
 
-static struct repo_dir *repo_commit_root_dir(struct repo_commit *commit)
-{
-	return dir_pointer(commit->root_dir_offset);
-}
-
-static struct repo_dirent *repo_first_dirent(struct repo_dir *dir)
-{
-	return dent_first(&dir->entries);
-}
-
-static int repo_dirent_name_cmp(const void *a, const void *b)
-{
-	const struct repo_dirent *dent1 = a, *dent2 = b;
-	uint32_t a_offset = dent1->name_offset;
-	uint32_t b_offset = dent2->name_offset;
-	return (a_offset > b_offset) - (a_offset < b_offset);
-}
-
-static int repo_dirent_is_dir(struct repo_dirent *dent)
-{
-	return dent != NULL && dent->mode == REPO_MODE_DIR;
-}
-
-static struct repo_dir *repo_dir_from_dirent(struct repo_dirent *dent)
-{
-	if (!repo_dirent_is_dir(dent))
+	strbuf_reset(&buf);
+	err = fast_export_ls(path, mode_out, &buf);
+	if (err) {
+		if (errno != ENOENT)
+			die_errno("BUG: unexpected fast_export_ls error");
+		/* Treat missing paths as directories. */
+		*mode_out = REPO_MODE_DIR;
 		return NULL;
-	return dir_pointer(dent->content_offset);
-}
-
-static struct repo_dir *repo_clone_dir(struct repo_dir *orig_dir)
-{
-	uint32_t orig_o, new_o;
-	orig_o = dir_offset(orig_dir);
-	if (orig_o >= dir_pool.committed)
-		return orig_dir;
-	new_o = dir_alloc(1);
-	orig_dir = dir_pointer(orig_o);
-	*dir_pointer(new_o) = *orig_dir;
-	return dir_pointer(new_o);
-}
-
-static struct repo_dirent *repo_read_dirent(uint32_t revision,
-					    const uint32_t *path)
-{
-	uint32_t name = 0;
-	struct repo_dirent *key = dent_pointer(dent_alloc(1));
-	struct repo_dir *dir = NULL;
-	struct repo_dirent *dent = NULL;
-	dir = repo_commit_root_dir(commit_pointer(revision));
-	while (~(name = *path++)) {
-		key->name_offset = name;
-		dent = dent_search(&dir->entries, key);
-		if (dent == NULL || !repo_dirent_is_dir(dent))
-			break;
-		dir = repo_dir_from_dirent(dent);
 	}
-	dent_free(1);
-	return dent;
+	return buf.buf;
 }
 
-static void repo_write_dirent(const uint32_t *path, uint32_t mode,
-			      uint32_t content_offset, uint32_t del)
+void repo_copy(uint32_t revision, const char *src, const char *dst)
 {
-	uint32_t name, revision, dir_o = ~0U, parent_dir_o = ~0U;
-	struct repo_dir *dir;
-	struct repo_dirent *key;
-	struct repo_dirent *dent = NULL;
-	revision = active_commit;
-	dir = repo_commit_root_dir(commit_pointer(revision));
-	dir = repo_clone_dir(dir);
-	commit_pointer(revision)->root_dir_offset = dir_offset(dir);
-	while (~(name = *path++)) {
-		parent_dir_o = dir_offset(dir);
-
-		key = dent_pointer(dent_alloc(1));
-		key->name_offset = name;
-
-		dent = dent_search(&dir->entries, key);
-		if (dent == NULL)
-			dent = key;
-		else
-			dent_free(1);
-
-		if (dent == key) {
-			dent->mode = REPO_MODE_DIR;
-			dent->content_offset = 0;
-			dent = dent_insert(&dir->entries, dent);
-		}
-
-		if (dent_offset(dent) < dent_pool.committed) {
-			dir_o = repo_dirent_is_dir(dent) ?
-					dent->content_offset : ~0;
-			dent_remove(&dir->entries, dent);
-			dent = dent_pointer(dent_alloc(1));
-			dent->name_offset = name;
-			dent->mode = REPO_MODE_DIR;
-			dent->content_offset = dir_o;
-			dent = dent_insert(&dir->entries, dent);
-		}
-
-		dir = repo_dir_from_dirent(dent);
-		dir = repo_clone_dir(dir);
-		dent->content_offset = dir_offset(dir);
-	}
-	if (dent == NULL)
+	int err;
+	uint32_t mode;
+	static struct strbuf data = STRBUF_INIT;
+
+	strbuf_reset(&data);
+	err = fast_export_ls_rev(revision, src, &mode, &data);
+	if (err) {
+		if (errno != ENOENT)
+			die_errno("BUG: unexpected fast_export_ls_rev error");
+		fast_export_delete(dst);
 		return;
-	dent->mode = mode;
-	dent->content_offset = content_offset;
-	if (del && ~parent_dir_o)
-		dent_remove(&dir_pointer(parent_dir_o)->entries, dent);
-}
-
-uint32_t repo_read_path(const uint32_t *path)
-{
-	uint32_t content_offset = 0;
-	struct repo_dirent *dent = repo_read_dirent(active_commit, path);
-	if (dent != NULL)
-		content_offset = dent->content_offset;
-	return content_offset;
-}
-
-uint32_t repo_read_mode(const uint32_t *path)
-{
-	struct repo_dirent *dent = repo_read_dirent(active_commit, path);
-	if (dent == NULL)
-		die("invalid dump: path to be modified is missing");
-	return dent->mode;
-}
-
-void repo_copy(uint32_t revision, const uint32_t *src, const uint32_t *dst)
-{
-	uint32_t mode = 0, content_offset = 0;
-	struct repo_dirent *src_dent;
-	src_dent = repo_read_dirent(revision, src);
-	if (src_dent != NULL) {
-		mode = src_dent->mode;
-		content_offset = src_dent->content_offset;
-		repo_write_dirent(dst, mode, content_offset, 0);
-	}
-}
-
-void repo_add(uint32_t *path, uint32_t mode, uint32_t blob_mark)
-{
-	repo_write_dirent(path, mode, blob_mark, 0);
-}
-
-void repo_delete(uint32_t *path)
-{
-	repo_write_dirent(path, 0, 0, 1);
-}
-
-static void repo_git_add_r(uint32_t depth, uint32_t *path, struct repo_dir *dir);
-
-static void repo_git_add(uint32_t depth, uint32_t *path, struct repo_dirent *dent)
-{
-	if (repo_dirent_is_dir(dent))
-		repo_git_add_r(depth, path, repo_dir_from_dirent(dent));
-	else
-		fast_export_modify(depth, path,
-				   dent->mode, dent->content_offset);
-}
-
-static void repo_git_add_r(uint32_t depth, uint32_t *path, struct repo_dir *dir)
-{
-	struct repo_dirent *de = repo_first_dirent(dir);
-	while (de) {
-		path[depth] = de->name_offset;
-		repo_git_add(depth + 1, path, de);
-		de = dent_next(&dir->entries, de);
-	}
-}
-
-static void repo_diff_r(uint32_t depth, uint32_t *path, struct repo_dir *dir1,
-			struct repo_dir *dir2)
-{
-	struct repo_dirent *de1, *de2;
-	de1 = repo_first_dirent(dir1);
-	de2 = repo_first_dirent(dir2);
-
-	while (de1 && de2) {
-		if (de1->name_offset < de2->name_offset) {
-			path[depth] = de1->name_offset;
-			fast_export_delete(depth + 1, path);
-			de1 = dent_next(&dir1->entries, de1);
-			continue;
-		}
-		if (de1->name_offset > de2->name_offset) {
-			path[depth] = de2->name_offset;
-			repo_git_add(depth + 1, path, de2);
-			de2 = dent_next(&dir2->entries, de2);
-			continue;
-		}
-		path[depth] = de1->name_offset;
-
-		if (de1->mode == de2->mode &&
-		    de1->content_offset == de2->content_offset) {
-			; /* No change. */
-		} else if (repo_dirent_is_dir(de1) && repo_dirent_is_dir(de2)) {
-			repo_diff_r(depth + 1, path,
-				    repo_dir_from_dirent(de1),
-				    repo_dir_from_dirent(de2));
-		} else if (!repo_dirent_is_dir(de1) && !repo_dirent_is_dir(de2)) {
-			repo_git_add(depth + 1, path, de2);
-		} else {
-			fast_export_delete(depth + 1, path);
-			repo_git_add(depth + 1, path, de2);
-		}
-		de1 = dent_next(&dir1->entries, de1);
-		de2 = dent_next(&dir2->entries, de2);
-	}
-	while (de1) {
-		path[depth] = de1->name_offset;
-		fast_export_delete(depth + 1, path);
-		de1 = dent_next(&dir1->entries, de1);
-	}
-	while (de2) {
-		path[depth] = de2->name_offset;
-		repo_git_add(depth + 1, path, de2);
-		de2 = dent_next(&dir2->entries, de2);
-	}
-}
-
-static uint32_t path_stack[REPO_MAX_PATH_DEPTH];
-
-void repo_diff(uint32_t r1, uint32_t r2)
-{
-	repo_diff_r(0,
-		    path_stack,
-		    repo_commit_root_dir(commit_pointer(r1)),
-		    repo_commit_root_dir(commit_pointer(r2)));
-}
-
-void repo_commit(uint32_t revision, const char *author,
-		const struct strbuf *log, const char *uuid, const char *url,
-		unsigned long timestamp)
-{
-	fast_export_commit(revision, author, log, uuid, url, timestamp);
-	dent_commit();
-	dir_commit();
-	active_commit = commit_alloc(1);
-	commit_pointer(active_commit)->root_dir_offset =
-		commit_pointer(active_commit - 1)->root_dir_offset;
-}
-
-static void mark_init(void)
-{
-	uint32_t i;
-	mark = 0;
-	for (i = 0; i < dent_pool.size; i++)
-		if (!repo_dirent_is_dir(dent_pointer(i)) &&
-		    dent_pointer(i)->content_offset > mark)
-			mark = dent_pointer(i)->content_offset;
-	mark++;
-}
-
-void repo_init(void)
-{
-	mark_init();
-	if (commit_pool.size == 0) {
-		/* Create empty tree for commit 0. */
-		commit_alloc(1);
-		commit_pointer(0)->root_dir_offset = dir_alloc(1);
-		dir_pointer(0)->entries.trp_root = ~0;
-		dir_commit();
 	}
-	/* Preallocate next commit, ready for changes. */
-	active_commit = commit_alloc(1);
-	commit_pointer(active_commit)->root_dir_offset =
-		commit_pointer(active_commit - 1)->root_dir_offset;
+	fast_export_modify(dst, mode, data.buf);
 }
 
-void repo_reset(void)
+void repo_delete(const char *path)
 {
-	pool_reset();
-	commit_reset();
-	dir_reset();
-	dent_reset();
+	fast_export_delete(path);
 }
diff --git a/vcs-svn/repo_tree.h b/vcs-svn/repo_tree.h
index 37bde2e37..889c6a3c9 100644
--- a/vcs-svn/repo_tree.h
+++ b/vcs-svn/repo_tree.h
@@ -8,15 +8,11 @@ struct strbuf;
 #define REPO_MODE_EXE 0100755
 #define REPO_MODE_LNK 0120000
 
-#define REPO_MAX_PATH_LEN 4096
-#define REPO_MAX_PATH_DEPTH 1000
-
 uint32_t next_blob_mark(void);
-void repo_copy(uint32_t revision, const uint32_t *src, const uint32_t *dst);
-void repo_add(uint32_t *path, uint32_t mode, uint32_t blob_mark);
-uint32_t repo_read_path(const uint32_t *path);
-uint32_t repo_read_mode(const uint32_t *path);
-void repo_delete(uint32_t *path);
+void repo_copy(uint32_t revision, const char *src, const char *dst);
+void repo_add(const char *path, uint32_t mode, uint32_t blob_mark);
+const char *repo_read_path(const char *path, uint32_t *mode_out);
+void repo_delete(const char *path);
 void repo_commit(uint32_t revision, const char *author,
 		const struct strbuf *log, const char *uuid, const char *url,
 		long unsigned timestamp);
diff --git a/vcs-svn/sliding_window.c b/vcs-svn/sliding_window.c
new file mode 100644
index 000000000..1bac7a4c7
--- /dev/null
+++ b/vcs-svn/sliding_window.c
@@ -0,0 +1,79 @@
+/*
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "git-compat-util.h"
+#include "sliding_window.h"
+#include "line_buffer.h"
+#include "strbuf.h"
+
+static int input_error(struct line_buffer *file)
+{
+	if (!buffer_ferror(file))
+		return error("delta preimage ends early");
+	return error("cannot read delta preimage: %s", strerror(errno));
+}
+
+static int skip_or_whine(struct line_buffer *file, off_t gap)
+{
+	if (buffer_skip_bytes(file, gap) != gap)
+		return input_error(file);
+	return 0;
+}
+
+static int read_to_fill_or_whine(struct line_buffer *file,
+				struct strbuf *buf, size_t width)
+{
+	buffer_read_binary(file, buf, width - buf->len);
+	if (buf->len != width)
+		return input_error(file);
+	return 0;
+}
+
+static int check_overflow(off_t a, size_t b)
+{
+	if (b > maximum_signed_value_of_type(off_t))
+		return error("unrepresentable length in delta: "
+				"%"PRIuMAX" > OFF_MAX", (uintmax_t) b);
+	if (signed_add_overflows(a, (off_t) b))
+		return error("unrepresentable offset in delta: "
+				"%"PRIuMAX" + %"PRIuMAX" > OFF_MAX",
+				(uintmax_t) a, (uintmax_t) b);
+	return 0;
+}
+
+int move_window(struct sliding_view *view, off_t off, size_t width)
+{
+	off_t file_offset;
+	assert(view);
+	assert(view->width <= view->buf.len);
+	assert(!check_overflow(view->off, view->buf.len));
+
+	if (check_overflow(off, width))
+		return -1;
+	if (off < view->off || off + width < view->off + view->width)
+		return error("invalid delta: window slides left");
+	if (view->max_off >= 0 && view->max_off < off + width)
+		return error("delta preimage ends early");
+
+	file_offset = view->off + view->buf.len;
+	if (off < file_offset) {
+		/* Move the overlapping region into place. */
+		strbuf_remove(&view->buf, 0, off - view->off);
+	} else {
+		/* Seek ahead to skip the gap. */
+		if (skip_or_whine(view->file, off - file_offset))
+			return -1;
+		strbuf_setlen(&view->buf, 0);
+	}
+
+	if (view->buf.len > width)
+		; /* Already read. */
+	else if (read_to_fill_or_whine(view->file, &view->buf, width))
+		return -1;
+
+	view->off = off;
+	view->width = width;
+	return 0;
+}
diff --git a/vcs-svn/sliding_window.h b/vcs-svn/sliding_window.h
new file mode 100644
index 000000000..b43a825cb
--- /dev/null
+++ b/vcs-svn/sliding_window.h
@@ -0,0 +1,18 @@
+#ifndef SLIDING_WINDOW_H_
+#define SLIDING_WINDOW_H_
+
+#include "strbuf.h"
+
+struct sliding_view {
+	struct line_buffer *file;
+	off_t off;
+	size_t width;
+	off_t max_off;	/* -1 means unlimited */
+	struct strbuf buf;
+};
+
+#define SLIDING_VIEW_INIT(input, len)	{ (input), 0, 0, (len), STRBUF_INIT }
+
+extern int move_window(struct sliding_view *view, off_t off, size_t width);
+
+#endif
diff --git a/vcs-svn/string_pool.c b/vcs-svn/string_pool.c
deleted file mode 100644
index 1b63b19a3..000000000
--- a/vcs-svn/string_pool.c
+++ /dev/null
@@ -1,102 +0,0 @@
-/*
- * Licensed under a two-clause BSD-style license.
- * See LICENSE for details.
- */
-
-#include "git-compat-util.h"
-#include "trp.h"
-#include "obj_pool.h"
-#include "string_pool.h"
-
-static struct trp_root tree = { ~0U };
-
-struct node {
-	uint32_t offset;
-	struct trp_node children;
-};
-
-/* Two memory pools: one for struct node, and another for strings */
-obj_pool_gen(node, struct node, 4096)
-obj_pool_gen(string, char, 4096)
-
-static char *node_value(struct node *node)
-{
-	return node ? string_pointer(node->offset) : NULL;
-}
-
-static int node_cmp(struct node *a, struct node *b)
-{
-	return strcmp(node_value(a), node_value(b));
-}
-
-/* Build a Treap from the node structure (a trp_node w/ offset) */
-trp_gen(static, tree_, struct node, children, node, node_cmp)
-
-const char *pool_fetch(uint32_t entry)
-{
-	return node_value(node_pointer(entry));
-}
-
-uint32_t pool_intern(const char *key)
-{
-	/* Canonicalize key */
-	struct node *match = NULL, *node;
-	uint32_t key_len;
-	if (key == NULL)
-		return ~0;
-	key_len = strlen(key) + 1;
-	node = node_pointer(node_alloc(1));
-	node->offset = string_alloc(key_len);
-	strcpy(node_value(node), key);
-	match = tree_search(&tree, node);
-	if (!match) {
-		tree_insert(&tree, node);
-	} else {
-		node_free(1);
-		string_free(key_len);
-		node = match;
-	}
-	return node_offset(node);
-}
-
-uint32_t pool_tok_r(char *str, const char *delim, char **saveptr)
-{
-	char *token = strtok_r(str, delim, saveptr);
-	return token ? pool_intern(token) : ~0;
-}
-
-void pool_print_seq(uint32_t len, uint32_t *seq, char delim, FILE *stream)
-{
-	uint32_t i;
-	for (i = 0; i < len && ~seq[i]; i++) {
-		fputs(pool_fetch(seq[i]), stream);
-		if (i < len - 1 && ~seq[i + 1])
-			fputc(delim, stream);
-	}
-}
-
-uint32_t pool_tok_seq(uint32_t sz, uint32_t *seq, const char *delim, char *str)
-{
-	char *context = NULL;
-	uint32_t token = ~0U;
-	uint32_t length;
-
-	if (sz == 0)
-		return ~0;
-	if (str)
-		token = pool_tok_r(str, delim, &context);
-	for (length = 0; length < sz; length++) {
-		seq[length] = token;
-		if (token == ~0)
-			return length;
-		token = pool_tok_r(NULL, delim, &context);
-	}
-	seq[sz - 1] = ~0;
-	return sz;
-}
-
-void pool_reset(void)
-{
-	node_reset();
-	string_reset();
-}
diff --git a/vcs-svn/string_pool.h b/vcs-svn/string_pool.h
deleted file mode 100644
index 222fb66e6..000000000
--- a/vcs-svn/string_pool.h
+++ /dev/null
@@ -1,11 +0,0 @@
-#ifndef STRING_POOL_H_
-#define STRING_POOL_H_
-
-uint32_t pool_intern(const char *key);
-const char *pool_fetch(uint32_t entry);
-uint32_t pool_tok_r(char *str, const char *delim, char **saveptr);
-void pool_print_seq(uint32_t len, uint32_t *seq, char delim, FILE *stream);
-uint32_t pool_tok_seq(uint32_t sz, uint32_t *seq, const char *delim, char *str);
-void pool_reset(void);
-
-#endif
diff --git a/vcs-svn/string_pool.txt b/vcs-svn/string_pool.txt
deleted file mode 100644
index 1b41f1562..000000000
--- a/vcs-svn/string_pool.txt
+++ /dev/null
@@ -1,43 +0,0 @@
-string_pool API
-===============
-
-The string_pool API provides facilities for replacing strings
-with integer keys that can be more easily compared and stored.
-The facilities are designed so that one could teach Git without
-too much trouble to store the information needed for these keys to
-remain valid over multiple executions.
-
-Functions
----------
-
-pool_intern::
-	Include a string in the string pool and get its key.
-	If that string is already in the pool, retrieves its
-	existing key.
-
-pool_fetch::
-	Retrieve the string associated to a given key.
-
-pool_tok_r::
-	Extract the key of the next token from a string.
-	Interface mimics strtok_r.
-
-pool_print_seq::
-	Print a sequence of strings named by key to a file, using the
-	specified delimiter to separate them.
-
-	If NULL (key ~0) appears in the sequence, the sequence ends
-	early.
-
-pool_tok_seq::
-	Split a string into tokens, storing the keys of segments
-	into a caller-provided array.
-
-	Unless sz is 0, the array will always be ~0-terminated.
-	If there is not enough room for all the tokens, the
-	array holds as many tokens as fit in the entries before
-	the terminating ~0.  Return value is the index after the
-	last token, or sz if the tokens did not fit.
-
-pool_reset::
-	Deallocate storage for the string pool.
diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c
new file mode 100644
index 000000000..9ee41bbc9
--- /dev/null
+++ b/vcs-svn/svndiff.c
@@ -0,0 +1,308 @@
+/*
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "git-compat-util.h"
+#include "sliding_window.h"
+#include "line_buffer.h"
+#include "svndiff.h"
+
+/*
+ * svndiff0 applier
+ *
+ * See http://svn.apache.org/repos/asf/subversion/trunk/notes/svndiff.
+ *
+ * svndiff0 ::= 'SVN\0' window*
+ * window ::= int int int int int instructions inline_data;
+ * instructions ::= instruction*;
+ * instruction ::= view_selector int int
+ *   | copyfrom_data int
+ *   | packed_view_selector int
+ *   | packed_copyfrom_data
+ *   ;
+ * view_selector ::= copyfrom_source
+ *   | copyfrom_target
+ *   ;
+ * copyfrom_source ::= # binary 00 000000;
+ * copyfrom_target ::= # binary 01 000000;
+ * copyfrom_data ::= # binary 10 000000;
+ * packed_view_selector ::= # view_selector OR-ed with 6 bit value;
+ * packed_copyfrom_data ::= # copyfrom_data OR-ed with 6 bit value;
+ * int ::= highdigit* lowdigit;
+ * highdigit ::= # binary 1000 0000 OR-ed with 7 bit value;
+ * lowdigit ::= # 7 bit value;
+ */
+
+#define INSN_MASK	0xc0
+#define INSN_COPYFROM_SOURCE	0x00
+#define INSN_COPYFROM_TARGET	0x40
+#define INSN_COPYFROM_DATA	0x80
+#define OPERAND_MASK	0x3f
+
+#define VLI_CONTINUE	0x80
+#define VLI_DIGIT_MASK	0x7f
+#define VLI_BITS_PER_DIGIT 7
+
+struct window {
+	struct sliding_view *in;
+	struct strbuf out;
+	struct strbuf instructions;
+	struct strbuf data;
+};
+
+#define WINDOW_INIT(w)	{ (w), STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
+
+static void window_release(struct window *ctx)
+{
+	strbuf_release(&ctx->out);
+	strbuf_release(&ctx->instructions);
+	strbuf_release(&ctx->data);
+}
+
+static int write_strbuf(struct strbuf *sb, FILE *out)
+{
+	if (fwrite(sb->buf, 1, sb->len, out) == sb->len)	/* Success. */
+		return 0;
+	return error("cannot write delta postimage: %s", strerror(errno));
+}
+
+static int error_short_read(struct line_buffer *input)
+{
+	if (buffer_ferror(input))
+		return error("error reading delta: %s", strerror(errno));
+	return error("invalid delta: unexpected end of file");
+}
+
+static int read_chunk(struct line_buffer *delta, off_t *delta_len,
+		      struct strbuf *buf, size_t len)
+{
+	strbuf_reset(buf);
+	if (len > *delta_len ||
+	    buffer_read_binary(delta, buf, len) != len)
+		return error_short_read(delta);
+	*delta_len -= buf->len;
+	return 0;
+}
+
+static int read_magic(struct line_buffer *in, off_t *len)
+{
+	static const char magic[] = {'S', 'V', 'N', '\0'};
+	struct strbuf sb = STRBUF_INIT;
+
+	if (read_chunk(in, len, &sb, sizeof(magic))) {
+		strbuf_release(&sb);
+		return -1;
+	}
+	if (memcmp(sb.buf, magic, sizeof(magic))) {
+		strbuf_release(&sb);
+		return error("invalid delta: unrecognized file type");
+	}
+	strbuf_release(&sb);
+	return 0;
+}
+
+static int read_int(struct line_buffer *in, uintmax_t *result, off_t *len)
+{
+	uintmax_t rv = 0;
+	off_t sz;
+	for (sz = *len; sz; sz--) {
+		const int ch = buffer_read_char(in);
+		if (ch == EOF)
+			break;
+
+		rv <<= VLI_BITS_PER_DIGIT;
+		rv += (ch & VLI_DIGIT_MASK);
+		if (ch & VLI_CONTINUE)
+			continue;
+
+		*result = rv;
+		*len = sz - 1;
+		return 0;
+	}
+	return error_short_read(in);
+}
+
+static int parse_int(const char **buf, size_t *result, const char *end)
+{
+	size_t rv = 0;
+	const char *pos;
+	for (pos = *buf; pos != end; pos++) {
+		unsigned char ch = *pos;
+
+		rv <<= VLI_BITS_PER_DIGIT;
+		rv += (ch & VLI_DIGIT_MASK);
+		if (ch & VLI_CONTINUE)
+			continue;
+
+		*result = rv;
+		*buf = pos + 1;
+		return 0;
+	}
+	return error("invalid delta: unexpected end of instructions section");
+}
+
+static int read_offset(struct line_buffer *in, off_t *result, off_t *len)
+{
+	uintmax_t val;
+	if (read_int(in, &val, len))
+		return -1;
+	if (val > maximum_signed_value_of_type(off_t))
+		return error("unrepresentable offset in delta: %"PRIuMAX"", val);
+	*result = val;
+	return 0;
+}
+
+static int read_length(struct line_buffer *in, size_t *result, off_t *len)
+{
+	uintmax_t val;
+	if (read_int(in, &val, len))
+		return -1;
+	if (val > SIZE_MAX)
+		return error("unrepresentable length in delta: %"PRIuMAX"", val);
+	*result = val;
+	return 0;
+}
+
+static int copyfrom_source(struct window *ctx, const char **instructions,
+			   size_t nbytes, const char *insns_end)
+{
+	size_t offset;
+	if (parse_int(instructions, &offset, insns_end))
+		return -1;
+	if (unsigned_add_overflows(offset, nbytes) ||
+	    offset + nbytes > ctx->in->width)
+		return error("invalid delta: copies source data outside view");
+	strbuf_add(&ctx->out, ctx->in->buf.buf + offset, nbytes);
+	return 0;
+}
+
+static int copyfrom_target(struct window *ctx, const char **instructions,
+			   size_t nbytes, const char *instructions_end)
+{
+	size_t offset;
+	if (parse_int(instructions, &offset, instructions_end))
+		return -1;
+	if (offset >= ctx->out.len)
+		return error("invalid delta: copies from the future");
+	for (; nbytes > 0; nbytes--)
+		strbuf_addch(&ctx->out, ctx->out.buf[offset++]);
+	return 0;
+}
+
+static int copyfrom_data(struct window *ctx, size_t *data_pos, size_t nbytes)
+{
+	const size_t pos = *data_pos;
+	if (unsigned_add_overflows(pos, nbytes) ||
+	    pos + nbytes > ctx->data.len)
+		return error("invalid delta: copies unavailable inline data");
+	strbuf_add(&ctx->out, ctx->data.buf + pos, nbytes);
+	*data_pos += nbytes;
+	return 0;
+}
+
+static int parse_first_operand(const char **buf, size_t *out, const char *end)
+{
+	size_t result = (unsigned char) *(*buf)++ & OPERAND_MASK;
+	if (result) {	/* immediate operand */
+		*out = result;
+		return 0;
+	}
+	return parse_int(buf, out, end);
+}
+
+static int execute_one_instruction(struct window *ctx,
+				const char **instructions, size_t *data_pos)
+{
+	unsigned int instruction;
+	const char *insns_end = ctx->instructions.buf + ctx->instructions.len;
+	size_t nbytes;
+	assert(ctx);
+	assert(instructions && *instructions);
+	assert(data_pos);
+
+	instruction = (unsigned char) **instructions;
+	if (parse_first_operand(instructions, &nbytes, insns_end))
+		return -1;
+	switch (instruction & INSN_MASK) {
+	case INSN_COPYFROM_SOURCE:
+		return copyfrom_source(ctx, instructions, nbytes, insns_end);
+	case INSN_COPYFROM_TARGET:
+		return copyfrom_target(ctx, instructions, nbytes, insns_end);
+	case INSN_COPYFROM_DATA:
+		return copyfrom_data(ctx, data_pos, nbytes);
+	default:
+		return error("invalid delta: unrecognized instruction");
+	}
+}
+
+static int apply_window_in_core(struct window *ctx)
+{
+	const char *instructions;
+	size_t data_pos = 0;
+
+	/*
+	 * Fill ctx->out.buf using data from the source, target,
+	 * and inline data views.
+	 */
+	for (instructions = ctx->instructions.buf;
+	     instructions != ctx->instructions.buf + ctx->instructions.len;
+	     )
+		if (execute_one_instruction(ctx, &instructions, &data_pos))
+			return -1;
+	if (data_pos != ctx->data.len)
+		return error("invalid delta: does not copy all inline data");
+	return 0;
+}
+
+static int apply_one_window(struct line_buffer *delta, off_t *delta_len,
+			    struct sliding_view *preimage, FILE *out)
+{
+	struct window ctx = WINDOW_INIT(preimage);
+	size_t out_len;
+	size_t instructions_len;
+	size_t data_len;
+	assert(delta_len);
+
+	/* "source view" offset and length already handled; */
+	if (read_length(delta, &out_len, delta_len) ||
+	    read_length(delta, &instructions_len, delta_len) ||
+	    read_length(delta, &data_len, delta_len) ||
+	    read_chunk(delta, delta_len, &ctx.instructions, instructions_len) ||
+	    read_chunk(delta, delta_len, &ctx.data, data_len))
+		goto error_out;
+	strbuf_grow(&ctx.out, out_len);
+	if (apply_window_in_core(&ctx))
+		goto error_out;
+	if (ctx.out.len != out_len) {
+		error("invalid delta: incorrect postimage length");
+		goto error_out;
+	}
+	if (write_strbuf(&ctx.out, out))
+		goto error_out;
+	window_release(&ctx);
+	return 0;
+error_out:
+	window_release(&ctx);
+	return -1;
+}
+
+int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
+			struct sliding_view *preimage, FILE *postimage)
+{
+	assert(delta && preimage && postimage);
+
+	if (read_magic(delta, &delta_len))
+		return -1;
+	while (delta_len) {	/* For each window: */
+		off_t pre_off;
+		size_t pre_len;
+
+		if (read_offset(delta, &pre_off, &delta_len) ||
+		    read_length(delta, &pre_len, &delta_len) ||
+		    move_window(preimage, pre_off, pre_len) ||
+		    apply_one_window(delta, &delta_len, preimage, postimage))
+			return -1;
+	}
+	return 0;
+}
diff --git a/vcs-svn/svndiff.h b/vcs-svn/svndiff.h
new file mode 100644
index 000000000..74eb464ba
--- /dev/null
+++ b/vcs-svn/svndiff.h
@@ -0,0 +1,10 @@
+#ifndef SVNDIFF_H_
+#define SVNDIFF_H_
+
+struct line_buffer;
+struct sliding_view;
+
+extern int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
+		struct sliding_view *preimage, FILE *postimage);
+
+#endif
diff --git a/vcs-svn/svndump.c b/vcs-svn/svndump.c
index bc792223b..ca63760fe 100644
--- a/vcs-svn/svndump.c
+++ b/vcs-svn/svndump.c
@@ -11,7 +11,6 @@
 #include "repo_tree.h"
 #include "fast_export.h"
 #include "line_buffer.h"
-#include "string_pool.h"
 #include "strbuf.h"
 #include "svndump.h"
 
@@ -21,15 +20,19 @@
  */
 #define constcmp(s, ref) memcmp(s, ref, sizeof(ref) - 1)
 
+#define REPORT_FILENO 3
+
 #define NODEACT_REPLACE 4
 #define NODEACT_DELETE 3
 #define NODEACT_ADD 2
 #define NODEACT_CHANGE 1
 #define NODEACT_UNKNOWN 0
 
-#define DUMP_CTX 0
-#define REV_CTX  1
-#define NODE_CTX 2
+/* States: */
+#define DUMP_CTX 0	/* dump metadata */
+#define REV_CTX  1	/* revision metadata */
+#define NODE_CTX 2	/* node metadata */
+#define INTERNODE_CTX 3	/* between nodes */
 
 #define LENGTH_UNKNOWN (~0)
 #define DATE_RFC2822_LEN 31
@@ -38,7 +41,7 @@ static struct line_buffer input = LINE_BUFFER_INIT;
 
 static struct {
 	uint32_t action, propLength, textLength, srcRev, type;
-	uint32_t src[REPO_MAX_PATH_DEPTH], dst[REPO_MAX_PATH_DEPTH];
+	struct strbuf src, dst;
 	uint32_t text_delta, prop_delta;
 } node_ctx;
 
@@ -59,9 +62,11 @@ static void reset_node_ctx(char *fname)
 	node_ctx.action = NODEACT_UNKNOWN;
 	node_ctx.propLength = LENGTH_UNKNOWN;
 	node_ctx.textLength = LENGTH_UNKNOWN;
-	node_ctx.src[0] = ~0;
+	strbuf_reset(&node_ctx.src);
 	node_ctx.srcRev = 0;
-	pool_tok_seq(REPO_MAX_PATH_DEPTH, node_ctx.dst, "/", fname);
+	strbuf_reset(&node_ctx.dst);
+	if (fname)
+		strbuf_addstr(&node_ctx.dst, fname);
 	node_ctx.text_delta = 0;
 	node_ctx.prop_delta = 0;
 }
@@ -202,28 +207,32 @@ static void read_props(void)
 
 static void handle_node(void)
 {
-	uint32_t mark = 0;
 	const uint32_t type = node_ctx.type;
 	const int have_props = node_ctx.propLength != LENGTH_UNKNOWN;
 	const int have_text = node_ctx.textLength != LENGTH_UNKNOWN;
+	/*
+	 * Old text for this node:
+	 *  NULL	- directory or bug
+	 *  empty_blob	- empty
+	 *  "<dataref>"	- data retrievable from fast-import
+	 */
+	static const char *const empty_blob = "::empty::";
+	const char *old_data = NULL;
+	uint32_t old_mode = REPO_MODE_BLB;
 
-	if (node_ctx.text_delta)
-		die("text deltas not supported");
-	if (have_text)
-		mark = next_blob_mark();
 	if (node_ctx.action == NODEACT_DELETE) {
 		if (have_text || have_props || node_ctx.srcRev)
 			die("invalid dump: deletion node has "
 				"copyfrom info, text, or properties");
-		repo_delete(node_ctx.dst);
+		repo_delete(node_ctx.dst.buf);
 		return;
 	}
 	if (node_ctx.action == NODEACT_REPLACE) {
-		repo_delete(node_ctx.dst);
+		repo_delete(node_ctx.dst.buf);
 		node_ctx.action = NODEACT_ADD;
 	}
 	if (node_ctx.srcRev) {
-		repo_copy(node_ctx.srcRev, node_ctx.src, node_ctx.dst);
+		repo_copy(node_ctx.srcRev, node_ctx.src.buf, node_ctx.dst.buf);
 		if (node_ctx.action == NODEACT_ADD)
 			node_ctx.action = NODEACT_CHANGE;
 	}
@@ -231,23 +240,27 @@ static void handle_node(void)
 		die("invalid dump: directories cannot have text attached");
 
 	/*
-	 * Decide on the new content (mark) and mode (node_ctx.type).
+	 * Find old content (old_data) and decide on the new mode.
 	 */
-	if (node_ctx.action == NODEACT_CHANGE && !~*node_ctx.dst) {
+	if (node_ctx.action == NODEACT_CHANGE && !*node_ctx.dst.buf) {
 		if (type != REPO_MODE_DIR)
 			die("invalid dump: root of tree is not a regular file");
+		old_data = NULL;
 	} else if (node_ctx.action == NODEACT_CHANGE) {
 		uint32_t mode;
-		if (!have_text)
-			mark = repo_read_path(node_ctx.dst);
-		mode = repo_read_mode(node_ctx.dst);
+		old_data = repo_read_path(node_ctx.dst.buf, &mode);
 		if (mode == REPO_MODE_DIR && type != REPO_MODE_DIR)
 			die("invalid dump: cannot modify a directory into a file");
 		if (mode != REPO_MODE_DIR && type == REPO_MODE_DIR)
 			die("invalid dump: cannot modify a file into a directory");
 		node_ctx.type = mode;
+		old_mode = mode;
 	} else if (node_ctx.action == NODEACT_ADD) {
-		if (!have_text && type != REPO_MODE_DIR)
+		if (type == REPO_MODE_DIR)
+			old_data = NULL;
+		else if (have_text)
+			old_data = empty_blob;
+		else
 			die("invalid dump: adds node without text");
 	} else {
 		die("invalid dump: Node-path block lacks Node-action");
@@ -266,18 +279,39 @@ static void handle_node(void)
 	/*
 	 * Save the result.
 	 */
-	repo_add(node_ctx.dst, node_ctx.type, mark);
-	if (have_text)
-		fast_export_blob(node_ctx.type, mark,
-				 node_ctx.textLength, &input);
+	if (type == REPO_MODE_DIR)	/* directories are not tracked. */
+		return;
+	assert(old_data);
+	if (old_data == empty_blob)
+		/* For the fast_export_* functions, NULL means empty. */
+		old_data = NULL;
+	if (!have_text) {
+		fast_export_modify(node_ctx.dst.buf, node_ctx.type, old_data);
+		return;
+	}
+	if (!node_ctx.text_delta) {
+		fast_export_modify(node_ctx.dst.buf, node_ctx.type, "inline");
+		fast_export_data(node_ctx.type, node_ctx.textLength, &input);
+		return;
+	}
+	fast_export_modify(node_ctx.dst.buf, node_ctx.type, "inline");
+	fast_export_blob_delta(node_ctx.type, old_mode, old_data,
+				node_ctx.textLength, &input);
+}
+
+static void begin_revision(void)
+{
+	if (!rev_ctx.revision)	/* revision 0 gets no git commit. */
+		return;
+	fast_export_begin_commit(rev_ctx.revision, rev_ctx.author.buf,
+		&rev_ctx.log, dump_ctx.uuid.buf, dump_ctx.url.buf,
+		rev_ctx.timestamp);
 }
 
-static void handle_revision(void)
+static void end_revision(void)
 {
 	if (rev_ctx.revision)
-		repo_commit(rev_ctx.revision, rev_ctx.author.buf,
-			&rev_ctx.log, dump_ctx.uuid.buf, dump_ctx.url.buf,
-			rev_ctx.timestamp);
+		fast_export_end_commit(rev_ctx.revision);
 }
 
 void svndump_read(const char *url)
@@ -318,8 +352,10 @@ void svndump_read(const char *url)
 				continue;
 			if (active_ctx == NODE_CTX)
 				handle_node();
+			if (active_ctx == REV_CTX)
+				begin_revision();
 			if (active_ctx != DUMP_CTX)
-				handle_revision();
+				end_revision();
 			active_ctx = REV_CTX;
 			reset_rev_ctx(atoi(val));
 			break;
@@ -329,6 +365,8 @@ void svndump_read(const char *url)
 			if (!constcmp(t + strlen("Node-"), "path")) {
 				if (active_ctx == NODE_CTX)
 					handle_node();
+				if (active_ctx == REV_CTX)
+					begin_revision();
 				active_ctx = NODE_CTX;
 				reset_node_ctx(val);
 				break;
@@ -361,7 +399,8 @@ void svndump_read(const char *url)
 		case sizeof("Node-copyfrom-path"):
 			if (constcmp(t, "Node-copyfrom-path"))
 				continue;
-			pool_tok_seq(REPO_MAX_PATH_DEPTH, node_ctx.src, "/", val);
+			strbuf_reset(&node_ctx.src);
+			strbuf_addstr(&node_ctx.src, val);
 			break;
 		case sizeof("Node-copyfrom-rev"):
 			if (constcmp(t, "Node-copyfrom-rev"))
@@ -399,7 +438,7 @@ void svndump_read(const char *url)
 				read_props();
 			} else if (active_ctx == NODE_CTX) {
 				handle_node();
-				active_ctx = REV_CTX;
+				active_ctx = INTERNODE_CTX;
 			} else {
 				fprintf(stderr, "Unexpected content length header: %"PRIu32"\n", len);
 				if (buffer_skip_bytes(&input, len) != len)
@@ -411,19 +450,23 @@ void svndump_read(const char *url)
 		die_short_read();
 	if (active_ctx == NODE_CTX)
 		handle_node();
+	if (active_ctx == REV_CTX)
+		begin_revision();
 	if (active_ctx != DUMP_CTX)
-		handle_revision();
+		end_revision();
 }
 
 int svndump_init(const char *filename)
 {
 	if (buffer_init(&input, filename))
 		return error("cannot open %s: %s", filename, strerror(errno));
-	repo_init();
+	fast_export_init(REPORT_FILENO);
 	strbuf_init(&dump_ctx.uuid, 4096);
 	strbuf_init(&dump_ctx.url, 4096);
 	strbuf_init(&rev_ctx.log, 4096);
 	strbuf_init(&rev_ctx.author, 4096);
+	strbuf_init(&node_ctx.src, 4096);
+	strbuf_init(&node_ctx.dst, 4096);
 	reset_dump_ctx(NULL);
 	reset_rev_ctx(0);
 	reset_node_ctx(NULL);
@@ -432,11 +475,13 @@ int svndump_init(const char *filename)
 
 void svndump_deinit(void)
 {
-	repo_reset();
+	fast_export_deinit();
 	reset_dump_ctx(NULL);
 	reset_rev_ctx(0);
 	reset_node_ctx(NULL);
 	strbuf_release(&rev_ctx.log);
+	strbuf_release(&node_ctx.src);
+	strbuf_release(&node_ctx.dst);
 	if (buffer_deinit(&input))
 		fprintf(stderr, "Input error\n");
 	if (ferror(stdout))
@@ -445,8 +490,8 @@ void svndump_deinit(void)
 
 void svndump_reset(void)
 {
+	fast_export_reset();
 	buffer_reset(&input);
-	repo_reset();
 	strbuf_release(&dump_ctx.uuid);
 	strbuf_release(&dump_ctx.url);
 	strbuf_release(&rev_ctx.log);
diff --git a/vcs-svn/trp.h b/vcs-svn/trp.h
deleted file mode 100644
index c32b9184e..000000000
--- a/vcs-svn/trp.h
+++ /dev/null
@@ -1,237 +0,0 @@
-/*
- * C macro implementation of treaps.
- *
- * Usage:
- *   #include <stdint.h>
- *   #include "trp.h"
- *   trp_gen(...)
- *
- * Licensed under a two-clause BSD-style license.
- * See LICENSE for details.
- */
-
-#ifndef TRP_H_
-#define TRP_H_
-
-#define MAYBE_UNUSED __attribute__((__unused__))
-
-/* Node structure. */
-struct trp_node {
-	uint32_t trpn_left;
-	uint32_t trpn_right;
-};
-
-/* Root structure. */
-struct trp_root {
-	uint32_t trp_root;
-};
-
-/* Pointer/Offset conversion. */
-#define trpn_pointer(a_base, a_offset) (a_base##_pointer(a_offset))
-#define trpn_offset(a_base, a_pointer) (a_base##_offset(a_pointer))
-#define trpn_modify(a_base, a_offset) \
-	do { \
-		if ((a_offset) < a_base##_pool.committed) { \
-			uint32_t old_offset = (a_offset);\
-			(a_offset) = a_base##_alloc(1); \
-			*trpn_pointer(a_base, a_offset) = \
-				*trpn_pointer(a_base, old_offset); \
-		} \
-	} while (0)
-
-/* Left accessors. */
-#define trp_left_get(a_base, a_field, a_node) \
-	(trpn_pointer(a_base, a_node)->a_field.trpn_left)
-#define trp_left_set(a_base, a_field, a_node, a_left) \
-	do { \
-		trpn_modify(a_base, a_node); \
-		trp_left_get(a_base, a_field, a_node) = (a_left); \
-	} while (0)
-
-/* Right accessors. */
-#define trp_right_get(a_base, a_field, a_node) \
-	(trpn_pointer(a_base, a_node)->a_field.trpn_right)
-#define trp_right_set(a_base, a_field, a_node, a_right) \
-	do { \
-		trpn_modify(a_base, a_node); \
-		trp_right_get(a_base, a_field, a_node) = (a_right); \
-	} while (0)
-
-/*
- * Fibonacci hash function.
- * The multiplier is the nearest prime to (2^32 times (√5 - 1)/2).
- * See Knuth §6.4: volume 3, 3rd ed, p518.
- */
-#define trpn_hash(a_node) (uint32_t) (2654435761u * (a_node))
-
-/* Priority accessors. */
-#define trp_prio_get(a_node) trpn_hash(a_node)
-
-/* Node initializer. */
-#define trp_node_new(a_base, a_field, a_node) \
-	do { \
-		trp_left_set(a_base, a_field, (a_node), ~0); \
-		trp_right_set(a_base, a_field, (a_node), ~0); \
-	} while (0)
-
-/* Internal utility macros. */
-#define trpn_first(a_base, a_field, a_root, r_node) \
-	do { \
-		(r_node) = (a_root); \
-		if ((r_node) == ~0) \
-			return NULL; \
-		while (~trp_left_get(a_base, a_field, (r_node))) \
-			(r_node) = trp_left_get(a_base, a_field, (r_node)); \
-	} while (0)
-
-#define trpn_rotate_left(a_base, a_field, a_node, r_node) \
-	do { \
-		(r_node) = trp_right_get(a_base, a_field, (a_node)); \
-		trp_right_set(a_base, a_field, (a_node), \
-			trp_left_get(a_base, a_field, (r_node))); \
-		trp_left_set(a_base, a_field, (r_node), (a_node)); \
-	} while (0)
-
-#define trpn_rotate_right(a_base, a_field, a_node, r_node) \
-	do { \
-		(r_node) = trp_left_get(a_base, a_field, (a_node)); \
-		trp_left_set(a_base, a_field, (a_node), \
-			trp_right_get(a_base, a_field, (r_node))); \
-		trp_right_set(a_base, a_field, (r_node), (a_node)); \
-	} while (0)
-
-#define trp_gen(a_attr, a_pre, a_type, a_field, a_base, a_cmp) \
-a_attr a_type MAYBE_UNUSED *a_pre##first(struct trp_root *treap) \
-{ \
-	uint32_t ret; \
-	trpn_first(a_base, a_field, treap->trp_root, ret); \
-	return trpn_pointer(a_base, ret); \
-} \
-a_attr a_type MAYBE_UNUSED *a_pre##next(struct trp_root *treap, a_type *node) \
-{ \
-	uint32_t ret; \
-	uint32_t offset = trpn_offset(a_base, node); \
-	if (~trp_right_get(a_base, a_field, offset)) { \
-		trpn_first(a_base, a_field, \
-			trp_right_get(a_base, a_field, offset), ret); \
-	} else { \
-		uint32_t tnode = treap->trp_root; \
-		ret = ~0; \
-		while (1) { \
-			int cmp = (a_cmp)(trpn_pointer(a_base, offset), \
-				trpn_pointer(a_base, tnode)); \
-			if (cmp < 0) { \
-				ret = tnode; \
-				tnode = trp_left_get(a_base, a_field, tnode); \
-			} else if (cmp > 0) { \
-				tnode = trp_right_get(a_base, a_field, tnode); \
-			} else { \
-				break; \
-			} \
-		} \
-	} \
-	return trpn_pointer(a_base, ret); \
-} \
-a_attr a_type MAYBE_UNUSED *a_pre##search(struct trp_root *treap, a_type *key) \
-{ \
-	int cmp; \
-	uint32_t ret = treap->trp_root; \
-	while (~ret && (cmp = (a_cmp)(key, trpn_pointer(a_base, ret)))) { \
-		if (cmp < 0) { \
-			ret = trp_left_get(a_base, a_field, ret); \
-		} else { \
-			ret = trp_right_get(a_base, a_field, ret); \
-		} \
-	} \
-	return trpn_pointer(a_base, ret); \
-} \
-a_attr a_type MAYBE_UNUSED *a_pre##nsearch(struct trp_root *treap, a_type *key) \
-{ \
-	int cmp; \
-	uint32_t ret = treap->trp_root; \
-	while (~ret && (cmp = (a_cmp)(key, trpn_pointer(a_base, ret)))) { \
-		if (cmp < 0) { \
-			if (!~trp_left_get(a_base, a_field, ret)) \
-				break; \
-			ret = trp_left_get(a_base, a_field, ret); \
-		} else { \
-			ret = trp_right_get(a_base, a_field, ret); \
-		} \
-	} \
-	return trpn_pointer(a_base, ret); \
-} \
-a_attr uint32_t MAYBE_UNUSED a_pre##insert_recurse(uint32_t cur_node, uint32_t ins_node) \
-{ \
-	if (cur_node == ~0) { \
-		return ins_node; \
-	} else { \
-		uint32_t ret; \
-		int cmp = (a_cmp)(trpn_pointer(a_base, ins_node), \
-					trpn_pointer(a_base, cur_node)); \
-		if (cmp < 0) { \
-			uint32_t left = a_pre##insert_recurse( \
-				trp_left_get(a_base, a_field, cur_node), ins_node); \
-			trp_left_set(a_base, a_field, cur_node, left); \
-			if (trp_prio_get(left) < trp_prio_get(cur_node)) \
-				trpn_rotate_right(a_base, a_field, cur_node, ret); \
-			else \
-				ret = cur_node; \
-		} else { \
-			uint32_t right = a_pre##insert_recurse( \
-				trp_right_get(a_base, a_field, cur_node), ins_node); \
-			trp_right_set(a_base, a_field, cur_node, right); \
-			if (trp_prio_get(right) < trp_prio_get(cur_node)) \
-				trpn_rotate_left(a_base, a_field, cur_node, ret); \
-			else \
-				ret = cur_node; \
-		} \
-		return ret; \
-	} \
-} \
-a_attr a_type *MAYBE_UNUSED a_pre##insert(struct trp_root *treap, a_type *node) \
-{ \
-	uint32_t offset = trpn_offset(a_base, node); \
-	trp_node_new(a_base, a_field, offset); \
-	treap->trp_root = a_pre##insert_recurse(treap->trp_root, offset); \
-	return trpn_pointer(a_base, offset); \
-} \
-a_attr uint32_t MAYBE_UNUSED a_pre##remove_recurse(uint32_t cur_node, uint32_t rem_node) \
-{ \
-	int cmp = a_cmp(trpn_pointer(a_base, rem_node), \
-			trpn_pointer(a_base, cur_node)); \
-	if (cmp == 0) { \
-		uint32_t ret; \
-		uint32_t left = trp_left_get(a_base, a_field, cur_node); \
-		uint32_t right = trp_right_get(a_base, a_field, cur_node); \
-		if (left == ~0) { \
-			if (right == ~0) \
-				return ~0; \
-		} else if (right == ~0 || trp_prio_get(left) < trp_prio_get(right)) { \
-			trpn_rotate_right(a_base, a_field, cur_node, ret); \
-			right = a_pre##remove_recurse(cur_node, rem_node); \
-			trp_right_set(a_base, a_field, ret, right); \
-			return ret; \
-		} \
-		trpn_rotate_left(a_base, a_field, cur_node, ret); \
-		left = a_pre##remove_recurse(cur_node, rem_node); \
-		trp_left_set(a_base, a_field, ret, left); \
-		return ret; \
-	} else if (cmp < 0) { \
-		uint32_t left = a_pre##remove_recurse( \
-			trp_left_get(a_base, a_field, cur_node), rem_node); \
-		trp_left_set(a_base, a_field, cur_node, left); \
-		return cur_node; \
-	} else { \
-		uint32_t right = a_pre##remove_recurse( \
-			trp_right_get(a_base, a_field, cur_node), rem_node); \
-		trp_right_set(a_base, a_field, cur_node, right); \
-		return cur_node; \
-	} \
-} \
-a_attr void MAYBE_UNUSED a_pre##remove(struct trp_root *treap, a_type *node) \
-{ \
-	treap->trp_root = a_pre##remove_recurse(treap->trp_root, \
-		trpn_offset(a_base, node)); \
-} \
-
-#endif
diff --git a/vcs-svn/trp.txt b/vcs-svn/trp.txt
deleted file mode 100644
index 177ebca33..000000000
--- a/vcs-svn/trp.txt
+++ /dev/null
@@ -1,109 +0,0 @@
-Motivation
-==========
-
-Treaps provide a memory-efficient binary search tree structure.
-Insertion/deletion/search are about as about as fast in the average
-case as red-black trees and the chances of worst-case behavior are
-vanishingly small, thanks to (pseudo-)randomness.  The bad worst-case
-behavior is a small price to pay, given that treaps are much simpler
-to implement.
-
-API
-===
-
-The trp API generates a data structure and functions to handle a
-large growing set of objects stored in a pool.
-
-The caller:
-
-. Specifies parameters for the generated functions with the
-  trp_gen(static, foo_, ...) macro.
-
-. Allocates a `struct trp_root` variable and sets it to {~0}.
-
-. Adds new nodes to the set using `foo_insert`.  Any pointers
-  to existing nodes cannot be relied upon any more, so the caller
-  might retrieve them anew with `foo_pointer`.
-
-. Can find a specific item in the set using `foo_search`.
-
-. Can iterate over items in the set using `foo_first` and `foo_next`.
-
-. Can remove an item from the set using `foo_remove`.
-
-Example:
-
-----
-struct ex_node {
-	const char *s;
-	struct trp_node ex_link;
-};
-static struct trp_root ex_base = {~0};
-obj_pool_gen(ex, struct ex_node, 4096);
-trp_gen(static, ex_, struct ex_node, ex_link, ex, strcmp)
-struct ex_node *item;
-
-item = ex_pointer(ex_alloc(1));
-item->s = "hello";
-ex_insert(&ex_base, item);
-item = ex_pointer(ex_alloc(1));
-item->s = "goodbye";
-ex_insert(&ex_base, item);
-for (item = ex_first(&ex_base); item; item = ex_next(&ex_base, item))
-	printf("%s\n", item->s);
-----
-
-Functions
----------
-
-trp_gen(attr, foo_, node_type, link_field, pool, cmp)::
-
-	Generate a type-specific treap implementation.
-+
-. The storage class for generated functions will be 'attr' (e.g., `static`).
-. Generated function names are prefixed with 'foo_' (e.g., `treap_`).
-. Treap nodes will be of type 'node_type' (e.g., `struct treap_node`).
-  This type must be a struct with at least one `struct trp_node` field
-  to point to its children.
-. The field used to access child nodes will be 'link_field'.
-. All treap nodes must lie in the 'pool' object pool.
-. Treap nodes must be totally ordered by the 'cmp' relation, with the
-  following prototype:
-+
-int (*cmp)(node_type \*a, node_type \*b)
-+
-and returning a value less than, equal to, or greater than zero
-according to the result of comparison.
-
-node_type {asterisk}foo_insert(struct trp_root *treap, node_type \*node)::
-
-	Insert node into treap.  If inserted multiple times,
-	a node will appear in the treap multiple times.
-+
-The return value is the address of the node within the treap,
-which might differ from `node` if `pool_alloc` had to call
-`realloc` to expand the pool.
-
-void foo_remove(struct trp_root *treap, node_type \*node)::
-
-	Remove node from treap.  Caller must ensure node is
-	present in treap before using this function.
-
-node_type *foo_search(struct trp_root \*treap, node_type \*key)::
-
-	Search for a node that matches key.  If no match is found,
-	result is NULL.
-
-node_type *foo_nsearch(struct trp_root \*treap, node_type \*key)::
-
-	Like `foo_search`, but if the key is missing return what
-	would be key's successor, were key in treap (NULL if no
-	successor).
-
-node_type *foo_first(struct trp_root \*treap)::
-
-	Find the first item from the treap, in sorted order.
-
-node_type *foo_next(struct trp_root \*treap, node_type \*node)::
-
-	Find the next item.