merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

12 files changed, 1630 insertions, 0 deletions

diff --git a/third_party/git/vcs-svn/LICENSE b/third_party/git/vcs-svn/LICENSE
new file mode 100644
index 0000000000..eb91858b82
--- /dev/null
+++ b/third_party/git/vcs-svn/LICENSE
@@ -0,0 +1,32 @@
+Copyright (C) 2010 David Barr <david.barr@cordelta.com>.
+All rights reserved.
+
+Copyright (C) 2010 Jonathan Nieder <jrnieder@gmail.com>.
+
+Copyright (C) 2005 Stefan Hegny, hydrografix Consulting GmbH,
+Frankfurt/Main, Germany
+and others, see http://svn2cc.sarovar.org
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice(s), this list of conditions and the following disclaimer
+   unmodified other than the allowable addition of one or more
+   copyright notices.
+2. Redistributions in binary form must reproduce the above copyright
+   notice(s), this list of conditions and the following disclaimer in
+   the documentation and/or other materials provided with the
+   distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/third_party/git/vcs-svn/fast_export.c b/third_party/git/vcs-svn/fast_export.c
new file mode 100644
index 0000000000..b5b8913cb0
--- /dev/null
+++ b/third_party/git/vcs-svn/fast_export.c
@@ -0,0 +1,365 @@
+/*
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "cache.h"
+#include "quote.h"
+#include "fast_export.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_delete(const char *path)
+{
+	putchar('D');
+	putchar(' ');
+	quote_c_style(path, NULL, stdout, 0);
+	putchar('\n');
+}
+
+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. */
+	if (!dataref) {
+		fast_export_truncate(path, mode);
+		return;
+	}
+	printf("M %06"PRIo32" %s ", mode, dataref);
+	quote_c_style(path, NULL, stdout, 0);
+	putchar('\n');
+}
+
+void fast_export_begin_note(uint32_t revision, const char *author,
+		const char *log, timestamp_t timestamp, const char *note_ref)
+{
+	static int firstnote = 1;
+	size_t loglen = strlen(log);
+	printf("commit %s\n", note_ref);
+	printf("committer %s <%s@%s> %"PRItime" +0000\n", author, author, "local", timestamp);
+	printf("data %"PRIuMAX"\n", (uintmax_t)loglen);
+	fwrite(log, loglen, 1, stdout);
+	if (firstnote) {
+		if (revision > 1)
+			printf("from %s^0", note_ref);
+		firstnote = 0;
+	}
+	fputc('\n', stdout);
+}
+
+void fast_export_note(const char *committish, const char *dataref)
+{
+	printf("N %s %s\n", dataref, committish);
+}
+
+static char gitsvnline[MAX_GITSVN_LINE_LEN];
+void fast_export_begin_commit(uint32_t revision, const char *author,
+			const struct strbuf *log,
+			const char *uuid, const char *url,
+			timestamp_t timestamp, const char *local_ref)
+{
+	static const struct strbuf empty = STRBUF_INIT;
+	if (!log)
+		log = &empty;
+	if (*uuid && *url) {
+		snprintf(gitsvnline, MAX_GITSVN_LINE_LEN,
+				"\n\ngit-svn-id: %s@%"PRIu32" %s\n",
+				 url, revision, uuid);
+	} else {
+		*gitsvnline = '\0';
+	}
+	printf("commit %s\n", local_ref);
+	printf("mark :%"PRIu32"\n", revision);
+	printf("committer %s <%s@%s> %"PRItime" +0000\n",
+		   *author ? author : "nobody",
+		   *author ? author : "nobody",
+		   *uuid ? uuid : "local", timestamp);
+	printf("data %"PRIuMAX"\n",
+		(uintmax_t) (log->len + strlen(gitsvnline)));
+	fwrite(log->buf, log->len, 1, stdout);
+	printf("%s\n", gitsvnline);
+	if (!first_commit_done) {
+		if (revision > 1)
+			printf("from :%"PRIu32"\n", revision - 1);
+		first_commit_done = 1;
+	}
+}
+
+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))
+		die_errno("error reading dump file");
+	die("invalid dump: unexpected end of file");
+}
+
+static int parse_cat_response_line(const char *header, off_t *len)
+{
+	uintmax_t n;
+	const char *type;
+	const char *end;
+
+	if (ends_with(header, " missing"))
+		return error("cat-blob reports missing blob: %s", header);
+	type = strstr(header, " 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 == S_IFLNK) {
+		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_buf_to_data(const struct strbuf *data)
+{
+	printf("data %"PRIuMAX"\n", (uintmax_t)data->len);
+	fwrite(data->buf, data->len, 1, stdout);
+	fputc('\n', stdout);
+}
+
+void fast_export_data(uint32_t mode, off_t len, struct line_buffer *input)
+{
+	assert(len >= 0);
+	if (mode == S_IFLNK) {
+		/* svn symlink blobs start with "link " */
+		if (len < 5)
+			die("invalid dump: symlink too short for \"link\" prefix");
+		len -= 5;
+		if (buffer_skip_bytes(input, 5) != 5)
+			die_short_read(input);
+	}
+	printf("data %"PRIuMAX"\n", (uintmax_t) 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 < (signed) 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 < (signed) 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);
+}
+
+const char *fast_export_read_path(const char *path, uint32_t *mode_out)
+{
+	int err;
+	static struct strbuf buf = STRBUF_INIT;
+
+	strbuf_reset(&buf);
+	err = fast_export_ls(path, mode_out, &buf);
+	if (err) {
+		if (errno != ENOENT)
+			BUG("unexpected fast_export_ls error: %s",
+			    strerror(errno));
+		/* Treat missing paths as directories. */
+		*mode_out = S_IFDIR;
+		return NULL;
+	}
+	return buf.buf;
+}
+
+void fast_export_copy(uint32_t revision, const char *src, const char *dst)
+{
+	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)
+			BUG("unexpected fast_export_ls_rev error: %s",
+			    strerror(errno));
+		fast_export_delete(dst);
+		return;
+	}
+	fast_export_modify(dst, mode, data.buf);
+}
+
+void fast_export_blob_delta(uint32_t mode,
+				uint32_t old_mode, const char *old_data,
+				off_t len, struct line_buffer *input)
+{
+	long postimage_len;
+
+	assert(len >= 0);
+	postimage_len = apply_delta(len, input, old_data, old_mode);
+	if (mode == S_IFLNK) {
+		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/third_party/git/vcs-svn/fast_export.h b/third_party/git/vcs-svn/fast_export.h
new file mode 100644
index 0000000000..9dcf9337c1
--- /dev/null
+++ b/third_party/git/vcs-svn/fast_export.h
@@ -0,0 +1,34 @@
+#ifndef FAST_EXPORT_H
+#define FAST_EXPORT_H
+
+struct strbuf;
+struct line_buffer;
+
+void fast_export_init(int fd);
+void fast_export_deinit(void);
+
+void fast_export_delete(const char *path);
+void fast_export_modify(const char *path, uint32_t mode, const char *dataref);
+void fast_export_note(const char *committish, const char *dataref);
+void fast_export_begin_note(uint32_t revision, const char *author,
+		const char *log, timestamp_t timestamp, const char *note_ref);
+void fast_export_begin_commit(uint32_t revision, const char *author,
+			const struct strbuf *log, const char *uuid,const char *url,
+			timestamp_t timestamp, const char *local_ref);
+void fast_export_end_commit(uint32_t revision);
+void fast_export_data(uint32_t mode, off_t len, struct line_buffer *input);
+void fast_export_buf_to_data(const struct strbuf *data);
+void fast_export_blob_delta(uint32_t mode,
+			uint32_t old_mode, const char *old_data,
+			off_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);
+
+void fast_export_copy(uint32_t revision, const char *src, const char *dst);
+const char *fast_export_read_path(const char *path, uint32_t *mode_out);
+
+#endif
diff --git a/third_party/git/vcs-svn/line_buffer.c b/third_party/git/vcs-svn/line_buffer.c
new file mode 100644
index 0000000000..e416caf8a4
--- /dev/null
+++ b/third_party/git/vcs-svn/line_buffer.c
@@ -0,0 +1,126 @@
+/*
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "git-compat-util.h"
+#include "line_buffer.h"
+#include "strbuf.h"
+
+#define COPY_BUFFER_LEN 4096
+
+int buffer_init(struct line_buffer *buf, const char *filename)
+{
+	buf->infile = filename ? fopen(filename, "r") : stdin;
+	if (!buf->infile)
+		return -1;
+	return 0;
+}
+
+int buffer_fdinit(struct line_buffer *buf, int fd)
+{
+	buf->infile = fdopen(fd, "r");
+	if (!buf->infile)
+		return -1;
+	return 0;
+}
+
+int buffer_tmpfile_init(struct line_buffer *buf)
+{
+	buf->infile = tmpfile();
+	if (!buf->infile)
+		return -1;
+	return 0;
+}
+
+int buffer_deinit(struct line_buffer *buf)
+{
+	int err;
+	if (buf->infile == stdin)
+		return ferror(buf->infile);
+	err = ferror(buf->infile);
+	err |= fclose(buf->infile);
+	return err;
+}
+
+FILE *buffer_tmpfile_rewind(struct line_buffer *buf)
+{
+	rewind(buf->infile);
+	return buf->infile;
+}
+
+long buffer_tmpfile_prepare_to_read(struct line_buffer *buf)
+{
+	long pos = ftell(buf->infile);
+	if (pos < 0)
+		return error_errno("ftell error");
+	if (fseek(buf->infile, 0, SEEK_SET))
+		return error_errno("seek error");
+	return pos;
+}
+
+int buffer_ferror(struct line_buffer *buf)
+{
+	return ferror(buf->infile);
+}
+
+int buffer_read_char(struct line_buffer *buf)
+{
+	return fgetc(buf->infile);
+}
+
+/* Read a line without trailing newline. */
+char *buffer_read_line(struct line_buffer *buf)
+{
+	char *end;
+	if (!fgets(buf->line_buffer, sizeof(buf->line_buffer), buf->infile))
+		/* Error or data exhausted. */
+		return NULL;
+	end = buf->line_buffer + strlen(buf->line_buffer);
+	if (end[-1] == '\n')
+		end[-1] = '\0';
+	else if (feof(buf->infile))
+		; /* No newline at end of file.  That's fine. */
+	else
+		/*
+		 * Line was too long.
+		 * There is probably a saner way to deal with this,
+		 * but for now let's return an error.
+		 */
+		return NULL;
+	return buf->line_buffer;
+}
+
+size_t buffer_read_binary(struct line_buffer *buf,
+				struct strbuf *sb, size_t size)
+{
+	return strbuf_fread(sb, size, buf->infile);
+}
+
+off_t buffer_copy_bytes(struct line_buffer *buf, off_t nbytes)
+{
+	char byte_buffer[COPY_BUFFER_LEN];
+	off_t done = 0;
+	while (done < nbytes && !feof(buf->infile) && !ferror(buf->infile)) {
+		off_t len = nbytes - done;
+		size_t in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+		in = fread(byte_buffer, 1, in, buf->infile);
+		done += in;
+		fwrite(byte_buffer, 1, in, stdout);
+		if (ferror(stdout))
+			return done + buffer_skip_bytes(buf, nbytes - done);
+	}
+	return done;
+}
+
+off_t buffer_skip_bytes(struct line_buffer *buf, off_t nbytes)
+{
+	char byte_buffer[COPY_BUFFER_LEN];
+	off_t done = 0;
+	while (done < nbytes && !feof(buf->infile) && !ferror(buf->infile)) {
+		off_t len = nbytes - done;
+		size_t in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+		done += fread(byte_buffer, 1, in, buf->infile);
+	}
+	return done;
+}
diff --git a/third_party/git/vcs-svn/line_buffer.h b/third_party/git/vcs-svn/line_buffer.h
new file mode 100644
index 0000000000..e192aedea2
--- /dev/null
+++ b/third_party/git/vcs-svn/line_buffer.h
@@ -0,0 +1,30 @@
+#ifndef LINE_BUFFER_H
+#define LINE_BUFFER_H
+
+#include "strbuf.h"
+
+#define LINE_BUFFER_LEN 10000
+
+struct line_buffer {
+	char line_buffer[LINE_BUFFER_LEN];
+	FILE *infile;
+};
+#define LINE_BUFFER_INIT { "", NULL }
+
+int buffer_init(struct line_buffer *buf, const char *filename);
+int buffer_fdinit(struct line_buffer *buf, int fd);
+int buffer_deinit(struct line_buffer *buf);
+
+int buffer_tmpfile_init(struct line_buffer *buf);
+FILE *buffer_tmpfile_rewind(struct line_buffer *buf);	/* prepare to write. */
+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);
+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);
+
+#endif
diff --git a/third_party/git/vcs-svn/line_buffer.txt b/third_party/git/vcs-svn/line_buffer.txt
new file mode 100644
index 0000000000..8e139eb22d
--- /dev/null
+++ b/third_party/git/vcs-svn/line_buffer.txt
@@ -0,0 +1,77 @@
+line_buffer API
+===============
+
+The line_buffer library provides a convenient interface for
+mostly-line-oriented input.
+
+Each line is not permitted to exceed 10000 bytes.  The provided
+functions are not thread-safe or async-signal-safe, and like
+`fgets()`, they generally do not function correctly if interrupted
+by a signal without SA_RESTART set.
+
+Calling sequence
+----------------
+
+The calling program:
+
+ - initializes a `struct line_buffer` to LINE_BUFFER_INIT
+ - specifies a file to read with `buffer_init`
+ - processes input with `buffer_read_line`, `buffer_skip_bytes`,
+   and `buffer_copy_bytes`
+ - closes the file with `buffer_deinit`, perhaps to start over and
+   read another file.
+
+When finished, the caller can use `buffer_reset` to deallocate
+resources.
+
+Using temporary files
+---------------------
+
+Temporary files provide a place to store data that should not outlive
+the calling program.  A program
+
+ - initializes a `struct line_buffer` to LINE_BUFFER_INIT
+ - requests a temporary file with `buffer_tmpfile_init`
+ - acquires an output handle by calling `buffer_tmpfile_rewind`
+ - uses standard I/O functions like `fprintf` and `fwrite` to fill
+   the temporary file
+ - declares writing is over with `buffer_tmpfile_prepare_to_read`
+ - can re-read what was written with `buffer_read_line`,
+   `buffer_copy_bytes`, and so on
+ - can reuse the temporary file by calling `buffer_tmpfile_rewind`
+   again
+ - removes the temporary file with `buffer_deinit`, perhaps to
+   reuse the line_buffer for some other file.
+
+When finished, the calling program can use `buffer_reset` to deallocate
+resources.
+
+Functions
+---------
+
+`buffer_init`, `buffer_fdinit`::
+	Open the named file or file descriptor for input.
+	buffer_init(buf, NULL) prepares to read from stdin.
+	On failure, returns -1 (with errno indicating the nature
+	of the failure).
+
+`buffer_deinit`::
+	Stop reading from the current file (closing it unless
+	it was stdin).  Returns nonzero if `fclose` fails or
+	the error indicator was set.
+
+`buffer_read_line`::
+	Read a line and strip off the trailing newline.
+	On failure or end of file, returns NULL.
+
+`buffer_copy_bytes`::
+	Read `len` bytes of input and dump them to the standard output
+	stream.  Returns early for error or end of file.
+
+`buffer_skip_bytes`::
+	Discards `len` bytes from the input stream (stopping early
+	if necessary because of an error or eof).  Return value is
+	the number of bytes successfully read.
+
+`buffer_reset`::
+	Deallocates non-static buffers.
diff --git a/third_party/git/vcs-svn/sliding_window.c b/third_party/git/vcs-svn/sliding_window.c
new file mode 100644
index 0000000000..06d273c9e8
--- /dev/null
+++ b/third_party/git/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_errno("cannot read delta preimage");
+}
+
+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_offset_overflow(off_t offset, uintmax_t len)
+{
+	if (len > maximum_signed_value_of_type(off_t))
+		return error("unrepresentable length in delta: "
+				"%"PRIuMAX" > OFF_MAX", len);
+	if (signed_add_overflows(offset, (off_t) len))
+		return error("unrepresentable offset in delta: "
+				"%"PRIuMAX" + %"PRIuMAX" > OFF_MAX",
+				(uintmax_t) offset, len);
+	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_offset_overflow(view->off, view->buf.len));
+
+	if (check_offset_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 + (off_t) 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/third_party/git/vcs-svn/sliding_window.h b/third_party/git/vcs-svn/sliding_window.h
new file mode 100644
index 0000000000..a7fc0999cb
--- /dev/null
+++ b/third_party/git/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 }
+
+int move_window(struct sliding_view *view, off_t off, size_t width);
+
+#endif
diff --git a/third_party/git/vcs-svn/svndiff.c b/third_party/git/vcs-svn/svndiff.c
new file mode 100644
index 0000000000..75c753162a
--- /dev/null
+++ b/third_party/git/vcs-svn/svndiff.c
@@ -0,0 +1,309 @@
+/*
+ * 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_errno("cannot write delta postimage");
+}
+
+static int error_short_read(struct line_buffer *input)
+{
+	if (buffer_ferror(input))
+		return error_errno("error reading delta");
+	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)
+{
+	assert(*delta_len >= 0);
+	strbuf_reset(buf);
+	if (len > (uintmax_t) *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)
+{
+	int rv = -1;
+	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) {
+		rv = error("invalid delta: incorrect postimage length");
+		goto error_out;
+	}
+	if (write_strbuf(&ctx.out, out))
+		goto error_out;
+	rv = 0;
+error_out:
+	window_release(&ctx);
+	return rv;
+}
+
+int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
+			struct sliding_view *preimage, FILE *postimage)
+{
+	assert(delta && preimage && postimage && delta_len >= 0);
+
+	if (read_magic(delta, &delta_len))
+		return -1;
+	while (delta_len) {	/* For each window: */
+		off_t pre_off = -1;
+		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/third_party/git/vcs-svn/svndiff.h b/third_party/git/vcs-svn/svndiff.h
new file mode 100644
index 0000000000..625d950bb8
--- /dev/null
+++ b/third_party/git/vcs-svn/svndiff.h
@@ -0,0 +1,10 @@
+#ifndef SVNDIFF_H
+#define SVNDIFF_H
+
+struct line_buffer;
+struct sliding_view;
+
+int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
+		   struct sliding_view *preimage, FILE *postimage);
+
+#endif
diff --git a/third_party/git/vcs-svn/svndump.c b/third_party/git/vcs-svn/svndump.c
new file mode 100644
index 0000000000..08d136b8cc
--- /dev/null
+++ b/third_party/git/vcs-svn/svndump.c
@@ -0,0 +1,540 @@
+/*
+ * Parse and rearrange a svnadmin dump.
+ * Create the dump with:
+ * svnadmin dump --incremental -r<startrev>:<endrev> <repository> >outfile
+ *
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "cache.h"
+#include "fast_export.h"
+#include "line_buffer.h"
+#include "strbuf.h"
+#include "svndump.h"
+
+/*
+ * Compare start of string to literal of equal length;
+ * must be guarded by length test.
+ */
+#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
+
+/* 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 DATE_RFC2822_LEN 31
+
+static struct line_buffer input = LINE_BUFFER_INIT;
+
+static struct {
+	uint32_t action, srcRev, type;
+	off_t prop_length, text_length;
+	struct strbuf src, dst;
+	uint32_t text_delta, prop_delta;
+} node_ctx;
+
+static struct {
+	uint32_t revision;
+	timestamp_t timestamp;
+	struct strbuf log, author, note;
+} rev_ctx;
+
+static struct {
+	uint32_t version;
+	struct strbuf uuid, url;
+} dump_ctx;
+
+static void reset_node_ctx(char *fname)
+{
+	node_ctx.type = 0;
+	node_ctx.action = NODEACT_UNKNOWN;
+	node_ctx.prop_length = -1;
+	node_ctx.text_length = -1;
+	strbuf_reset(&node_ctx.src);
+	node_ctx.srcRev = 0;
+	strbuf_reset(&node_ctx.dst);
+	if (fname)
+		strbuf_addstr(&node_ctx.dst, fname);
+	node_ctx.text_delta = 0;
+	node_ctx.prop_delta = 0;
+}
+
+static void reset_rev_ctx(uint32_t revision)
+{
+	rev_ctx.revision = revision;
+	rev_ctx.timestamp = 0;
+	strbuf_reset(&rev_ctx.log);
+	strbuf_reset(&rev_ctx.author);
+	strbuf_reset(&rev_ctx.note);
+}
+
+static void reset_dump_ctx(const char *url)
+{
+	strbuf_reset(&dump_ctx.url);
+	if (url)
+		strbuf_addstr(&dump_ctx.url, url);
+	dump_ctx.version = 1;
+	strbuf_reset(&dump_ctx.uuid);
+}
+
+static void handle_property(const struct strbuf *key_buf,
+				struct strbuf *val,
+				uint32_t *type_set)
+{
+	const char *key = key_buf->buf;
+	size_t keylen = key_buf->len;
+
+	switch (keylen + 1) {
+	case sizeof("svn:log"):
+		if (constcmp(key, "svn:log"))
+			break;
+		if (!val)
+			die("invalid dump: unsets svn:log");
+		strbuf_swap(&rev_ctx.log, val);
+		break;
+	case sizeof("svn:author"):
+		if (constcmp(key, "svn:author"))
+			break;
+		if (!val)
+			strbuf_reset(&rev_ctx.author);
+		else
+			strbuf_swap(&rev_ctx.author, val);
+		break;
+	case sizeof("svn:date"):
+		if (constcmp(key, "svn:date"))
+			break;
+		if (!val)
+			die("invalid dump: unsets svn:date");
+		if (parse_date_basic(val->buf, &rev_ctx.timestamp, NULL))
+			warning("invalid timestamp: %s", val->buf);
+		break;
+	case sizeof("svn:executable"):
+	case sizeof("svn:special"):
+		if (keylen == strlen("svn:executable") &&
+		    constcmp(key, "svn:executable"))
+			break;
+		if (keylen == strlen("svn:special") &&
+		    constcmp(key, "svn:special"))
+			break;
+		if (*type_set) {
+			if (!val)
+				return;
+			die("invalid dump: sets type twice");
+		}
+		if (!val) {
+			node_ctx.type = S_IFREG | 0644;
+			return;
+		}
+		*type_set = 1;
+		node_ctx.type = keylen == strlen("svn:executable") ?
+				(S_IFREG | 0755) :
+				S_IFLNK;
+	}
+}
+
+static void die_short_read(void)
+{
+	if (buffer_ferror(&input))
+		die_errno("error reading dump file");
+	die("invalid dump: unexpected end of file");
+}
+
+static void read_props(void)
+{
+	static struct strbuf key = STRBUF_INIT;
+	static struct strbuf val = STRBUF_INIT;
+	const char *t;
+	/*
+	 * NEEDSWORK: to support simple mode changes like
+	 *	K 11
+	 *	svn:special
+	 *	V 1
+	 *	*
+	 *	D 14
+	 *	svn:executable
+	 * we keep track of whether a mode has been set and reset to
+	 * plain file only if not.  We should be keeping track of the
+	 * symlink and executable bits separately instead.
+	 */
+	uint32_t type_set = 0;
+	while ((t = buffer_read_line(&input)) && strcmp(t, "PROPS-END")) {
+		uint32_t len;
+		const char type = t[0];
+		int ch;
+
+		if (!type || t[1] != ' ')
+			die("invalid property line: %s", t);
+		len = atoi(&t[2]);
+		strbuf_reset(&val);
+		buffer_read_binary(&input, &val, len);
+		if (val.len < len)
+			die_short_read();
+
+		/* Discard trailing newline. */
+		ch = buffer_read_char(&input);
+		if (ch == EOF)
+			die_short_read();
+		if (ch != '\n')
+			die("invalid dump: expected newline after %s", val.buf);
+
+		switch (type) {
+		case 'K':
+			strbuf_swap(&key, &val);
+			continue;
+		case 'D':
+			handle_property(&val, NULL, &type_set);
+			continue;
+		case 'V':
+			handle_property(&key, &val, &type_set);
+			strbuf_reset(&key);
+			continue;
+		default:
+			die("invalid property line: %s", t);
+		}
+	}
+}
+
+static void handle_node(void)
+{
+	const uint32_t type = node_ctx.type;
+	const int have_props = node_ctx.prop_length != -1;
+	const int have_text = node_ctx.text_length != -1;
+	/*
+	 * 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 = S_IFREG | 0644;
+
+	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");
+		fast_export_delete(node_ctx.dst.buf);
+		return;
+	}
+	if (node_ctx.action == NODEACT_REPLACE) {
+		fast_export_delete(node_ctx.dst.buf);
+		node_ctx.action = NODEACT_ADD;
+	}
+	if (node_ctx.srcRev) {
+		fast_export_copy(node_ctx.srcRev, node_ctx.src.buf, node_ctx.dst.buf);
+		if (node_ctx.action == NODEACT_ADD)
+			node_ctx.action = NODEACT_CHANGE;
+	}
+	if (have_text && type == S_IFDIR)
+		die("invalid dump: directories cannot have text attached");
+
+	/*
+	 * Find old content (old_data) and decide on the new mode.
+	 */
+	if (node_ctx.action == NODEACT_CHANGE && !*node_ctx.dst.buf) {
+		if (type != S_IFDIR)
+			die("invalid dump: root of tree is not a regular file");
+		old_data = NULL;
+	} else if (node_ctx.action == NODEACT_CHANGE) {
+		uint32_t mode;
+		old_data = fast_export_read_path(node_ctx.dst.buf, &mode);
+		if (mode == S_IFDIR && type != S_IFDIR)
+			die("invalid dump: cannot modify a directory into a file");
+		if (mode != S_IFDIR && type == S_IFDIR)
+			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 (type == S_IFDIR)
+			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");
+	}
+
+	/*
+	 * Adjust mode to reflect properties.
+	 */
+	if (have_props) {
+		if (!node_ctx.prop_delta)
+			node_ctx.type = type;
+		if (node_ctx.prop_length)
+			read_props();
+	}
+
+	/*
+	 * Save the result.
+	 */
+	if (type == S_IFDIR)	/* 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.text_length, &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.text_length, &input);
+}
+
+static void begin_revision(const char *remote_ref)
+{
+	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, remote_ref);
+}
+
+static void end_revision(const char *note_ref)
+{
+	struct strbuf mark = STRBUF_INIT;
+	if (rev_ctx.revision) {
+		fast_export_end_commit(rev_ctx.revision);
+		fast_export_begin_note(rev_ctx.revision, "remote-svn",
+				"Note created by remote-svn.", rev_ctx.timestamp, note_ref);
+		strbuf_addf(&mark, ":%"PRIu32, rev_ctx.revision);
+		fast_export_note(mark.buf, "inline");
+		fast_export_buf_to_data(&rev_ctx.note);
+		strbuf_release(&mark);
+	}
+}
+
+void svndump_read(const char *url, const char *local_ref, const char *notes_ref)
+{
+	char *val;
+	char *t;
+	uint32_t active_ctx = DUMP_CTX;
+	uint32_t len;
+
+	reset_dump_ctx(url);
+	while ((t = buffer_read_line(&input))) {
+		val = strchr(t, ':');
+		if (!val)
+			continue;
+		val++;
+		if (*val != ' ')
+			continue;
+		val++;
+
+		/* strlen(key) + 1 */
+		switch (val - t - 1) {
+		case sizeof("SVN-fs-dump-format-version"):
+			if (constcmp(t, "SVN-fs-dump-format-version"))
+				continue;
+			dump_ctx.version = atoi(val);
+			if (dump_ctx.version > 3)
+				die("expected svn dump format version <= 3, found %"PRIu32,
+				    dump_ctx.version);
+			break;
+		case sizeof("UUID"):
+			if (constcmp(t, "UUID"))
+				continue;
+			strbuf_reset(&dump_ctx.uuid);
+			strbuf_addstr(&dump_ctx.uuid, val);
+			break;
+		case sizeof("Revision-number"):
+			if (constcmp(t, "Revision-number"))
+				continue;
+			if (active_ctx == NODE_CTX)
+				handle_node();
+			if (active_ctx == REV_CTX)
+				begin_revision(local_ref);
+			if (active_ctx != DUMP_CTX)
+				end_revision(notes_ref);
+			active_ctx = REV_CTX;
+			reset_rev_ctx(atoi(val));
+			strbuf_addf(&rev_ctx.note, "%s\n", t);
+			break;
+		case sizeof("Node-path"):
+			if (constcmp(t, "Node-"))
+				continue;
+			if (!constcmp(t + strlen("Node-"), "path")) {
+				if (active_ctx == NODE_CTX)
+					handle_node();
+				if (active_ctx == REV_CTX)
+					begin_revision(local_ref);
+				active_ctx = NODE_CTX;
+				reset_node_ctx(val);
+				strbuf_addf(&rev_ctx.note, "%s\n", t);
+				break;
+			}
+			if (constcmp(t + strlen("Node-"), "kind"))
+				continue;
+			strbuf_addf(&rev_ctx.note, "%s\n", t);
+			if (!strcmp(val, "dir"))
+				node_ctx.type = S_IFDIR;
+			else if (!strcmp(val, "file"))
+				node_ctx.type = S_IFREG | 0644;
+			else
+				fprintf(stderr, "Unknown node-kind: %s\n", val);
+			break;
+		case sizeof("Node-action"):
+			if (constcmp(t, "Node-action"))
+				continue;
+			strbuf_addf(&rev_ctx.note, "%s\n", t);
+			if (!strcmp(val, "delete")) {
+				node_ctx.action = NODEACT_DELETE;
+			} else if (!strcmp(val, "add")) {
+				node_ctx.action = NODEACT_ADD;
+			} else if (!strcmp(val, "change")) {
+				node_ctx.action = NODEACT_CHANGE;
+			} else if (!strcmp(val, "replace")) {
+				node_ctx.action = NODEACT_REPLACE;
+			} else {
+				fprintf(stderr, "Unknown node-action: %s\n", val);
+				node_ctx.action = NODEACT_UNKNOWN;
+			}
+			break;
+		case sizeof("Node-copyfrom-path"):
+			if (constcmp(t, "Node-copyfrom-path"))
+				continue;
+			strbuf_reset(&node_ctx.src);
+			strbuf_addstr(&node_ctx.src, val);
+			strbuf_addf(&rev_ctx.note, "%s\n", t);
+			break;
+		case sizeof("Node-copyfrom-rev"):
+			if (constcmp(t, "Node-copyfrom-rev"))
+				continue;
+			node_ctx.srcRev = atoi(val);
+			strbuf_addf(&rev_ctx.note, "%s\n", t);
+			break;
+		case sizeof("Text-content-length"):
+			if (constcmp(t, "Text") && constcmp(t, "Prop"))
+				continue;
+			if (constcmp(t + 4, "-content-length"))
+				continue;
+			{
+				char *end;
+				uintmax_t len;
+
+				len = strtoumax(val, &end, 10);
+				if (!isdigit(*val) || *end)
+					die("invalid dump: non-numeric length %s", val);
+				if (len > maximum_signed_value_of_type(off_t))
+					die("unrepresentable length in dump: %s", val);
+
+				if (*t == 'T')
+					node_ctx.text_length = (off_t) len;
+				else
+					node_ctx.prop_length = (off_t) len;
+				break;
+			}
+		case sizeof("Text-delta"):
+			if (!constcmp(t, "Text-delta")) {
+				node_ctx.text_delta = !strcmp(val, "true");
+				break;
+			}
+			if (constcmp(t, "Prop-delta"))
+				continue;
+			node_ctx.prop_delta = !strcmp(val, "true");
+			break;
+		case sizeof("Content-length"):
+			if (constcmp(t, "Content-length"))
+				continue;
+			len = atoi(val);
+			t = buffer_read_line(&input);
+			if (!t)
+				die_short_read();
+			if (*t)
+				die("invalid dump: expected blank line after content length header");
+			if (active_ctx == REV_CTX) {
+				read_props();
+			} else if (active_ctx == NODE_CTX) {
+				handle_node();
+				active_ctx = INTERNODE_CTX;
+			} else {
+				fprintf(stderr, "Unexpected content length header: %"PRIu32"\n", len);
+				if (buffer_skip_bytes(&input, len) != len)
+					die_short_read();
+			}
+		}
+	}
+	if (buffer_ferror(&input))
+		die_short_read();
+	if (active_ctx == NODE_CTX)
+		handle_node();
+	if (active_ctx == REV_CTX)
+		begin_revision(local_ref);
+	if (active_ctx != DUMP_CTX)
+		end_revision(notes_ref);
+}
+
+static void init(int report_fd)
+{
+	fast_export_init(report_fd);
+	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(&rev_ctx.note, 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);
+	return;
+}
+
+int svndump_init(const char *filename)
+{
+	if (buffer_init(&input, filename))
+		return error_errno("cannot open %s", filename ? filename : "NULL");
+	init(REPORT_FILENO);
+	return 0;
+}
+
+int svndump_init_fd(int in_fd, int back_fd)
+{
+	if(buffer_fdinit(&input, xdup(in_fd)))
+		return error_errno("cannot open fd %d", in_fd);
+	init(xdup(back_fd));
+	return 0;
+}
+
+void svndump_deinit(void)
+{
+	fast_export_deinit();
+	reset_dump_ctx(NULL);
+	reset_rev_ctx(0);
+	reset_node_ctx(NULL);
+	strbuf_release(&rev_ctx.log);
+	strbuf_release(&rev_ctx.author);
+	strbuf_release(&rev_ctx.note);
+	strbuf_release(&node_ctx.src);
+	strbuf_release(&node_ctx.dst);
+	if (buffer_deinit(&input))
+		fprintf(stderr, "Input error\n");
+	if (ferror(stdout))
+		fprintf(stderr, "Output error\n");
+}
+
+void svndump_reset(void)
+{
+	strbuf_release(&dump_ctx.uuid);
+	strbuf_release(&dump_ctx.url);
+	strbuf_release(&rev_ctx.log);
+	strbuf_release(&rev_ctx.author);
+}
diff --git a/third_party/git/vcs-svn/svndump.h b/third_party/git/vcs-svn/svndump.h
new file mode 100644
index 0000000000..26faed5968
--- /dev/null
+++ b/third_party/git/vcs-svn/svndump.h
@@ -0,0 +1,10 @@
+#ifndef SVNDUMP_H
+#define SVNDUMP_H
+
+int svndump_init(const char *filename);
+int svndump_init_fd(int in_fd, int back_fd);
+void svndump_read(const char *url, const char *local_ref, const char *notes_ref);
+void svndump_deinit(void);
+void svndump_reset(void);
+
+#endif