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authorJonathan Nieder <jrnieder@gmail.com>2011-05-26 07:27:48 (GMT)
committerJonathan Nieder <jrnieder@gmail.com>2011-05-26 07:27:48 (GMT)
commite9f3f8b6f4141dae526e9792ba6dede7aa038622 (patch)
treee4d1b8abaaef180f844b1d0f57afbc87e4c4f677 /vcs-svn
parentc19d653c4fcdc93169507c09f8f66ebffbdbb9a5 (diff)
parentc846e4107876936bed7177a811559bd74a72dcd8 (diff)
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Merge branch 'db/delta-applier' into db/text-delta
* db/delta-applier: 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 Conflicts: Makefile vcs-svn/LICENSE
Diffstat (limited to 'vcs-svn')
-rw-r--r--vcs-svn/LICENSE2
-rw-r--r--vcs-svn/line_buffer.c6
-rw-r--r--vcs-svn/line_buffer.h2
-rw-r--r--vcs-svn/sliding_window.c77
-rw-r--r--vcs-svn/sliding_window.h17
-rw-r--r--vcs-svn/svndiff.c308
-rw-r--r--vcs-svn/svndiff.h10
7 files changed, 418 insertions, 4 deletions
diff --git a/vcs-svn/LICENSE b/vcs-svn/LICENSE
index 533f585..eb91858 100644
--- a/vcs-svn/LICENSE
+++ b/vcs-svn/LICENSE
@@ -1,6 +1,8 @@
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
diff --git a/vcs-svn/line_buffer.c b/vcs-svn/line_buffer.c
index c390387..01fcb84 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 d0b22dd..8901f21 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/sliding_window.c b/vcs-svn/sliding_window.c
new file mode 100644
index 0000000..1b8d987
--- /dev/null
+++ b/vcs-svn/sliding_window.c
@@ -0,0 +1,77 @@
+/*
+ * 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");
+
+ 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 0000000..ed0bfdd
--- /dev/null
+++ b/vcs-svn/sliding_window.h
@@ -0,0 +1,17 @@
+#ifndef SLIDING_WINDOW_H_
+#define SLIDING_WINDOW_H_
+
+#include "strbuf.h"
+
+struct sliding_view {
+ struct line_buffer *file;
+ off_t off;
+ size_t width;
+ struct strbuf buf;
+};
+
+#define SLIDING_VIEW_INIT(input) { (input), 0, 0, STRBUF_INIT }
+
+extern int move_window(struct sliding_view *view, off_t off, size_t width);
+
+#endif
diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c
new file mode 100644
index 0000000..9ee41bb
--- /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 0000000..74eb464
--- /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