[PATCH 14/16] vcs-svn: let deltas use data from preimage

From

David Barr <david.barr@cordelta.com>

Date

Mar 19, 2011, 07:20 UTC

Message-ID

<1300519254-20201-15-git-send-email-david.barr@cordelta.com>

In-Reply-To

<1300519254-20201-1-git-send-email-david.barr@cordelta.com>

From: Jonathan Nieder <jrnieder@gmail.com>

	mkfifo backflow
	svn-fe <svn-asf-public-r0:940166 3<backflow |
	git fast-import --cat-blob-fd=3 3>backflow

Improved-by: Ramkumar Ramachandra <artagnon@gmail.com>
Improved-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
---
 t/t9011-svn-da.sh |   35 +++++++++++++++++++++++++++++++++++
 vcs-svn/svndiff.c |   28 +++++++++++++++++++++++-----
 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/t/t9011-svn-da.sh b/t/t9011-svn-da.sh
index d13115a..45e396f 100755
--- a/t/t9011-svn-da.sh
+++ b/t/t9011-svn-da.sh
@@ -212,4 +212,39 @@ test_expect_success 'catch copy that overflows' '
 	test_must_fail test-svn-fe -d preimage copytarget.overflow $len
 '
 
+test_expect_success 'copyfrom source' '
+	printf foo >expect &&
+	printf "SVNQ%b%b" "Q\003\003\002Q" "\003Q" | q_to_nul >copysource.all &&
+	test-svn-fe -d preimage copysource.all 11 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'copy backwards' '
+	printf oof >expect &&
+	printf "SVNQ%b%b" "Q\003\003\006Q" "\001\002\001\001\001Q" |
+		q_to_nul >copysource.rev &&
+	test-svn-fe -d preimage copysource.rev 15 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'offsets are relative to window' '
+	printf fo >expect &&
+	printf "SVNQ%b%b%b%b" "Q\003\001\002Q" "\001Q" \
+		"\002\001\001\002Q" "\001Q" |
+		q_to_nul >copysource.two &&
+	test-svn-fe -d preimage copysource.two 18 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'example from notes/svndiff' '
+	printf aaaaccccdddddddd >expect &&
+	printf aaaabbbbcccc >source &&
+	printf "SVNQ%b%b%s" "Q\014\020\007\001" \
+		"\004Q\004\010\0201\0107\010" d |
+		q_to_nul >delta.example &&
+	len=$(wc -c <delta.example) &&
+	test-svn-fe -d source delta.example $len >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c
index f4c5dae..b7d40c8 100644
--- a/vcs-svn/svndiff.c
+++ b/vcs-svn/svndiff.c
@@ -24,6 +24,7 @@
  * 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;
@@ -34,6 +35,7 @@
  */
 
 #define INSN_MASK	0xc0
+#define INSN_COPYFROM_SOURCE	0x00
 #define INSN_COPYFROM_TARGET	0x40
 #define INSN_COPYFROM_DATA	0x80
 #define OPERAND_MASK	0x3f
@@ -43,12 +45,13 @@
 #define VLI_BITS_PER_DIGIT 7
 
 struct window {
+	struct sliding_view *in;
 	struct strbuf out;
 	struct strbuf instructions;
 	struct strbuf data;
 };
 
-#define WINDOW_INIT	{ STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
+#define WINDOW_INIT(w)	{ w, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
 
 static void window_release(struct window *ctx)
 {
@@ -161,6 +164,19 @@ static int read_length(struct line_buffer *in, size_t *result, off_t *len)
 	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)
 {
@@ -209,12 +225,14 @@ static int execute_one_instruction(struct window *ctx,
 	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("Unknown instruction %x", instruction);
+		return error("invalid delta: unrecognized instruction");
 	}
 }
 
@@ -238,9 +256,9 @@ static int apply_window_in_core(struct window *ctx)
 }
 
 static int apply_one_window(struct line_buffer *delta, off_t *delta_len,
-			    FILE *out)
+			    struct sliding_view *preimage, FILE *out)
 {
-	struct window ctx = WINDOW_INIT;
+	struct window ctx = WINDOW_INIT(preimage);
 	size_t out_len;
 	size_t instructions_len;
 	size_t data_len;
@@ -285,7 +303,7 @@ int svndiff0_apply(struct line_buffer *delta, off_t delta_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, postimage))
+		    apply_one_window(delta, &delta_len, preimage, postimage))
 			return -1;
 	}
 	return 0;

-- 
1.7.3.2.846.gf4b062