Add content offset to git_diff_line

For additions and deletions, external consumers like subversion
can make use of the content offset to generate diffs in their
proprietary formats.

include/git2/diff.h

@@ -446,6 +446,7 @@ struct git_diff_line {
 	int    new_lineno;   /** Line number in new file or -1 for deleted line */
 	int    num_lines;    /** Number of newline characters in content */
 	size_t content_len;  /** Number of bytes of data */
+	git_off_t content_offset; /** Offset in the original file to the content */
 	const char *content; /** Pointer to diff text, not NUL-byte terminated */
 };
 

src/diff_xdiff.c

@@ -54,6 +54,7 @@ typedef struct {
 	git_patch *patch;
 	git_diff_hunk hunk;
 	int old_lineno, new_lineno;
+	mmfile_t xd_old_data, xd_new_data;
 } git_xdiff_info;
 
 static int diff_update_lines(
@@ -135,6 +136,13 @@ static int git_xdiff_cb(void *priv, mmbuffer_t *bufs, int len)
 			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
 			GIT_DIFF_LINE_CONTEXT;
 
+		if (line.origin == GIT_DIFF_LINE_ADDITION)
+			line.content_offset = bufs[1].ptr - info->xd_new_data.ptr;
+		else if (line.origin == GIT_DIFF_LINE_DELETION)
+			line.content_offset = bufs[1].ptr - info->xd_old_data.ptr;
+		else
+			line.content_offset = -1;
+
 		output->error = diff_update_lines(
 			info, &line, bufs[1].ptr, bufs[1].size);
 
@@ -155,6 +163,8 @@ static int git_xdiff_cb(void *priv, mmbuffer_t *bufs, int len)
 			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_ADD_EOFNL :
 			GIT_DIFF_LINE_CONTEXT_EOFNL;
 
+		line.content_offset = -1;
+
 		output->error = diff_update_lines(
 			info, &line, bufs[2].ptr, bufs[2].size);
 
@@ -172,7 +182,6 @@ static int git_xdiff(git_diff_output *output, git_patch *patch)
 	git_xdiff_output *xo = (git_xdiff_output *)output;
 	git_xdiff_info info;
 	git_diff_find_context_payload findctxt;
-	mmfile_t xd_old_data, xd_new_data;
 
 	memset(&info, 0, sizeof(info));
 	info.patch = patch;
@@ -193,10 +202,10 @@ static int git_xdiff(git_diff_output *output, git_patch *patch)
 	 * updates are needed to xo->params.flags
 	 */
 
-	git_patch__old_data(&xd_old_data.ptr, &xd_old_data.size, patch);
-	git_patch__new_data(&xd_new_data.ptr, &xd_new_data.size, patch);
+	git_patch__old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch);
+	git_patch__new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch);
 
-	xdl_diff(&xd_old_data, &xd_new_data,
+	xdl_diff(&info.xd_old_data, &info.xd_new_data,
 		&xo->params, &xo->config, &xo->callback);
 
 	git_diff_find_context_clear(&findctxt);

tests/diff/patch.c

@@ -275,6 +275,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("Ivory their outposts were--the guardrooms of them gilded,\n", actual.ptr);
 	cl_assert_equal_i(6, line->old_lineno);
 	cl_assert_equal_i(6, line->new_lineno);
+	cl_assert_equal_i(-1, line->content_offset);
 
 	cl_git_pass(git_patch_get_line_in_hunk(&line, patch, 0, 3));
 	cl_assert_equal_i(GIT_DIFF_LINE_DELETION, (int)line->origin);
@@ -282,6 +283,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("All the world went softly when it walked before my Cities--\n", actual.ptr);
 	cl_assert_equal_i(9, line->old_lineno);
 	cl_assert_equal_i(-1, line->new_lineno);
+	cl_assert_equal_i(252, line->content_offset);
 
 	cl_git_pass(git_patch_get_line_in_hunk(&line, patch, 0, 12));
 	cl_assert_equal_i(GIT_DIFF_LINE_ADDITION, (int)line->origin);
@@ -289,6 +291,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("This is some new text;\n", actual.ptr);
 	cl_assert_equal_i(-1, line->old_lineno);
 	cl_assert_equal_i(9, line->new_lineno);
+	cl_assert_equal_i(252, line->content_offset);
 
 	/* check hunk 1 */
 
@@ -309,6 +312,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("My rulers and their treasure and their unborn populations,\n", actual.ptr);
 	cl_assert_equal_i(31, line->old_lineno);
 	cl_assert_equal_i(25, line->new_lineno);
+	cl_assert_equal_i(-1, line->content_offset);
 
 	cl_git_pass(git_patch_get_line_in_hunk(&line, patch, 1, 3));
 	cl_assert_equal_i(GIT_DIFF_LINE_DELETION, (int)line->origin);
@@ -316,6 +320,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("The Daughters of the Palace whom they cherished in my Cities,\n", actual.ptr);
 	cl_assert_equal_i(34, line->old_lineno);
 	cl_assert_equal_i(-1, line->new_lineno);
+	cl_assert_equal_i(1468, line->content_offset);
 
 	cl_git_pass(git_patch_get_line_in_hunk(&line, patch, 1, 12));
 	cl_assert_equal_i(GIT_DIFF_LINE_ADDITION, (int)line->origin);
@@ -323,6 +328,7 @@ void test_diff_patch__hunks_have_correct_line_numbers(void)
 	cl_assert_equal_s("Another replacement;\n", actual.ptr);
 	cl_assert_equal_i(-1, line->old_lineno);
 	cl_assert_equal_i(28, line->new_lineno);
+	cl_assert_equal_i(1066, line->content_offset);
 
 	git_patch_free(patch);
 	git_diff_free(diff);