Add "as_path" parameters to blob and buffer diffs

This adds parameters to the four functions that allow for blob-to-
blob and blob-to-buffer differencing (either via callbacks or by
making a git_diff_patch object).  These parameters let you say
that filename we should pretend the blob has while doing the diff.
If you pass NULL, there should be no change from the existing
behavior, which is to skip using attributes for file type checks
and just look at content.  With the parameters, you can plug into
the new diff driver functionality and get binary or non-binary
behavior, plus function context regular expressions, etc.

This commit also fixes things so that the git_diff_delta that is
generated by these functions will actually be populated with the
data that we know about the blobs (or buffers) so you can use it
appropriately.  It also fixes a bug in generating patches from
the git_diff_patch objects created via these functions.

Lastly, there is one other behavior change that may matter.  If
there is no difference between the two blobs, these functions no
longer generate any diff callbacks / patches unless you have
passed in GIT_DIFF_INCLUDE_UNMODIFIED.  This is pretty natural,
but could potentially change the behavior of existing usage.

1 files changed, 113 insertions, 46 deletions

diff --git a/src/diff_patch.c b/src/diff_patch.c
index 40cb3371a..9060d0a24 100644
--- a/src/diff_patch.c
+++ b/src/diff_patch.c
@@ -64,12 +64,12 @@ static void diff_patch_update_binary(git_diff_patch *patch)
 	if ((patch->delta->flags & DIFF_FLAGS_KNOWN_BINARY) != 0)
 		return;
 
-	if ((patch->ofile.file.flags & GIT_DIFF_FLAG_BINARY) != 0 ||
-		(patch->nfile.file.flags & GIT_DIFF_FLAG_BINARY) != 0)
+	if ((patch->ofile.file->flags & GIT_DIFF_FLAG_BINARY) != 0 ||
+		(patch->nfile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
 		patch->delta->flags |= GIT_DIFF_FLAG_BINARY;
 
-	else if ((patch->ofile.file.flags & DIFF_FLAGS_NOT_BINARY) != 0 &&
-			 (patch->nfile.file.flags & DIFF_FLAGS_NOT_BINARY) != 0)
+	else if ((patch->ofile.file->flags & DIFF_FLAGS_NOT_BINARY) != 0 &&
+			 (patch->nfile.file->flags & DIFF_FLAGS_NOT_BINARY) != 0)
 		patch->delta->flags |= GIT_DIFF_FLAG_NOT_BINARY;
 }
 
@@ -143,42 +143,42 @@ static int diff_patch_load(git_diff_patch *patch, git_diff_output *output)
 		output && !output->hunk_cb && !output->data_cb)
 		return 0;
 
-#define DIFF_FLAGS_KNOWN_DATA (GIT_DIFF_FLAG__NO_DATA|GIT_DIFF_FLAG_VALID_OID)
-
 	incomplete_data =
-		((patch->ofile.file.flags & DIFF_FLAGS_KNOWN_DATA) != 0 &&
-		 (patch->nfile.file.flags & DIFF_FLAGS_KNOWN_DATA) != 0);
+		(((patch->ofile.flags & GIT_DIFF_FLAG__NO_DATA) != 0 ||
+		  (patch->ofile.file->flags & GIT_DIFF_FLAG_VALID_OID) != 0) &&
+		 ((patch->nfile.flags & GIT_DIFF_FLAG__NO_DATA) != 0 ||
+		  (patch->nfile.file->flags & GIT_DIFF_FLAG_VALID_OID) != 0));
 
 	/* always try to load workdir content first because filtering may
 	 * need 2x data size and this minimizes peak memory footprint
 	 */
 	if (patch->ofile.src == GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_diff_file_content__load(&patch->ofile)) < 0 ||
-			(patch->ofile.file.flags & GIT_DIFF_FLAG_BINARY) != 0)
+			(patch->ofile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
 			goto cleanup;
 	}
 	if (patch->nfile.src == GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_diff_file_content__load(&patch->nfile)) < 0 ||
-			(patch->nfile.file.flags & GIT_DIFF_FLAG_BINARY) != 0)
+			(patch->nfile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
 			goto cleanup;
 	}
 
 	/* once workdir has been tried, load other data as needed */
 	if (patch->ofile.src != GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_diff_file_content__load(&patch->ofile)) < 0 ||
-			(patch->ofile.file.flags & GIT_DIFF_FLAG_BINARY) != 0)
+			(patch->ofile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
 			goto cleanup;
 	}
 	if (patch->nfile.src != GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_diff_file_content__load(&patch->nfile)) < 0 ||
-			(patch->nfile.file.flags & GIT_DIFF_FLAG_BINARY) != 0)
+			(patch->nfile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
 			goto cleanup;
 	}
 
 	/* if we were previously missing an oid, update MODIFIED->UNMODIFIED */
 	if (incomplete_data &&
-		patch->ofile.file.mode == patch->nfile.file.mode &&
-		git_oid_equal(&patch->ofile.file.oid, &patch->nfile.file.oid) &&
+		patch->ofile.file->mode == patch->nfile.file->mode &&
+		git_oid_equal(&patch->ofile.file->oid, &patch->nfile.file->oid) &&
 		patch->delta->status == GIT_DELTA_MODIFIED) /* not RENAMED/COPIED! */
 		patch->delta->status = GIT_DELTA_UNMODIFIED;
 
@@ -193,7 +193,7 @@ cleanup:
 			patch->delta->status != GIT_DELTA_UNMODIFIED &&
 			(patch->ofile.map.len || patch->nfile.map.len) &&
 			(patch->ofile.map.len != patch->nfile.map.len ||
-			 !git_oid_equal(&patch->ofile.file.oid, &patch->nfile.file.oid)))
+			 !git_oid_equal(&patch->ofile.file->oid, &patch->nfile.file->oid)))
 			patch->flags |= GIT_DIFF_PATCH_DIFFABLE;
 
 		patch->flags |= GIT_DIFF_PATCH_LOADED;
@@ -312,26 +312,31 @@ int git_diff_foreach(
 typedef struct {
 	git_diff_patch patch;
 	git_diff_delta delta;
+	char paths[GIT_FLEX_ARRAY];
 } diff_patch_with_delta;
 
 static int diff_single_generate(diff_patch_with_delta *pd, git_xdiff_output *xo)
 {
 	int error = 0;
 	git_diff_patch *patch = &pd->patch;
-	bool has_old = ((patch->ofile.file.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
-	bool has_new = ((patch->nfile.file.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
+	bool has_old = ((patch->ofile.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
+	bool has_new = ((patch->nfile.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
 
 	pd->delta.status = has_new ?
 		(has_old ? GIT_DELTA_MODIFIED : GIT_DELTA_ADDED) :
 		(has_old ? GIT_DELTA_DELETED : GIT_DELTA_UNTRACKED);
 
-	if (git_oid_equal(&patch->nfile.file.oid, &patch->ofile.file.oid))
+	if (git_oid_equal(&patch->nfile.file->oid, &patch->ofile.file->oid))
 		pd->delta.status = GIT_DELTA_UNMODIFIED;
 
 	patch->delta = &pd->delta;
 
 	diff_patch_init_common(patch);
 
+	if (pd->delta.status == GIT_DELTA_UNMODIFIED &&
+		!(patch->ofile.opts_flags & GIT_DIFF_INCLUDE_UNMODIFIED))
+		return error;
+
 	error = diff_patch_file_callback(patch, (git_diff_output *)xo);
 
 	if (!error)
@@ -347,7 +352,9 @@ static int diff_patch_from_blobs(
 	diff_patch_with_delta *pd,
 	git_xdiff_output *xo,
 	const git_blob *old_blob,
+	const char *old_path,
 	const git_blob *new_blob,
+	const char *new_path,
 	const git_diff_options *opts)
 {
 	int error = 0;
@@ -357,29 +364,61 @@ static int diff_patch_from_blobs(
 
 	GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options");
 
-	pd->patch.delta = &pd->delta;
-
-	if (!repo) /* return two NULL items as UNMODIFIED delta */
-		return 0;
-
 	if (opts && (opts->flags & GIT_DIFF_REVERSE) != 0) {
-		const git_blob *swap = old_blob;
-		old_blob = new_blob;
-		new_blob = swap;
+		const git_blob *tmp_blob;
+		const char *tmp_path;
+		tmp_blob = old_blob; old_blob = new_blob; new_blob = tmp_blob;
+		tmp_path = old_path; old_path = new_path; new_path = tmp_path;
 	}
 
+	pd->patch.delta = &pd->delta;
+
+	pd->delta.old_file.path = old_path;
+	pd->delta.new_file.path = new_path;
+
 	if ((error = git_diff_file_content__init_from_blob(
-			&pd->patch.ofile, repo, opts, old_blob)) < 0 ||
+			&pd->patch.ofile, repo, opts, old_blob, &pd->delta.old_file)) < 0 ||
 		(error = git_diff_file_content__init_from_blob(
-			&pd->patch.nfile, repo, opts, new_blob)) < 0)
+			&pd->patch.nfile, repo, opts, new_blob, &pd->delta.new_file)) < 0)
 		return error;
 
 	return diff_single_generate(pd, xo);
 }
 
+static int diff_patch_with_delta_alloc(
+	diff_patch_with_delta **out,
+	const char **old_path,
+	const char **new_path)
+{
+	diff_patch_with_delta *pd;
+	size_t old_len = *old_path ? strlen(*old_path) : 0;
+	size_t new_len = *new_path ? strlen(*new_path) : 0;
+
+	*out = pd = git__calloc(1, sizeof(*pd) + old_len + new_len + 2);
+	GITERR_CHECK_ALLOC(pd);
+
+	pd->patch.flags = GIT_DIFF_PATCH_ALLOCATED;
+
+	if (*old_path) {
+		memcpy(&pd->paths[0], *old_path, old_len);
+		*old_path = &pd->paths[0];
+	} else if (*new_path)
+		*old_path = &pd->paths[old_len + 1];
+
+	if (*new_path) {
+		memcpy(&pd->paths[old_len + 1], *new_path, new_len);
+		*new_path = &pd->paths[old_len + 1];
+	} else if (*old_path)
+		*new_path = &pd->paths[0];
+
+	return 0;
+}
+
 int git_diff_blobs(
 	const git_blob *old_blob,
+	const char *old_path,
 	const git_blob *new_blob,
+	const char *new_path,
 	const git_diff_options *opts,
 	git_diff_file_cb file_cb,
 	git_diff_hunk_cb hunk_cb,
@@ -397,7 +436,13 @@ int git_diff_blobs(
 		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
-	error = diff_patch_from_blobs(&pd, &xo, old_blob, new_blob, opts);
+	if (!old_path && new_path)
+		old_path = new_path;
+	else if (!new_path && old_path)
+		new_path = old_path;
+
+	error = diff_patch_from_blobs(
+		&pd, &xo, old_blob, old_path, new_blob, new_path, opts);
 
 	git_diff_patch_free((git_diff_patch *)&pd);
 
@@ -407,7 +452,9 @@ int git_diff_blobs(
 int git_diff_patch_from_blobs(
 	git_diff_patch **out,
 	const git_blob *old_blob,
+	const char *old_path,
 	const git_blob *new_blob,
+	const char *new_path,
 	const git_diff_options *opts)
 {
 	int error = 0;
@@ -417,16 +464,18 @@ int git_diff_patch_from_blobs(
 	assert(out);
 	*out = NULL;
 
-	pd = git__calloc(1, sizeof(*pd));
-	GITERR_CHECK_ALLOC(pd);
-	pd->patch.flags = GIT_DIFF_PATCH_ALLOCATED;
+	if (diff_patch_with_delta_alloc(&pd, &old_path, &new_path) < 0)
+		return -1;
 
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
-	if (!(error = diff_patch_from_blobs(pd, &xo, old_blob, new_blob, opts)))
+	error = diff_patch_from_blobs(
+		pd, &xo, old_blob, old_path, new_blob, new_path, opts);
+
+	if (!error)
 		*out = (git_diff_patch *)pd;
 	else
 		git_diff_patch_free((git_diff_patch *)pd);
@@ -438,8 +487,10 @@ static int diff_patch_from_blob_and_buffer(
 	diff_patch_with_delta *pd,
 	git_xdiff_output *xo,
 	const git_blob *old_blob,
+	const char *old_path,
 	const char *buf,
 	size_t buflen,
+	const char *buf_path,
 	const git_diff_options *opts)
 {
 	int error = 0;
@@ -450,28 +501,36 @@ static int diff_patch_from_blob_and_buffer(
 
 	pd->patch.delta = &pd->delta;
 
-	if (!repo && !buf) /* return two NULL items as UNMODIFIED delta */
-		return 0;
-
 	if (opts && (opts->flags & GIT_DIFF_REVERSE) != 0) {
+		pd->delta.old_file.path = buf_path;
+		pd->delta.new_file.path = old_path;
+
 		if (!(error = git_diff_file_content__init_from_raw(
-				&pd->patch.ofile, repo, opts, buf, buflen)))
+				&pd->patch.ofile, repo, opts, buf, buflen, &pd->delta.old_file)))
 			error = git_diff_file_content__init_from_blob(
-				&pd->patch.nfile, repo, opts, old_blob);
+				&pd->patch.nfile, repo, opts, old_blob, &pd->delta.new_file);
 	} else {
+		pd->delta.old_file.path = old_path;
+		pd->delta.new_file.path = buf_path;
+
 		if (!(error = git_diff_file_content__init_from_blob(
-				&pd->patch.ofile, repo, opts, old_blob)))
+				&pd->patch.ofile, repo, opts, old_blob, &pd->delta.old_file)))
 			error = git_diff_file_content__init_from_raw(
-				&pd->patch.nfile, repo, opts, buf, buflen);
+				&pd->patch.nfile, repo, opts, buf, buflen, &pd->delta.new_file);
 	}
 
+	if (error < 0)
+		return error;
+
 	return diff_single_generate(pd, xo);
 }
 
 int git_diff_blob_to_buffer(
 	const git_blob *old_blob,
+	const char *old_path,
 	const char *buf,
 	size_t buflen,
+	const char *buf_path,
 	const git_diff_options *opts,
 	git_diff_file_cb file_cb,
 	git_diff_hunk_cb hunk_cb,
@@ -489,8 +548,13 @@ int git_diff_blob_to_buffer(
 		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
+	if (!old_path && buf_path)
+		old_path = buf_path;
+	else if (!buf_path && old_path)
+		buf_path = old_path;
+
 	error = diff_patch_from_blob_and_buffer(
-		&pd, &xo, old_blob, buf, buflen, opts);
+		&pd, &xo, old_blob, old_path, buf, buflen, buf_path, opts);
 
 	git_diff_patch_free((git_diff_patch *)&pd);
 
@@ -500,8 +564,10 @@ int git_diff_blob_to_buffer(
 int git_diff_patch_from_blob_and_buffer(
 	git_diff_patch **out,
 	const git_blob *old_blob,
+	const char *old_path,
 	const char *buf,
 	size_t buflen,
+	const char *buf_path,
 	const git_diff_options *opts)
 {
 	int error = 0;
@@ -511,17 +577,18 @@ int git_diff_patch_from_blob_and_buffer(
 	assert(out);
 	*out = NULL;
 
-	pd = git__calloc(1, sizeof(*pd));
-	GITERR_CHECK_ALLOC(pd);
-	pd->patch.flags = GIT_DIFF_PATCH_ALLOCATED;
+	if (diff_patch_with_delta_alloc(&pd, &old_path, &buf_path) < 0)
+		return -1;
 
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
-	if (!(error = diff_patch_from_blob_and_buffer(
-			pd, &xo, old_blob, buf, buflen, opts)))
+	error = diff_patch_from_blob_and_buffer(
+		pd, &xo, old_blob, old_path, buf, buflen, buf_path, opts);
+
+	if (!error)
 		*out = (git_diff_patch *)pd;
 	else
 		git_diff_patch_free((git_diff_patch *)pd);