Initial implementation of new diff patch API

Replacing the `git_iterator` object, this creates a simple API
for accessing the "patch" for any file pair in a diff list and
then gives indexed access to the hunks in the patch and the lines
in the hunk.  This is the initial implementation of this revised
API - it is still broken, but at least builds cleanly.

10 files changed, 967 insertions, 826 deletions

diff --git a/include/git2/diff.h b/include/git2/diff.h
index 2a5cdacc0..d216c1303 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -98,6 +98,9 @@ enum {
 	GIT_DIFF_FILE_FREE_PATH  = (1 << 1),
 	GIT_DIFF_FILE_BINARY     = (1 << 2),
 	GIT_DIFF_FILE_NOT_BINARY = (1 << 3),
+	GIT_DIFF_FILE_FREE_DATA  = (1 << 4),
+	GIT_DIFF_FILE_UNMAP_DATA = (1 << 5),
+	GIT_DIFF_FILE_NO_DATA    = (1 << 6),
 };
 
 /**
@@ -425,7 +428,7 @@ GIT_EXTERN(int) git_diff_print_patch(
  * @param diff A git_diff_list generated by one of the above functions
  * @return Count of number of deltas in the list
  */
-GIT_EXTERN(size_t) git_diff_entrycount(git_diff_list *diff);
+GIT_EXTERN(size_t) git_diff_num_deltas(git_diff_list *diff);
 
 /**
  * Query how many diff deltas are there in a diff list filtered by type.
@@ -438,7 +441,7 @@ GIT_EXTERN(size_t) git_diff_entrycount(git_diff_list *diff);
  * @param type A git_delta_t value to filter the count
  * @return Count of number of deltas matching delta_t type
  */
-GIT_EXTERN(size_t) git_diff_entrycount_of_type(
+GIT_EXTERN(size_t) git_diff_num_deltas_of_type(
 	git_diff_list *diff,
 	git_delta_t type);
 
@@ -469,7 +472,7 @@ GIT_EXTERN(size_t) git_diff_entrycount_of_type(
  */
 GIT_EXTERN(int) git_diff_get_patch(
 	git_diff_patch **patch,
-	const git_diff_delta **delta,
+	git_diff_delta **delta,
 	git_diff_list *diff,
 	size_t idx);
 
@@ -482,43 +485,76 @@ GIT_EXTERN(void) git_diff_patch_free(
 /**
  * Get the delta associated with a patch
  */
-GIT_EXTERN(void) git_diff_patch_get_delta(
-	const git_diff_delta **delta,
+GIT_EXTERN(const git_diff_delta *) git_diff_patch_delta(
 	git_diff_patch *patch);
 
 /**
  * Get the number of hunks in a patch
  */
-GIT_EXTERN(size_t) git_diff_patch_hunks(
+GIT_EXTERN(size_t) git_diff_patch_num_hunks(
 	git_diff_patch *patch);
 
 /**
  * Get the information about a hunk in a patch
+ *
+ * Given a patch and a hunk index into the patch, this returns detailed
+ * information about that hunk.  Any of the output pointers can be passed
+ * as NULL if you don't care about that particular piece of information.
+ *
+ * @param range Output pointer to git_diff_range of hunk
+ * @param header Output pointer to header string for hunk.  Unlike the
+ *               content pointer for each line, this will be NUL-terminated
+ * @param header_len Output value of characters in header string
+ * @param lines_in_hunk Output count of total lines in this hunk
+ * @param patch Input pointer to patch object
+ * @param hunk_idx Input index of hunk to get information about
+ * @return 0 on success, GIT_ENOTFOUND if hunk_idx out of range, <0 on error
  */
 GIT_EXTERN(int) git_diff_patch_get_hunk(
-	const git_diff_range **range,
+	git_diff_range **range,
 	const char **header,
 	size_t *header_len,
 	size_t *lines_in_hunk,
 	git_diff_patch *patch,
-	size_t hunk);
+	size_t hunk_idx);
 
 /**
- * Get the number of lines in a hunk
+ * Get the number of lines in a hunk.
+ *
+ * @param patch The git_diff_patch object
+ * @param hunk_idx Index of the hunk
+ * @return Number of lines in hunk or -1 if invalid hunk index
  */
-GIT_EXTERN(size_t) git_diff_patch_lines_in_hunk(
+GIT_EXTERN(int) git_diff_patch_num_lines_in_hunk(
 	git_diff_patch *patch,
-	size_t hunk);
+	size_t hunk_idx);
 
 /**
- * Get a line in a hunk of a patch
+ * Get data about a line in a hunk of a patch.
+ *
+ * Given a patch, a hunk index, and a line index in the hunk, this
+ * will return a lot of details about that line.  If you pass a hunk
+ * index larger than the number of hunks or a line index larger than
+ * the number of lines in the hunk, this will return -1.
+ *
+ * @param line_origin A GIT_DIFF_LINE constant from above
+ * @param content Pointer to content of diff line, not NUL-terminated
+ * @param content_len Number of characters in content
+ * @param old_lineno Line number in old file or -1 if line is added
+ * @param new_lineno Line number in new file or -1 if line is deleted
+ * @param patch The patch to look in
+ * @param hunk_idx The index of the hunk
+ * @param line_of_index The index of the line in the hunk
+ * @return 0 on success, <0 on failure
  */
 GIT_EXTERN(int) git_diff_patch_get_line_in_hunk(
 	char *line_origin,
 	const char **content,
 	size_t *content_len,
+	int *old_lineno,
+	int *new_lineno,
 	git_diff_patch *patch,
-	size_t hunk,
+	size_t hunk_idx,
 	size_t line_of_hunk);
 
 /**@}*/
diff --git a/src/diff.c b/src/diff.c
index 499b95b44..7c8e2a9bb 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -5,8 +5,6 @@
  * a Linking Exception. For full terms see the included COPYING file.
  */
 #include "common.h"
-#include "git2/diff.h"
-#include "git2/oid.h"
 #include "diff.h"
 #include "fileops.h"
 #include "config.h"
@@ -268,9 +266,17 @@ static int diff_delta__from_two(
 	delta->old_file.mode = old_mode;
 	delta->old_file.flags |= GIT_DIFF_FILE_VALID_OID;
 
-	git_oid_cpy(&delta->new_file.oid, new_oid ? new_oid : &new_entry->oid);
+	git_oid_cpy(&delta->new_file.oid, &new_entry->oid);
 	delta->new_file.size = new_entry->file_size;
 	delta->new_file.mode = new_mode;
+
+	if (new_oid) {
+		if ((diff->opts.flags & GIT_DIFF_REVERSE) != 0)
+			git_oid_cpy(&delta->old_file.oid, new_oid);
+		else
+			git_oid_cpy(&delta->new_file.oid, new_oid);
+	}
+
 	if (new_oid || !git_oid_iszero(&new_entry->oid))
 		delta->new_file.flags |= GIT_DIFF_FILE_VALID_OID;
 
@@ -425,6 +431,11 @@ void git_diff_list_free(git_diff_list *diff)
 	GIT_REFCOUNT_DEC(diff, diff_list_free);
 }
 
+void git_diff_list_addref(git_diff_list *diff)
+{
+	GIT_REFCOUNT_INC(diff);
+}
+
 static int oid_for_workdir_item(
 	git_repository *repo,
 	const git_index_entry *item,
@@ -519,17 +530,17 @@ static int maybe_modified(
 			 omode == nmode)
 		status = GIT_DELTA_UNMODIFIED;
 
-	/* if modes match and we have an unknown OID and a workdir iterator,
-	 * then check deeper for matching
+	/* if we have an unknown OID and a workdir iterator, then check some
+	 * circumstances that can accelerate things or need special handling
 	 */
-	else if (omode == nmode &&
-		git_oid_iszero(&nitem->oid) &&
-		new_iter->type == GIT_ITERATOR_WORKDIR)
+	else if (git_oid_iszero(&nitem->oid) &&
+			 new_iter->type == GIT_ITERATOR_WORKDIR)
 	{
 		/* TODO: add check against index file st_mtime to avoid racy-git */
 
-		/* if they files look exactly alike, then we'll assume the same */
-		if (oitem->file_size == nitem->file_size &&
+		/* if the stat data looks exactly alike, then assume the same */
+		if (omode == nmode &&
+			oitem->file_size == nitem->file_size &&
 			(!(diff->diffcaps & GIT_DIFFCAPS_TRUST_CTIME) ||
 			 (oitem->ctime.seconds == nitem->ctime.seconds)) &&
 			oitem->mtime.seconds == nitem->mtime.seconds &&
@@ -554,16 +565,15 @@ static int maybe_modified(
 				status = GIT_DELTA_UNMODIFIED;
 			}
 		}
+	}
 
-		/* TODO: check git attributes so we will not have to read the file
-		 * in if it is marked binary.
-		 */
-
-		else if (oid_for_workdir_item(diff->repo, nitem, &noid) < 0)
+	/* if we got here and decided that the files are modified, but we
+	 * haven't calculated the OID of the new item, then calculate it now
+	 */
+	if (status == GIT_DELTA_MODIFIED && git_oid_iszero(&nitem->oid)) {
+		if (oid_for_workdir_item(diff->repo, nitem, &noid) < 0)
 			return -1;
-
-		else if (git_oid_cmp(&oitem->oid, &noid) == 0 &&
-				 omode == nmode)
+		else if (omode == nmode && git_oid_equal(&oitem->oid, &noid))
 			status = GIT_DELTA_UNMODIFIED;
 
 		/* store calculated oid so we don't have to recalc later */
diff --git a/src/diff.h b/src/diff.h
index ea38a678f..862c33c1b 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -7,6 +7,9 @@
 #ifndef INCLUDE_diff_h__
 #define INCLUDE_diff_h__
 
+#include "git2/diff.h"
+#include "git2/oid.h"
+
 #include <stdio.h>
 #include "vector.h"
 #include "buffer.h"
@@ -25,14 +28,17 @@ enum {
 	GIT_DIFFCAPS_USE_DEV          = (1 << 4), /* use st_dev? */
 };
 
-#define MAX_DIFF_FILESIZE 0x20000000
+typedef struct {
+	git_refcount   rc;
+	git_diff_delta delta;
+} git_diff_delta_refcounted;
 
 struct git_diff_list {
 	git_refcount     rc;
 	git_repository   *repo;
 	git_diff_options opts;
 	git_vector       pathspec;
-	git_vector       deltas;    /* vector of git_diff_file_delta */
+	git_vector       deltas;    /* vector of git_diff_delta_refcounted */
 	git_pool pool;
 	git_iterator_type_t old_src;
 	git_iterator_type_t new_src;
@@ -42,27 +48,7 @@ struct git_diff_list {
 extern void git_diff__cleanup_modes(
 	uint32_t diffcaps, uint32_t *omode, uint32_t *nmode);
 
-/**
- * Return the maximum possible number of files in the diff.
- *
- * NOTE: This number has to be treated as an upper bound on the number of
- * files that have changed if the diff is with the working directory.
- *
- * Why?! For efficiency, we defer loading the file contents as long as
- * possible, so if a file has been "touched" in the working directory and
- * then reverted to the original content, it may get stored in the diff list
- * as MODIFIED along with a flag that the status should be reconfirmed when
- * it is actually loaded into memory.  When that load happens, it could get
- * flipped to UNMODIFIED. If unmodified files are being skipped, then the
- * iterator will skip that file and this number may be too high.
- *
- * This behavior is true of `git_diff_foreach` as well, but the only
- * implication there is that the `progress` value would not advance evenly.
- *
- * @param iterator The iterator object
- * @return The maximum number of files to be iterated over
- */
-int git_diff_iterator__max_files(git_diff_iterator *iterator);
+extern void git_diff_list_addref(git_diff_list *diff);
 
 #endif
 
diff --git a/src/diff_output.c b/src/diff_output.c
index 58a1a3567..b84b0c2a4 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -5,58 +5,13 @@
  * a Linking Exception. For full terms see the included COPYING file.
  */
 #include "common.h"
-#include "git2/diff.h"
 #include "git2/attr.h"
-#include "git2/blob.h"
 #include "git2/oid.h"
-#include "xdiff/xdiff.h"
+#include "diff_output.h"
 #include <ctype.h>
-#include "diff.h"
-#include "map.h"
 #include "fileops.h"
 #include "filter.h"
 
-/*
- * A diff_delta_context represents all of the information that goes into
- * processing the diff of an observed file change.  In the case of the
- * git_diff_foreach() call it is an emphemeral structure that is filled
- * in to execute each diff.  In the case of a git_diff_iterator, it holds
- * most of the information for the diff in progress.
- *
- * As each delta is processed, it goes through 3 phases: prep, load, exec.
- *
- * - In the prep phase, we just set the delta and quickly check the file
- *   attributes to see if it should be treated as binary.
- * - In the load phase, we actually load the file content into memory.
- *   At this point, if we had deferred calculating OIDs, we might have to
- *   correct the delta to be UNMODIFIED.
- * - In the exec phase, we actually run the diff and execute the callbacks.
- *   For foreach, this is just a pass-through to the user's callbacks.  For
- *   iterators, we record the hunks and data spans into memory.
-  */
-typedef struct {
-	git_repository   *repo;
-	git_diff_options *opts;
-	xdemitconf_t xdiff_config;
-	xpparam_t    xdiff_params;
-	git_diff_delta *delta;
-	uint32_t prepped  : 1;
-	uint32_t loaded   : 1;
-	uint32_t diffable : 1;
-	uint32_t diffed   : 1;
-	git_iterator_type_t old_src;
-	git_iterator_type_t new_src;
-	git_blob *old_blob;
-	git_blob *new_blob;
-	git_map   old_data;
-	git_map   new_data;
-	void *cb_data;
-	git_diff_hunk_fn per_hunk;
-	git_diff_data_fn per_line;
-	int cb_error;
-	git_diff_range range;
-} diff_delta_context;
-
 static int read_next_int(const char **str, int *value)
 {
 	const char *scan = *str;
@@ -96,55 +51,28 @@ static int parse_hunk_header(git_diff_range *range, const char *header)
 	return 0;
 }
 
-static int format_hunk_header(char *header, size_t len, git_diff_range *range)
+static bool diff_delta_should_skip(
+	diff_context *ctxt, git_diff_delta *delta)
 {
-	if (range->old_lines != 1) {
-		if (range->new_lines != 1)
-			return p_snprintf(
-				header, len, "@@ -%d,%d +%d,%d @@",
-				range->old_start, range->old_lines,
-				range->new_start, range->new_lines);
-		else
-			return p_snprintf(
-				header, len, "@@ -%d,%d +%d @@",
-				range->old_start, range->old_lines, range->new_start);
-	} else {
-		if (range->new_lines != 1)
-			return p_snprintf(
-				header, len, "@@ -%d +%d,%d @@",
-				range->old_start, range->new_start, range->new_lines);
-		else
-			return p_snprintf(
-				header, len, "@@ -%d +%d @@",
-				range->old_start, range->new_start);
-	}
-}
-
-static bool diff_delta_is_ambiguous(git_diff_delta *delta)
-{
-	return (git_oid_iszero(&delta->new_file.oid) &&
-			(delta->new_file.flags & GIT_DIFF_FILE_VALID_OID) == 0 &&
-			delta->status == GIT_DELTA_MODIFIED);
-}
+	uint32_t flags = ctxt->opts ? ctxt->opts->flags : 0;
 
-static bool diff_delta_should_skip(git_diff_options *opts, git_diff_delta *delta)
-{
 	if (delta->status == GIT_DELTA_UNMODIFIED &&
-		(opts->flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
+		(flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
 		return true;
 
 	if (delta->status == GIT_DELTA_IGNORED &&
-		(opts->flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
+		(flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
 		return true;
 
 	if (delta->status == GIT_DELTA_UNTRACKED &&
-		(opts->flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
+		(flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
 		return true;
 
 	return false;
 }
 
-#define BINARY_DIFF_FLAGS (GIT_DIFF_FILE_BINARY|GIT_DIFF_FILE_NOT_BINARY)
+#define KNOWN_BINARY_FLAGS (GIT_DIFF_FILE_BINARY|GIT_DIFF_FILE_NOT_BINARY)
+#define NOT_BINARY_FLAGS   (GIT_DIFF_FILE_NOT_BINARY|GIT_DIFF_FILE_NO_DATA)
 
 static int update_file_is_binary_by_attr(
 	git_repository *repo, git_diff_file *file)
@@ -173,8 +101,6 @@ static void update_delta_is_binary(git_diff_delta *delta)
 		(delta->new_file.flags & GIT_DIFF_FILE_BINARY) != 0)
 		delta->binary = 1;
 
-#define NOT_BINARY_FLAGS (GIT_DIFF_FILE_NOT_BINARY|GIT_DIFF_FILE_NO_DATA)
-
 	else if ((delta->old_file.flags & NOT_BINARY_FLAGS) != 0 &&
 			 (delta->new_file.flags & NOT_BINARY_FLAGS) != 0)
 		delta->binary = 0;
@@ -182,10 +108,11 @@ static void update_delta_is_binary(git_diff_delta *delta)
 	/* otherwise leave delta->binary value untouched */
 }
 
-static int diff_delta_is_binary_by_attr(diff_delta_context *ctxt)
+static int diff_delta_is_binary_by_attr(
+	diff_context *ctxt, git_diff_patch *patch)
 {
 	int error = 0, mirror_new;
-	git_diff_delta *delta = ctxt->delta;
+	git_diff_delta *delta = patch->delta;
 
 	delta->binary = -1;
 
@@ -200,7 +127,7 @@ static int diff_delta_is_binary_by_attr(diff_delta_context *ctxt)
 	}
 
 	/* check if user is forcing us to text diff these files */
-	if (ctxt->opts->flags & GIT_DIFF_FORCE_TEXT) {
+	if (ctxt->opts && (ctxt->opts->flags & GIT_DIFF_FORCE_TEXT) != 0) {
 		delta->old_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
 		delta->new_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
 		delta->binary = 0;
@@ -214,7 +141,7 @@ static int diff_delta_is_binary_by_attr(diff_delta_context *ctxt)
 	mirror_new = (delta->new_file.path == delta->old_file.path ||
 				  strcmp(delta->new_file.path, delta->old_file.path) == 0);
 	if (mirror_new)
-		delta->new_file.flags |= (delta->old_file.flags & BINARY_DIFF_FLAGS);
+		delta->new_file.flags |= (delta->old_file.flags & KNOWN_BINARY_FLAGS);
 	else
 		error = update_file_is_binary_by_attr(ctxt->repo, &delta->new_file);
 
@@ -224,11 +151,13 @@ static int diff_delta_is_binary_by_attr(diff_delta_context *ctxt)
 }
 
 static int diff_delta_is_binary_by_content(
-	diff_delta_context *ctxt, git_diff_file *file, git_map *map)
+	diff_context *ctxt, git_diff_delta *delta, git_diff_file *file, git_map *map)
 {
 	git_buf search;
 
-	if ((file->flags & BINARY_DIFF_FLAGS) == 0) {
+	GIT_UNUSED(ctxt);
+
+	if ((file->flags & KNOWN_BINARY_FLAGS) == 0) {
 		search.ptr  = map->data;
 		search.size = min(map->len, 4000);
 
@@ -238,17 +167,17 @@ static int diff_delta_is_binary_by_content(
 			file->flags |= GIT_DIFF_FILE_NOT_BINARY;
 	}
 
-	update_delta_is_binary(ctxt->delta);
+	update_delta_is_binary(delta);
 
 	return 0;
 }
 
 static int diff_delta_is_binary_by_size(
-	diff_delta_context *ctxt, git_diff_file *file)
+	diff_context *ctxt, git_diff_delta *delta, git_diff_file *file)
 {
 	git_off_t threshold = MAX_DIFF_FILESIZE;
 
-	if ((file->flags & BINARY_DIFF_FLAGS) != 0)
+	if ((file->flags & KNOWN_BINARY_FLAGS) != 0)
 		return 0;
 
 	if (ctxt && ctxt->opts) {
@@ -262,7 +191,7 @@ static int diff_delta_is_binary_by_size(
 	if (file->size > threshold)
 		file->flags |= GIT_DIFF_FILE_BINARY;
 
-	update_delta_is_binary(ctxt->delta);
+	update_delta_is_binary(delta);
 
 	return 0;
 }
@@ -289,8 +218,10 @@ static void setup_xdiff_options(
 		param->flags |= XDF_IGNORE_WHITESPACE_AT_EOL;
 }
 
+
 static int get_blob_content(
-	diff_delta_context *ctxt,
+	diff_context *ctxt,
+	git_diff_delta *delta,
 	git_diff_file *file,
 	git_map *map,
 	git_blob **blob)
@@ -318,9 +249,9 @@ static int get_blob_content(
 	}
 
 	/* if blob is too large to diff, mark as binary */
-	if ((error = diff_delta_is_binary_by_size(ctxt, file)) < 0)
+	if ((error = diff_delta_is_binary_by_size(ctxt, delta, file)) < 0)
 		return error;
-	if (ctxt->delta->binary == 1)
+	if (delta->binary == 1)
 		return 0;
 
 	if (odb_obj != NULL) {
@@ -336,11 +267,12 @@ static int get_blob_content(
 	map->data = (void *)git_blob_rawcontent(*blob);
 	map->len  = git_blob_rawsize(*blob);
 
-	return diff_delta_is_binary_by_content(ctxt, file, map);
+	return diff_delta_is_binary_by_content(ctxt, delta, file, map);
 }
 
 static int get_workdir_content(
-	diff_delta_context *ctxt,
+	diff_context *ctxt,
+	git_diff_delta *delta,
 	git_diff_file *file,
 	git_map *map)
 {
@@ -386,8 +318,8 @@ static int get_workdir_content(
 		if (!file->size)
 			file->size = git_futils_filesize(fd);
 
-		if ((error = diff_delta_is_binary_by_size(ctxt, file)) < 0 ||
-			ctxt->delta->binary == 1)
+		if ((error = diff_delta_is_binary_by_size(ctxt, delta, file)) < 0 ||
+			delta->binary == 1)
 			goto close_and_cleanup;
 
 		error = git_filters_load(
@@ -428,7 +360,7 @@ close_and_cleanup:
 	}
 
 	if (!error)
-		error = diff_delta_is_binary_by_content(ctxt, file, map);
+		error = diff_delta_is_binary_by_content(ctxt, delta, file, map);
 
 cleanup:
 	git_buf_free(&path);
@@ -454,78 +386,101 @@ static void release_content(git_diff_file *file, git_map *map, git_blob *blob)
 	}
 }
 
-static void diff_delta_init_context(
-	diff_delta_context *ctxt,
-	git_repository   *repo,
+
+static void diff_context_init(
+	diff_context *ctxt,
+	git_diff_list *diff,
+	git_repository *repo,
 	git_diff_options *opts,
-	git_iterator_type_t old_src,
-	git_iterator_type_t new_src)
+	void *data,
+	git_diff_file_fn file_cb,
+	git_diff_hunk_fn hunk_cb,
+	git_diff_data_fn data_cb)
 {
-	memset(ctxt, 0, sizeof(diff_delta_context));
+	memset(ctxt, 0, sizeof(diff_context));
 
 	ctxt->repo = repo;
+	ctxt->diff = diff;
 	ctxt->opts = opts;
-	ctxt->old_src = old_src;
-	ctxt->new_src = new_src;
+	ctxt->file_cb = file_cb;
+	ctxt->hunk_cb = hunk_cb;
+	ctxt->data_cb = data_cb;
+	ctxt->cb_data = data;
+	ctxt->cb_error = 0;
 
-	setup_xdiff_options(opts, &ctxt->xdiff_config, &ctxt->xdiff_params);
+	setup_xdiff_options(ctxt->opts, &ctxt->xdiff_config, &ctxt->xdiff_params);
 }
 
-static void diff_delta_init_context_from_diff_list(
-	diff_delta_context *ctxt,
-	git_diff_list *diff)
+static bool diff_delta_file_callback(
+	diff_context *ctxt, git_diff_delta *delta, size_t idx)
 {
-	diff_delta_init_context(
-		ctxt, diff->repo, &diff->opts, diff->old_src, diff->new_src);
+	float progress;
+
+	if (!ctxt->file_cb)
+		return 0;
+
+	progress = (float)idx / ctxt->diff->deltas.length;
+
+	if (ctxt->file_cb(ctxt->cb_data, delta, progress) != 0)
+		return GIT_EUSER;
+
+	return 0;
 }
 
-static void diff_delta_unload(diff_delta_context *ctxt)
+static void diff_patch_init(
+	diff_context *ctxt, git_diff_patch *patch)
 {
-	ctxt->diffed = 0;
+	memset(patch, 0, sizeof(*patch));
 
-	if (ctxt->loaded) {
-		release_content(&ctxt->delta->old_file, &ctxt->old_data, ctxt->old_blob);
-		release_content(&ctxt->delta->new_file, &ctxt->new_data, ctxt->new_blob);
-		ctxt->loaded = 0;
-	}
+	patch->diff = ctxt->diff;
+	patch->ctxt = ctxt;
 
-	ctxt->delta = NULL;
-	ctxt->prepped = 0;
+	if (patch->diff) {
+		patch->old_src = patch->diff->old_src;
+		patch->new_src = patch->diff->new_src;
+	} else {
+		patch->old_src = patch->new_src = GIT_ITERATOR_TREE;
+	}
 }
 
-static int diff_delta_prep(diff_delta_context *ctxt)
+static git_diff_patch *diff_patch_alloc(
+	diff_context *ctxt, git_diff_delta *delta)
 {
-	int error;
+	git_diff_patch *patch = git__malloc(sizeof(git_diff_patch));
+	if (!patch)
+		return NULL;
 
-	if (ctxt->prepped || !ctxt->delta)
-		return 0;
+	diff_patch_init(ctxt, patch);
 
-	error = diff_delta_is_binary_by_attr(ctxt);
+	git_diff_list_addref(patch->diff);
 
-	ctxt->prepped = !error;
+	GIT_REFCOUNT_INC(&patch);
 
-	return error;
+	patch->delta = delta;
+	patch->flags = GIT_DIFF_PATCH_ALLOCATED;
+
+	return patch;
 }
 
-static int diff_delta_load(diff_delta_context *ctxt)
+static int diff_patch_load(
+	diff_context *ctxt, git_diff_patch *patch)
 {
 	int error = 0;
-	git_diff_delta *delta = ctxt->delta;
+	git_diff_delta *delta = patch->delta;
 	bool check_if_unmodified = false;
 
-	if (ctxt->loaded || !ctxt->delta)
+	if ((patch->flags & GIT_DIFF_PATCH_LOADED) != 0)
 		return 0;
 
-	if (!ctxt->prepped && (error = diff_delta_prep(ctxt)) < 0)
-		goto cleanup;
+	error = diff_delta_is_binary_by_attr(ctxt, patch);
 
-	ctxt->old_data.data = "";
-	ctxt->old_data.len  = 0;
-	ctxt->old_blob      = NULL;
+	patch->old_data.data = "";
+	patch->old_data.len  = 0;
+	patch->old_blob      = NULL;
 
-	ctxt->new_data.data = "";
-	ctxt->new_data.len  = 0;
-	ctxt->new_blob      = NULL;
+	patch->new_data.data = "";
+	patch->new_data.len  = 0;
+	patch->new_blob      = NULL;
 
 	if (delta->binary == 1)
 		goto cleanup;
@@ -557,36 +512,38 @@ static int diff_delta_load(diff_delta_context *ctxt)
 	 */
 
 	if ((delta->old_file.flags & GIT_DIFF_FILE_NO_DATA) == 0 &&
-		ctxt->old_src == GIT_ITERATOR_WORKDIR) {
+		patch->old_src == GIT_ITERATOR_WORKDIR) {
 		if ((error = get_workdir_content(
-				ctxt, &delta->old_file, &ctxt->old_data)) < 0)
+				ctxt, delta, &delta->old_file, &patch->old_data)) < 0)
 			goto cleanup;
 		if (delta->binary == 1)
 			goto cleanup;
 	}
 
 	if ((delta->new_file.flags & GIT_DIFF_FILE_NO_DATA) == 0 &&
-		ctxt->new_src == GIT_ITERATOR_WORKDIR) {
+		patch->new_src == GIT_ITERATOR_WORKDIR) {
 		if ((error = get_workdir_content(
-				ctxt, &delta->new_file, &ctxt->new_data)) < 0)
+				ctxt, delta, &delta->new_file, &patch->new_data)) < 0)
 			goto cleanup;
 		if (delta->binary == 1)
 			goto cleanup;
 	}
 
 	if ((delta->old_file.flags & GIT_DIFF_FILE_NO_DATA) == 0 &&
-		ctxt->old_src != GIT_ITERATOR_WORKDIR) {
+		patch->old_src != GIT_ITERATOR_WORKDIR) {
 		if ((error = get_blob_content(
-				ctxt, &delta->old_file, &ctxt->old_data, &ctxt->old_blob)) < 0)
+				ctxt, delta, &delta->old_file,
+				&patch->old_data, &patch->old_blob)) < 0)
 			goto cleanup;
 		if (delta->binary == 1)
 			goto cleanup;
 	}
 
 	if ((delta->new_file.flags & GIT_DIFF_FILE_NO_DATA) == 0 &&
-		ctxt->new_src != GIT_ITERATOR_WORKDIR) {
+		patch->new_src != GIT_ITERATOR_WORKDIR) {
 		if ((error = get_blob_content(
-				ctxt, &delta->new_file, &ctxt->new_data, &ctxt->new_blob)) < 0)
+				ctxt, delta, &delta->new_file,
+				&patch->new_data, &patch->new_blob)) < 0)
 			goto cleanup;
 		if (delta->binary == 1)
 			goto cleanup;
@@ -606,33 +563,34 @@ static int diff_delta_load(diff_delta_context *ctxt)
 	}
 
 cleanup:
-	/* last change to update binary flag */
 	if (delta->binary == -1)
 		update_delta_is_binary(delta);
 
-	ctxt->loaded = !error;
+	if (!error) {
+		patch->flags |= GIT_DIFF_PATCH_LOADED;
 
-	/* flag if we would want to diff the contents of these files */
-	if (ctxt->loaded)
-		ctxt->diffable =
-			(delta->binary != 1 &&
-			 delta->status != GIT_DELTA_UNMODIFIED &&
-			 (ctxt->old_data.len || ctxt->new_data.len) &&
-			 git_oid_cmp(&delta->old_file.oid, &delta->new_file.oid));
+		if (delta->binary != 1 &&
+			delta->status != GIT_DELTA_UNMODIFIED &&
+			(patch->old_data.len || patch->new_data.len) &&
+			!git_oid_equal(&delta->old_file.oid, &delta->new_file.oid))
+			patch->flags |= GIT_DIFF_PATCH_DIFFABLE;
+	}
 
 	return error;
 }
 
-static int diff_delta_cb(void *priv, mmbuffer_t *bufs, int len)
+static int diff_patch_cb(void *priv, mmbuffer_t *bufs, int len)
 {
-	diff_delta_context *ctxt = priv;
+	git_diff_patch *patch = priv;
+	diff_context   *ctxt  = patch->ctxt;
 
 	if (len == 1) {
-		if ((ctxt->cb_error = parse_hunk_header(&ctxt->range, bufs[0].ptr)) < 0)
+		ctxt->cb_error = parse_hunk_header(&ctxt->cb_range, bufs[0].ptr);
+		if (ctxt->cb_error < 0)
 			return ctxt->cb_error;
 
-		if (ctxt->per_hunk != NULL &&
-			ctxt->per_hunk(ctxt->cb_data, ctxt->delta, &ctxt->range,
+		if (ctxt->hunk_cb != NULL &&
+			ctxt->hunk_cb(ctxt->cb_data, patch->delta, &ctxt->cb_range,
 				bufs[0].ptr, bufs[0].size))
 			ctxt->cb_error = GIT_EUSER;
 	}
@@ -644,9 +602,9 @@ static int diff_delta_cb(void *priv, mmbuffer_t *bufs, int len)
 			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
 			GIT_DIFF_LINE_CONTEXT;
 
-		if (ctxt->per_line != NULL &&
-			ctxt->per_line(ctxt->cb_data, ctxt->delta, &ctxt->range, origin,
-				bufs[1].ptr, bufs[1].size))
+		if (ctxt->data_cb != NULL &&
+			ctxt->data_cb(ctxt->cb_data, patch->delta, &ctxt->cb_range,
+				origin, bufs[1].ptr, bufs[1].size))
 			ctxt->cb_error = GIT_EUSER;
 	}
 
@@ -661,105 +619,268 @@ static int diff_delta_cb(void *priv, mmbuffer_t *bufs, int len)
 			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_ADD_EOFNL :
 			GIT_DIFF_LINE_CONTEXT;
 
-		if (ctxt->per_line != NULL &&
-			ctxt->per_line(ctxt->cb_data, ctxt->delta, &ctxt->range, origin,
-				bufs[2].ptr, bufs[2].size))
+		if (ctxt->data_cb != NULL &&
+			ctxt->data_cb(ctxt->cb_data, patch->delta, &ctxt->cb_range,
+				origin, bufs[2].ptr, bufs[2].size))
 			ctxt->cb_error = GIT_EUSER;
 	}
 
 	return ctxt->cb_error;
 }
 
-static int diff_delta_exec(
-	diff_delta_context *ctxt,
-	void *cb_data,
-	git_diff_hunk_fn per_hunk,
-	git_diff_data_fn per_line)
+static int diff_patch_generate(
+	diff_context *ctxt, git_diff_patch *patch)
 {
 	int error = 0;
 	xdemitcb_t xdiff_callback;
 	mmfile_t old_xdiff_data, new_xdiff_data;
 
-	if (ctxt->diffed || !ctxt->delta)
+	if ((patch->flags & GIT_DIFF_PATCH_DIFFED) != 0)
 		return 0;
 
-	if (!ctxt->loaded && (error = diff_delta_load(ctxt)) < 0)
-		goto cleanup;
+	if ((patch->flags & GIT_DIFF_PATCH_LOADED) == 0)
+		if ((error = diff_patch_load(ctxt, patch)) < 0)
+			return error;
 
-	if (!ctxt->diffable)
+	if ((patch->flags & GIT_DIFF_PATCH_DIFFABLE) == 0)
 		return 0;
 
-	ctxt->cb_data  = cb_data;
-	ctxt->per_hunk = per_hunk;
-	ctxt->per_line = per_line;
-	ctxt->cb_error = 0;
+	if (ctxt)
+		patch->ctxt = ctxt;
 
 	memset(&xdiff_callback, 0, sizeof(xdiff_callback));
-	xdiff_callback.outf = diff_delta_cb;
-	xdiff_callback.priv = ctxt;
+	xdiff_callback.outf = diff_patch_cb;
+	xdiff_callback.priv = patch;
 
-	old_xdiff_data.ptr  = ctxt->old_data.data;
-	old_xdiff_data.size = ctxt->old_data.len;
-	new_xdiff_data.ptr  = ctxt->new_data.data;
-	new_xdiff_data.size = ctxt->new_data.len;
+	old_xdiff_data.ptr  = patch->old_data.data;
+	old_xdiff_data.size = patch->old_data.len;
+	new_xdiff_data.ptr  = patch->new_data.data;
+	new_xdiff_data.size = patch->new_data.len;
 
 	xdl_diff(&old_xdiff_data, &new_xdiff_data,
 		&ctxt->xdiff_params, &ctxt->xdiff_config, &xdiff_callback);
 
 	error = ctxt->cb_error;
 
-cleanup:
-	ctxt->diffed = !error;
+	if (!error)
+		patch->flags |= GIT_DIFF_PATCH_DIFFED;
 
 	return error;
 }
 
+static void diff_patch_unload(git_diff_patch *patch)
+{
+	if ((patch->flags & GIT_DIFF_PATCH_DIFFED) != 0) {
+		patch->flags = (patch->flags & ~GIT_DIFF_PATCH_DIFFED);
+
+		patch->hunks_size = 0;
+		patch->lines_size = 0;
+	}
+
+	if ((patch->flags & GIT_DIFF_PATCH_LOADED) != 0) {
+		patch->flags = (patch->flags & ~GIT_DIFF_PATCH_LOADED);
+
+		release_content(
+			&patch->delta->old_file, &patch->old_data, patch->old_blob);
+		release_content(
+			&patch->delta->new_file, &patch->new_data, patch->new_blob);
+	}
+}
+
+static void diff_patch_free(git_diff_patch *patch)
+{
+	diff_patch_unload(patch);
+
+	git__free(patch->lines);
+	patch->lines = NULL;
+	patch->lines_asize = 0;
+
+	git__free(patch->hunks);
+	patch->hunks = NULL;
+	patch->hunks_asize = 0;
+
+	if (!(patch->flags & GIT_DIFF_PATCH_ALLOCATED))
+		return;
+
+	patch->flags = 0;
+
+	git_diff_list_free(patch->diff); /* decrements refcount */
+
+	git__free(patch);
+}
+
+#define MAX_HUNK_STEP 128
+#define MIN_HUNK_STEP 8
+#define MAX_LINE_STEP 256
+#define MIN_LINE_STEP 8
+
+static int diff_patch_hunk_cb(
+	void *cb_data,
+	git_diff_delta *delta,
+	git_diff_range *range,
+	const char *header,
+	size_t header_len)
+{
+	git_diff_patch *patch = cb_data;
+	diff_patch_hunk *hunk;
+
+	GIT_UNUSED(delta);
+
+	if (patch->hunks_size >= patch->hunks_asize) {
+		size_t new_size;
+		diff_patch_hunk *new_hunks;
+
+		if (patch->hunks_asize > MAX_HUNK_STEP)
+			new_size = patch->hunks_asize + MAX_HUNK_STEP;
+		else
+			new_size = patch->hunks_asize * 2;
+		if (new_size < MIN_HUNK_STEP)
+			new_size = MIN_HUNK_STEP;
+
+		new_hunks = git__realloc(
+			patch->hunks, new_size * sizeof(diff_patch_hunk));
+		if (!new_hunks)
+			return -1;
+
+		patch->hunks = new_hunks;
+		patch->hunks_asize = new_size;
+	}
+
+	hunk = &patch->hunks[patch->hunks_size++];
+
+	memcpy(&hunk->range, range, sizeof(hunk->range));
+
+	assert(header_len + 1 < sizeof(hunk->header));
+	memcpy(&hunk->header, header, header_len);
+	hunk->header[header_len] = '\0';
+	hunk->header_len = header_len;
+
+	hunk->line_start = patch->lines_size;
+	hunk->line_count = 0;
+
+	return 0;
+}
+
+static int diff_patch_line_cb(
+	void *cb_data,
+	git_diff_delta *delta,
+	git_diff_range *range,
+	char line_origin,
+	const char *content,
+	size_t content_len)
+{
+	git_diff_patch *patch = cb_data;
+	diff_patch_hunk *hunk;
+	diff_patch_line *last, *line;
+
+	GIT_UNUSED(delta);
+	GIT_UNUSED(range);
+
+	assert(patch->hunks_size > 0);
+	assert(patch->hunks != NULL);
+
+	hunk = &patch->hunks[patch->hunks_size - 1];
+
+	if (patch->lines_size >= patch->lines_asize) {
+		size_t new_size;
+		diff_patch_line *new_lines;
+
+		if (patch->lines_asize > MAX_LINE_STEP)
+			new_size = patch->lines_asize + MAX_LINE_STEP;
+		else
+			new_size = patch->lines_asize * 2;
+		if (new_size < MIN_LINE_STEP)
+			new_size = MIN_LINE_STEP;
+
+		new_lines = git__realloc(
+			patch->lines, new_size * sizeof(diff_patch_line));
+		if (!new_lines)
+			return -1;
+
+		patch->lines = new_lines;
+		patch->lines_asize = new_size;
+	}
+
+	last = (patch->lines_size > 0) ?
+		&patch->lines[patch->lines_size - 1] : NULL;
+	line = &patch->lines[patch->lines_size++];
+
+	line->ptr = content;
+	line->len = content_len;
+	line->origin = line_origin;
+
+	/* do some bookkeeping so we can provide old/new line numbers */
+
+	for (line->lines = 0; content_len > 0; --content_len) {
+		if (*content++ == '\n')
+			++line->lines;
+	}
+
+	if (!last) {
+		line->oldno = hunk->range.old_start;
+		line->newno = hunk->range.new_start;
+	} else {
+		switch (last->origin) {
+		case GIT_DIFF_LINE_ADDITION:
+			line->oldno = last->oldno;
+			line->newno = last->newno + last->lines;
+			break;
+		case GIT_DIFF_LINE_DELETION:
+			line->oldno = last->oldno + last->lines;
+			line->newno = last->newno;
+			break;
+		default:
+			line->oldno = last->oldno + last->lines;
+			line->newno = last->newno + last->lines;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+
 int git_diff_foreach(
 	git_diff_list *diff,
-	void *data,
+	void *cb_data,
 	git_diff_file_fn file_cb,
 	git_diff_hunk_fn hunk_cb,
-	git_diff_data_fn line_cb)
+	git_diff_data_fn data_cb)
 {
-	int error = 0;
-	diff_delta_context ctxt;
+	int error;
+	diff_context ctxt;
 	size_t idx;
+	git_diff_patch patch;
 
-	diff_delta_init_context_from_diff_list(&ctxt, diff);
+	diff_context_init(
+		&ctxt, diff, diff->repo, &diff->opts,
+		cb_data, file_cb, hunk_cb, data_cb);
 
-	git_vector_foreach(&diff->deltas, idx, ctxt.delta) {
-		if (diff_delta_is_ambiguous(ctxt.delta))
-			if ((error = diff_delta_load(&ctxt)) < 0)
-				goto cleanup;
+	diff_patch_init(&ctxt, &patch);
 
-		if (diff_delta_should_skip(ctxt.opts, ctxt.delta))
-			continue;
+	git_vector_foreach(&diff->deltas, idx, patch.delta) {
 
-		if ((error = diff_delta_load(&ctxt)) < 0)
-			goto cleanup;
-
-		if (file_cb != NULL &&
-			file_cb(data, ctxt.delta, (float)idx / diff->deltas.length) != 0)
-		{
-			error = GIT_EUSER;
-			goto cleanup;
-		}
+		/* check flags against patch status */
+		if (diff_delta_should_skip(&ctxt, patch.delta))
+			continue;
 
-		error = diff_delta_exec(&ctxt, data, hunk_cb, line_cb);
+		if (!(error = diff_patch_load(&ctxt, &patch)) &&
+			!(error = diff_delta_file_callback(&ctxt, patch.delta, idx)))
+			error = diff_patch_generate(&ctxt, &patch);
 
-cleanup:
-		diff_delta_unload(&ctxt);
+		diff_patch_unload(&patch);
 
 		if (error < 0)
 			break;
 	}
 
 	if (error == GIT_EUSER)
-		giterr_clear();
+		giterr_clear(); /* don't let error message leak */
 
 	return error;
 }
 
+
 typedef struct {
 	git_diff_list *diff;
 	git_diff_data_fn print_cb;
@@ -851,7 +972,6 @@ int git_diff_print_compact(
 	return error;
 }
 
-
 static int print_oid_range(diff_print_info *pi, git_diff_delta *delta)
 {
 	char start_oid[8], end_oid[8];
@@ -1024,30 +1144,6 @@ int git_diff_print_patch(
 	return error;
 }
 
-int git_diff_entrycount(git_diff_list *diff, int delta_t)
-{
-	int count = 0;
-	unsigned int i;
-	git_diff_delta *delta;
-
-	assert(diff);
-
-	git_vector_foreach(&diff->deltas, i, delta) {
-		if (diff_delta_should_skip(&diff->opts, delta))
-			continue;
-
-		if (delta_t < 0 || delta->status == (git_delta_t)delta_t)
-			count++;
-	}
-
-	/* It is possible that this has overcounted the number of diffs because
-	 * there may be entries that are marked as MODIFIED due to differences
-	 * in stat() output that will turn out to be the same once we calculate
-	 * the actual SHA of the data on disk.
-	 */
-
-	return count;
-}
 
 static void set_data_from_blob(
 	git_blob *blob, git_map *map, git_diff_file *file)
@@ -1056,6 +1152,7 @@ static void set_data_from_blob(
 		map->data = (char *)git_blob_rawcontent(blob);
 		file->size = map->len = git_blob_rawsize(blob);
 		git_oid_cpy(&file->oid, git_object_id((const git_object *)blob));
+		file->mode = 0644;
 	} else {
 		map->data = "";
 		file->size = map->len = 0;
@@ -1070,429 +1167,250 @@ int git_diff_blobs(
 	void *cb_data,
 	git_diff_file_fn file_cb,
 	git_diff_hunk_fn hunk_cb,
-	git_diff_data_fn line_cb)
+	git_diff_data_fn data_cb)
 {
 	int error;
-	diff_delta_context ctxt;
-	git_diff_delta delta;
-	git_blob *new, *old;
 	git_repository *repo;
-
-	new = new_blob;
-	old = old_blob;
+	diff_context ctxt;
+	git_diff_delta delta;
+	git_diff_patch patch;
 
 	if (options && (options->flags & GIT_DIFF_REVERSE)) {
-		git_blob *swap = old;
-		old = new;
-		new = swap;
+		git_blob *swap = old_blob;
+		old_blob = new_blob;
+		new_blob = swap;
 	}
 
-	if (new)
-		repo = git_object_owner((git_object *)new);
-	else if (old)
-		repo = git_object_owner((git_object *)old);
+	if (new_blob)
+		repo = git_object_owner((git_object *)new_blob);
+	else if (old_blob)
+		repo = git_object_owner((git_object *)old_blob);
 	else
 		repo = NULL;
 
-	diff_delta_init_context(
-		&ctxt, repo, options, GIT_ITERATOR_TREE, GIT_ITERATOR_TREE);
+	diff_context_init(
+		&ctxt, NULL, repo, options,
+		cb_data, file_cb, hunk_cb, data_cb);
+
+	diff_patch_init(&ctxt, &patch);
 
-	/* populate a "fake" delta record */
+	/* create a fake delta record and simulate diff_patch_load */
 
 	memset(&delta, 0, sizeof(delta));
+	delta.binary = -1;
 
-	set_data_from_blob(old, &ctxt.old_data, &delta.old_file);
-	set_data_from_blob(new, &ctxt.new_data, &delta.new_file);
+	set_data_from_blob(old_blob, &patch.old_data, &delta.old_file);
+	set_data_from_blob(new_blob, &patch.new_data, &delta.new_file);
 
-	delta.status = new ?
-		(old ? GIT_DELTA_MODIFIED : GIT_DELTA_ADDED) :
-		(old ? GIT_DELTA_DELETED : GIT_DELTA_UNTRACKED);
+	delta.status = new_blob ?
+		(old_blob ? GIT_DELTA_MODIFIED : GIT_DELTA_ADDED) :
+		(old_blob ? GIT_DELTA_DELETED : GIT_DELTA_UNTRACKED);
 
 	if (git_oid_cmp(&delta.new_file.oid, &delta.old_file.oid) == 0)
 		delta.status = GIT_DELTA_UNMODIFIED;
 
-	ctxt.delta = &delta;
+	patch.delta = &delta;
 
-	if ((error = diff_delta_prep(&ctxt)) < 0)
+	if ((error = diff_delta_is_binary_by_content(
+			 &ctxt, &delta, &delta.old_file, &patch.old_data)) < 0 ||
+		(error = diff_delta_is_binary_by_content(
+			&ctxt, &delta, &delta.new_file, &patch.new_data)) < 0)
 		goto cleanup;
 
-	if (delta.binary == -1) {
-		if ((error = diff_delta_is_binary_by_content(
-				&ctxt, &delta.old_file, &ctxt.old_data)) < 0 ||
-			(error = diff_delta_is_binary_by_content(
-				&ctxt, &delta.new_file, &ctxt.new_data)) < 0)
-			goto cleanup;
-	}
-
-	ctxt.loaded = 1;
-	ctxt.diffable = (delta.binary != 1 && delta.status != GIT_DELTA_UNMODIFIED);
+	patch.flags |= GIT_DIFF_PATCH_LOADED;
+	if (delta.binary != 1 && delta.status != GIT_DELTA_UNMODIFIED)
+		patch.flags |= GIT_DIFF_PATCH_DIFFABLE;
 
 	/* do diffs */
 
-	if (file_cb != NULL && file_cb(cb_data, &delta, 1)) {
-		error = GIT_EUSER;
-		goto cleanup;
-	}
-
-	error = diff_delta_exec(&ctxt, cb_data, hunk_cb, line_cb);
+	if (!(error = diff_delta_file_callback(&ctxt, patch.delta, 1)))
+		error = diff_patch_generate(&ctxt, &patch);
 
 cleanup:
+	diff_patch_unload(&patch);
+
 	if (error == GIT_EUSER)
 		giterr_clear();
 
-	diff_delta_unload(&ctxt);
-
 	return error;
 }
 
-typedef struct diffiter_line diffiter_line;
-struct diffiter_line {
-	diffiter_line *next;
-	char origin;
-	const char *ptr;
-	size_t len;
-};
-
-typedef struct diffiter_hunk diffiter_hunk;
-struct diffiter_hunk {
-	diffiter_hunk *next;
-	git_diff_range range;
-	diffiter_line *line_head;
-	size_t line_count;
-};
-
-struct git_diff_iterator {
-	git_diff_list *diff;
-	diff_delta_context ctxt;
-	size_t file_index;
-	size_t next_index;
-	git_pool hunks;
-	size_t   hunk_count;
-	diffiter_hunk *hunk_head;
-	diffiter_hunk *hunk_curr;
-	char hunk_header[128];
-	git_pool lines;
-	diffiter_line *line_curr;
-};
-
-typedef struct {
-	git_diff_iterator *iter;
-	diffiter_hunk *last_hunk;
-	diffiter_line *last_line;
-} diffiter_cb_info;
 
-static int diffiter_hunk_cb(
-	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
-	const char *header,
-	size_t header_len)
+size_t git_diff_num_deltas(git_diff_list *diff)
 {
-	diffiter_cb_info *info = cb_data;
-	git_diff_iterator *iter = info->iter;
-	diffiter_hunk *hunk;
-
-	GIT_UNUSED(delta);
-	GIT_UNUSED(header);
-	GIT_UNUSED(header_len);
-
-	if ((hunk = git_pool_mallocz(&iter->hunks, 1)) == NULL) {
-		iter->ctxt.cb_error = -1;
-		return -1;
-	}
-
-	if (info->last_hunk)
-		info->last_hunk->next = hunk;
-	info->last_hunk = hunk;
-	info->last_line = NULL;
-
-	memcpy(&hunk->range, range, sizeof(hunk->range));
-
-	iter->hunk_count++;
-
-	/* adding first hunk to list */
-	if (iter->hunk_head == NULL) {
-		iter->hunk_head = hunk;
-		iter->hunk_curr = NULL;
-	}
-
-	return 0;
+	assert(diff);
+	return (size_t)diff->deltas.length;
 }
 
-static int diffiter_line_cb(
-	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
-	char line_origin,
-	const char *content,
-	size_t content_len)
+size_t git_diff_num_deltas_of_type(git_diff_list *diff, git_delta_t type)
 {
-	diffiter_cb_info *info = cb_data;
-	git_diff_iterator *iter = info->iter;
-	diffiter_line *line;
+	size_t i, count = 0;
+	git_diff_delta *delta;
 
-	GIT_UNUSED(delta);
-	GIT_UNUSED(range);
+	assert(diff);
 
-	if ((line = git_pool_mallocz(&iter->lines, 1)) == NULL) {
-		iter->ctxt.cb_error = -1;
-		return -1;
+	git_vector_foreach(&diff->deltas, i, delta) {
+		count += (delta->status == type);
 	}
 
-	if (info->last_line)
-		info->last_line->next = line;
-	info->last_line = line;
-
-	line->origin = line_origin;
-	line->ptr = content;
-	line->len = content_len;
-
-	info->last_hunk->line_count++;
-
-	if (info->last_hunk->line_head == NULL)
-		info->last_hunk->line_head = line;
-
-	return 0;
+	return count;
 }
 
-static int diffiter_do_diff_file(git_diff_iterator *iter)
+int git_diff_get_patch(
+	git_diff_patch **patch_ptr,
+	git_diff_delta **delta_ptr,
+	git_diff_list *diff,
+	size_t idx)
 {
 	int error;
-	diffiter_cb_info info;
-
-	if (iter->ctxt.diffed || !iter->ctxt.delta)
-		return 0;
-
-	memset(&info, 0, sizeof(info));
-	info.iter = iter;
-
-	error = diff_delta_exec(
-		&iter->ctxt, &info, diffiter_hunk_cb, diffiter_line_cb);
-
-	if (error == GIT_EUSER)
-		error = iter->ctxt.cb_error;
-
-	return error;
-}
+	diff_context ctxt;
+	git_diff_delta *delta;
+	git_diff_patch *patch;
 
-static void diffiter_do_unload_file(git_diff_iterator *iter)
-{
-	if (iter->ctxt.loaded) {
-		diff_delta_unload(&iter->ctxt);
+	if (patch_ptr)
+		*patch_ptr = NULL;
 
-		git_pool_clear(&iter->lines);
-		git_pool_clear(&iter->hunks);
+	delta = git_vector_get(&diff->deltas, idx);
+	if (!delta) {
+		if (delta_ptr)
+			*delta_ptr = NULL;
+		giterr_set(GITERR_INVALID, "Index out of range for delta in diff");
+		return GIT_ENOTFOUND;
 	}
 
-	iter->ctxt.delta = NULL;
-	iter->hunk_curr = iter->hunk_head = NULL;
-	iter->hunk_count = 0;
-	iter->line_curr = NULL;
-}
-
-int git_diff_iterator_new(
-	git_diff_iterator **iterator_ptr,
-	git_diff_list *diff)
-{
-	git_diff_iterator *iter;
-
-	assert(diff && iterator_ptr);
-
-	*iterator_ptr = NULL;
-
-	iter = git__malloc(sizeof(git_diff_iterator));
-	GITERR_CHECK_ALLOC(iter);
-
-	memset(iter, 0, sizeof(*iter));
+	if (delta_ptr)
+		*delta_ptr = delta;
 
-	iter->diff = diff;
-	GIT_REFCOUNT_INC(iter->diff);
+	if (!patch_ptr && delta->binary != -1)
+		return 0;
 
-	diff_delta_init_context_from_diff_list(&iter->ctxt, diff);
+	diff_context_init(
+		&ctxt, diff, diff->repo, &diff->opts,
+		NULL, NULL, diff_patch_hunk_cb, diff_patch_line_cb);
 
-	if (git_pool_init(&iter->hunks, sizeof(diffiter_hunk), 0) < 0 ||
-		git_pool_init(&iter->lines, sizeof(diffiter_line), 0) < 0)
-		goto fail;
+	if (diff_delta_should_skip(&ctxt, delta))
+		return 0;
 
-	*iterator_ptr = iter;
+	patch = diff_patch_alloc(&ctxt, delta);
+	if (!patch)
+		return -1;
 
-	return 0;
+	if (!(error = diff_patch_load(&ctxt, patch))) {
+		ctxt.cb_data = patch;
 
-fail:
-	git_diff_iterator_free(iter);
+		error = diff_patch_generate(&ctxt, patch);
 
-	return -1;
-}
-
-void git_diff_iterator_free(git_diff_iterator *iter)
-{
-	diffiter_do_unload_file(iter);
-	git_diff_list_free(iter->diff); /* decrement ref count */
-	git__free(iter);
-}
+		if (error == GIT_EUSER)
+			error = ctxt.cb_error;
+	}
 
-float git_diff_iterator_progress(git_diff_iterator *iter)
-{
-	return (float)iter->next_index / (float)iter->diff->deltas.length;
-}
+	if (error)
+		git_diff_patch_free(patch);
+	else if (patch_ptr)
+		*patch_ptr = patch;
 
-int git_diff_iterator__max_files(git_diff_iterator *iter)
-{
-	return (int)iter->diff->deltas.length;
+	return error;
 }
 
-int git_diff_iterator_num_hunks_in_file(git_diff_iterator *iter)
+void git_diff_patch_free(git_diff_patch *patch)
 {
-	int error = diffiter_do_diff_file(iter);
-	return (error != 0) ? error : (int)iter->hunk_count;
+	if (patch)
+		GIT_REFCOUNT_DEC(patch, diff_patch_free);
 }
 
-int git_diff_iterator_num_lines_in_hunk(git_diff_iterator *iter)
+const git_diff_delta *git_diff_patch_delta(git_diff_patch *patch)
 {
-	int error = diffiter_do_diff_file(iter);
-	if (error)
-		return error;
-
-	if (iter->hunk_curr)
-		return (int)iter->hunk_curr->line_count;
-	if (iter->hunk_head)
-		return (int)iter->hunk_head->line_count;
-	return 0;
+	assert(patch);
+	return patch->delta;
 }
 
-int git_diff_iterator_next_file(
-	git_diff_delta **delta_ptr,
-	git_diff_iterator *iter)
+size_t git_diff_patch_num_hunks(git_diff_patch *patch)
 {
-	int error = 0;
-
-	assert(iter);
-
-	iter->file_index = iter->next_index;
-
-	diffiter_do_unload_file(iter);
-
-	while (!error) {
-		iter->ctxt.delta = git_vector_get(&iter->diff->deltas, iter->file_index);
-		if (!iter->ctxt.delta) {
-			error = GIT_ITEROVER;
-			break;
-		}
-
-		if (diff_delta_is_ambiguous(iter->ctxt.delta) &&
-			(error = diff_delta_load(&iter->ctxt)) < 0)
-			break;
-
-		if (!diff_delta_should_skip(iter->ctxt.opts, iter->ctxt.delta))
-			break;
-
-		iter->file_index++;
-	}
-
-	if (!error) {
-		iter->next_index = iter->file_index + 1;
-
-		error = diff_delta_prep(&iter->ctxt);
-	}
-
-	if (iter->ctxt.delta == NULL) {
-		iter->hunk_curr = iter->hunk_head = NULL;
-		iter->line_curr = NULL;
-	}
-
-	if (delta_ptr != NULL)
-		*delta_ptr = !error ? iter->ctxt.delta : NULL;
-
-	return error;
+	assert(patch);
+	return patch->hunks_size;
 }
 
-int git_diff_iterator_next_hunk(
-	git_diff_range **range_ptr,
+int git_diff_patch_get_hunk(
+	git_diff_range **range,
 	const char **header,
 	size_t *header_len,
-	git_diff_iterator *iter)
+	size_t *lines_in_hunk,
+	git_diff_patch *patch,
+	size_t hunk_idx)
 {
-	int error = diffiter_do_diff_file(iter);
-	git_diff_range *range;
+	diff_patch_hunk *hunk;
 
-	if (error)
-		return error;
+	assert(patch);
 
-	if (iter->hunk_curr == NULL) {
-		if (iter->hunk_head == NULL)
-			goto no_more_hunks;
-		iter->hunk_curr = iter->hunk_head;
-	} else {
-		if (iter->hunk_curr->next == NULL)
-			goto no_more_hunks;
-		iter->hunk_curr = iter->hunk_curr->next;
+	if (hunk_idx >= patch->hunks_size) {
+		if (range) *range = NULL;
+		if (header) *header = NULL;
+		if (header_len) *header_len = 0;
+		if (lines_in_hunk) *lines_in_hunk = 0;
+		return GIT_ENOTFOUND;
 	}
 
-	range = &iter->hunk_curr->range;
-
-	if (range_ptr)
-		*range_ptr = range;
-
-	if (header) {
-		int out = format_hunk_header(
-			iter->hunk_header, sizeof(iter->hunk_header), range);
-
-		/* TODO: append function name to header */
+	hunk = &patch->hunks[hunk_idx];
 
-		*(iter->hunk_header + out++) = '\n';
+	if (range) *range = &hunk->range;
+	if (header) *header = hunk->header;
+	if (header_len) *header_len = hunk->header_len;
+	if (lines_in_hunk) *lines_in_hunk = hunk->line_count;
 
-		*header = iter->hunk_header;
-
-		if (header_len)
-			*header_len = (size_t)out;
-	}
-
-	iter->line_curr = iter->hunk_curr->line_head;
-
-	return error;
+	return 0;
+}
 
-no_more_hunks:
-	if (range_ptr) *range_ptr = NULL;
-	if (header) *header = NULL;
-	if (header_len) *header_len = 0;
-	iter->line_curr = NULL;
+int git_diff_patch_num_lines_in_hunk(
+	git_diff_patch *patch,
+	size_t hunk_idx)
+{
+	assert(patch);
 
-	return GIT_ITEROVER;
+	if (hunk_idx >= patch->hunks_size)
+		return GIT_ENOTFOUND;
+	else
+		return patch->hunks[hunk_idx].line_count;
 }
 
-int git_diff_iterator_next_line(
-	char *line_origin, /**< GIT_DIFF_LINE_... value from above */
-	const char **content_ptr,
+int git_diff_patch_get_line_in_hunk(
+	char *line_origin,
+	const char **content,
 	size_t *content_len,
-	git_diff_iterator *iter)
+	int *old_lineno,
+	int *new_lineno,
+	git_diff_patch *patch,
+	size_t hunk_idx,
+	size_t line_of_hunk)
 {
-	int error = diffiter_do_diff_file(iter);
+	diff_patch_hunk *hunk;
+	diff_patch_line *line;
 
-	if (error)
-		return error;
+	assert(patch);
 
-	/* if the user has not called next_hunk yet, call it implicitly (OK?) */
-	if (iter->hunk_curr == NULL) {
-		error = git_diff_iterator_next_hunk(NULL, NULL, NULL, iter);
-		if (error)
-			return error;
-	}
+	if (hunk_idx >= patch->hunks_size)
+		goto notfound;
+	hunk = &patch->hunks[hunk_idx];
 
-	if (iter->line_curr == NULL) {
-		if (line_origin) *line_origin = GIT_DIFF_LINE_CONTEXT;
-		if (content_ptr) *content_ptr = NULL;
-		if (content_len) *content_len = 0;
-		return GIT_ITEROVER;
-	}
+	if (line_of_hunk >= hunk->line_count)
+		goto notfound;
 
-	if (line_origin)
-		*line_origin = iter->line_curr->origin;
-	if (content_ptr)
-		*content_ptr = iter->line_curr->ptr;
-	if (content_len)
-		*content_len = iter->line_curr->len;
+	line = &patch->lines[hunk->line_start + line_of_hunk];
 
-	iter->line_curr = iter->line_curr->next;
+	if (line_origin) *line_origin = line->origin;
+	if (content) *content = line->ptr;
+	if (content_len) *content_len = line->len;
+	if (old_lineno) *old_lineno = line->oldno;
+	if (new_lineno) *new_lineno = line->newno;
 
-	return error;
+	return 0;
+
+notfound:
+	if (line_origin) *line_origin = GIT_DIFF_LINE_CONTEXT;
+	if (content) *content = NULL;
+	if (content_len) *content_len = 0;
+	if (old_lineno) *old_lineno = -1;
+	if (new_lineno) *new_lineno = -1;
+
+	return GIT_ENOTFOUND;
 }
+
diff --git a/src/diff_output.h b/src/diff_output.h
new file mode 100644
index 000000000..f54639088
--- /dev/null
+++ b/src/diff_output.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_diff_output_h__
+#define INCLUDE_diff_output_h__
+
+#include "git2/blob.h"
+#include "diff.h"
+#include "map.h"
+#include "xdiff/xdiff.h"
+
+#define MAX_DIFF_FILESIZE 0x20000000
+
+enum {
+	GIT_DIFF_PATCH_ALLOCATED  = (1 << 0),
+	GIT_DIFF_PATCH_PREPPED    = (1 << 1),
+	GIT_DIFF_PATCH_LOADED     = (1 << 2),
+	GIT_DIFF_PATCH_DIFFABLE   = (1 << 3),
+	GIT_DIFF_PATCH_DIFFED     = (1 << 4),
+};
+
+/* context for performing diffs */
+typedef struct {
+	git_repository   *repo;
+	git_diff_list    *diff;
+	git_diff_options *opts;
+	git_diff_file_fn  file_cb;
+	git_diff_hunk_fn  hunk_cb;
+	git_diff_data_fn  data_cb;
+	void *cb_data;
+	int   cb_error;
+	git_diff_range cb_range;
+	xdemitconf_t xdiff_config;
+	xpparam_t    xdiff_params;
+} diff_context;
+
+/* cached information about a single span in a diff */
+typedef struct diff_patch_line diff_patch_line;
+struct diff_patch_line {
+	const char *ptr;
+	size_t len;
+	int lines, oldno, newno;
+	char origin;
+};
+
+/* cached information about a hunk in a diff */
+typedef struct diff_patch_hunk diff_patch_hunk;
+struct diff_patch_hunk {
+	git_diff_range range;
+	char   header[128];
+	size_t header_len;
+	size_t line_start;
+	size_t line_count;
+};
+
+struct git_diff_patch {
+	git_refcount rc;
+	git_diff_list *diff; /* for refcount purposes, maybe NULL for blob diffs */
+	git_diff_delta *delta;
+	diff_context *ctxt; /* only valid while generating patch */
+	git_iterator_type_t old_src;
+	git_iterator_type_t new_src;
+	git_blob *old_blob;
+	git_blob *new_blob;
+	git_map  old_data;
+	git_map  new_data;
+	uint32_t flags;
+	diff_patch_hunk *hunks;
+	size_t hunks_asize, hunks_size;
+	diff_patch_line *lines;
+	size_t lines_asize, lines_size;
+};
+
+/* context for performing diff on a single delta */
+typedef struct {
+	git_diff_patch *patch;
+	uint32_t prepped  : 1;
+	uint32_t loaded   : 1;
+	uint32_t diffable : 1;
+	uint32_t diffed   : 1;
+} diff_delta_context;
+
+#endif
diff --git a/src/submodule.c b/src/submodule.c
index 5ae38bccd..e55e12863 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -1457,7 +1457,7 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 		error = git_diff_index_to_tree(sm_repo, &opt, sm_head, &diff);
 
 		if (!error) {
-			if (git_diff_entrycount(diff, -1) > 0)
+			if (git_diff_num_deltas(diff) > 0)
 				*status |= GIT_SUBMODULE_STATUS_WD_INDEX_MODIFIED;
 
 			git_diff_list_free(diff);
@@ -1474,12 +1474,13 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 		error = git_diff_workdir_to_index(sm_repo, &opt, &diff);
 
 		if (!error) {
-			int untracked = git_diff_entrycount(diff, GIT_DELTA_UNTRACKED);
+			int untracked =
+				git_diff_num_deltas_of_type(diff, GIT_DELTA_UNTRACKED);
 
 			if (untracked > 0)
 				*status |= GIT_SUBMODULE_STATUS_WD_UNTRACKED;
 
-			if (git_diff_entrycount(diff, -1) - untracked > 0)
+			if ((git_diff_num_deltas(diff) - untracked) > 0)
 				*status |= GIT_SUBMODULE_STATUS_WD_WD_MODIFIED;
 
 			git_diff_list_free(diff);
diff --git a/tests-clar/diff/diff_helpers.c b/tests-clar/diff/diff_helpers.c
index 767b34392..1c0435975 100644
--- a/tests-clar/diff/diff_helpers.c
+++ b/tests-clar/diff/diff_helpers.c
@@ -112,64 +112,65 @@ int diff_foreach_via_iterator(
 	git_diff_hunk_fn hunk_cb,
 	git_diff_data_fn line_cb)
 {
-	int error;
-	git_diff_iterator *iter;
-	git_diff_delta *delta;
+	size_t d, num_d = git_diff_num_deltas(diff);
 
-	if ((error = git_diff_iterator_new(&iter, diff)) < 0)
-		return error;
+	for (d = 0; d < num_d; ++d) {
+		git_diff_patch *patch;
+		git_diff_delta *delta;
+		size_t h, num_h;
 
-	while (!(error = git_diff_iterator_next_file(&delta, iter))) {
-		git_diff_range *range;
-		const char *hdr;
-		size_t hdr_len;
-		float progress = git_diff_iterator_progress(iter);
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
+		cl_assert(delta && patch);
 
 		/* call file_cb for this file */
-		if (file_cb != NULL && file_cb(data, delta, progress) != 0)
+		if (file_cb != NULL && file_cb(data, delta, (float)d / num_d) != 0) {
+			git_diff_patch_free(patch);
 			goto abort;
+		}
 
-		if (!hunk_cb && !line_cb)
+		if (!hunk_cb && !line_cb) {
+			git_diff_patch_free(patch);
 			continue;
+		}
+
+		num_h = git_diff_patch_num_hunks(patch);
 
-		while (!(error = git_diff_iterator_next_hunk(
-				&range, &hdr, &hdr_len, iter))) {
-			char origin;
-			const char *line;
-			size_t line_len;
+		for (h = 0; h < num_h; h++) {
+			git_diff_range *range;
+			const char *hdr;
+			size_t hdr_len, l, num_l;
 
-			if (hunk_cb && hunk_cb(data, delta, range, hdr, hdr_len) != 0)
+			cl_git_pass(git_diff_patch_get_hunk(
+				&range, &hdr, &hdr_len, &num_l, patch, h));
+
+			if (hunk_cb && hunk_cb(data, delta, range, hdr, hdr_len) != 0) {
+				git_diff_patch_free(patch);
 				goto abort;
+			}
 
-			if (!line_cb)
-				continue;
+			for (l = 0; l < num_l; ++l) {
+				char origin;
+				const char *line;
+				size_t line_len;
+				int old_lineno, new_lineno;
 
-			while (!(error = git_diff_iterator_next_line(
-				&origin, &line, &line_len, iter))) {
+				cl_git_pass(git_diff_patch_get_line_in_hunk(
+					&origin, &line, &line_len, &old_lineno, &new_lineno,
+					patch, h, l));
 
-				if (line_cb(data, delta, range, origin, line, line_len) != 0)
+				if (line_cb(data, delta, range, origin, line, line_len) != 0) {
+					git_diff_patch_free(patch);
 					goto abort;
+				}
 			}
-
-			if (error && error != GIT_ITEROVER)
-				goto done;
 		}
 
-		if (error && error != GIT_ITEROVER)
-			goto done;
+		git_diff_patch_free(patch);
 	}
 
-done:
-	git_diff_iterator_free(iter);
-
-	if (error == GIT_ITEROVER)
-		error = 0;
-
-	return error;
+	return 0;
 
 abort:
-	git_diff_iterator_free(iter);
 	giterr_clear();
-
 	return GIT_EUSER;
 }
diff --git a/tests-clar/diff/diffiter.c b/tests-clar/diff/diffiter.c
index 23071e48b..9e33d91e1 100644
--- a/tests-clar/diff/diffiter.c
+++ b/tests-clar/diff/diffiter.c
@@ -14,11 +14,16 @@ void test_diff_diffiter__create(void)
 {
 	git_repository *repo = cl_git_sandbox_init("attr");
 	git_diff_list *diff;
-	git_diff_iterator *iter;
+	size_t d, num_d;
 
 	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
-	git_diff_iterator_free(iter);
+
+	num_d = git_diff_num_deltas(diff);
+	for (d = 0; d < num_d; ++d) {
+		git_diff_delta *delta;
+		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
+	}
+
 	git_diff_list_free(diff);
 }
 
@@ -26,24 +31,22 @@ void test_diff_diffiter__iterate_files(void)
 {
 	git_repository *repo = cl_git_sandbox_init("attr");
 	git_diff_list *diff;
-	git_diff_iterator *iter;
-	git_diff_delta *delta;
-	int error, count = 0;
+	size_t d, num_d;
+	int count = 0;
 
 	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
 
-	while ((error = git_diff_iterator_next_file(&delta, iter)) != GIT_ITEROVER) {
-		cl_assert_equal_i(0, error);
+	num_d = git_diff_num_deltas(diff);
+	cl_assert_equal_i(6, num_d);
+
+	for (d = 0; d < num_d; ++d) {
+		git_diff_delta *delta;
+		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
 		cl_assert(delta != NULL);
 		count++;
 	}
-
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert(delta == NULL);
 	cl_assert_equal_i(6, count);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
 }
 
@@ -51,24 +54,22 @@ void test_diff_diffiter__iterate_files_2(void)
 {
 	git_repository *repo = cl_git_sandbox_init("status");
 	git_diff_list *diff;
-	git_diff_iterator *iter;
-	git_diff_delta *delta;
-	int error, count = 0;
+	size_t d, num_d;
+	int count = 0;
 
 	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
 
-	while ((error = git_diff_iterator_next_file(&delta, iter)) != GIT_ITEROVER) {
-		cl_assert_equal_i(0, error);
+	num_d = git_diff_num_deltas(diff);
+	cl_assert_equal_i(8, num_d);
+
+	for (d = 0; d < num_d; ++d) {
+		git_diff_delta *delta;
+		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
 		cl_assert(delta != NULL);
 		count++;
 	}
-
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert(delta == NULL);
 	cl_assert_equal_i(8, count);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
 }
 
@@ -77,12 +78,8 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 	git_repository *repo = cl_git_sandbox_init("status");
 	git_diff_options opts = {0};
 	git_diff_list *diff = NULL;
-	git_diff_iterator *iter;
-	git_diff_delta *delta;
-	git_diff_range *range;
-	const char *header;
-	size_t header_len;
-	int error, file_count = 0, hunk_count = 0;
+	size_t d, num_d;
+	int file_count = 0, hunk_count = 0;
 
 	opts.context_lines = 3;
 	opts.interhunk_lines = 1;
@@ -90,28 +87,42 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 
 	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
 
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
+	num_d = git_diff_num_deltas(diff);
+
+	for (d = 0; d < num_d; ++d) {
+		git_diff_patch *patch;
+		git_diff_delta *delta;
+		size_t h, num_h;
+
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
 
-	while ((error = git_diff_iterator_next_file(&delta, iter)) != GIT_ITEROVER) {
-		cl_assert_equal_i(0, error);
 		cl_assert(delta);
+		cl_assert(patch);
 
 		file_count++;
 
-		while ((error = git_diff_iterator_next_hunk(
-				&range, &header, &header_len, iter)) != GIT_ITEROVER) {
-			cl_assert_equal_i(0, error);
+		num_h = git_diff_patch_num_hunks(patch);
+
+		for (h = 0; h < num_h; h++) {
+			git_diff_range *range;
+			const char *header;
+			size_t header_len, num_l;
+
+			cl_git_pass(git_diff_patch_get_hunk(
+				&range, &header, &header_len, &num_l, patch, h));
+
 			cl_assert(range);
+			cl_assert(header);
+
 			hunk_count++;
 		}
+
+		git_diff_patch_free(patch);
 	}
 
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert(delta == NULL);
 	cl_assert_equal_i(13, file_count);
 	cl_assert_equal_i(8, hunk_count);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
 }
 
@@ -120,45 +131,42 @@ void test_diff_diffiter__max_size_threshold(void)
 	git_repository *repo = cl_git_sandbox_init("status");
 	git_diff_options opts = {0};
 	git_diff_list *diff = NULL;
-	git_diff_iterator *iter;
-	git_diff_delta *delta;
-	int error, file_count = 0, binary_count = 0, hunk_count = 0;
+	int file_count = 0, binary_count = 0, hunk_count = 0;
+	size_t d, num_d;
 
 	opts.context_lines = 3;
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
 	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
+	num_d = git_diff_num_deltas(diff);
 
-	while ((error = git_diff_iterator_next_file(&delta, iter)) != GIT_ITEROVER) {
-		cl_assert_equal_i(0, error);
+	for (d = 0; d < num_d; ++d) {
+		git_diff_patch *patch;
+		git_diff_delta *delta;
+
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
 		cl_assert(delta);
+		cl_assert(patch);
 
 		file_count++;
-
-		hunk_count += git_diff_iterator_num_hunks_in_file(iter);
+		hunk_count += git_diff_patch_num_hunks(patch);
 
 		assert(delta->binary == 0 || delta->binary == 1);
-
 		binary_count += delta->binary;
-	}
 
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert(delta == NULL);
+		git_diff_patch_free(patch);
+	}
 
 	cl_assert_equal_i(13, file_count);
 	cl_assert_equal_i(0, binary_count);
 	cl_assert_equal_i(8, hunk_count);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
 
 	/* try again with low file size threshold */
 
-	file_count = 0;
-	binary_count = 0;
-	hunk_count = 0;
+	file_count = binary_count = hunk_count = 0;
 
 	opts.context_lines = 3;
 	opts.interhunk_lines = 1;
@@ -166,36 +174,169 @@ void test_diff_diffiter__max_size_threshold(void)
 	opts.max_size = 50; /* treat anything over 50 bytes as binary! */
 
 	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
+	num_d = git_diff_num_deltas(diff);
 
-	while ((error = git_diff_iterator_next_file(&delta, iter)) != GIT_ITEROVER) {
-		cl_assert_equal_i(0, error);
-		cl_assert(delta);
+	for (d = 0; d < num_d; ++d) {
+		git_diff_patch *patch;
+		git_diff_delta *delta;
 
-		file_count++;
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
 
-		hunk_count += git_diff_iterator_num_hunks_in_file(iter);
+		file_count++;
+		hunk_count += git_diff_patch_num_hunks(patch);
 
 		assert(delta->binary == 0 || delta->binary == 1);
-
 		binary_count += delta->binary;
-	}
 
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert(delta == NULL);
+		git_diff_patch_free(patch);
+	}
 
 	cl_assert_equal_i(13, file_count);
-
 	/* Three files are over the 50 byte threshold:
 	 * - staged_changes_file_deleted
 	 * - staged_changes_modified_file
 	 * - staged_new_file_modified_file
 	 */
 	cl_assert_equal_i(3, binary_count);
-
 	cl_assert_equal_i(5, hunk_count);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
+}
+
+
+void test_diff_diffiter__iterate_all(void)
+{
+	git_repository *repo = cl_git_sandbox_init("status");
+	git_diff_options opts = {0};
+	git_diff_list *diff = NULL;
+	diff_expects exp = {0};
+	size_t d, num_d;
+
+	opts.context_lines = 3;
+	opts.interhunk_lines = 1;
+	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
+
+	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+
+	num_d = git_diff_num_deltas(diff);
+	for (d = 0; d < num_d; ++d) {
+		git_diff_patch *patch;
+		git_diff_delta *delta;
+		size_t h, num_h;
+
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
+		cl_assert(patch && delta);
+		exp.files++;
+
+		num_h = git_diff_patch_num_hunks(patch);
+		for (h = 0; h < num_h; h++) {
+			git_diff_range *range;
+			const char *header;
+			size_t header_len, l, num_l;
+
+			cl_git_pass(git_diff_patch_get_hunk(
+				&range, &header, &header_len, &num_l, patch, h));
+			cl_assert(range && header);
+			exp.hunks++;
+
+			for (l = 0; l < num_l; ++l) {
+				char origin;
+				const char *content;
+				size_t content_len;
+
+				cl_git_pass(git_diff_patch_get_line_in_hunk(
+					&origin, &content, &content_len, NULL, NULL, patch, h, l));
+				cl_assert(content);
+				exp.lines++;
+			}
+		}
+
+		git_diff_patch_free(patch);
+	}
+
+	cl_assert_equal_i(13, exp.files);
+	cl_assert_equal_i(8, exp.hunks);
+	cl_assert_equal_i(13, exp.lines);
+
+	git_diff_list_free(diff);
+}
+
+static void iterate_over_patch(git_diff_patch *patch, diff_expects *exp)
+{
+	size_t h, num_h = git_diff_patch_num_hunks(patch);
+
+	exp->files++;
+	exp->hunks += num_h;
+
+	/* let's iterate in reverse, just because we can! */
+	for (h = 1; h <= num_h; ++h)
+		exp->lines += git_diff_patch_num_lines_in_hunk(patch, num_h - h);
+}
+
+#define PATCH_CACHE 5
+
+void test_diff_diffiter__iterate_randomly_while_saving_state(void)
+{
+	git_repository *repo = cl_git_sandbox_init("status");
+	git_diff_options opts = {0};
+	git_diff_list *diff = NULL;
+	diff_expects exp = {0};
+	git_diff_patch *patches[PATCH_CACHE];
+	size_t p, d, num_d;
+
+	memset(patches, 0, sizeof(patches));
+
+	opts.context_lines = 3;
+	opts.interhunk_lines = 1;
+	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
+
+	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+
+	num_d = git_diff_num_deltas(diff);
+
+	/* To make sure that references counts work for diff and patch objects,
+	 * this generates patches and randomly caches them.  Only when the patch
+	 * is removed from the cache are hunks and lines counted.  At the end,
+	 * there are still patches in the cache, so free the diff and try to
+	 * process remaining patches after the diff is freed.
+	 */
+
+	srand(121212);
+	p = rand() % PATCH_CACHE;
+
+	for (d = 0; d < num_d; ++d) {
+		/* take old patch */
+		git_diff_patch *patch = patches[p];
+		patches[p] = NULL;
+
+		/* cache new patch */
+		cl_git_pass(git_diff_get_patch(&patches[p], NULL, diff, d));
+		cl_assert(patches[p] != NULL);
+
+		/* process old patch if non-NULL */
+		if (patch != NULL) {
+			iterate_over_patch(patch, &exp);
+			git_diff_patch_free(patch);
+		}
+
+		p = rand() % PATCH_CACHE;
+	}
+
+	/* free diff list now - refcounts should keep things safe */
+	git_diff_list_free(diff);
+
+	/* process remaining unprocessed patches */
+	for (p = 0; p < PATCH_CACHE; p++) {
+		git_diff_patch *patch = patches[p];
+
+		if (patch != NULL) {
+			iterate_over_patch(patch, &exp);
+			git_diff_patch_free(patch);
+		}
+	}
 
+	/* hopefully it all still added up right */
+	cl_assert_equal_i(13, exp.files);
+	cl_assert_equal_i(8, exp.hunks);
+	cl_assert_equal_i(13, exp.lines);
 }
diff --git a/tests-clar/diff/tree.c b/tests-clar/diff/tree.c
index f5e72cadc..78ab093ed 100644
--- a/tests-clar/diff/tree.c
+++ b/tests-clar/diff/tree.c
@@ -264,10 +264,12 @@ void test_diff_tree__larger_hunks(void)
 	git_tree *a, *b;
 	git_diff_options opts = {0};
 	git_diff_list *diff = NULL;
-	git_diff_iterator *iter = NULL;
+	size_t d, num_d, h, num_h, l, num_l, header_len, line_len;
 	git_diff_delta *delta;
-	diff_expects exp;
-	int error, num_files = 0;
+	git_diff_patch *patch;
+	git_diff_range *range;
+	const char *header, *line;
+	char origin;
 
 	g_repo = cl_git_sandbox_init("diff");
 
@@ -277,61 +279,38 @@ void test_diff_tree__larger_hunks(void)
 	opts.context_lines = 1;
 	opts.interhunk_lines = 0;
 
-	memset(&exp, 0, sizeof(exp));
-
 	cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, a, b, &diff));
-	cl_git_pass(git_diff_iterator_new(&iter, diff));
 
-	/* this should be exact */
-	cl_assert(git_diff_iterator_progress(iter) == 0.0f);
+	num_d = git_diff_num_deltas(diff);
+	for (d = 0; d < num_d; ++d) {
+		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
+		cl_assert(patch && delta);
 
-	/* You wouldn't actually structure an iterator loop this way, but
-	 * I have here for testing purposes of the return value
-	 */
-	while (!(error = git_diff_iterator_next_file(&delta, iter))) {
-		git_diff_range *range;
-		const char *header;
-		size_t header_len;
-		int actual_hunks = 0, num_hunks;
-		float expected_progress;
-
-		num_files++;
-
-		expected_progress = (float)num_files / 2.0f;
-		cl_assert(expected_progress == git_diff_iterator_progress(iter));
-
-		num_hunks = git_diff_iterator_num_hunks_in_file(iter);
-
-		while (!(error = git_diff_iterator_next_hunk(
-					&range, &header, &header_len, iter)))
-		{
-			int actual_lines = 0;
-			int num_lines = git_diff_iterator_num_lines_in_hunk(iter);
-			char origin;
-			const char *line;
-			size_t line_len;
-
-			while (!(error = git_diff_iterator_next_line(
-						&origin, &line, &line_len, iter)))
-			{
-				actual_lines++;
-			}
+		num_h = git_diff_patch_num_hunks(patch);
+		for (h = 0; h < num_h; h++) {
+			cl_git_pass(git_diff_patch_get_hunk(
+				&range, &header, &header_len, &num_l, patch, h));
 
-			cl_assert_equal_i(GIT_ITEROVER, error);
-			cl_assert_equal_i(actual_lines, num_lines);
+			for (l = 0; l < num_l; ++l) {
+				cl_git_pass(git_diff_patch_get_line_in_hunk(
+					&origin, &line, &line_len, NULL, NULL, patch, h, l));
+				cl_assert(line);
+			}
 
-			actual_hunks++;
+			cl_git_fail(git_diff_patch_get_line_in_hunk(
+				&origin, &line, &line_len, NULL, NULL, patch, h, num_l));
 		}
 
-		cl_assert_equal_i(GIT_ITEROVER, error);
-		cl_assert_equal_i(actual_hunks, num_hunks);
+		cl_git_fail(git_diff_patch_get_hunk(
+			&range, &header, &header_len, &num_l, patch, num_h));
+
+		git_diff_patch_free(patch);
 	}
 
-	cl_assert_equal_i(GIT_ITEROVER, error);
-	cl_assert_equal_i(2, num_files);
-	cl_assert(git_diff_iterator_progress(iter) == 1.0f);
+	cl_git_fail(git_diff_get_patch(&patch, &delta, diff, num_d));
+
+	cl_assert_equal_i(2, num_d);
 
-	git_diff_iterator_free(iter);
 	git_diff_list_free(diff);
 	diff = NULL;
 
diff --git a/tests-clar/diff/workdir.c b/tests-clar/diff/workdir.c
index 40a888544..612e44303 100644
--- a/tests-clar/diff/workdir.c
+++ b/tests-clar/diff/workdir.c
@@ -678,7 +678,7 @@ void test_diff_workdir__larger_hunks(void)
 	const char *b_commit = "7a9e0b02e63179929fed24f0a3e0f19168114d10";
 	git_tree *a, *b;
 	git_diff_options opts = {0};
-	int i, error;
+	size_t i, d, num_d, h, num_h, l, num_l, header_len, line_len;
 
 	g_repo = cl_git_sandbox_init("diff");
 
@@ -690,9 +690,10 @@ void test_diff_workdir__larger_hunks(void)
 
 	for (i = 0; i <= 2; ++i) {
 		git_diff_list *diff = NULL;
-		git_diff_iterator *iter = NULL;
-		git_diff_delta *delta;
-		int num_files = 0;
+		git_diff_patch *patch;
+		git_diff_range *range;
+		const char *header, *line;
+		char origin;
 
 		/* okay, this is a bit silly, but oh well */
 		switch (i) {
@@ -707,54 +708,36 @@ void test_diff_workdir__larger_hunks(void)
 			break;
 		}
 
-		cl_git_pass(git_diff_iterator_new(&iter, diff));
+		num_d = git_diff_num_deltas(diff);
+		cl_assert_equal_i(2, (int)num_d);
 
-		cl_assert(git_diff_iterator_progress(iter) == 0.0f);
+		for (d = 0; d < num_d; ++d) {
+			cl_git_pass(git_diff_get_patch(&patch, NULL, diff, d));
+			cl_assert(patch);
 
-		while (!(error = git_diff_iterator_next_file(&delta, iter))) {
-			git_diff_range *range;
-			const char *header;
-			size_t header_len;
-			int actual_hunks = 0, num_hunks;
-			float expected_progress;
+			num_h = git_diff_patch_num_hunks(patch);
+			for (h = 0; h < num_h; h++) {
+				cl_git_pass(git_diff_patch_get_hunk(
+					&range, &header, &header_len, &num_l, patch, h));
 
-			num_files++;
-
-			expected_progress = (float)num_files / 2.0f;
-			cl_assert(expected_progress == git_diff_iterator_progress(iter));
-
-			num_hunks = git_diff_iterator_num_hunks_in_file(iter);
-
-			while (!(error = git_diff_iterator_next_hunk(
-						 &range, &header, &header_len, iter)))
-			{
-				int actual_lines = 0;
-				int num_lines = git_diff_iterator_num_lines_in_hunk(iter);
-				char origin;
-				const char *line;
-				size_t line_len;
-
-				while (!(error = git_diff_iterator_next_line(
-							 &origin, &line, &line_len, iter)))
-				{
-					actual_lines++;
+				for (l = 0; l < num_l; ++l) {
+					cl_git_pass(git_diff_patch_get_line_in_hunk(
+						&origin, &line, &line_len, NULL, NULL, patch, h, l));
+					cl_assert(line);
 				}
 
-				cl_assert_equal_i(GIT_ITEROVER, error);
-				cl_assert_equal_i(actual_lines, num_lines);
-
-				actual_hunks++;
+				/* confirm fail after the last item */
+				cl_git_fail(git_diff_patch_get_line_in_hunk(
+					&origin, &line, &line_len, NULL, NULL, patch, h, num_l));
 			}
 
-			cl_assert_equal_i(GIT_ITEROVER, error);
-			cl_assert_equal_i(actual_hunks, num_hunks);
-		}
+			/* confirm fail after the last item */
+			cl_git_fail(git_diff_patch_get_hunk(
+				&range, &header, &header_len, &num_l, patch, num_h));
 
-		cl_assert_equal_i(GIT_ITEROVER, error);
-		cl_assert_equal_i(2, num_files);
-		cl_assert(git_diff_iterator_progress(iter) == 1.0f);
+			git_diff_patch_free(patch);
+		}
 
-		git_diff_iterator_free(iter);
 		git_diff_list_free(diff);
 	}