Move blame to cffi

This requires fairly little work on the pygit2 side to kick off all the
searching on the libgit2 side, so it's a fairly good candidate.

This changes the return value for the commit ids to Oid instead of
strings, which is what we generally try to return.

Author: carlosmn

pygit2/decl.h

@@ -5,7 +5,6 @@ typedef ... git_push;
 typedef ... git_cred;
 typedef ... git_object;
 typedef ... git_tree;
-typedef ... git_signature;
 typedef ... git_index;
 typedef ... git_diff;
 typedef ... git_index_conflict_iterator;
@@ -29,6 +28,7 @@ typedef struct git_strarray {
 } git_strarray;
 
 typedef int64_t git_off_t;
+typedef int64_t git_time_t;
 
 typedef enum {
 	GIT_OK = 0,
@@ -55,6 +55,17 @@ typedef struct {
 	int klass;
 } git_error;
 
+typedef struct git_time {
+	git_time_t time;
+	int offset;
+} git_time;
+
+typedef struct git_signature {
+	char *name;
+	char *email;
+	git_time when;
+} git_signature;
+
 const git_error * giterr_last(void);
 
 void git_strarray_free(git_strarray *array);
@@ -506,3 +517,44 @@ int git_index_conflict_iterator_new(git_index_conflict_iterator **iterator_out,
 int git_index_conflict_get(const git_index_entry **ancestor_out, const git_index_entry **our_out, const git_index_entry **their_out, git_index *index, const char *path);
 int git_index_conflict_next(const git_index_entry **ancestor_out, const git_index_entry **our_out, const git_index_entry **their_out, git_index_conflict_iterator *iterator);
 int git_index_conflict_remove(git_index *index, const char *path);
+
+/*
+ * git_blame
+ */
+
+typedef ... git_blame;
+
+typedef struct git_blame_options {
+	unsigned int version;
+
+	uint32_t flags;
+	uint16_t min_match_characters;
+	git_oid newest_commit;
+	git_oid oldest_commit;
+	uint32_t min_line;
+	uint32_t max_line;
+} git_blame_options;
+
+#define GIT_BLAME_OPTIONS_VERSION ...
+
+typedef struct git_blame_hunk {
+	uint16_t lines_in_hunk;
+
+	git_oid final_commit_id;
+	uint16_t final_start_line_number;
+	git_signature *final_signature;
+
+	git_oid orig_commit_id;
+	const char *orig_path;
+	uint16_t orig_start_line_number;
+	git_signature *orig_signature;
+
+	char boundary;
+} git_blame_hunk;
+
+int git_blame_init_options(git_blame_options *opts, unsigned int version);
+uint32_t git_blame_get_hunk_count(git_blame *blame);
+const git_blame_hunk *git_blame_get_hunk_byindex(git_blame *blame, uint32_t index);
+const git_blame_hunk *git_blame_get_hunk_byline(git_blame *blame, uint32_t lineno);
+int git_blame_file(git_blame **out, git_repository *repo, const char *path, git_blame_options *options);
+void git_blame_free(git_blame *blame);

pygit2/repository.py

@@ -42,7 +42,8 @@
 from .ffi import ffi, C
 from .index import Index
 from .remote import Remote
-from .utils import to_bytes
+from .blame import Blame
+from .utils import to_bytes, to_str
 
 
 class Repository(_Repository):
@@ -370,6 +371,61 @@ def state_cleanup(self):
         """
         C.git_repository_state_cleanup(self._repo)
 
+    #
+    # blame
+    #
+    def blame(self, path, flags=None, min_match_characters=None, newest_commit=None, oldest_commit=None, min_line=None, max_line=None):
+        """blame(path, [flags, min_match_characters, newest_commit, oldest_commit,\n"
+                 min_line, max_line]) -> Blame
+
+        Get the blame for a single file.
+
+        Arguments:
+
+        path
+            Path to the file to blame.
+        flags
+            A GIT_BLAME_* constant.
+        min_match_characters
+            The number of alphanum chars that must be detected as moving/copying
+            within a file for it to associate those lines with the parent commit.
+        newest_commit
+            The id of the newest commit to consider.
+        oldest_commit
+          The id of the oldest commit to consider.
+        min_line
+            The first line in the file to blame.
+        max_line
+            The last line in the file to blame.
+
+        Examples::
+
+            repo.blame('foo.c', flags=GIT_BLAME_TRACK_COPIES_SAME_FILE)");
+        """
+
+        options = ffi.new('git_blame_options *')
+        C.git_blame_init_options(options, C.GIT_BLAME_OPTIONS_VERSION)
+        if min_match_characters:
+            options.min_match_characters = min_match_characters
+        if newest_commit:
+            if not isinstance(newest_commit, Oid):
+                newest_commit = Oid(hex=newest_commit)
+            ffi.buffer(ffi.addressof(options, 'newest_commit'))[:] = newest_commit.raw
+        if oldest_commit:
+            if not isinstance(oldest_commit, Oid):
+                oldest_commit = Oid(hex=oldest_commit)
+            ffi.buffer(ffi.addressof(options, 'oldest_commit'))[:] = oldest_commit.raw
+        if min_line:
+            options.min_line = min_line
+        if max_line:
+            options.max_line = max_line
+
+        cblame = ffi.new('git_blame **')
+        err = C.git_blame_file(cblame, self._repo, to_str(path), options)
+        check_error(err)
+
+        return Blame._from_c(self, cblame[0])
+
     #
     # Index
     #