Merge remote-tracking branch 'nulltoken/topic/reflog-delete' into development

include/git2/reflog.h

@@ -23,6 +23,10 @@ GIT_BEGIN_DECL
 /**
  * Read the reflog for the given reference
  *
+ * If there is no reflog file for the given
+ * reference yet, an empty reflog object will
+ * be returned.
+ *
  * The reflog must be freed manually by using
  * git_reflog_free().
  *
@@ -33,22 +37,26 @@ GIT_BEGIN_DECL
 GIT_EXTERN(int) git_reflog_read(git_reflog **reflog, git_reference *ref);
 
 /**
- * Write a new reflog for the given reference
- *
- * If there is no reflog file for the given
- * reference yet, it will be created.
+ * Write an existing in-memory reflog object back to disk
+ * using an atomic file lock.
  *
- * `oid_old` may be NULL in case it's a new reference.
+ * @param reflog an existing reflog object
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_reflog_write(git_reflog *reflog);
+
+/**
+ * Add a new entry to the reflog.
  *
  * `msg` is optional and can be NULL.
  *
- * @param ref the changed reference
- * @param oid_old the OID the reference was pointing to
+ * @param reflog an existing reflog object
+ * @param new_oid the OID the reference is now pointing to
  * @param committer the signature of the committer
  * @param msg the reflog message
  * @return 0 or an error code
  */
-GIT_EXTERN(int) git_reflog_write(git_reference *ref, const git_oid *oid_old, const git_signature *committer, const char *msg);
+GIT_EXTERN(int) git_reflog_append(git_reflog *reflog, const git_oid *new_oid, const git_signature *committer, const char *msg);
 
 /**
  * Rename the reflog for the given reference
@@ -87,6 +95,26 @@ GIT_EXTERN(unsigned int) git_reflog_entrycount(git_reflog *reflog);
 GIT_EXTERN(const git_reflog_entry *) git_reflog_entry_byindex(git_reflog *reflog, unsigned int idx);
 
 /**
+ * Remove an entry from the reflog by its index
+ *
+ * To ensure there's no gap in the log history, set the `rewrite_previosu_entry` to 1.
+ * When deleting entry `n`, member old_oid of entry `n-1` (if any) will be updated with
+ * the value of memeber new_oid of entry `n+1`.
+ *
+ * @param reflog a previously loaded reflog.
+ *
+ * @param idx the position of the entry to remove.
+ *
+ * @param rewrite_previous_entry 1 to rewrite the history; 0 otherwise.
+ *
+ * @return 0 on success or an error code.
+ */
+GIT_EXTERN(int) git_reflog_entry_drop(
+	git_reflog *reflog,
+	unsigned int idx,
+	int rewrite_previous_entry);
+
+/**
  * Get the old oid
  *
  * @param entry a reflog entry

src/reflog.c

@@ -28,66 +28,68 @@ static int reflog_init(git_reflog **reflog, git_reference *ref)
 		return -1;
 	}
 
+	log->owner = git_reference_owner(ref);
 	*reflog = log;
 
 	return 0;
 }
 
-static int reflog_write(const char *log_path, const char *oid_old,
-			const char *oid_new, const git_signature *committer,
+static int serialize_reflog_entry(
+	git_buf *buf,
+	const git_oid *oid_old,
+	const git_oid *oid_new,
+	const git_signature *committer,
 	const char *msg)
 {
-	int error;
-	git_buf log = GIT_BUF_INIT;
-	git_filebuf fbuf = GIT_FILEBUF_INIT;
-	bool trailing_newline = false;
+	char raw_old[GIT_OID_HEXSZ+1];
+	char raw_new[GIT_OID_HEXSZ+1];
 
-	assert(log_path && oid_old && oid_new && committer);
+	git_oid_tostr(raw_old, GIT_OID_HEXSZ+1, oid_old);
+	git_oid_tostr(raw_new, GIT_OID_HEXSZ+1, oid_new);
 
-	if (msg) {
-		const char *newline = strchr(msg, '\n');
-		if (newline) {
-			if (*(newline + 1) == '\0')
-				trailing_newline = true;
-			else {
-				giterr_set(GITERR_INVALID, "Reflog message cannot contain newline");
-				return -1;
-			}
-		}
-	}
+	git_buf_clear(buf);
 
-	git_buf_puts(&log, oid_old);
-	git_buf_putc(&log, ' ');
+	git_buf_puts(buf, raw_old);
+	git_buf_putc(buf, ' ');
+	git_buf_puts(buf, raw_new);
 
-	git_buf_puts(&log, oid_new);
+	git_signature__writebuf(buf, " ", committer);
 
-	git_signature__writebuf(&log, " ", committer);
-	git_buf_truncate(&log, log.size - 1); /* drop LF */
+	/* drop trailing LF */
+	git_buf_rtrim(buf);
 
 	if (msg) {
-		git_buf_putc(&log, '\t');
-		git_buf_puts(&log, msg);
+		git_buf_putc(buf, '\t');
+		git_buf_puts(buf, msg);
 	}
 
-	if (!trailing_newline)
-		git_buf_putc(&log, '\n');
+	git_buf_putc(buf, '\n');
 
-	if (git_buf_oom(&log)) {
-		git_buf_free(&log);
-		return -1;
-	}
+	return git_buf_oom(buf);
+}
 
-	error = git_filebuf_open(&fbuf, log_path, GIT_FILEBUF_APPEND);
-	if (!error) {
-		if ((error = git_filebuf_write(&fbuf, log.ptr, log.size)) < 0)
-			git_filebuf_cleanup(&fbuf);
-		else
-			error = git_filebuf_commit(&fbuf, GIT_REFLOG_FILE_MODE);
-	}
+static int reflog_entry_new(git_reflog_entry **entry)
+{
+	git_reflog_entry *e;
 
-	git_buf_free(&log);
+	assert(entry);
 
-	return error;
+	e = git__malloc(sizeof(git_reflog_entry));
+	GITERR_CHECK_ALLOC(e);
+
+	memset(e, 0, sizeof(git_reflog_entry));
+
+	*entry = e;
+
+	return 0;
+}
+
+static void reflog_entry_free(git_reflog_entry *entry)
+{
+	git_signature_free(entry->committer);
+
+	git__free(entry->msg);
+	git__free(entry);
 }
 
 static int reflog_parse(git_reflog *log, const char *buf, size_t buf_size)
@@ -105,8 +107,8 @@ static int reflog_parse(git_reflog *log, const char *buf, size_t buf_size)
 	} while (0)
 
 	while (buf_size > GIT_REFLOG_SIZE_MIN) {
-		entry = git__malloc(sizeof(git_reflog_entry));
-		GITERR_CHECK_ALLOC(entry);
+		if (reflog_entry_new(&entry) < 0)
+			return -1;
 
 		entry->committer = git__malloc(sizeof(git_signature));
 		GITERR_CHECK_ALLOC(entry->committer);
@@ -153,10 +155,9 @@ static int reflog_parse(git_reflog *log, const char *buf, size_t buf_size)
 #undef seek_forward
 
 fail:
-	if (entry) {
-		git__free(entry->committer);
-		git__free(entry);
-	}
+	if (entry)
+		reflog_entry_free(entry);
+
 	return -1;
 }
 
@@ -168,10 +169,7 @@ void git_reflog_free(git_reflog *reflog)
 	for (i=0; i < reflog->entries.length; i++) {
 		entry = git_vector_get(&reflog->entries, i);
 
-		git_signature_free(entry->committer);
-
-		git__free(entry->msg);
-		git__free(entry);
+		reflog_entry_free(entry);
 	}
 
 	git_vector_free(&reflog->entries);
@@ -179,6 +177,24 @@ void git_reflog_free(git_reflog *reflog)
 	git__free(reflog);
 }
 
+static int retrieve_reflog_path(git_buf *path, git_reference *ref)
+{
+	return git_buf_join_n(path, '/', 3,
+		git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR, ref->name);
+}
+
+int create_new_reflog_file(const char *filepath)
+{
+	int fd;
+
+	if ((fd = p_open(filepath,
+			O_WRONLY | O_CREAT | O_TRUNC,
+			GIT_REFLOG_FILE_MODE)) < 0)
+		return -1;
+
+	return p_close(fd);
+}
+
 int git_reflog_read(git_reflog **reflog, git_reference *ref)
 {
 	int error;
@@ -188,85 +204,138 @@ int git_reflog_read(git_reflog **reflog, git_reference *ref)
 
 	*reflog = NULL;
 
+	assert(reflog && ref);
+
 	if (reflog_init(&log, ref) < 0)
 		return -1;
 
-	error = git_buf_join_n(&log_path, '/', 3,
-		ref->owner->path_repository, GIT_REFLOG_DIR, ref->name);
+	if (retrieve_reflog_path(&log_path, ref) < 0)
+		goto cleanup;
 
-	if (!error)
-		error = git_futils_readbuffer(&log_file, log_path.ptr);
+	error = git_futils_readbuffer(&log_file, git_buf_cstr(&log_path));
+	if (error < 0 && error != GIT_ENOTFOUND)
+		goto cleanup;
 
-	if (!error)
-		error = reflog_parse(log, log_file.ptr, log_file.size);
+	if ((error == GIT_ENOTFOUND) &&
+		((error = create_new_reflog_file(git_buf_cstr(&log_path))) < 0))
+		goto cleanup;
+
+	if ((error = reflog_parse(log,
+		git_buf_cstr(&log_file), git_buf_len(&log_file))) < 0)
+		goto cleanup;
 
-	if (!error)
 	*reflog = log;
-	else
+	goto success;
+
+cleanup:
 	git_reflog_free(log);
 
+success:
 	git_buf_free(&log_file);
 	git_buf_free(&log_path);
 
 	return error;
 }
 
-int git_reflog_write(git_reference *ref, const git_oid *oid_old,
-				const git_signature *committer, const char *msg)
+int git_reflog_write(git_reflog *reflog)
 {
-	int error;
-	char old[GIT_OID_HEXSZ+1];
-	char new[GIT_OID_HEXSZ+1];
+	int error = -1;
+	unsigned int i;
+	git_reflog_entry *entry;
 	git_buf log_path = GIT_BUF_INIT;
-	git_reference *r;
-	const git_oid *oid;
+	git_buf log = GIT_BUF_INIT;
+	git_filebuf fbuf = GIT_FILEBUF_INIT;
 
-	if ((error = git_reference_resolve(&r, ref)) < 0)
-		return error;
+	assert(reflog);
 
-	oid = git_reference_oid(r);
-	if (oid == NULL) {
-		giterr_set(GITERR_REFERENCE,
-			"Failed to write reflog. Cannot resolve reference `%s`", r->name);
-		git_reference_free(r);
-		return -1;
-	}
 
-	git_oid_tostr(new, GIT_OID_HEXSZ+1, oid);
+	if (git_buf_join_n(&log_path, '/', 3,
+		git_repository_path(reflog->owner), GIT_REFLOG_DIR, reflog->ref_name) < 0)
+		return -1;
 
-	git_reference_free(r);
+	if (!git_path_isfile(git_buf_cstr(&log_path))) {
+		giterr_set(GITERR_INVALID,
+			"Log file for reference '%s' doesn't exist.", reflog->ref_name);
+		goto cleanup;
+	}
 
-	error = git_buf_join_n(&log_path, '/', 3,
-		ref->owner->path_repository, GIT_REFLOG_DIR, ref->name);
-	if (error < 0)
+	if ((error = git_filebuf_open(&fbuf, git_buf_cstr(&log_path), 0)) < 0)
 		goto cleanup;
 
-	if (git_path_exists(log_path.ptr) == false) {
-		error = git_futils_mkpath2file(log_path.ptr, GIT_REFLOG_DIR_MODE);
-	} else if (git_path_isfile(log_path.ptr) == false) {
-		giterr_set(GITERR_REFERENCE,
-			"Failed to write reflog. `%s` is directory", log_path.ptr);
-		error = -1;
-	} else if (oid_old == NULL) {
-		giterr_set(GITERR_REFERENCE,
-			"Failed to write reflog. Old OID cannot be NULL for existing reference");
-		error = -1;
-	}
-	if (error < 0)
+	git_vector_foreach(&reflog->entries, i, entry) {
+		if (serialize_reflog_entry(&log, &(entry->oid_old), &(entry->oid_cur), entry->committer, entry->msg) < 0)
 			goto cleanup;
 
-	if (oid_old)
-		git_oid_tostr(old, sizeof(old), oid_old);
-	else
-		p_snprintf(old, sizeof(old), "%0*d", GIT_OID_HEXSZ, 0);
+		if ((error = git_filebuf_write(&fbuf, log.ptr, log.size)) < 0)
+			goto cleanup;
+	}
 	
-	error = reflog_write(log_path.ptr, old, new, committer, msg);
+	error = git_filebuf_commit(&fbuf, GIT_REFLOG_FILE_MODE);
+	goto success;
 
 cleanup:
+	git_filebuf_cleanup(&fbuf);
+
+success:
+	git_buf_free(&log);
 	git_buf_free(&log_path);
 	return error;
 }
 
+int git_reflog_append(git_reflog *reflog, const git_oid *new_oid,
+				const git_signature *committer, const char *msg)
+{
+	int count;
+	git_reflog_entry *entry;
+	const char *newline;
+
+	assert(reflog && new_oid && committer);
+
+	if (reflog_entry_new(&entry) < 0)
+		return -1;
+
+	if ((entry->committer = git_signature_dup(committer)) == NULL)
+		goto cleanup;
+
+	if (msg != NULL) {
+		if ((entry->msg = git__strdup(msg)) == NULL)
+			goto cleanup;
+
+		newline = strchr(msg, '\n');
+
+		if (newline) {
+			if (newline[1] != '\0') {
+				giterr_set(GITERR_INVALID, "Reflog message cannot contain newline");
+				goto cleanup;
+			}
+
+			entry->msg[newline - msg] = '\0';
+		}
+	}
+
+	count = git_reflog_entrycount(reflog);
+
+	if (count == 0)
+		git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO);
+	else {
+		const git_reflog_entry *previous;
+
+		previous = git_reflog_entry_byindex(reflog, count -1);
+		git_oid_cpy(&entry->oid_old, &previous->oid_cur);
+	}
+
+	git_oid_cpy(&entry->oid_cur, new_oid);
+
+	if (git_vector_insert(&reflog->entries, entry) < 0)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	reflog_entry_free(entry);
+	return -1;
+}
+
 int git_reflog_rename(git_reference *ref, const char *new_name)
 {
 	int error = -1, fd;
@@ -276,7 +345,7 @@ int git_reflog_rename(git_reference *ref, const char *new_name)
 
 	assert(ref && new_name);
 
-	if (git_buf_joinpath(&temp_path, ref->owner->path_repository, GIT_REFLOG_DIR) < 0)
+	if (git_buf_joinpath(&temp_path, git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR) < 0)
 		return -1;
 
 	if (git_buf_joinpath(&old_path, git_buf_cstr(&temp_path), ref->name) < 0)
@@ -324,8 +393,7 @@ int git_reflog_delete(git_reference *ref)
 	int error;
 	git_buf path = GIT_BUF_INIT;
 
-	error = git_buf_join_n(
-		&path, '/', 3, ref->owner->path_repository, GIT_REFLOG_DIR, ref->name);
+	error = retrieve_reflog_path(&path, ref);
 
 	if (!error && git_path_exists(path.ptr))
 		error = p_unlink(path.ptr);
@@ -370,3 +438,52 @@ char * git_reflog_entry_msg(const git_reflog_entry *entry)
 	assert(entry);
 	return entry->msg;
 }
+
+int git_reflog_entry_drop(
+	git_reflog *reflog,
+	unsigned int idx,
+	int rewrite_previous_entry)
+{
+	unsigned int entrycount;
+	git_reflog_entry *entry, *previous;
+
+	assert(reflog);
+
+	entrycount = git_reflog_entrycount(reflog);
+
+	if (idx >= entrycount)
+		return GIT_ENOTFOUND;
+
+	entry = git_vector_get(&reflog->entries, idx);
+	reflog_entry_free(entry);
+
+	if (git_vector_remove(&reflog->entries, idx) < 0)
+		return -1;
+
+	if (!rewrite_previous_entry)
+		return 0;
+
+	/* No need to rewrite anything when removing the first entry */
+	if (idx == 0)
+		return 0;
+
+	/* There are no more entries in the log */
+	if (entrycount == 1)
+		return 0;
+
+	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);
+
+	/* If the last entry has just been removed... */
+	if (idx == entrycount - 1) {
+		/* ...clear the oid_old member of the "new" last entry */
+		if (git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO) < 0)
+			return -1;
+		
+		return 0;
+	}
+
+	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
+	git_oid_cpy(&entry->oid_old, &previous->oid_cur);
+
+	return 0;
+}

src/reflog.h

@@ -17,6 +17,8 @@
 
 #define GIT_REFLOG_SIZE_MIN (2*GIT_OID_HEXSZ+2+17)
 
+#define GIT_OID_HEX_ZERO "0000000000000000000000000000000000000000"
+
 struct git_reflog_entry {
 	git_oid oid_old;
 	git_oid oid_cur;
@@ -28,6 +30,7 @@ struct git_reflog_entry {
 
 struct git_reflog {
 	char *ref_name;
+	git_repository *owner;
 	git_vector entries;
 };
 

tests-clar/refs/reflog/drop.c

+#include "clar_libgit2.h"
+
+#include "reflog.h"
+
+static git_repository *g_repo;
+static git_reflog *g_reflog;
+static unsigned int entrycount;
+
+void test_refs_reflog_drop__initialize(void)
+{
+	git_reference *ref;
+	
+	g_repo = cl_git_sandbox_init("testrepo.git");
+	cl_git_pass(git_reference_lookup(&ref, g_repo, "HEAD"));
+	
+	git_reflog_read(&g_reflog, ref);
+	entrycount = git_reflog_entrycount(g_reflog);
+
+	git_reference_free(ref);
+}
+
+void test_refs_reflog_drop__cleanup(void)
+{
+	git_reflog_free(g_reflog);
+
+	cl_git_sandbox_cleanup();
+}
+
+void test_refs_reflog_drop__dropping_a_non_exisiting_entry_from_the_log_returns_ENOTFOUND(void)
+{
+	cl_assert_equal_i(GIT_ENOTFOUND, git_reflog_entry_drop(g_reflog, entrycount, 0));
+
+	cl_assert_equal_i(entrycount, git_reflog_entrycount(g_reflog));
+}
+
+void test_refs_reflog_drop__can_drop_an_entry(void)
+{
+	cl_assert(entrycount > 4);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, 2, 0));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+}
+
+void test_refs_reflog_drop__can_drop_an_entry_and_rewrite_the_log_history(void)
+{
+	const git_reflog_entry *before_previous, *before_next;
+	const git_reflog_entry *after_next;
+	git_oid before_next_old_oid;
+
+	cl_assert(entrycount > 4);
+
+	before_previous = git_reflog_entry_byindex(g_reflog, 3);
+	before_next = git_reflog_entry_byindex(g_reflog, 1);
+	git_oid_cpy(&before_next_old_oid, &before_next->oid_old);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, 2, 1));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+
+	after_next = git_reflog_entry_byindex(g_reflog, 1);
+
+	cl_assert_equal_i(0, git_oid_cmp(&before_next->oid_cur, &after_next->oid_cur));
+	cl_assert(git_oid_cmp(&before_next_old_oid, &after_next->oid_old) != 0);
+	cl_assert_equal_i(0, git_oid_cmp(&before_previous->oid_cur, &after_next->oid_old));
+}
+
+void test_refs_reflog_drop__can_drop_the_first_entry(void)
+{
+	cl_assert(entrycount > 2);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, 0, 0));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+}
+
+void test_refs_reflog_drop__can_drop_the_last_entry(void)
+{
+	const git_reflog_entry *entry;
+
+	cl_assert(entrycount > 2);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, entrycount - 1, 0));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+
+	entry = git_reflog_entry_byindex(g_reflog, entrycount - 2);
+	cl_assert(git_oid_streq(&entry->oid_old, GIT_OID_HEX_ZERO) != 0);
+}
+
+void test_refs_reflog_drop__can_drop_the_last_entry_and_rewrite_the_log_history(void)
+{
+	const git_reflog_entry *entry;
+
+	cl_assert(entrycount > 2);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, entrycount - 1, 1));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+
+	entry = git_reflog_entry_byindex(g_reflog, entrycount - 2);
+	cl_assert(git_oid_streq(&entry->oid_old, GIT_OID_HEX_ZERO) == 0);
+}
+
+void test_refs_reflog_drop__can_drop_all_the_entries(void)
+{
+	cl_assert(--entrycount > 0);
+
+	do 	{
+		cl_git_pass(git_reflog_entry_drop(g_reflog, --entrycount, 1));
+	} while (entrycount > 0);
+
+	cl_git_pass(git_reflog_entry_drop(g_reflog, 0, 1));
+
+	cl_assert_equal_i(0, git_reflog_entrycount(g_reflog));
+}
+
+void test_refs_reflog_drop__can_persist_deletion_on_disk(void)
+{
+	git_reference *ref;
+
+	cl_assert(entrycount > 2);
+
+	cl_git_pass(git_reference_lookup(&ref, g_repo, g_reflog->ref_name));
+	cl_git_pass(git_reflog_entry_drop(g_reflog, entrycount - 1, 1));
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+	cl_git_pass(git_reflog_write(g_reflog));
+
+	git_reflog_free(g_reflog);
+
+	git_reflog_read(&g_reflog, ref);
+	git_reference_free(ref);
+
+	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
+}

tests-clar/refs/reflog.c → tests-clar/refs/reflog/reflog.c

@@ -7,7 +7,7 @@
 
 static const char *new_ref = "refs/heads/test-reflog";
 static const char *current_master_tip = "a65fedf39aefe402d3bb6e24df4d4f5fe4547750";
-static const char *commit_msg = "commit: bla bla";
+#define commit_msg "commit: bla bla"
 
 static git_repository *g_repo;
 
@@ -24,19 +24,17 @@ static void assert_signature(git_signature *expected, git_signature *actual)
 
 
 // Fixture setup and teardown
-void test_refs_reflog__initialize(void)
+void test_refs_reflog_reflog__initialize(void)
 {
    g_repo = cl_git_sandbox_init("testrepo.git");
 }
 
-void test_refs_reflog__cleanup(void)
+void test_refs_reflog_reflog__cleanup(void)
 {
    cl_git_sandbox_cleanup();
 }
 
-
-
-void test_refs_reflog__write_then_read(void)
+void test_refs_reflog_reflog__append_then_read(void)
 {
    // write a reflog for a given reference and ensure it can be read back
 	git_repository *repo2;
@@ -44,46 +42,42 @@ void test_refs_reflog__write_then_read(void)
 	git_oid oid;
 	git_signature *committer;
 	git_reflog *reflog;
-	git_reflog_entry *entry;
-	char oid_str[GIT_OID_HEXSZ+1];
+	const git_reflog_entry *entry;
 
 	/* Create a new branch pointing at the HEAD */
 	git_oid_fromstr(&oid, current_master_tip);
 	cl_git_pass(git_reference_create_oid(&ref, g_repo, new_ref, &oid, 0));
-	git_reference_free(ref);
-	cl_git_pass(git_reference_lookup(&ref, g_repo, new_ref));
 
 	cl_git_pass(git_signature_now(&committer, "foo", "foo@bar"));
 
-	cl_git_pass(git_reflog_write(ref, NULL, committer, NULL));
-	cl_git_fail(git_reflog_write(ref, NULL, committer, "no ancestor NULL for an existing reflog"));
-	cl_git_fail(git_reflog_write(ref, NULL, committer, "no\nnewline"));
-	cl_git_pass(git_reflog_write(ref, &oid, committer, commit_msg));
+	cl_git_pass(git_reflog_read(&reflog, ref));
+
+	cl_git_fail(git_reflog_append(reflog, &oid, committer, "no inner\nnewline"));
+	cl_git_pass(git_reflog_append(reflog, &oid, committer, NULL));
+	cl_git_pass(git_reflog_append(reflog, &oid, committer, commit_msg "\n"));
+	cl_git_pass(git_reflog_write(reflog));
+	git_reflog_free(reflog);
 
 	/* Reopen a new instance of the repository */
 	cl_git_pass(git_repository_open(&repo2, "testrepo.git"));
 
-	/* Lookup the preivously created branch */
+	/* Lookup the previously created branch */
 	cl_git_pass(git_reference_lookup(&lookedup_ref, repo2, new_ref));
 
 	/* Read and parse the reflog for this branch */
 	cl_git_pass(git_reflog_read(&reflog, lookedup_ref));
-	cl_assert(reflog->entries.length == 2);
+	cl_assert_equal_i(2, git_reflog_entrycount(reflog));
 
-	entry = (git_reflog_entry *)git_vector_get(&reflog->entries, 0);
+	entry = git_reflog_entry_byindex(reflog, 0);
 	assert_signature(committer, entry->committer);
-	git_oid_tostr(oid_str, GIT_OID_HEXSZ+1, &entry->oid_old);
-	cl_assert_equal_s("0000000000000000000000000000000000000000", oid_str);
-	git_oid_tostr(oid_str, GIT_OID_HEXSZ+1, &entry->oid_cur);
-	cl_assert_equal_s(current_master_tip, oid_str);
+	cl_assert(git_oid_streq(&entry->oid_old, GIT_OID_HEX_ZERO) == 0);
+	cl_assert(git_oid_cmp(&oid, &entry->oid_cur) == 0);
 	cl_assert(entry->msg == NULL);
 
-	entry = (git_reflog_entry *)git_vector_get(&reflog->entries, 1);
+	entry = git_reflog_entry_byindex(reflog, 1);
 	assert_signature(committer, entry->committer);
-	git_oid_tostr(oid_str, GIT_OID_HEXSZ+1, &entry->oid_old);
-	cl_assert_equal_s(current_master_tip, oid_str);
-	git_oid_tostr(oid_str, GIT_OID_HEXSZ+1, &entry->oid_cur);
-	cl_assert_equal_s(current_master_tip, oid_str);
+	cl_assert(git_oid_cmp(&oid, &entry->oid_old) == 0);
+	cl_assert(git_oid_cmp(&oid, &entry->oid_cur) == 0);
 	cl_assert_equal_s(commit_msg, entry->msg);
 
 	git_signature_free(committer);
@@ -94,35 +88,7 @@ void test_refs_reflog__write_then_read(void)
 	git_reference_free(lookedup_ref);
 }
 
-void test_refs_reflog__dont_write_bad(void)
-{
-   // avoid writing an obviously wrong reflog
-	git_reference *ref;
-	git_oid oid;
-	git_signature *committer;
-
-	/* Create a new branch pointing at the HEAD */
-	git_oid_fromstr(&oid, current_master_tip);
-	cl_git_pass(git_reference_create_oid(&ref, g_repo, new_ref, &oid, 0));
-	git_reference_free(ref);
-	cl_git_pass(git_reference_lookup(&ref, g_repo, new_ref));
-
-	cl_git_pass(git_signature_now(&committer, "foo", "foo@bar"));
-
-	/* Write the reflog for the new branch */
-	cl_git_pass(git_reflog_write(ref, NULL, committer, NULL));
-
-	/* Try to update the reflog with wrong information:
-	 * It's no new reference, so the ancestor OID cannot
-	 * be NULL. */
-	cl_git_fail(git_reflog_write(ref, NULL, committer, NULL));
-
-	git_signature_free(committer);
-
-	git_reference_free(ref);
-}
-
-void test_refs_reflog__renaming_the_reference_moves_the_reflog(void)
+void test_refs_reflog_reflog__renaming_the_reference_moves_the_reflog(void)
 {
 	git_reference *master;
 	git_buf master_log_path = GIT_BUF_INIT, moved_log_path = GIT_BUF_INIT;
@@ -145,6 +111,7 @@ void test_refs_reflog__renaming_the_reference_moves_the_reflog(void)
 	git_buf_free(&moved_log_path);
 	git_buf_free(&master_log_path);
 }
+
 static void assert_has_reflog(bool expected_result, const char *name)
 {
 	git_reference *ref;
@@ -156,9 +123,50 @@ static void assert_has_reflog(bool expected_result, const char *name)
 	git_reference_free(ref);
 }
 
-void test_refs_reflog__reference_has_reflog(void)
+void test_refs_reflog_reflog__reference_has_reflog(void)
 {
 	assert_has_reflog(true, "HEAD");
 	assert_has_reflog(true, "refs/heads/master");
 	assert_has_reflog(false, "refs/heads/subtrees");
 }
+
+void test_refs_reflog_reflog__reading_the_reflog_from_a_reference_with_no_log_returns_an_empty_one(void)
+{
+	git_reference *subtrees;
+	git_reflog *reflog;
+	git_buf subtrees_log_path = GIT_BUF_INIT;
+
+	cl_git_pass(git_reference_lookup(&subtrees, g_repo, "refs/heads/subtrees"));
+
+	git_buf_join_n(&subtrees_log_path, '/', 3, git_repository_path(g_repo), GIT_REFLOG_DIR, git_reference_name(subtrees));
+	cl_assert_equal_i(false, git_path_isfile(git_buf_cstr(&subtrees_log_path)));
+
+	cl_git_pass(git_reflog_read(&reflog, subtrees));
+
+	cl_assert_equal_i(0, git_reflog_entrycount(reflog));
+
+	git_reflog_free(reflog);
+	git_reference_free(subtrees);
+	git_buf_free(&subtrees_log_path);
+}
+
+void test_refs_reflog_reflog__cannot_write_a_moved_reflog(void)
+{
+	git_reference *master;
+	git_buf master_log_path = GIT_BUF_INIT, moved_log_path = GIT_BUF_INIT;
+	git_reflog *reflog;
+
+	cl_git_pass(git_reference_lookup(&master, g_repo, "refs/heads/master"));
+	cl_git_pass(git_reflog_read(&reflog, master));
+
+	cl_git_pass(git_reflog_write(reflog));
+	
+	cl_git_pass(git_reference_rename(master, "refs/moved", 0));
+
+	cl_git_fail(git_reflog_write(reflog));
+
+	git_reflog_free(reflog);
+	git_reference_free(master);
+	git_buf_free(&moved_log_path);
+	git_buf_free(&master_log_path);
+}