thodg/libgit2

diff --git a/src/checkout.c b/src/checkout.c
index 06407bb..640b048 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -603,19 +603,6 @@ static int checkout_create_submodules(
 	return 0;
 }
 
-static bool opts_is_valid_version(git_checkout_opts *opts)
-{
-	if (!opts)
-		return true;
-
-	if (opts->version > 0 &&  opts->version <= GIT_CHECKOUT_OPTS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d on git_checkout_opts structure",
-			opts->version);
-	return false;
-}
-
 int git_checkout_index(
 	git_repository *repo,
 	git_index *index,
@@ -632,6 +619,8 @@ int git_checkout_index(
 
 	assert(repo);
 
+	GITERR_CHECK_VERSION(opts, GIT_CHECKOUT_OPTS_VERSION, "git_checkout_opts");
+
 	if ((error = git_repository__ensure_not_bare(repo, "checkout")) < 0)
 		return error;
 
@@ -639,11 +628,6 @@ int git_checkout_index(
 		GIT_DIFF_INCLUDE_UNMODIFIED | GIT_DIFF_INCLUDE_UNTRACKED |
 		GIT_DIFF_INCLUDE_TYPECHANGE | GIT_DIFF_SKIP_BINARY_CHECK;
 
-	if (!opts_is_valid_version(opts)) {
-      error = -1;
-		goto cleanup;
-   }
-
 	if (opts && opts->paths.count > 0)
 		diff_opts.pathspec = opts->paths;
 
diff --git a/src/commit.c b/src/commit.c
index 5197fdb..f9606dd 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -93,9 +93,8 @@ int git_commit_create(
 	git_odb *odb;
 
 	assert(git_object_owner((const git_object *)tree) == repo);
-	if (!git_signature__has_valid_version(author) ||
-		 !git_signature__has_valid_version(committer))
-		return -1;
+	GITERR_CHECK_VERSION(author, GIT_SIGNATURE_VERSION, "git_signature");
+	GITERR_CHECK_VERSION(committer, GIT_SIGNATURE_VERSION, "git_signature");
 
 	git_oid__writebuf(&commit, "tree ", git_object_id((const git_object *)tree));
 
diff --git a/src/common.h b/src/common.h
index a35239e..b779d28 100644
--- a/src/common.h
+++ b/src/common.h
@@ -65,6 +65,23 @@ void giterr_set(int error_class, const char *string, ...);
  */
 void giterr_set_regex(const regex_t *regex, int error_code);
 
+/**
+ * Check a versioned structure for validity
+ */
+GIT_INLINE(bool) giterr__check_version(const void *structure, unsigned int expected_max, const char *name)
+{
+	if (!structure)
+		return true;
+
+	unsigned int actual = *(unsigned int*)structure;
+	if (actual > 0 && actual <= expected_max)
+		return true;
+
+	giterr_set(GITERR_INVALID, "Invalid version %d on %s", actual, name);
+	return false;
+}
+#define GITERR_CHECK_VERSION(S,V,N) if (!giterr__check_version(S,V,N)) return -1
+
 /* NOTE: other giterr functions are in the public errors.h header file */
 
 #include "util.h"
diff --git a/src/config.c b/src/config.c
index 913108a..d422447 100644
--- a/src/config.c
+++ b/src/config.c
@@ -248,18 +248,6 @@ int git_config_open_level(
 	return 0;
 }
 
-static bool config_backend_has_valid_version(git_config_backend *backend)
-{
-	if (!backend)
-		return true;
-
-	if (backend->version > 0 && backend->version <= GIT_CONFIG_BACKEND_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d for git_config_backend", backend->version);
-	return false;
-}
-
 int git_config_add_backend(
 	git_config *cfg,
 	git_config_backend *file,
@@ -271,8 +259,7 @@ int git_config_add_backend(
 
 	assert(cfg && file);
 
-	if (!config_backend_has_valid_version(file))
-		return -1;
+	GITERR_CHECK_VERSION(file, GIT_CONFIG_BACKEND_VERSION, "git_config_backend");
 
 	if ((result = file->open(file, level)) < 0)
 		return result;
diff --git a/src/diff.c b/src/diff.c
index 722acbe..46d96bb 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -758,9 +758,8 @@ fail:
 #define DIFF_FROM_ITERATORS(MAKE_FIRST, MAKE_SECOND) do { \
 	git_iterator *a = NULL, *b = NULL; \
 	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL; \
-	if (!git_diff__opts_has_valid_version(opts)) \
-		error = -1; \
-	else if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
+	GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options"); \
+	if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
 		error = diff_from_iterators(diff, repo, a, b, opts); \
 	git__free(pfx); git_iterator_free(a); git_iterator_free(b); \
 } while (0)
diff --git a/src/diff.h b/src/diff.h
index 1f45af1..f93bab1 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -62,18 +62,5 @@ extern int git_diff__oid_for_file(
 	git_repository *, const char *, uint16_t, git_off_t, git_oid *);
 
 
-GIT_INLINE(bool) git_diff__opts_has_valid_version(const git_diff_options *opts)
-{
-	if (!opts)
-		return true;
-
-	if (opts->version > 0 && opts->version <= GIT_DIFF_OPTIONS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d in git_diff_options", opts->version);
-	return false;
-}
-
-
 #endif
 
diff --git a/src/diff_output.c b/src/diff_output.c
index 6316bfa..b18255d 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -1266,8 +1266,7 @@ int git_diff_blobs(
 	git_diff_delta delta;
 	git_diff_patch patch;
 
-   if (!git_diff__opts_has_valid_version(options))
-		return -1;
+	GITERR_CHECK_VERSION(options, GIT_DIFF_OPTIONS_VERSION, "git_diff_options");
 
 	if (options && (options->flags & GIT_DIFF_REVERSE)) {
 		git_blob *swap = old_blob;
diff --git a/src/diff_tform.c b/src/diff_tform.c
index 1df0410..0c58859 100644
--- a/src/diff_tform.c
+++ b/src/diff_tform.c
@@ -168,18 +168,6 @@ int git_diff_merge(
 	return error;
 }
 
-static bool find_opts_has_valid_version(const git_diff_find_options *opts)
-{
-	if (!opts)
-		return true;
-
-	if (opts->version > 0 && opts->version <= GIT_DIFF_FIND_OPTIONS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d on git_diff_find_options", opts->version);
-	return false;
-}
-
 #define DEFAULT_THRESHOLD 50
 #define DEFAULT_BREAK_REWRITE_THRESHOLD 60
 #define DEFAULT_TARGET_LIMIT 200
@@ -211,8 +199,7 @@ static int normalize_find_opts(
 			opts->flags = GIT_DIFF_FIND_RENAMES | GIT_DIFF_FIND_COPIES;
 	}
 
-	if (!find_opts_has_valid_version(opts))
-		return -1;
+	GITERR_CHECK_VERSION(opts, GIT_DIFF_FIND_OPTIONS_VERSION, "git_diff_find_options");
 
 	/* some flags imply others */
 
diff --git a/src/notes.c b/src/notes.c
index 87ee1e7..71a9e33 100644
--- a/src/notes.c
+++ b/src/notes.c
@@ -456,9 +456,8 @@ int git_note_create(
 	git_commit *commit = NULL;
 	git_tree *tree = NULL;
 
-	if (!git_signature__has_valid_version(author) ||
-		 !git_signature__has_valid_version(committer))
-		return -1;
+	GITERR_CHECK_VERSION(author, GIT_SIGNATURE_VERSION, "git_signature");
+	GITERR_CHECK_VERSION(committer, GIT_SIGNATURE_VERSION, "git_signature");
 
 	target = git_oid_allocfmt(oid);
 	GITERR_CHECK_ALLOC(target);
@@ -487,9 +486,8 @@ int git_note_remove(git_repository *repo, const char *notes_ref,
 	git_commit *commit = NULL;
 	git_tree *tree = NULL;
 
-	if (!git_signature__has_valid_version(author) ||
-		 !git_signature__has_valid_version(committer))
-		return -1;
+	GITERR_CHECK_VERSION(author, GIT_SIGNATURE_VERSION, "git_signature");
+	GITERR_CHECK_VERSION(committer, GIT_SIGNATURE_VERSION, "git_signature");
 
 	target = git_oid_allocfmt(oid);
 	GITERR_CHECK_ALLOC(target);
diff --git a/src/odb.c b/src/odb.c
index e35e4ca..b6d1f79 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -363,26 +363,13 @@ int git_odb_new(git_odb **out)
 	return 0;
 }
 
-static bool backend_has_valid_version(git_odb_backend *backend)
-{
-	if (!backend)
-		return true;
-
-	if (backend->version > 0 && backend->version <= GIT_ODB_BACKEND_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d on git_odb_backend", backend->version);
-	return false;
-}
-
 static int add_backend_internal(git_odb *odb, git_odb_backend *backend, int priority, int is_alternate)
 {
 	backend_internal *internal;
 
 	assert(odb && backend);
 
-	if (!backend_has_valid_version(backend))
-		return -1;
+	GITERR_CHECK_VERSION(backend, GIT_ODB_BACKEND_VERSION, "git_odb_backend");
 
 	/* Check if the backend is already owned by another ODB */
 	assert(!backend->odb || backend->odb == odb);
diff --git a/src/reflog.c b/src/reflog.c
index 4d119ba..c0af60f 100644
--- a/src/reflog.c
+++ b/src/reflog.c
@@ -298,8 +298,7 @@ int git_reflog_append(git_reflog *reflog, const git_oid *new_oid,
 
 	assert(reflog && new_oid && committer);
 
-	if (!git_signature__has_valid_version(committer))
-		return -1;
+	GITERR_CHECK_VERSION(committer, GIT_SIGNATURE_VERSION, "git_signature");
 
 	if (reflog_entry_new(&entry) < 0)
 		return -1;
diff --git a/src/remote.c b/src/remote.c
index 5fc6b4f..4f5aa9d 100644
--- a/src/remote.c
+++ b/src/remote.c
@@ -985,24 +985,11 @@ void git_remote_check_cert(git_remote *remote, int check)
 	remote->check_cert = check;
 }
 
-static bool callbacks_have_valid_version(git_remote_callbacks *callbacks)
-{
-	if (!callbacks)
-		return true;
-
-	if (callbacks->version > 0 && callbacks->version <= GIT_REMOTE_CALLBACKS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d for git_remote_callbacks", callbacks->version);
-	return false;
-}
-
 int git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callbacks)
 {
 	assert(remote && callbacks);
 
-	if (!callbacks_have_valid_version(callbacks))
-		return -1;
+	GITERR_CHECK_VERSION(callbacks, GIT_REMOTE_CALLBACKS_VERSION, "git_remote_callbacks");
 
 	memcpy(&remote->callbacks, callbacks, sizeof(git_remote_callbacks));
 
@@ -1024,24 +1011,11 @@ void git_remote_set_cred_acquire_cb(
 	remote->cred_acquire_cb = cred_acquire_cb;
 }
 
-static bool transport_has_valid_version(const git_transport *transport)
-{
-	if (!transport)
-		return true;
-
-	if (transport->version > 0 && transport->version <= GIT_TRANSPORT_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d on git_transport", transport->version);
-	return false;
-}
-
 int git_remote_set_transport(git_remote *remote, git_transport *transport)
 {
 	assert(remote && transport);
 
-	if (!transport_has_valid_version(transport))
-		return -1;
+	GITERR_CHECK_VERSION(transport, GIT_TRANSPORT_VERSION, "git_transport");
 
 	if (remote->transport) {
 		giterr_set(GITERR_NET, "A transport is already bound to this remote");
diff --git a/src/repository.c b/src/repository.c
index 073efa4..10ed12b 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -1160,18 +1160,6 @@ int git_repository_init(
 	return git_repository_init_ext(repo_out, path, &opts);
 }
 
-static bool options_have_valid_version(git_repository_init_options *opts)
-{
-	if (!opts)
-		return true;
-
-	if (opts->version > 0 && opts->version <= GIT_REMOTE_CALLBACKS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d for git_repository_init_options", opts->version);
-	return false;
-}
-
 int git_repository_init_ext(
 	git_repository **out,
 	const char *given_repo,
@@ -1182,8 +1170,7 @@ int git_repository_init_ext(
 
 	assert(out && given_repo && opts);
 
-	if (!options_have_valid_version(opts))
-		return -1;
+	GITERR_CHECK_VERSION(opts, GIT_REPOSITORY_INIT_OPTIONS_VERSION, "git_repository_init_options");
 
 	error = repo_init_directories(&repo_path, &wd_path, given_repo, opts);
 	if (error < 0)
diff --git a/src/signature.h b/src/signature.h
index 599e199..97b3a05 100644
--- a/src/signature.h
+++ b/src/signature.h
@@ -15,16 +15,4 @@
 int git_signature__parse(git_signature *sig, const char **buffer_out, const char *buffer_end, const char *header, char ender);
 void git_signature__writebuf(git_buf *buf, const char *header, const git_signature *sig);
 
-GIT_INLINE(bool) git_signature__has_valid_version(const git_signature *sig)
-{
-	if (!sig)
-		return true;
-
-	if (sig->version > 0 && sig->version <= GIT_SIGNATURE_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d on git_signature", sig->version);
-	return false;
-}
-
 #endif
diff --git a/src/stash.c b/src/stash.c
index 67fa498..14b48a5 100644
--- a/src/stash.c
+++ b/src/stash.c
@@ -523,8 +523,7 @@ int git_stash_save(
 
 	assert(out && repo && stasher);
 
-	if (!git_signature__has_valid_version(stasher))
-		return -1;
+	GITERR_CHECK_VERSION(stasher, GIT_SIGNATURE_VERSION, "git_signature");
 
 	if ((error = ensure_non_bare_repository(repo)) < 0)
 		return error;
diff --git a/src/status.c b/src/status.c
index f23f40e..1ad835a 100644
--- a/src/status.c
+++ b/src/status.c
@@ -101,18 +101,6 @@ static int status_invoke_cb(
 	return usercb->cb(path, status, usercb->payload);
 }
 
-static bool options_have_valid_version(const git_status_options *opts)
-{
-	if (!opts)
-		return true;
-
-	if (opts->version > 0 && opts->version <= GIT_REMOTE_CALLBACKS_VERSION)
-		return true;
-
-	giterr_set(GITERR_INVALID, "Invalid version %d for git_repository_init_options", opts->version);
-	return false;
-}
-
 int git_status_foreach_ext(
 	git_repository *repo,
 	const git_status_options *opts,
@@ -129,8 +117,7 @@ int git_status_foreach_ext(
 
 	assert(show <= GIT_STATUS_SHOW_INDEX_THEN_WORKDIR);
 
-	if (!options_have_valid_version(opts))
-		return -1;
+	GITERR_CHECK_VERSION(opts, GIT_STATUS_OPTIONS_VERSION, "git_status_options");
 
 	if (show != GIT_STATUS_SHOW_INDEX_ONLY &&
 		(err = git_repository__ensure_not_bare(repo, "status")) < 0)
diff --git a/src/tag.c b/src/tag.c
index fb70837..c3b3319 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -244,8 +244,7 @@ static int git_tag_create__internal(
 	assert(repo && tag_name && target);
 	assert(!create_tag_annotation || (tagger && message));
 
-	if (!git_signature__has_valid_version(tagger))
-		return -1;
+	GITERR_CHECK_VERSION(tagger, GIT_SIGNATURE_VERSION, "git_signature");
 
 	if (git_object_owner(target) != repo) {
 		giterr_set(GITERR_INVALID, "The given target does not belong to this repository");