thodg/libgit2

diff --git a/src/thread.c b/src/thread.c
new file mode 100644
index 0000000..d9ca374
--- /dev/null
+++ b/src/thread.c
@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "common.h"
+
+#ifndef GIT_THREADS
+
+struct git_tls_data {
+	void GIT_CALLBACK(free_fn)(void *payload);
+	void *storage;
+};
+
+int git_tls_data__init(git_tls_data **out,
+	void GIT_CALLBACK(free_fn)(void *storage))
+{
+	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
+	GIT_ERROR_CHECK_ALLOC(tls);
+
+	tls->storage = NULL;
+	tls->free_fn = free_fn;
+	*out = tls;
+
+	return 0;
+}
+
+int git_tls_data__set(git_tls_data *tls, void *payload)
+{
+	tls->storage = payload;
+	return 0;
+}
+
+void *git_tls_data__get(git_tls_data *tls)
+{
+	return tls->storage;
+}
+
+void git_tls_data__free(git_tls_data *tls)
+{
+	tls->free_fn(tls->storage);
+	git__free(tls);
+}
+
+#elif defined(GIT_WIN32)
+
+struct git_tls_data {
+	void GIT_CALLBACK(free_fn)(void *payload);
+	DWORD fls_index;
+};
+
+struct git_tls_cell {
+	void GIT_CALLBACK(free_fn)(void *storage);
+	void *storage;
+};
+
+static void WINAPI git_tls_cell__free(void *sc)
+{
+  struct git_tls_cell *storage_cell = sc;
+	if (storage_cell == NULL) {
+		return;
+	}
+
+	storage_cell->free_fn(storage_cell->storage);
+	git__free(storage_cell);
+}
+
+int git_tls_data__init(git_tls_data **out,
+	void GIT_CALLBACK(free_fn)(void *payload))
+{
+	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
+	GIT_ERROR_CHECK_ALLOC(tls);
+
+	if ((tls->fls_index = FlsAlloc(git_tls_cell__free)) == FLS_OUT_OF_INDEXES) {
+		git__free(tls);
+		return -1;
+	}
+
+	tls->free_fn = free_fn;
+	*out = tls;
+
+	return 0;
+}
+
+int git_tls_data__set(git_tls_data *tls, void *payload)
+{
+	struct git_tls_cell *storage_cell;
+
+	if (payload == NULL) {
+		if ((storage_cell = FlsGetValue(tls->fls_index)) != NULL)
+			git_tls_cell__free(storage_cell);
+
+		if (FlsSetValue(tls->fls_index, NULL) == 0)
+			return -1;
+
+		return 0;
+	}
+
+	storage_cell = git__malloc(sizeof(struct git_tls_cell));
+	GIT_ERROR_CHECK_ALLOC(storage_cell);
+
+	storage_cell->free_fn = tls->free_fn;
+	storage_cell->storage = payload;
+
+	if (FlsSetValue(tls->fls_index, storage_cell) == 0) {
+		git__free(storage_cell);
+		return -1;
+	}
+
+	return 0;
+}
+
+void *git_tls_data__get(git_tls_data *tls)
+{
+	struct git_tls_cell *storage_cell = FlsGetValue(tls->fls_index);
+	if (storage_cell == NULL)
+		return NULL;
+
+	return storage_cell->storage;
+}
+
+void git_tls_data__free(git_tls_data *tls)
+{
+	FlsFree(tls->fls_index);
+	tls->free_fn = NULL;
+	git__free(tls);
+}
+
+#elif defined(_POSIX_THREADS)
+
+struct git_tls_data {
+	void GIT_CALLBACK(free_fn)(void *payload);
+	pthread_key_t tls_key;
+};
+
+struct git_tls_cell {
+	void GIT_CALLBACK(free_fn)(void *storage);
+	void *storage;
+};
+
+static void git_tls_cell__free(void *sc)
+{
+  struct git_tls_cell *storage_cell = sc;
+	storage_cell->free_fn(storage_cell->storage);
+	git__free(storage_cell);
+}
+
+int git_tls_data__init(git_tls_data **out,
+	void GIT_CALLBACK(free_fn)(void *payload))
+{
+	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
+	GIT_ERROR_CHECK_ALLOC(tls);
+
+	if (pthread_key_create(&tls->tls_key, git_tls_cell__free) != 0) {
+		git__free(tls);
+		return -1;
+	}
+
+	tls->free_fn = free_fn;
+	*out = tls;
+
+	return 0;
+}
+
+int git_tls_data__set(git_tls_data *tls, void *payload)
+{
+	struct git_tls_cell *storage_cell;
+
+	if (payload == NULL) {
+		if ((storage_cell = pthread_getspecific(tls->tls_key)) != NULL)
+			git_tls_cell__free(storage_cell);
+
+		if (pthread_setspecific(tls->tls_key, NULL) != 0)
+			return -1;
+
+		return 0;
+	}
+
+	storage_cell = git__malloc(sizeof(struct git_tls_cell));
+	GIT_ERROR_CHECK_ALLOC(storage_cell);
+
+	storage_cell->free_fn = tls->free_fn;
+	storage_cell->storage = payload;
+
+	if (pthread_setspecific(tls->tls_key, storage_cell) != 0) {
+		git__free(storage_cell);
+		return -1;
+	}
+
+	return 0;
+}
+
+void *git_tls_data__get(git_tls_data *tls)
+{
+	struct git_tls_cell *storage_cell = pthread_getspecific(tls->tls_key);
+	if (storage_cell == NULL)
+		return NULL;
+
+	return storage_cell->storage;
+}
+
+void git_tls_data__free(git_tls_data *tls)
+{
+	git_tls_data__set(tls, NULL);
+	pthread_key_delete(tls->tls_key);
+	git__free(tls);
+}
+
+#else
+#  error unknown threading model
+#endif
diff --git a/src/thread.h b/src/thread.h
index 561e6ec..6cdf738 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -367,4 +367,52 @@ GIT_INLINE(int64_t) git_atomic64_get(git_atomic64 *a)
 
 #endif
 
+/**
+ * An opaque structure for managing TLS in the library
+ */
+typedef struct git_tls_data git_tls_data;
+
+/**
+ * Initializes a thread local storage container.
+ * This has an implementation even without GIT_THREADS
+ * which just serves to encourage use of this where TLS
+ * is necessary.
+ *
+ * Do not call this before the allocator has been initialized.
+ *
+ * @param  out a pointer to store the TLS container in
+ * @param  free_fn the method that should be called when
+ *                 deleting something in the TLS. Will be
+ *                 registered as the clean up callback for
+ *                 the OS specific TLS construct.
+ * @return 0 on success, non-zero on failure
+ */
+int git_tls_data__init(git_tls_data **out,
+	void GIT_CALLBACK(free_fn)(void *payload));
+
+/**
+ * Will set a thread specific value on the TLS. Passing NULL will free the
+ * currently held thread specific value.
+ *
+ * @param  tls the TLS instance to store data on
+ * @param  payload the pointer to store
+ * @return 0 on success, non-zero on failure
+ */
+int git_tls_data__set(git_tls_data *tls, void *payload);
+
+/**
+ * Will get the thread specific value stored in TLS.
+ *
+ * @param  tls the TLS instance to retrieve data from
+ */
+void *git_tls_data__get(git_tls_data *tls);
+
+/**
+ * Must call this to clean up the TLS when no longer in use.
+ * The TLS pointer is unusable after a call to this.
+ *
+ * @param tls the TLS to free
+ */
+void git_tls_data__free(git_tls_data *tls);
+
 #endif