thodg/libgit2

diff --git a/src/idxmap.h b/src/idxmap.h
new file mode 100644
index 0000000..74304bb
--- /dev/null
+++ b/src/idxmap.h
@@ -0,0 +1,92 @@
+/*
+ * 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.
+ */
+#ifndef INCLUDE_idxmap_h__
+#define INCLUDE_idxmap_h__
+
+#include <ctype.h>
+#include "common.h"
+#include "git2/index.h"
+
+#define kmalloc git__malloc
+#define kcalloc git__calloc
+#define krealloc git__realloc
+#define kreallocarray git__reallocarray
+#define kfree git__free
+#include "khash.h"
+
+__KHASH_TYPE(idx, const git_index_entry *, git_index_entry *)
+__KHASH_TYPE(idxicase, const git_index_entry *, git_index_entry *)
+
+typedef khash_t(idx) git_idxmap;
+typedef khash_t(idxicase) git_idxmap_icase;
+
+typedef khiter_t git_idxmap_iter;
+
+/* This is __ac_X31_hash_string but with tolower and it takes the entry's stage into account */
+static kh_inline khint_t idxentry_hash(const git_index_entry *e)
+{
+	const char *s = e->path;
+	khint_t h = (khint_t)git__tolower(*s);
+	if (h) for (++s ; *s; ++s) h = (h << 5) - h + (khint_t)git__tolower(*s);
+	return h + GIT_IDXENTRY_STAGE(e);
+}
+
+#define idxentry_equal(a, b) (GIT_IDXENTRY_STAGE(a) == GIT_IDXENTRY_STAGE(b) && strcmp(a->path, b->path) == 0)
+#define idxentry_icase_equal(a, b) (GIT_IDXENTRY_STAGE(a) == GIT_IDXENTRY_STAGE(b) && strcasecmp(a->path, b->path) == 0)
+
+#define GIT__USE_IDXMAP \
+	__KHASH_IMPL(idx, static kh_inline, const git_index_entry *, git_index_entry *, 1, idxentry_hash, idxentry_equal)
+
+#define GIT__USE_IDXMAP_ICASE \
+	__KHASH_IMPL(idxicase, static kh_inline, const git_index_entry *, git_index_entry *, 1, idxentry_hash, idxentry_icase_equal)
+
+#define git_idxmap_alloc(hp) \
+	((*(hp) = kh_init(idx)) == NULL) ? giterr_set_oom(), -1 : 0
+
+#define git_idxmap_icase_alloc(hp) \
+	((*(hp) = kh_init(idxicase)) == NULL) ? giterr_set_oom(), -1 : 0
+
+#define git_idxmap_insert(h, key, val, rval) do { \
+	khiter_t __pos = kh_put(idx, h, key, &rval); \
+	if (rval >= 0) { \
+		if (rval == 0) kh_key(h, __pos) = key; \
+		kh_val(h, __pos) = val; \
+	} } while (0)
+
+#define git_idxmap_icase_insert(h, key, val, rval) do { \
+	khiter_t __pos = kh_put(idxicase, h, key, &rval); \
+	if (rval >= 0) { \
+		if (rval == 0) kh_key(h, __pos) = key; \
+		kh_val(h, __pos) = val; \
+	} } while (0)
+
+#define git_idxmap_lookup_index(h, k)  kh_get(idx, h, k)
+#define git_idxmap_icase_lookup_index(h, k)  kh_get(idxicase, h, k)
+#define git_idxmap_value_at(h, idx)        kh_val(h, idx)
+#define git_idxmap_valid_index(h, idx) (idx != kh_end(h))
+#define git_idxmap_has_data(h, idx) kh_exist(h, idx)
+
+#define git_idxmap_free(h)  kh_destroy(idx, h), h = NULL
+#define git_idxmap_clear(h) kh_clear(idx, h)
+
+#define git_idxmap_delete_at(h, id)       kh_del(idx, h, id)
+#define git_idxmap_icase_delete_at(h, id)       kh_del(idxicase, h, id)
+
+#define git_idxmap_delete(h, key) do { \
+	khiter_t __pos = git_idxmap_lookup_index(h, key); \
+	if (git_idxmap_valid_index(h, __pos)) \
+		git_idxmap_delete_at(h, __pos); } while (0)
+
+#define git_idxmap_icase_delete(h, key) do { \
+	khiter_t __pos = git_idxmap_icase_lookup_index(h, key); \
+	if (git_idxmap_valid_index(h, __pos)) \
+		git_idxmap_icase_delete_at(h, __pos); } while (0)
+
+#define git_idxmap_begin		kh_begin
+#define git_idxmap_end		kh_end
+
+#endif
diff --git a/src/index.c b/src/index.c
index 53120e4..6be73d2 100644
--- a/src/index.c
+++ b/src/index.c
@@ -17,6 +17,7 @@
 #include "pathspec.h"
 #include "ignore.h"
 #include "blob.h"
+#include "idxmap.h"
 
 #include "git2/odb.h"
 #include "git2/oid.h"
@@ -24,6 +25,32 @@
 #include "git2/config.h"
 #include "git2/sys/index.h"
 
+GIT__USE_IDXMAP
+GIT__USE_IDXMAP_ICASE
+
+#define INSERT_IN_MAP_EX(idx, map, e, err) do {				\
+		if ((idx)->ignore_case)					\
+			git_idxmap_icase_insert((khash_t(idxicase) *) (map), (e), (e), (err)); \
+		else							\
+			git_idxmap_insert((map), (e), (e), (err));	\
+	} while (0)
+
+#define INSERT_IN_MAP(idx, e, err) INSERT_IN_MAP_EX(idx, (idx)->entries_map, e, err)
+
+#define LOOKUP_IN_MAP(p, idx, k) do {					\
+		if ((idx)->ignore_case)					\
+			(p) = git_idxmap_icase_lookup_index((khash_t(idxicase) *) index->entries_map, (k)); \
+		else							\
+			(p) = git_idxmap_lookup_index(index->entries_map, (k)); \
+	} while (0)
+
+#define DELETE_IN_MAP(idx, e) do {					\
+		if ((idx)->ignore_case)					\
+			git_idxmap_icase_delete((khash_t(idxicase) *) (idx)->entries_map, (e)); \
+		else							\
+			git_idxmap_delete((idx)->entries_map, (e));	\
+	} while (0)
+
 static int index_apply_to_wd_diff(git_index *index, int action, const git_strarray *paths,
 				  unsigned int flags,
 				  git_index_matched_path_cb cb, void *payload);
@@ -425,6 +452,7 @@ int git_index_open(git_index **index_out, const char *index_path)
 	}
 
 	if (git_vector_init(&index->entries, 32, git_index_entry_cmp) < 0 ||
+		git_idxmap_alloc(&index->entries_map) < 0 ||
 		git_vector_init(&index->names, 8, conflict_name_cmp) < 0 ||
 		git_vector_init(&index->reuc, 8, reuc_cmp) < 0 ||
 		git_vector_init(&index->deleted, 8, git_index_entry_cmp) < 0)
@@ -462,6 +490,7 @@ static void index_free(git_index *index)
 	assert(!git_atomic_get(&index->readers));
 
 	git_index_clear(index);
+	git_idxmap_free(index->entries_map);
 	git_vector_free(&index->entries);
 	git_vector_free(&index->names);
 	git_vector_free(&index->reuc);
@@ -508,6 +537,7 @@ static int index_remove_entry(git_index *index, size_t pos)
 	if (entry != NULL)
 		git_tree_cache_invalidate_path(index->tree, entry->path);
 
+	DELETE_IN_MAP(index, entry);
 	error = git_vector_remove(&index->entries, pos);
 
 	if (!error) {
@@ -535,6 +565,7 @@ int git_index_clear(git_index *index)
 		return -1;
 	}
 
+	git_idxmap_clear(index->entries_map);
 	while (!error && index->entries.length > 0)
 		error = index_remove_entry(index, index->entries.length - 1);
 	index_free_deleted(index);
@@ -805,16 +836,21 @@ const git_index_entry *git_index_get_byindex(
 const git_index_entry *git_index_get_bypath(
 	git_index *index, const char *path, int stage)
 {
-	size_t pos;
+	khiter_t pos;
+	git_index_entry key = {{ 0 }};
 
 	assert(index);
 
-	if (index_find(&pos, index, path, 0, stage, true) < 0) {
-		giterr_set(GITERR_INDEX, "Index does not contain %s", path);
-		return NULL;
-	}
+	key.path = path;
+	GIT_IDXENTRY_STAGE_SET(&key, stage);
+
+	LOOKUP_IN_MAP(pos, index, &key);
+
+	if (git_idxmap_valid_index(index->entries_map, pos))
+		return git_idxmap_value_at(index->entries_map, pos);
 
-	return git_index_get_byindex(index, pos);
+	giterr_set(GITERR_INDEX, "Index does not contain %s", path);
+	return NULL;
 }
 
 void git_index_entry__init_from_stat(
@@ -1140,6 +1176,10 @@ static int index_insert(
 		 * check for dups, this is actually cheaper in the long run.)
 		 */
 		error = git_vector_insert_sorted(&index->entries, entry, index_no_dups);
+
+		if (error == 0) {
+			INSERT_IN_MAP(index, entry, error);
+		}
 	}
 
 	if (error < 0) {
@@ -1365,12 +1405,18 @@ int git_index_remove(git_index *index, const char *path, int stage)
 {
 	int error;
 	size_t position;
+	git_index_entry remove_key = {{ 0 }};
 
 	if (git_mutex_lock(&index->lock) < 0) {
 		giterr_set(GITERR_OS, "Failed to lock index");
 		return -1;
 	}
 
+	remove_key.path = path;
+	GIT_IDXENTRY_STAGE_SET(&remove_key, stage);
+
+	DELETE_IN_MAP(index, &remove_key);
+
 	if (index_find(&position, index, path, 0, stage, false) < 0) {
 		giterr_set(
 			GITERR_INDEX, "Index does not contain %s at stage %d", path, stage);
@@ -2181,6 +2227,11 @@ static int parse_index(git_index *index, const char *buffer, size_t buffer_size)
 
 	assert(!index->entries.length);
 
+	if (index->ignore_case)
+		kh_resize(idxicase, (khash_t(idxicase) *) index->entries_map, header.entry_count);
+	else
+		kh_resize(idx, index->entries_map, header.entry_count);
+
 	/* Parse all the entries */
 	for (i = 0; i < header.entry_count && buffer_size > INDEX_FOOTER_SIZE; ++i) {
 		git_index_entry *entry;
@@ -2197,6 +2248,13 @@ static int parse_index(git_index *index, const char *buffer, size_t buffer_size)
 			goto done;
 		}
 
+		INSERT_IN_MAP(index, entry, error);
+
+		if (error < 0) {
+			index_entry_free(entry);
+			goto done;
+		}
+
 		seek_forward(entry_size);
 	}
 
@@ -2611,7 +2669,13 @@ int git_index_read_tree(git_index *index, const git_tree *tree)
 {
 	int error = 0;
 	git_vector entries = GIT_VECTOR_INIT;
+	git_idxmap *entries_map;
 	read_tree_data data;
+	size_t i;
+	git_index_entry *e;
+
+	if (git_idxmap_alloc(&entries_map) < 0)
+		return -1;
 
 	git_vector_set_cmp(&entries, index->entries._cmp); /* match sort */
 
@@ -2626,23 +2690,41 @@ int git_index_read_tree(git_index *index, const git_tree *tree)
 	if (index_sort_if_needed(index, true) < 0)
 		return -1;
 
-	error = git_tree_walk(tree, GIT_TREEWALK_POST, read_tree_cb, &data);
+	if ((error = git_tree_walk(tree, GIT_TREEWALK_POST, read_tree_cb, &data)) < 0)
+		goto cleanup;
 
-	if (!error) {
-		git_vector_sort(&entries);
+	if (index->ignore_case)
+		kh_resize(idxicase, (khash_t(idxicase) *) entries_map, entries.length);
+	else
+		kh_resize(idx, entries_map, entries.length);
 
-		if ((error = git_index_clear(index)) < 0)
-			/* well, this isn't good */;
-		else if (git_mutex_lock(&index->lock) < 0) {
-			giterr_set(GITERR_OS, "Unable to acquire index lock");
-			error = -1;
-		} else {
-			git_vector_swap(&entries, &index->entries);
-			git_mutex_unlock(&index->lock);
+	git_vector_foreach(&entries, i, e) {
+		INSERT_IN_MAP_EX(index, entries_map, e, error);
+
+		if (error < 0) {
+			giterr_set(GITERR_INDEX, "failed to insert entry into map");
+			return error;
 		}
 	}
 
+	error = 0;
+
+	git_vector_sort(&entries);
+
+	if ((error = git_index_clear(index)) < 0)
+		/* well, this isn't good */;
+	else if (git_mutex_lock(&index->lock) < 0) {
+		giterr_set(GITERR_OS, "Unable to acquire index lock");
+		error = -1;
+	} else {
+		git_vector_swap(&entries, &index->entries);
+		entries_map = git__swap(index->entries_map, entries_map);
+		git_mutex_unlock(&index->lock);
+	}
+
+cleanup:
 	git_vector_free(&entries);
+	git_idxmap_free(entries_map);
 	if (error < 0)
 		return error;
 
diff --git a/src/index.h b/src/index.h
index 9c60b01..546e677 100644
--- a/src/index.h
+++ b/src/index.h
@@ -10,6 +10,7 @@
 #include "fileops.h"
 #include "filebuf.h"
 #include "vector.h"
+#include "idxmap.h"
 #include "tree-cache.h"
 #include "git2/odb.h"
 #include "git2/index.h"
@@ -25,6 +26,7 @@ struct git_index {
 	git_oid checksum;   /* checksum at the end of the file */
 
 	git_vector entries;
+	git_idxmap *entries_map;
 
 	git_mutex  lock;    /* lock held while entries is being changed */
 	git_vector deleted; /* deleted entries if readers > 0 */
diff --git a/tests/index/filemodes.c b/tests/index/filemodes.c
index b390799..6442d77 100644
--- a/tests/index/filemodes.c
+++ b/tests/index/filemodes.c
@@ -239,6 +239,7 @@ void test_index_filemodes__invalid(void)
 
 	cl_git_pass(git_repository_index(&index, g_repo));
 
+	GIT_IDXENTRY_STAGE_SET(&entry, 0);
 	entry.path = "foo";
 	entry.mode = GIT_OBJ_BLOB;
 	cl_git_fail(git_index_add(index, &entry));
diff --git a/tests/index/tests.c b/tests/index/tests.c
index e1ff12a..f1a0578 100644
--- a/tests/index/tests.c
+++ b/tests/index/tests.c
@@ -792,10 +792,43 @@ void test_index_tests__reload_while_ignoring_case(void)
 	cl_git_pass(git_index_set_caps(index, caps &= ~GIT_INDEXCAP_IGNORE_CASE));
 	cl_git_pass(git_index_read(index, true));
 	cl_git_pass(git_vector_verify_sorted(&index->entries));
+	cl_assert(git_index_get_bypath(index, ".HEADER", 0));
+	cl_assert_equal_p(NULL, git_index_get_bypath(index, ".header", 0));
 
 	cl_git_pass(git_index_set_caps(index, caps | GIT_INDEXCAP_IGNORE_CASE));
 	cl_git_pass(git_index_read(index, true));
 	cl_git_pass(git_vector_verify_sorted(&index->entries));
+	cl_assert(git_index_get_bypath(index, ".HEADER", 0));
+	cl_assert(git_index_get_bypath(index, ".header", 0));
+
+	git_index_free(index);
+}
+
+void test_index_tests__change_icase_on_instance(void)
+{
+	git_index *index;
+	unsigned int caps;
+	const git_index_entry *e;
+
+	cl_git_pass(git_index_open(&index, TEST_INDEX_PATH));
+	cl_git_pass(git_vector_verify_sorted(&index->entries));
+
+	caps = git_index_caps(index);
+	cl_git_pass(git_index_set_caps(index, caps &= ~GIT_INDEXCAP_IGNORE_CASE));
+	cl_assert_equal_i(false, index->ignore_case);
+	cl_git_pass(git_vector_verify_sorted(&index->entries));
+	cl_assert(e = git_index_get_bypath(index, "src/common.h", 0));
+	cl_assert_equal_p(NULL, e = git_index_get_bypath(index, "SRC/Common.h", 0));
+	cl_assert(e = git_index_get_bypath(index, "COPYING", 0));
+	cl_assert_equal_p(NULL, e = git_index_get_bypath(index, "copying", 0));
+
+	cl_git_pass(git_index_set_caps(index, caps | GIT_INDEXCAP_IGNORE_CASE));
+	cl_assert_equal_i(true, index->ignore_case);
+	cl_git_pass(git_vector_verify_sorted(&index->entries));
+	cl_assert(e = git_index_get_bypath(index, "COPYING", 0));
+	cl_assert_equal_s("COPYING", e->path);
+	cl_assert(e = git_index_get_bypath(index, "copying", 0));
+	cl_assert_equal_s("COPYING", e->path);
 
 	git_index_free(index);
 }