init

Just some C wares; hmap, list, optional, unit tests.

20 files changed, 2318 insertions, 0 deletions

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..008800f
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,187 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# clang-format configuration file. Intended for clang-format >= 11.
+#
+# For more information, see:
+#
+#   Documentation/process/clang-format.rst
+#   https://clang.llvm.org/docs/ClangFormat.html
+#   https://clang.llvm.org/docs/ClangFormatStyleOptions.html
+#
+# Taken from Linux v6.0 with some adjustments
+---
+AccessModifierOffset: -4
+AlignAfterOpenBracket: Align
+AlignArrayOfStructures: Left
+AlignConsecutiveAssignments: Consecutive
+AlignConsecutiveDeclarations: Consecutive
+AlignConsecutiveMacros: Consecutive
+AlignConsecutiveBitFields: Consecutive
+AlignEscapedNewlines: Left
+AlignOperands: AlignAfterOperator
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: false
+# Taken from RAIDIX Generic
+AttributeMacros:
+  - '__init'
+  - '__exit'
+  - '__packed'
+  - '__aligned'
+  - '__rcu'
+  - '__must_hold'
+  - '__read_mostly'
+
+BinPackArguments: true
+BinPackParameters: true
+BraceWrapping:
+  AfterClass: false
+  AfterControlStatement: false
+  AfterEnum: false
+  AfterFunction: true
+  AfterNamespace: true
+  AfterObjCDeclaration: false
+  AfterStruct: false
+  AfterUnion: false
+  AfterExternBlock: false
+  BeforeCatch: false
+  BeforeElse: false
+  IndentBraces: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: NonAssignment
+BreakBeforeBraces: Custom
+BreakBeforeInheritanceComma: false
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+BreakConstructorInitializers: BeforeComma
+BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: false
+ColumnLimit: 80
+CommentPragmas: '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 8
+ContinuationIndentWidth: 8
+Cpp11BracedListStyle: false
+DerivePointerAlignment: false
+DisableFormat: false
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: false
+
+# Taken from:
+#   git grep -h '^#define [^[:space:]]*for_each[^[:space:]]*(' include/ tools/ \
+#   | sed "s,^#define \([^[:space:]]*for_each[^[:space:]]*\)(.*$,  - '\1'," \
+#   | LC_ALL=C sort -u
+ForEachMacros:
+  - 'hlist_bl_for_each_entry'
+  - 'hlist_bl_for_each_entry_rcu'
+  - 'hlist_bl_for_each_entry_safe'
+  - 'hlist_for_each'
+  - 'hlist_for_each_entry'
+  - 'hlist_for_each_entry_continue'
+  - 'hlist_for_each_entry_continue_rcu'
+  - 'hlist_for_each_entry_continue_rcu_bh'
+  - 'hlist_for_each_entry_from'
+  - 'hlist_for_each_entry_from_rcu'
+  - 'hlist_for_each_entry_rcu'
+  - 'hlist_for_each_entry_rcu_bh'
+  - 'hlist_for_each_entry_rcu_notrace'
+  - 'hlist_for_each_entry_safe'
+  - 'hlist_for_each_entry_srcu'
+  - 'hlist_for_each_safe'
+  - 'hlist_nulls_for_each_entry'
+  - 'hlist_nulls_for_each_entry_from'
+  - 'hlist_nulls_for_each_entry_rcu'
+  - 'hlist_nulls_for_each_entry_safe'
+  - 'hmap_iter_foreach'
+  - 'list_for_each'
+  - 'list_for_each_codec'
+  - 'list_for_each_codec_safe'
+  - 'list_for_each_continue'
+  - 'list_for_each_entry'
+  - 'list_for_each_entry_continue'
+  - 'list_for_each_entry_continue_rcu'
+  - 'list_for_each_entry_continue_reverse'
+  - 'list_for_each_entry_from'
+  - 'list_for_each_entry_from_rcu'
+  - 'list_for_each_entry_from_reverse'
+  - 'list_for_each_entry_lockless'
+  - 'list_for_each_entry_rcu'
+  - 'list_for_each_entry_reverse'
+  - 'list_for_each_entry_safe'
+  - 'list_for_each_entry_safe_continue'
+  - 'list_for_each_entry_safe_from'
+  - 'list_for_each_entry_safe_reverse'
+  - 'list_for_each_entry_srcu'
+  - 'list_for_each_from'
+  - 'list_for_each_prev'
+  - 'list_for_each_prev_safe'
+  - 'list_for_each_safe'
+  - 'llist_for_each'
+  - 'llist_for_each_entry'
+  - 'llist_for_each_entry_safe'
+  - 'llist_for_each_safe'
+
+IncludeBlocks: Preserve
+IncludeCategories:
+  - Regex: '.*'
+    Priority: 1
+IncludeIsMainRegex: '(Test)?$'
+IndentCaseLabels: false
+IndentGotoLabels: false
+IndentPPDirectives: None
+IndentWidth: 4
+IndentWrappedFunctionNames: false
+JavaScriptQuotes: Leave
+JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: true
+MacroBlockBegin: ''
+MacroBlockEnd: ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBinPackProtocolList: Auto
+ObjCBlockIndentWidth: 4
+ObjCSpaceAfterProperty: true
+ObjCSpaceBeforeProtocolList: true
+
+# Taken from git's rules
+PenaltyBreakAssignment: 30
+PenaltyBreakBeforeFirstCallParameter: 10
+PenaltyBreakComment: 10
+PenaltyBreakFirstLessLess: 0
+PenaltyBreakString: 10
+PenaltyExcessCharacter: 100
+PenaltyReturnTypeOnItsOwnLine: 60
+
+PointerAlignment: Right
+ReflowComments: false
+SortIncludes: false
+SortUsingDeclarations: false
+SpaceAfterCStyleCast: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeParens: ControlStatementsExceptForEachMacros
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles: false
+SpacesInContainerLiterals: false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard: Auto
+TabWidth: 4
+UseTab: Always
+...
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..af407b2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+.cache/
+compile_commands.json
+build/
+.gdb_history
+
+*/*-test
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..37d4f4d
--- /dev/null
+++ b/README.md
@@ -0,0 +1,28 @@
+# C Wares
+
+This repo is intended as a collection of different data structures, and other
+small utilities in C, that I've collected over time. Some of the stuff here is
+written by me, some other stuff I've extracted from open source projects for my
+own personal use.
+
+This repo is not intended as a library or framework, but rather just a
+collection of useful simple stuff that is hard to come by when writing programs
+in C.
+
+## Wares
+
+Currently this repo contains the following:
+
+* hmap - simple generic hashmap with no macro vodoo-magic.
+* list - double-link listed as seen on the Linux Kernel™; extracted from Git.
+* optional - header-only poor man's optional "type templates" for C.
+* utest - micro header-only unit test "framework"
+* utils.h - various useful macros, needed by some of the "libs" in this repo,
+  but that can also be useful on their own.
+
+hmap, optional and utest have unit test of their own that serve as examples of
+their respective APIs. list.h doesn't have its own unit tests since it wasn't
+written by me.
+
+To run any of the tests just cd into the respective dir, run `make` and then
+`./*-test`.
diff --git a/hmap/Makefile b/hmap/Makefile
new file mode 100644
index 0000000..dc52ab3
--- /dev/null
+++ b/hmap/Makefile
@@ -0,0 +1,9 @@
+CC?=gcc
+CFLAGS+=-Wall -Werror -std=gnu11 -Og -g
+
+ifdef DEBUG
+CFLAGS+=-DHMAP_DEBUG
+endif
+
+all:
+	$(CC) $(CFLAGS) -o hmap-test hmap-test.c hmap.c
diff --git a/hmap/README.md b/hmap/README.md
new file mode 100644
index 0000000..a39d14a
--- /dev/null
+++ b/hmap/README.md
@@ -0,0 +1,8 @@
+# Hmap
+
+Simple generic hash map with no macro vodoo magic. Inspired by other data
+structures in the Linux Kernel.
+
+## Example usage
+
+If you want to see an example on how to use hmap, take a look at `hmap-test.c`.
diff --git a/hmap/hash.h b/hmap/hash.h
new file mode 100644
index 0000000..9d4d8dd
--- /dev/null
+++ b/hmap/hash.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: MIT */
+/**
+ * hash.h - implementations of the FNV1a hashing algorithm.
+ *
+ * Copyright (c) 2022-2023 - Yaroslav de la Peña Smirnov
+ */
+#ifndef HMAP_HASH_H
+#define HMAP_HASH_H
+
+#include <inttypes.h>
+#include <stdlib.h>
+
+#if SIZE_MAX == 0xFFFFFFFF
+/* size_t is 32bit */
+static const size_t fnv_prime	= 16777619u;
+static const size_t fnv_offsetb = 2166136261u;
+#elif SIZE_MAX == 0xFFFFFFFFFFFFFFFF
+/* size_t is 64bit */
+static const size_t fnv_prime	= 1099511628211u;
+static const size_t fnv_offsetb = 14695981039346656037u;
+#endif
+
+/**
+ * fnv1a_bytes_hash() - generic fnv1a hash function.
+ * @data:	pointer to data to hash.
+ * @len:	size of @data in bytes.
+ *
+ * Return:	hash value.
+ */
+static inline size_t fnv1a_bytes_hash(const void *data, size_t len)
+{
+	const char *bytes = (const char *)data;
+	size_t		hash  = fnv_offsetb;
+
+	for (size_t i = 0; i < len; i++) {
+		hash ^= bytes[i];
+		hash *= fnv_prime;
+	}
+
+	return hash;
+}
+
+/**
+ * fnv1a_str_hash() - fnv1a hash function for nul-terminated strings.
+ * @str:	nul-terminated string of characters to hash.
+ *
+ * Return:	hash value.
+ */
+static inline size_t fnv1a_str_hash(const char *str)
+{
+	size_t hash = fnv_offsetb;
+
+	for (size_t i = 0; str[i]; i++) {
+		hash ^= str[i];
+		hash *= fnv_prime;
+	}
+
+	return hash;
+}
+
+#endif /* HMAP_HASH_H */
diff --git a/hmap/hmap-test.c b/hmap/hmap-test.c
new file mode 100644
index 0000000..bf3ebe2
--- /dev/null
+++ b/hmap/hmap-test.c
@@ -0,0 +1,291 @@
+#include "hash.h"
+#include "hmap.h"
+#include "../utest/utest.h"
+
+#include <string.h>
+
+struct hmap_test_s {
+	const char		 *key;
+	uint64_t		  data;
+	struct hmap_entry entry;
+};
+
+#define entry_to_test_s(ent) hmap_item(ent, struct hmap_test_s, entry)
+
+bool hmap_test_cmp(const struct hmap_entry *ent, const struct hmap_entry *key)
+{
+	struct hmap_test_s *a = entry_to_test_s(ent);
+	struct hmap_test_s *b = entry_to_test_s(key);
+
+	return !strcmp(a->key, b->key);
+}
+
+void hmap_test_hash(struct hmap_entry *ent)
+{
+	struct hmap_test_s *e = entry_to_test_s(ent);
+	ent->hash			  = fnv1a_str_hash(e->key);
+}
+
+struct hmap *map;
+
+/* clang-format off */
+struct hmap_test_s inputs[] = {
+	{ .key = "alpha",	.data = 10, },
+	{ .key = "bravo",	.data = 24, },
+	{ .key = "charlie",	.data = 30, },
+	{ .key = "delta",	.data = 42, },
+	{ .key = "echo",	.data = 50, },
+	{ .key = "foxtrot",	.data = 69, },
+	{ .key = "golf",	.data = 70, },
+	{ .key = "hotel",	.data = 80, },
+	{ .key = "india",	.data = 99, },
+};
+
+struct hmap_test_s inputs2[] = {
+	{ .key = "aa" },
+	{ .key = "ab" },
+	{ .key = "ac" },
+	{ .key = "ad" },
+	{ .key = "ae" },
+	{ .key = "af" },
+	{ .key = "ag" },
+	{ .key = "ah" },
+	{ .key = "ai" },
+	{ .key = "aj" },
+	{ .key = "ak" },
+	{ .key = "al" },
+	{ .key = "am" },
+	{ .key = "an" },
+	{ .key = "ao" },
+	{ .key = "ap" },
+	{ .key = "aq" },
+	{ .key = "ar" },
+	{ .key = "as" },
+	{ .key = "at" },
+	{ .key = "au" },
+	{ .key = "av" },
+	{ .key = "aw" },
+	{ .key = "ax" },
+	{ .key = "ay" },
+	{ .key = "az" },
+	{ .key = "ba" },
+	{ .key = "bb" },
+	{ .key = "bc" },
+	{ .key = "bd" },
+	{ .key = "be" },
+	{ .key = "bf" },
+	{ .key = "bg" },
+	{ .key = "bh" },
+	{ .key = "bi" },
+	{ .key = "bj" },
+	{ .key = "bk" },
+	{ .key = "bl" },
+	{ .key = "bm" },
+	{ .key = "bn" },
+	{ .key = "bo" },
+	{ .key = "bp" },
+	{ .key = "bq" },
+	{ .key = "br" },
+	{ .key = "bs" },
+	{ .key = "bt" },
+	{ .key = "bu" },
+	{ .key = "bv" },
+	{ .key = "bw" },
+	{ .key = "bx" },
+	{ .key = "by" },
+};
+/* clang-format on */
+
+struct hmap_test_s duplicate = { .key = "foxtrot", .data = 420 };
+
+#ifndef HMAP_DEBUG
+
+TEST_BEGIN(test_hmap_add)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		hmap_add(map, &inputs[i].entry);
+	}
+	size_t cnt = hmap_entry_cnt(map);
+	expect(cnt == ARRAY_SIZE(inputs),
+		   "number of entries in hashmap (%lu) != number of entries added "
+		   "(%lu)",
+		   cnt, ARRAY_SIZE(inputs));
+	TEST_OUT
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_get)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		struct hmap_test_s	key	   = { .key = inputs[i].key };
+		struct hmap_test_s *expect = inputs + i;
+		struct hmap_entry  *ent	   = hmap_get(map, &key.entry);
+
+		assertneq(ent, NULL);
+
+		struct hmap_test_s *got = entry_to_test_s(ent);
+		asserteq(expect, got);
+	}
+	TEST_OUT
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_get_next_dup)
+{
+	hmap_add(map, &duplicate.entry);
+	struct hmap_test_s key = { .key = duplicate.key };
+	struct hmap_entry *ent = hmap_get(map, &key.entry);
+
+	assertneq(ent, NULL);
+
+	struct hmap_test_s *got = entry_to_test_s(ent);
+
+	struct hmap_entry *next = hmap_get_next_dup(map, ent);
+
+	assertneq(next, NULL);
+
+	struct hmap_test_s *got_dup = entry_to_test_s(next);
+	if (got->data != duplicate.data) {
+		asserteq(got_dup->data, duplicate.data);
+	} else {
+		assertneq(got_dup->data, duplicate.data);
+	}
+	TEST_OUT
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_remove)
+{
+	struct hmap_entry *removed;
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		struct hmap_test_s key = { .key = inputs[i].key };
+		removed				   = hmap_remove(map, &key.entry);
+
+		assertneq(removed, NULL);
+	}
+
+	expect(hmap_entry_cnt(map) == 1, "expected only duplicate entry left");
+	removed = hmap_remove(map, &duplicate.entry);
+	asserteq(removed, &duplicate.entry);
+
+	TEST_OUT
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_realloc)
+{
+	/* This test case assumes default hmap settings */
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		hmap_add(map, &inputs[i].entry);
+	}
+	expect(hmap_cur_cap(map) <= 64, "hashmap shouldn't grow so fast");
+
+	for (size_t i = 0; i < ARRAY_SIZE(inputs2); i++) {
+		hmap_add(map, &inputs2[i].entry);
+	}
+	asserteq(hmap_entry_cnt(map), ARRAY_SIZE(inputs) + ARRAY_SIZE(inputs2));
+	expect(hmap_cur_cap(map) > 64, "expected hashmap to grow");
+
+	for (size_t i = 0; i < ARRAY_SIZE(inputs2); i++) {
+		hmap_remove(map, &inputs2[i].entry);
+	}
+	expect(hmap_cur_cap(map) <= 64, "expected hashmap to shrink");
+
+	TEST_OUT
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		hmap_remove(map, &inputs[i].entry);
+	}
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_iter)
+{
+	struct hmap_iter   iter;
+	struct hmap_entry *ent, *prev = NULL;
+	size_t			   cnt = 0;
+
+	hmap_iter_init(&iter, map);
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		hmap_add(map, &inputs[i].entry);
+	}
+
+	hmap_iter_foreach(&iter, ent) {
+		cnt++;
+		expect(ent != prev, "hmap_iter shouldn't return same entry on next");
+	}
+	asserteq(cnt, ARRAY_SIZE(inputs));
+
+	TEST_OUT
+}
+TEST_END
+
+TEST_BEGIN(test_hmap_iter_remove)
+{
+	struct hmap_iter   iter;
+	struct hmap_entry *ent;
+
+	for (size_t i = 0; i < ARRAY_SIZE(inputs2); i++) {
+		hmap_add(map, &inputs2[i].entry);
+	}
+
+	hmap_dynamic_set(map, false);
+	expect(!hmap_dynamic_get(map), "expected dynamic setting to be off");
+
+	hmap_iter_init(&iter, map);
+	hmap_iter_foreach(&iter, ent) {
+		expect(hmap_remove(map, ent), "expected entry to be removed");
+	}
+	asserteq(hmap_entry_cnt(map), 0);
+
+	hmap_dynamic_set(map, true);
+	expect(hmap_dynamic_get(map), "expected dynamic setting to be on");
+
+	TEST_OUT
+}
+TEST_END
+
+#else
+
+TEST_BEGIN(test_hmap_collisions)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(inputs); i++) {
+		hmap_add(map, &inputs[i].entry);
+	}
+	for (size_t i = 0; i < ARRAY_SIZE(inputs2); i++) {
+		hmap_add(map, &inputs2[i].entry);
+	}
+	asserteq(hmap_entry_cnt(map), ARRAY_SIZE(inputs) + ARRAY_SIZE(inputs2));
+	TEST_OUT
+}
+TEST_END
+
+#endif /* HMAP_DEBUG */
+
+void hmap_test_init(void)
+{
+#ifdef HMAP_DEBUG
+#ifndef HMAP_DEBUG_CAP
+#define HMAP_DEBUG_CAP 128
+#endif /* HMAP_DEBUG_CAP */
+	map = hmap_new_with(hmap_test_cmp, hmap_test_hash, HMAP_DEBUG_CAP, false);
+#else
+	map = hmap_new(hmap_test_cmp, hmap_test_hash);
+#endif /* HMAP_DEBUG */
+}
+
+void hmap_test_destroy(void)
+{
+	hmap_free(map);
+}
+
+#ifdef HMAP_DEBUG
+
+RUN_TEST_SUITE(hmap_test_init, hmap_test_destroy, test_hmap_collisions);
+
+#else
+
+RUN_TEST_SUITE(hmap_test_init, hmap_test_destroy, test_hmap_add, test_hmap_get,
+			   test_hmap_get_next_dup, test_hmap_remove, test_hmap_realloc,
+			   test_hmap_iter, test_hmap_iter_remove)
+
+#endif /* HMAP_DEBUG */
diff --git a/hmap/hmap.c b/hmap/hmap.c
new file mode 100644
index 0000000..8bc5760
--- /dev/null
+++ b/hmap/hmap.c
@@ -0,0 +1,297 @@
+/* SPDX-License-Identifier: MIT */
+#include "hmap.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <limits.h>
+#ifdef HMAP_DEBUG
+#include <stdio.h>
+#endif
+
+#ifndef HMAP_LOAD_FACTOR
+#define HMAP_LOAD_FACTOR 80
+#endif
+#ifndef HMAP_GROWTH_RATE
+#define HMAP_GROWTH_RATE 2
+#endif
+
+/**
+ * Structures
+ * ==========
+ */
+
+/**
+ * struct hmap - generic hash map.
+ * @buckets:	table where we store our buckets.
+ * @cap:		current capacity.
+ * @cnt:		how many entries we currently hold.
+ * @grow_at:	load factor at which we grow. > 100 if hmap is not dynamic.
+ * @shrink_at:	load factor at which we shrink.
+ * @cmp:		key compare function.
+ */
+struct hmap {
+	struct hmap_entry **buckets;
+
+	size_t cap;
+	size_t cnt;
+
+	size_t grow_at;
+	size_t shrink_at;
+
+	hmap_cmp_fn	 cmp;
+	hmap_hash_fn hash_key;
+
+	uint8_t dynamic : 1;
+};
+
+/**
+ * Internal methods
+ * ================
+ */
+
+/**
+ * find_hmap_bucket() - find the bucket for @key.
+ * @map:	hashmap.
+ * @key:	key with hash.
+ *
+ * Return:	pointer to bucket in buckets table.
+ */
+static inline struct hmap_entry **find_hmap_bucket(struct hmap		 *map,
+												   struct hmap_entry *key)
+{
+	size_t i = key->hash % map->cap;
+
+	return map->buckets + i;
+}
+
+/**
+ * find_hmap_entry() - find entry that has @key.
+ * @map:	hashmap.
+ * @key:	key with hash.
+ *
+ * Return:	pointer where the entry is stored.
+ */
+static struct hmap_entry **find_hmap_entry(struct hmap		 *map,
+										   struct hmap_entry *key)
+{
+	map->hash_key(key);
+
+	struct hmap_entry **ptr = find_hmap_bucket(map, key);
+	while (*ptr) {
+		if (map->cmp(*ptr, key)) {
+			return ptr;
+		}
+		ptr = &(*ptr)->next;
+	}
+
+	return ptr;
+}
+
+/**
+ * __hmap_add() -- low level add function.
+ * @map:	hashmap.
+ * @ent:	entry to add.
+ */
+static void __hmap_add(struct hmap *map, struct hmap_entry *ent)
+{
+	struct hmap_entry **bucket = find_hmap_bucket(map, ent);
+	if (*bucket) {
+		struct hmap_entry *coll = *bucket;
+		struct hmap_entry *next = coll->next;
+#ifdef HMAP_DEBUG
+		fprintf(stderr, "\nCOLLISION!\n");
+#endif
+		while (next) {
+#ifdef HMAP_DEBUG
+			fprintf(stderr, "\nCOLLISION!\n");
+#endif
+			coll = next;
+			next = coll->next;
+		}
+		coll->next = ent;
+	} else {
+		*bucket = ent;
+	}
+}
+
+/**
+ * set_thresholds() - set growth and shrink thresholds.
+ * @map:	hashmap.
+ */
+static inline void set_thresholds(struct hmap *map)
+{
+	map->grow_at = map->cap * HMAP_LOAD_FACTOR / 100;
+	if (map->cap <= HMAP_INIT_CAP) {
+		map->shrink_at = 0;
+	} else {
+		map->shrink_at = map->grow_at / HMAP_GROWTH_RATE - 2;
+	}
+}
+
+/**
+ * alloc_buckets() - allocate buckets table.
+ * @map:	hashmap.
+ */
+static inline void alloc_buckets(struct hmap *map)
+{
+	map->buckets = calloc(map->cap, sizeof(struct hmap_entry *));
+}
+
+/**
+ * maybe_realloc() - grow/shrink buckets table if needed.
+ * @map:	hashmap.
+ */
+static void maybe_realloc(struct hmap *map)
+{
+	if (!map->dynamic) {
+		return;
+	}
+
+	size_t oldcap = map->cap;
+
+	if (map->cnt >= map->grow_at) {
+		map->cap = map->cap * HMAP_GROWTH_RATE;
+	} else if (map->cnt < map->shrink_at) {
+		map->cap = map->cap / HMAP_GROWTH_RATE;
+	} else {
+		return;
+	}
+
+	struct hmap_entry **oldbucks = map->buckets;
+
+	alloc_buckets(map);
+	set_thresholds(map);
+
+	for (size_t i = 0; i < oldcap; i++) {
+		struct hmap_entry *next = oldbucks[i], *cur;
+		while (next) {
+			cur		  = next;
+			next	  = cur->next;
+			cur->next = NULL;
+			__hmap_add(map, cur);
+		}
+	}
+
+	free(oldbucks);
+}
+
+/**
+ * Public methods
+ * ==============
+ */
+
+struct hmap *hmap_new_with(hmap_cmp_fn cmp_fn, hmap_hash_fn hash_fn, size_t cap,
+						   bool dynamic)
+{
+	struct hmap *map = malloc(sizeof(*map));
+
+	map->cap	  = cap;
+	map->cnt	  = 0;
+	map->cmp	  = cmp_fn;
+	map->hash_key = hash_fn;
+	map->dynamic  = dynamic;
+	alloc_buckets(map);
+	if (dynamic) {
+		set_thresholds(map);
+	}
+
+	return map;
+}
+
+void hmap_add(struct hmap *map, struct hmap_entry *ent)
+{
+	ent->next = NULL;
+	map->hash_key(ent);
+
+	map->cnt++;
+	maybe_realloc(map);
+
+	__hmap_add(map, ent);
+}
+
+struct hmap_entry *hmap_get(struct hmap *map, struct hmap_entry *key)
+{
+	return *find_hmap_entry(map, key);
+}
+
+struct hmap_entry *hmap_get_next_dup(struct hmap *map, struct hmap_entry *ent)
+{
+	struct hmap_entry *next = ent->next;
+	while (next) {
+		if (map->cmp(next, ent)) {
+			return next;
+		}
+	}
+
+	return next;
+}
+
+struct hmap_entry *hmap_remove(struct hmap *map, struct hmap_entry *key)
+{
+	struct hmap_entry **ptr = find_hmap_entry(map, key), *old;
+
+	if (*ptr) {
+		if (map->cmp(*ptr, key)) {
+			old	 = *ptr;
+			*ptr = old->next;
+
+			map->cnt--;
+			maybe_realloc(map);
+
+			return old;
+		}
+	}
+
+	return NULL;
+}
+
+size_t hmap_entry_cnt(struct hmap *map)
+{
+	return map->cnt;
+}
+
+size_t hmap_cur_cap(struct hmap *map)
+{
+	return map->cap;
+}
+
+void hmap_dynamic_set(struct hmap *map, bool on)
+{
+	map->dynamic = on;
+}
+
+bool hmap_dynamic_get(struct hmap *map)
+{
+	return map->dynamic;
+}
+
+void hmap_free(struct hmap *map)
+{
+	free(map->buckets);
+	free(map);
+}
+
+void hmap_iter_init(struct hmap_iter *iter, struct hmap *map)
+{
+	iter->map	 = map;
+	iter->cursor = 0;
+	iter->next	 = NULL;
+}
+
+struct hmap_entry *hmap_iter_next(struct hmap_iter *iter)
+{
+	struct hmap_entry *cur = iter->next;
+
+	for (;;) {
+		if (cur) {
+			iter->next = cur->next;
+			return cur;
+		}
+
+		if (iter->cursor >= iter->map->cap) {
+			return NULL;
+		}
+
+		cur = iter->map->buckets[iter->cursor++];
+	}
+}
diff --git a/hmap/hmap.h b/hmap/hmap.h
new file mode 100644
index 0000000..bbd95f3
--- /dev/null
+++ b/hmap/hmap.h
@@ -0,0 +1,238 @@
+/* SPDX-License-Identifier: LGPL-2.1 */
+/**
+ * hmap.h - a simple generic hashmap. v2.0.0
+ *
+ * Copyright (c) 2022-2023 - Yaroslav de la Peña Smirnov
+ *
+ * Documentation
+ * =============
+ *
+ * In order to use this hashmap, you need to incapsulate struct hmap_entry
+ * inside your own structure. For example::
+ *
+ * 	struct my_struct {
+ * 		char				*key;
+ * 		uint64_t 			data;
+ * 		struct hmap_entry	entry;
+ * 	};
+ *
+ * Then you can insert any instance of such struct into the hashmap by calling
+ * the corresponding method and passing it the pointer to @entry.
+ *
+ * For search and removal operations you just need to fill your structure with
+ * your key. The hmap_cmp_fn and hmap_hash_fn functions you provided will be
+ * called by hmap in order to perform the needed operations.
+ *
+ * When you get a hmap_entry pointer from hmap's API, you can get your
+ * containing structure with the help of the hmap_item macro, for example::
+ *
+ * 	struct hmap_entry *e = hmap_get(map, key);
+ * 	struct my_struct *my = hmap_item(e, struct my_struct, entry);
+ *
+ */
+#ifndef HMAP_H
+#define HMAP_H
+#include "../utils.h"
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <sys/types.h>
+
+#ifndef HMAP_INIT_CAP
+#define HMAP_INIT_CAP 64
+#endif
+
+/**
+ * Structures
+ * ==========
+ */
+
+/**
+ * struct hmap - opaque structure for generic hashmap.
+ */
+struct hmap;
+
+/**
+ * struct hmap_entry - the base class for a hashmap entry.
+ * @next:	linked list in case of collisions.
+ * @hash:	the hash value of the entry key.
+ *
+ * This structure should only be manipulated using the methods below. The @hash
+ * member should be filled by the hmap_hash_fn function provided to hmap_new().
+ */
+struct hmap_entry {
+	struct hmap_entry *next;
+	size_t			   hash;
+};
+
+/**
+ * struct hmap_iter - iterator over hmap entries.
+ * @map:	hashmap.
+ * @next:	next item to be returned.
+ * @cursor:	current position in buckets table.
+ *
+ * If you want to remove entries while iterating, be sure to change the dynamic
+ * resizing setting to on = false with hmap_dynamic_get().
+ */
+struct hmap_iter {
+	struct hmap		  *map;
+	struct hmap_entry *next;
+	size_t			   cursor;
+};
+
+/**
+ * Typedefs
+ * ========
+ */
+
+typedef bool (*hmap_cmp_fn)(const struct hmap_entry *ent,
+							const struct hmap_entry *key);
+typedef void (*hmap_hash_fn)(struct hmap_entry *ent);
+
+/**
+ * Methods
+ * =======
+ */
+
+/**
+ * hmap_new_with() - allocate new hashmap with given parameters.
+ * @cmp_fn:		key comparison function.
+ * @hash_fn:	key hashing function.
+ * @cap:		initial hashmap capacity.
+ * @dynamic:	whether the hashmap should dynamically grow/shrink based on load
+ * 				factor.
+ * 
+ * Return:	pointer to hmap object.
+ */
+struct hmap *hmap_new_with(hmap_cmp_fn cmp_fn, hmap_hash_fn hash_fn, size_t cap,
+						   bool dynamic);
+
+/**
+ * hmap_new - allocate new hashmap with default parameters.
+ * @cmp_fn:		key comparison function.
+ * @hash_fn:	key hashing function.
+ * 
+ * Return:	pointer to hmap object.
+ */
+#define hmap_new(cmp_fn, hash_fn) \
+	hmap_new_with(cmp_fn, hash_fn, HMAP_INIT_CAP, true)
+
+/**
+ * hmap_free() - free all resources used by @map.
+ * @map:	hashmap.
+ *
+ * This function does not release or free any resources associated with any
+ * entries stored in the hashmap. It is the responsibility of the caller to free
+ * any such resources.
+ */
+void hmap_free(struct hmap *map);
+
+/**
+ * hmap_item - get the pointer to the containing structure for this entry.
+ * @entry:	struct hmap_entry pointer.
+ * @type:	containing struct.
+ * @member:	the member in the struct that holds hmap_entry.
+ */
+#define hmap_item(entry, type, member) container_of(entry, type, member)
+
+/**
+ * hmap_add() - add entry to @map.
+ * @map:	hashmap.
+ * @ent:	entry to add.
+ *
+ * If there's already an entry with the same key, it wil still add it and hold
+ * both.
+ */
+void hmap_add(struct hmap *map, struct hmap_entry *ent);
+
+/**
+ * hmap_get() - get entry with @key from @map.
+ * @map:	hashmap.
+ * @key:	hmap_entry object that holds the key.
+ *
+ * In order to pass the key, you just need to fill what is needed by your
+ * hashing and comparison functions; you could even use a separate structure
+ * that just holds the key, if you use the appropriate logic in your functions.
+ *
+ * If there are entries with duplicate keys, it will get the first it finds. If
+ * your want to get the next duplicate-key entry use hmap_get_next_dup().
+ *
+ * Return: pointer to entry; NULL if no entry with such key.
+ */
+struct hmap_entry *hmap_get(struct hmap *map, struct hmap_entry *key);
+
+/**
+ * hmap_get_next_dup() - get the next entry with the same key as @ent.
+ * @map:	hashmap.
+ * @ent:	entry with duplicate key.
+ *
+ * Return: pointer to entry; NULL if no more entries with same key.
+ */
+struct hmap_entry *hmap_get_next_dup(struct hmap *map, struct hmap_entry *ent);
+
+/**
+ * hmap_remove() - remove entry with @key from @map.
+ * @map:	hashmap.
+ * @key:	hmap_entry object that holds the key.
+ *
+ * If there are entries with duplicates keys, it will remove the first it finds.
+ *
+ * Return: pointer to removed entry; NULL if no entry with such key.
+ */
+struct hmap_entry *hmap_remove(struct hmap *map, struct hmap_entry *key);
+
+/**
+ * hmap_entry_cnt() - get the current number of entries in @map.
+ * @map:	hashmap.
+ *
+ * Return: number of entries held by @map.
+ */
+size_t hmap_entry_cnt(struct hmap *map);
+
+/**
+ * hmap_dynamic_set() - enable/disable hashmap resizing.
+ * @map:	hashmap.
+ * @on:		whether to turn on/off.
+ */
+void hmap_dynamic_set(struct hmap *map, bool on);
+
+/**
+ * hmap_dynamic_get() - get current hashmap resizing setting.
+ * @map:	hashmap.
+ *
+ * Return: current dynamic resizing setting.
+ */
+bool hmap_dynamic_get(struct hmap *map);
+
+/**
+ * hmap_cur_cap() - get the current capacity of @map.
+ * @map:	hashmap.
+ *
+ * Return: current @map capacity.
+ */
+size_t hmap_cur_cap(struct hmap *map);
+
+/**
+ * hmap_iter_init() - initialize and reset hmap iterator.
+ * @iter:	pointer to hmap_iter object.
+ * @map:	hashmap to iterate over.
+ */
+void hmap_iter_init(struct hmap_iter *iter, struct hmap *map);
+
+/**
+ * hmap_iter_next() - get the next entry.
+ * @iter:	iterator.
+ *
+ * Return: pointer to entry; NULL if no more entries are left.
+ */
+struct hmap_entry *hmap_iter_next(struct hmap_iter *iter);
+
+/**
+ * hmap_iter_foreach - loop to iterate over every entry.
+ * @iter:	pointer to iterator.
+ * @entry:	hmap_entry pointer to hold the next entry.
+ */
+#define hmap_iter_foreach(iter, entry) \
+	for (entry = hmap_iter_next((iter)); entry; entry = hmap_iter_next((iter)))
+
+#endif /* HMAP_H */
diff --git a/licenses/LGPL-2.1 b/licenses/LGPL-2.1
new file mode 100644
index 0000000..d38b1b9
--- /dev/null
+++ b/licenses/LGPL-2.1
@@ -0,0 +1,511 @@
+
+ While most of this project is under the GPL (see COPYING), the xdiff/
+ library and some libc code from compat/ are licensed under the
+ GNU LGPL, version 2.1 or (at your option) any later version and some
+ other files are under other licenses.  Check the individual files to
+ be sure.
+
+----------------------------------------
+
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.]
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+Licenses are intended to guarantee your freedom to share and change
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+
+  This license, the Lesser General Public License, applies to some
+specially designated software packages--typically libraries--of the
+Free Software Foundation and other authors who decide to use it.  You
+can use it too, but we suggest you first think carefully about whether
+this license or the ordinary General Public License is the better
+strategy to use in any particular case, based on the explanations below.
+
+  When we speak of free software, we are referring to freedom of use,
+not price.  Our General Public Licenses are designed to make sure that
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+
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+
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+
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+  When a "work that uses the Library" uses material from a header file
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+
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+  10. Each time you redistribute the Library (or any work based on the
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+
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+infringement or for any other reason (not limited to patent issues),
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+This section is intended to make thoroughly clear what is believed to
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+  12. If the distribution and/or use of the Library is restricted in
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+
+  13. The Free Software Foundation may publish revised and/or new
+versions of the Lesser General Public License from time to time.
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+
+Each version is given a distinguishing version number.  If the Library
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+conditions either of that version or of any later version published by
+the Free Software Foundation.  If the Library does not specify a
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+
+  14. If you wish to incorporate parts of the Library into other free
+programs whose distribution conditions are incompatible with these,
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+DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+           How to Apply These Terms to Your New Libraries
+
+  If you develop a new library, and you want it to be of the greatest
+possible use to the public, we recommend making it free software that
+everyone can redistribute and change.  You can do so by permitting
+redistribution under these terms (or, alternatively, under the terms of the
+ordinary General Public License).
+
+  To apply these terms, attach the following notices to the library.  It is
+safest to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least the
+"copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the library's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+Also add information on how to contact you by electronic and paper mail.
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+You should also get your employer (if you work as a programmer) or your
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+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the
+  library `Frob' (a library for tweaking knobs) written by James Random Hacker.
+
+  <signature of Ty Coon>, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!
diff --git a/licenses/MIT b/licenses/MIT
new file mode 100644
index 0000000..b8f727e
--- /dev/null
+++ b/licenses/MIT
@@ -0,0 +1,18 @@
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/list/list.h b/list/list.h
new file mode 100644
index 0000000..e944a0a
--- /dev/null
+++ b/list/list.h
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2002 Free Software Foundation, Inc.
+ * (originally part of the GNU C Library and Userspace RCU; extracted from Git)
+ * Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+ *
+ * Copyright (C) 2009 Pierre-Marc Fournier
+ * Conversion to RCU list.
+ * Copyright (C) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIST_H
+#define LIST_H 1
+
+#include <stddef.h>
+
+/*
+ * The definitions of this file are adopted from those which can be
+ * found in the Linux kernel headers to enable people familiar with the
+ * latter find their way in these sources as well.
+ */
+
+/* Basic type for the double-link list. */
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+/* avoid conflicts with BSD-only sys/queue.h */
+#undef LIST_HEAD
+/* Define a variable with the head and tail of the list. */
+#define LIST_HEAD(name) struct list_head name = { &(name), &(name) }
+
+/* Initialize a new list head. */
+#define INIT_LIST_HEAD(ptr) (ptr)->next = (ptr)->prev = (ptr)
+
+#define LIST_HEAD_INIT(name)              \
+	{                                     \
+		.next = &(name), .prev = &(name), \
+	}
+
+/* Add new element at the head of the list. */
+static inline void list_add(struct list_head *newp, struct list_head *head)
+{
+	head->next->prev = newp;
+	newp->next		 = head->next;
+	newp->prev		 = head;
+	head->next		 = newp;
+}
+
+/* Add new element at the tail of the list. */
+static inline void list_add_tail(struct list_head *newp, struct list_head *head)
+{
+	head->prev->next = newp;
+	newp->next		 = head;
+	newp->prev		 = head->prev;
+	head->prev		 = newp;
+}
+
+/* Remove element from list. */
+static inline void __list_del(struct list_head *prev, struct list_head *next)
+{
+	next->prev = prev;
+	prev->next = next;
+}
+
+/* Remove element from list. */
+static inline void list_del(struct list_head *elem)
+{
+	__list_del(elem->prev, elem->next);
+}
+
+/* Remove element from list, initializing the element's list pointers. */
+static inline void list_del_init(struct list_head *elem)
+{
+	list_del(elem);
+	INIT_LIST_HEAD(elem);
+}
+
+/* Delete from list, add to another list as head. */
+static inline void list_move(struct list_head *elem, struct list_head *head)
+{
+	__list_del(elem->prev, elem->next);
+	list_add(elem, head);
+}
+
+/* Replace an old entry. */
+static inline void list_replace(struct list_head *old, struct list_head *newp)
+{
+	newp->next		 = old->next;
+	newp->prev		 = old->prev;
+	newp->prev->next = newp;
+	newp->next->prev = newp;
+}
+
+/* Join two lists. */
+static inline void list_splice(struct list_head *add, struct list_head *head)
+{
+	/* Do nothing if the list which gets added is empty. */
+	if (add != add->next) {
+		add->next->prev	 = head;
+		add->prev->next	 = head->next;
+		head->next->prev = add->prev;
+		head->next		 = add->next;
+	}
+}
+
+/* Get typed element from list at a given position. */
+#define list_entry(ptr, type, member) \
+	((type *)((char *)(ptr)-offsetof(type, member)))
+
+/* Get first entry from a list. */
+#define list_first_entry(ptr, type, member) \
+	list_entry((ptr)->next, type, member)
+
+/* Iterate forward over the elements of the list. */
+#define list_for_each(pos, head) \
+	for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/*
+ * Iterate forward over the elements list. The list elements can be
+ * removed from the list while doing this.
+ */
+#define list_for_each_safe(pos, p, head)                   \
+	for (pos = (head)->next, p = pos->next; pos != (head); \
+		 pos = p, p = pos->next)
+
+/* Iterate backward over the elements of the list. */
+#define list_for_each_prev(pos, head) \
+	for (pos = (head)->prev; pos != (head); pos = pos->prev)
+
+/*
+ * Iterate backwards over the elements list. The list elements can be
+ * removed from the list while doing this.
+ */
+#define list_for_each_prev_safe(pos, p, head)              \
+	for (pos = (head)->prev, p = pos->prev; pos != (head); \
+		 pos = p, p = pos->prev)
+
+static inline int list_empty(struct list_head *head)
+{
+	return head == head->next;
+}
+
+static inline void list_replace_init(struct list_head *old,
+									 struct list_head *newp)
+{
+	struct list_head *head = old->next;
+
+	list_del(old);
+	list_add_tail(newp, head);
+	INIT_LIST_HEAD(old);
+}
+
+/*
+ * This is exactly the same as a normal list_head, except that it can be
+ * declared volatile (e.g., if you have a list that may be accessed from signal
+ * handlers).
+ */
+struct volatile_list_head {
+	volatile struct volatile_list_head *next, *prev;
+};
+
+#define VOLATILE_LIST_HEAD(name) \
+	volatile struct volatile_list_head name = { &(name), &(name) }
+
+static inline void __volatile_list_del(volatile struct volatile_list_head *prev,
+									   volatile struct volatile_list_head *next)
+{
+	next->prev = prev;
+	prev->next = next;
+}
+
+static inline void volatile_list_del(volatile struct volatile_list_head *elem)
+{
+	__volatile_list_del(elem->prev, elem->next);
+}
+
+static inline int volatile_list_empty(volatile struct volatile_list_head *head)
+{
+	return head == head->next;
+}
+
+static inline void volatile_list_add(volatile struct volatile_list_head *newp,
+									 volatile struct volatile_list_head *head)
+{
+	head->next->prev = newp;
+	newp->next		 = head->next;
+	newp->prev		 = head;
+	head->next		 = newp;
+}
+
+#endif /* LIST_H */
diff --git a/optional/Makefile b/optional/Makefile
new file mode 100644
index 0000000..32e87b2
--- /dev/null
+++ b/optional/Makefile
@@ -0,0 +1,5 @@
+CC?=gcc
+CFLAGS+=-Wall -Werror -Wno-unused -std=gnu11 -Og -g
+
+all:
+	$(CC) $(CFLAGS) -o optional-test optional-test.c
diff --git a/optional/README.md b/optional/README.md
new file mode 100644
index 0000000..c039b85
--- /dev/null
+++ b/optional/README.md
@@ -0,0 +1,12 @@
+# Optional
+
+Poor man's optional "type templates" for C. Just for fun.
+
+In its current form it's intended to be used with "single token" types. Might
+or might not "make it compatible" with structs, enums, unions, etc. in the
+future, if the need arises.
+
+## Example usage
+
+If you want to see an example on how to use optional, take a look at
+`optional-test.c`.
diff --git a/optional/optional-test.c b/optional/optional-test.c
new file mode 100644
index 0000000..88577d3
--- /dev/null
+++ b/optional/optional-test.c
@@ -0,0 +1,55 @@
+#include "optional.h"
+#include "../utest/utest.h"
+
+#include <stdio.h>
+
+OPTIONALDEC(int);
+OPTIONALDEC(char);
+
+struct my_struct {
+	OPTIONAL(int) a;
+	OPTIONAL(int) b;
+};
+
+void optput(OPTIONAL(char) * dst, char src)
+{
+	opt_set_some(*dst, src);
+}
+
+TEST_BEGIN(test_optional_example)
+{
+	int a, b;
+
+	struct my_struct my = {
+		.a = OPTSOME(69),
+		.b = OPTNONE,
+	};
+
+	OPTIONAL(char) y = OPTNONE;
+	OPTIONAL(char) z = OPTSOME('z');
+	float xy, xz;
+
+	expect(opt_has(my.a), "expected to contain something");
+	expect(opt_unwrap(my.a, a), "expected to contain something");
+	asserteq(a, 69);
+
+	expect(!opt_unwrap(my.b, b), "expected to contain nothing");
+
+	optput(&y, 'y');
+	opt_set_none(z);
+
+	expect(opt_unwrap(y, xy), "expected to contain something");
+	asserteq(xy, 'y');
+
+	expect(!opt_unwrap(z, xz), "expected to contain nothing");
+
+	xy = opt_default(y, 'd'), xz = opt_default(z, 'd');
+
+	asserteq(xy, 'y');
+	asserteq(xz, 'd');
+
+	TEST_OUT
+}
+TEST_END
+
+RUN_TESTS(test_optional_example)
diff --git a/optional/optional.h b/optional/optional.h
new file mode 100644
index 0000000..6dcc3e2
--- /dev/null
+++ b/optional/optional.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: MIT */
+/**
+ * optional.h - Macros for optional types. v0.1.0
+ *
+ * Copyright (C) 2023 Yaroslav de la Peña Smirnov
+ *
+ * Documentation
+ * =============
+ *
+ * Poor man's optional "type templates" for C.
+ *
+ * An object of optional type is an object that may or may not hold an object of
+ * a certain type inside itself at any time. Before declaring a variable of a
+ * certain OPTIONAL type, said OPTIONAL type should be declared with the
+ * OPTIONALDEC macro.
+ *
+ * Currently only supports types that are composed of one token, i.e. no
+ * structs, enums, unions, etc. Might expand it in the future to support them.
+ */
+
+#ifndef OPTIONAL_H
+#define OPTIONAL_H
+
+#include <stdbool.h>
+
+/**
+ * OPTIONALDEC - declare OPTIONAL type that holds data of type @T
+ * @T:		the type of data to hold.
+ */
+#define OPTIONALDEC(T) struct __OPTIONAL_##T { bool has; T data; }
+
+/**
+ * OPTIONAL - declare an object that optionally holds type @T
+ * @T:		the type of data to hold.
+ */
+#define OPTIONAL(T) struct __OPTIONAL_##T
+
+/**
+ * OPTNONE - initialize an OPTIONAL object to hold nothing.
+ */
+#define OPTNONE { .has = false }
+
+/**
+ * OPTSOME - initialize an OPTIONAL object to hold something.
+ * @d:	data to hold.
+ */
+#define OPTSOME(d) { .has = true, .data = d }
+
+/**
+ * opt_set_none - set an OPTIONAL object to hold nothing.
+ * @opt:	OPTIONAL object.
+ */
+#define opt_set_none(opt) opt.has = false
+
+/**
+ * opt_set_some - set an OPTIONAL object to hold something.
+ * @opt:	OPTIONAL object.
+ * @d:		data to hold.
+ */
+#define opt_set_some(opt, d) \
+	((opt).has = true, (opt).data = d)
+
+/**
+ * opt_has - true if an OPTIONAL object has something.
+ * @opt:	OPTIONAL object.
+ */
+#define opt_has(opt) ((opt).has)
+
+/**
+ * opt_hasnt - true if an OPTIONAL object has nothing.
+ * @opt:	OPTIONAL object.
+ */
+#define opt_hasnt(opt) (!(opt).has)
+
+/**
+ * opt_unwrap - if there's something in @src, copy it to @dst.
+ * @src:	OPTIONAL object to copy data of type T from.
+ * @dst:	variable of type T to copy to.
+ *
+ * Returns true if there was something, false if there wasn't.
+ */
+#define opt_unwrap(src, dst) \
+	(opt_has(src) ? (dst = (src).data, true) : (false))
+
+/**
+ * opt_default - get something from @src or default to @def.
+ * @src:	OPTIONAL object to get data from.
+ * @def:	default value if there's nothing.
+ */
+#define opt_default(src, def) opt_has(src) ? (src).data : def
+
+#endif
diff --git a/utest/Makefile b/utest/Makefile
new file mode 100644
index 0000000..0ecb1c5
--- /dev/null
+++ b/utest/Makefile
@@ -0,0 +1,5 @@
+CC?=gcc
+CFLAGS+=-Wall -Werror -Wno-unused -std=gnu11 -Og -g
+
+all:
+	$(CC) $(CFLAGS) -o utest-test utest-test.c
diff --git a/utest/utest-test.c b/utest/utest-test.c
new file mode 100644
index 0000000..591ee32
--- /dev/null
+++ b/utest/utest-test.c
@@ -0,0 +1,34 @@
+#include "utest.h"
+
+static int a, b;
+
+/* This should pass */
+TEST_BEGIN(test_pass)
+{
+	asserteq(a, 0);
+	assertneq(a, b);
+	expect(b > a, "expected b > a");
+	TEST_OUT
+}
+TEST_END
+
+/* This should fail */
+TEST_BEGIN(test_fail)
+{
+	expect(0, "oopsie!");
+	TEST_OUT
+}
+TEST_END
+
+void test_init(void)
+{
+	a = 0, b = 1;
+	printf("hello, world!\n\n");
+}
+
+void test_destroy(void)
+{
+	printf("\ngood bye!\n");
+}
+
+RUN_TEST_SUITE(test_init, test_destroy, test_pass, test_fail);
diff --git a/utest/utest.h b/utest/utest.h
new file mode 100644
index 0000000..218b2b7
--- /dev/null
+++ b/utest/utest.h
@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: LGPL-2.1 */
+/**
+ * utest.h - header-only unit testing micro "framework". v1.0.0
+ *
+ * Copyright (c) 2021-2023 Yaroslav de la Peña Smirnov
+ */
+#ifndef UTEST_H
+#define UTEST_H
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+/*
+ * TODO?: test runners that run in different processes in order to not crash the
+ * whole test unit when a single test crashes.
+ */
+
+/**
+ * Constants
+ * =========
+ */
+
+/**
+ * Terminal escape codes
+ * ---------------------
+ *
+ * TBLD:	bold text.
+ * TRED:	red text.
+ * TGRN:	green text.
+ * TBLU:	blue text.
+ * TRST:	reset colors.
+ * TDEL:	delete current line.
+ */
+#ifndef NOCOLOR
+#define TBLD "\033[1m"
+#define TRED "\033[31m"
+#define TGRN "\033[32m"
+#define TBLU "\033[34m"
+#define TRST "\033[0m"
+#else
+#define TBLD ""
+#define TRED ""
+#define TGRN ""
+#define TBLU ""
+#define TRST ""
+#endif
+#define TDEL "\33[2K\r"
+
+/**
+ * Typedefs
+ * ========
+ */
+
+typedef bool (*test_fn)(void);
+typedef void (*setup_fn)(void);
+
+/**
+ * Internal variables
+ * ==================
+ */
+
+static setup_fn tests_init	  = NULL;
+static setup_fn tests_destroy = NULL;
+
+/**
+ * Functions and function-like macros
+ * ==================================
+ */
+
+/**
+ * FAIL_TEST - fail the test and print the @reason.
+ * @reason:	a variable list of arguments, where the first argument is the format
+ * 			text.
+ */
+#define FAIL_TEST(reason...)                                                  \
+	printf(TDEL " [" TBLD TRED "×" TRST "]\t%s: " TBLD TRED "FAILED!\n" TRST, \
+		   __this_name);                                                      \
+	printf("\t﹂%s:%d: ", __FILE__, __LINE__);                                \
+	printf(reason);                                                           \
+	printf("\n");                                                             \
+	__ret = false;                                                            \
+	goto test_out
+
+/**
+ * asserteq - assert @a and @b's equality; fail test if not equal.
+ * @a:	argument to compare to b.
+ * @b:	argument to compare to a.
+ */
+#define asserteq(a, b)                                                     \
+	({                                                                     \
+		if ((a) != (b)) {                                                      \
+			FAIL_TEST("assertion " TBLD TBLU #a " == " #b TRST " failed"); \
+		}                                                                  \
+	})
+
+/**
+ * assertneq - assert @a and @b's inequality; fail test if equal.
+ * @a:	argument to compare to b.
+ * @b:	argument to compare to a.
+ */
+#define assertneq(a, b)                                                    \
+	({                                                                     \
+		if ((a) == (b)) {                                                      \
+			FAIL_TEST("assertion " TBLD TBLU #a " != " #b TRST " failed"); \
+		}                                                                  \
+	})
+
+/**
+ * expect - fail the test on !@cond and print the reason.
+ * @cond:	condition to test.
+ * @reason:	a variable list of arguments, where the first argument is the format
+ * 			text.
+ */
+#define expect(cond, reason...) \
+	({                          \
+		if (!(cond)) {            \
+			FAIL_TEST(reason);  \
+		}                       \
+	})
+
+/**
+ * TEST_BEGIN - declare test function @name.
+ * @name:	name of test function to declare.
+ *
+ * Should be followed by TEST_OUT and TEST_END.
+ */
+#define TEST_BEGIN(name)                                          \
+	int name(void)                                                \
+	{                                                             \
+		const char *__this_name = #name;                          \
+		bool		__ret		= true;                           \
+		printf(" [⏳]\t%s: " TBLU "running..." TRST, __this_name); \
+		fflush(stdout);
+
+/**
+ * TEST_OUT - code that should be executed on test exit goes after this.
+ * This declares a goto label, so that on test failure anything that needs to be
+ * cleaned up is cleaned up. You need to use this even if there's nothing to be
+ * cleaned up.
+ */
+#define TEST_OUT \
+test_out:;
+
+/**
+ * TEST_END - close the test scope.
+ */
+#define TEST_END                                                \
+	if (__ret) {                                                \
+		printf(TDEL " [" TBLD TGRN "✓" TRST "]\t%s: " TBLD TGRN \
+					"PASSED!\n" TRST,                           \
+			   __this_name);                                    \
+	}                                                           \
+	return __ret;                                               \
+	}
+
+/**
+ * __run_tests() - runs tests; for internal use.
+ */
+static inline int __run_tests(const char *const unit_name, ...)
+{
+	va_list args;
+	test_fn test;
+	size_t	passed = 0, total = 0, failed = 0;
+
+	if (tests_init) {
+		tests_init();
+	}
+
+	printf("[***]\t" TBLD "running:" TRST TBLU " %s " TRST "tests\n",
+		   unit_name);
+
+	va_start(args, unit_name);
+	test = va_arg(args, test_fn);
+	while (test) {
+		test() ? passed++ : 0;
+		total++;
+		test = va_arg(args, test_fn);
+	}
+	va_end(args);
+
+	failed = total - passed;
+
+	printf("[***]\t" TBLD "finished:" TRST TBLU " %s: " TRST "tests: " TBLU
+		   "%lu" TRST ", passed: " TGRN "%lu" TRST ", failed: " TRED "%lu" TRST
+		   "\n",
+		   unit_name, total, passed, failed);
+
+	if (tests_destroy) {
+		tests_destroy();
+	}
+
+	return failed;
+}
+
+/**
+ * RUN_TEST_SUITE - runs the @tests given as arguments.
+ * @init_fn:		initialization function.
+ * @destroy_fn:		cleanup function.
+ * @tests...:		tests to run.
+ *
+ * @init_fn and @destroy_fn are used to initialize and cleanup test-related data
+ * respectively.
+ */
+#define RUN_TEST_SUITE(init_fn, destroy_fn, tests...) \
+	int main(void)                                    \
+	{                                                 \
+		tests_init	  = init_fn;                      \
+		tests_destroy = destroy_fn;                   \
+		return __run_tests(__FILE__, tests, NULL);    \
+	}
+
+/**
+ * RUN_TESTS - runs the @tests given as arguments.
+ * @tests...:	tests to run.
+ *
+ * Same as RUN_TEST_SUITE, but without initialization and cleanup functions
+ */
+#define RUN_TESTS(tests...) RUN_TEST_SUITE(NULL, NULL, tests)
+
+#endif /* UTEST_H */
diff --git a/utils.h b/utils.h
new file mode 100644
index 0000000..cb7d795
--- /dev/null
+++ b/utils.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: MIT */
+/**
+ * utils.h - useful macros for compile-time magic
+ *
+ * Inspired by similar macros in the Linux Kernel.
+ *
+ * Copyright (c) 2023 - Yaroslav de la Peña Smirnov
+ */
+#ifndef CWARE_UTILS_H
+#define CWARE_UTILS_H
+
+#include <stddef.h>
+
+#ifndef static_assert
+#define static_assert(exp, msg) _Static_assert(exp, msg)
+#endif
+
+#define same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+
+#define container_of(ptr, T, member)                      \
+	({                                                    \
+		static_assert(same_type(*(ptr), ((T *)0)->member) \
+							  || same_type(*(ptr), void), \
+					  "type mismatch in container_of()"); \
+		(T *)((void *)(ptr)-offsetof(T, member));         \
+	})
+
+#define ARRAY_SIZE(arr)                             \
+	({                                              \
+		static_assert(!same_type((arr), &(arr)[0]), \
+					  "variable is not an array");  \
+		sizeof(arr) / sizeof(*arr);                 \
+	})
+
+#endif