treewide: Rewrite in C

Over the past couple of years I've thought about rewriting clipmenu
(both client and daemon) in C. Among many other reasons supporting this
are:

- clipmenu and friends as they stand right now in bash are fairly
  unwieldy. They have over time built up a lot of workarounds and hacks
  for xclip/xsel behaviour, and cases where bash itself works against us
  (like the way it handles newlines in command substitution). All in
  all, it makes more sense to have more granular control with Xlib
  itself.
- xclip/xsel have nasty edge cases. Just as one example, the fact that
  we take ownership when there's not even an XA_STRING/UTF8_STRING
  target with the current logic is one of the main things which have
  resulted in bug reports like issue #188 which are hard to work around,
  and make clipmenu not usable for some workflows.
- In general, using Xlib allows us to be more careful about how we
  implement things like owning the clipboard, instead of hacks like how
  we currently implement `CM_SYNC_PRIMARY_TO_CLIPBOARD` and its ilk.

The new version also introduces support for a config file at
~/.config/clipmenu/clipmenu.conf, as opposed to always having to use
environment variables. Documentation right now is sparse (read:
nonexistent), but you can look at config_setup_internal. Before release
it will be documented properly.

This new C version will become clipmenu 7.

Breaking changes to invocation:

- CM_LAUNCHER=rofi-script mode is removed (if more than one person used
  this maybe I will reconsider, but it doesn't work well with the new
  indexing logic in clipmenu so we need to think about how that should
  work).
- CM_LAUNCHER=fzf now requires CM_LAUNCHER_PASS_DMENU_ARGS=0. You can,
  in general, use any launcher like this now and just pass whatever args
  you want via clipmenu itself.
- clipfsck is gone, not that it ever really did much anyway.

.clang-format

@@ -0,0 +1,10 @@
+BinPackArguments: true
+BreakStringLiterals: false
+ColumnLimit: 80
+IndentCaseLabels: true
+IndentPPDirectives: BeforeHash
+IndentWidth: 4
+PenaltyBreakComment: 0
+SortIncludes: true
+SpaceBeforeParens: ControlStatementsExceptForEachMacros
+UseTab: Never

.github/workflows/ci.yml

@@ -0,0 +1,25 @@
+jobs:
+  build_and_test:
+    name: CI
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - run: sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
+      - run: sudo apt-get update
+
+      - uses: awalsh128/cache-apt-pkgs-action@v1
+        with:
+          packages: gcc-10 clang clang-format clang-tidy cppcheck xvfb xsel libxfixes-dev libx11-dev
+          version: 1.0
+
+      - run: gcc --version
+
+      - run: make clean analyse
+      - run: tests/x_integration_tests
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:

.gitignore

@@ -0,0 +1,7 @@
+src/clipmenud
+src/clipctl
+src/clipdel
+src/clipmenu
+src/clipserve
+tests/test
+*.o

LICENSE

@@ -1,5 +1,21 @@
-This is free and unencumbered software released into the public domain.
+The MIT License
 
-Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
-software, either in source code form or as a compiled binary, for any purpose,
-commercial or non-commercial, and by any means.
+Copyright (c) 2014-present Christopher Down
+
+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.

Makefile

@@ -1,12 +1,89 @@
-# `dmenu` is not a hard dependency, but you need it unless
-# you plan to set CM_LAUNCHER to another value like `rofi`
-REQUIRED_BINS := xsel clipnotify
-PREFIX ?= /usr
-$(foreach bin,$(REQUIRED_BINS),\
-    $(if $(shell command -v $(bin) 2> /dev/null),$(info Found `$(bin)`),$(error Missing Dep. Please install `$(bin)`)))
-
-.PHONY: install
-
-install:
-	install --target "${PREFIX}/bin" -D -m755 clipmenu clipmenud clipdel clipctl
-	install -D -m644 init/clipmenud.service "${PREFIX}/lib/systemd/user/clipmenud.service"
+CFLAGS := -std=gnu11 -O2 -Wall -Wextra -Wshadow -Wpointer-arith \
+	  -Wcast-align -Wmissing-prototypes -Wstrict-overflow -Wformat=2 \
+	  -Wwrite-strings -Warray-bounds -Wstrict-prototypes \
+	  -Werror $(CFLAGS)
+CPPFLAGS := -I/usr/X11R6/include -L/usr/X11R6/lib
+LDLIBS := -lX11 -lXfixes
+PREFIX ?= /usr/local
+bindir := $(PREFIX)/bin
+debug_cflags := -D_FORTIFY_SOURCE=2 -fsanitize=leak -fsanitize=address \
+	        -fsanitize=undefined -Og -ggdb -fno-omit-frame-pointer \
+	        -fstack-protector-strong
+c_files := $(wildcard src/*.c)
+h_files := $(wildcard src/*.h)
+libs := $(filter $(c_files:.c=.o), $(h_files:.h=.o))
+
+bins := clipctl clipmenud clipdel clipserve clipmenu
+
+all: $(addprefix src/,$(bins))
+
+src/%: src/%.c $(libs)
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(LDLIBS) $^ -o $@
+
+src/%.o: src/%.c src/%.h
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
+
+debug: all
+debug: CFLAGS+=$(debug_cflags)
+
+install: all
+	mkdir -p $(DESTDIR)$(bindir)/
+	install -pt $(DESTDIR)$(bindir)/ $(addprefix src/,$(bins))
+	install -Dp -m 644 init/clipmenud.service $(DESTDIR)$(PREFIX)/lib/systemd/user/clipmenud.service
+
+uninstall:
+	rm -f $(addprefix $(DESTDIR)$(PREFIX)/bin/,$(bins))
+	rm -f "$(DESTDIR)${PREFIX}/lib/systemd/user/clipmenud.service"
+
+clean:
+	rm -f src/*.o src/*~ $(addprefix src/,$(bins))
+
+clang_supports_unsafe_buffer_usage := $(shell clang -x c -c /dev/null -o /dev/null -Werror -Wunsafe-buffer-usage > /dev/null 2>&1; echo $$?)
+ifeq ($(clang_supports_unsafe_buffer_usage),0)
+    extra_clang_flags := -Wno-unsafe-buffer-usage
+else
+    extra_clang_flags :=
+endif
+
+c_analyse_targets := $(c_files:%=%-analyse)
+h_analyse_targets := $(h_files:%=%-analyse)
+
+analyse: CFLAGS+=$(debug_cflags)
+analyse: $(c_analyse_targets) $(h_analyse_targets)
+
+$(c_analyse_targets): %-analyse:
+	# -W options here are not clang compatible, so out of generic CFLAGS
+	gcc $< -o /dev/null -c \
+		-std=gnu99 -Ofast -fwhole-program -Wall -Wextra \
+		-Wlogical-op -Wduplicated-cond \
+		-fanalyzer $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(LDLIBS)
+	clang $< -o /dev/null -c -std=gnu99 -Ofast -Weverything \
+		-Wno-documentation-unknown-command \
+		-Wno-language-extension-token \
+		-Wno-disabled-macro-expansion \
+		-Wno-padded \
+		-Wno-covered-switch-default \
+		-Wno-gnu-zero-variadic-macro-arguments \
+		-Wno-declaration-after-statement \
+		-Wno-cast-qual \
+		-Wno-unused-command-line-argument \
+		$(extra_clang_flags) \
+		$(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(LDLIBS)
+	$(MAKE) $*-shared-analyse
+
+$(h_analyse_targets): %-analyse:
+	$(MAKE) $*-shared-analyse
+
+%-shared-analyse: %
+	# cppcheck is a bit dim about unused functions/variables, leave that to
+	# clang/GCC
+	cppcheck $< --std=c99 --quiet --inline-suppr --force \
+		--enable=all --suppress=missingIncludeSystem \
+		--suppress=unusedFunction --suppress=unmatchedSuppression \
+		--suppress=unreadVariable \
+		--max-ctu-depth=32 --error-exitcode=1
+	# clang-analyzer-unix.Malloc does not understand _drop_()
+	clang-tidy $< --quiet -checks=-clang-analyzer-unix.Malloc -- -std=gnu99
+	clang-format --dry-run --Werror $<
+
+.PHONY: all debug install uninstall clean analyse