move util.c to util.h

This allows single-source compilation and whole-program optimization using something like:

make CFLAGS='-flto -ffunction-sections -fdata-sections -Wl,--gc-sections'

Furthermore, move more compositor-agnostic utility functions/macros to util.h,
similar to the original dwm sources.

Makefile

@@ -5,7 +5,7 @@ include config.mk
 
 # flags for compiling
 DWLCPPFLAGS = -I. -DWLR_USE_UNSTABLE -D_POSIX_C_SOURCE=200809L \
-	-DVERSION=\"$(VERSION)\" $(XWAYLAND)
+	-DVERSION=\"$(VERSION)\" $(XWAYLAND) $(CPPFLAGS)
 DWLDEVCFLAGS = -g -Wpedantic -Wall -Wextra -Wdeclaration-after-statement \
 	-Wno-unused-parameter -Wshadow -Wunused-macros -Werror=strict-prototypes \
 	-Werror=implicit -Werror=return-type -Werror=incompatible-pointer-types \
@@ -17,12 +17,10 @@ DWLCFLAGS = `$(PKG_CONFIG) --cflags $(PKGS)` $(WLR_INCS) $(DWLCPPFLAGS) $(DWLDEV
 LDLIBS    = `$(PKG_CONFIG) --libs $(PKGS)` $(WLR_LIBS) -lm $(LIBS)
 
 all: dwl
-dwl: dwl.o util.o
-	$(CC) dwl.o util.o $(DWLCFLAGS) $(LDFLAGS) $(LDLIBS) -o $@
-dwl.o: dwl.c client.h config.h config.mk cursor-shape-v1-protocol.h \
+dwl: dwl.c client.h config.h util.h config.mk cursor-shape-v1-protocol.h \
 	pointer-constraints-unstable-v1-protocol.h wlr-layer-shell-unstable-v1-protocol.h \
 	wlr-output-power-management-unstable-v1-protocol.h xdg-shell-protocol.h
-util.o: util.c util.h
+	$(CC) dwl.c $(DWLCFLAGS) $(LDFLAGS) $(LDLIBS) -o $@
 
 # wayland-scanner is a tool which generates C headers and rigging for Wayland
 # protocols, which are specified in XML. wlroots requires you to rig these up
@@ -54,7 +52,7 @@ clean:
 dist: clean
 	mkdir -p dwl-$(VERSION)
 	cp -R LICENSE* Makefile CHANGELOG.md README.md client.h config.def.h \
-		config.mk protocols dwl.1 dwl.c util.c util.h dwl.desktop \
+		config.mk protocols dwl.1 dwl.c util.h dwl.desktop \
 		dwl-$(VERSION)
 	tar -caf dwl-$(VERSION).tar.gz dwl-$(VERSION)
 	rm -rf dwl-$(VERSION)
@@ -73,7 +71,3 @@ install: dwl
 uninstall:
 	rm -f $(DESTDIR)$(PREFIX)/bin/dwl $(DESTDIR)$(MANDIR)/man1/dwl.1 \
 		$(DESTDIR)$(DATADIR)/wayland-sessions/dwl.desktop
-
-.SUFFIXES: .c .o
-.c.o:
-	$(CC) $(CPPFLAGS) $(DWLCFLAGS) -o $@ -c $<

README.md

@@ -10,7 +10,7 @@ primarily in terms of functionality, and secondarily in terms of
 philosophy. Like [dwm], dwl is:
 
 - Easy to understand, hack on, and extend with patches
-- One C source file (or a very small number) configurable via `config.h`
+- One C source file configurable via `config.h`
 - Tied to as few external dependencies as possible
 
 ## Getting Started:

dwl.c

@@ -72,12 +72,8 @@
 #include "util.h"
 
 /* macros */
-#define MAX(A, B)               ((A) > (B) ? (A) : (B))
-#define MIN(A, B)               ((A) < (B) ? (A) : (B))
 #define CLEANMASK(mask)         (mask & ~WLR_MODIFIER_CAPS)
 #define VISIBLEON(C, M)         ((M) && (C)->mon == (M) && ((C)->tags & (M)->tagset[(M)->seltags]))
-#define LENGTH(X)               (sizeof X / sizeof X[0])
-#define END(A)                  ((A) + LENGTH(A))
 #define TAGMASK                 ((1u << TAGCOUNT) - 1)
 #define LISTEN(E, L, H)         wl_signal_add((E), ((L)->notify = (H), (L)))
 #define LISTEN_STATIC(E, H)     do { struct wl_listener *_l = ecalloc(1, sizeof(*_l)); _l->notify = (H); wl_signal_add((E), _l); } while (0)

util.c

@@ -1,51 +0,0 @@
-/* See LICENSE.dwm file for copyright and license details. */
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <fcntl.h>
-
-#include "util.h"
-
-void
-die(const char *fmt, ...) {
-	va_list ap;
-
-	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
-	va_end(ap);
-
-	if (fmt[0] && fmt[strlen(fmt)-1] == ':') {
-		fputc(' ', stderr);
-		perror(NULL);
-	} else {
-		fputc('\n', stderr);
-	}
-
-	exit(1);
-}
-
-void *
-ecalloc(size_t nmemb, size_t size)
-{
-	void *p;
-
-	if (!(p = calloc(nmemb, size)))
-		die("calloc:");
-	return p;
-}
-
-int
-fd_set_nonblock(int fd) {
-	int flags = fcntl(fd, F_GETFL);
-	if (flags < 0) {
-		perror("fcntl(F_GETFL):");
-		return -1;
-	}
-	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) < 0) {
-		perror("fcntl(F_SETFL):");
-		return -1;
-	}
-
-	return 0;
-}

util.h

@@ -1,5 +1,58 @@
 /* See LICENSE.dwm file for copyright and license details. */
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
 
-void die(const char *fmt, ...);
-void *ecalloc(size_t nmemb, size_t size);
-int fd_set_nonblock(int fd);
+#define MAX(A, B)               ((A) > (B) ? (A) : (B))
+#define MIN(A, B)               ((A) < (B) ? (A) : (B))
+#define LENGTH(X)               (sizeof X / sizeof X[0])
+#define END(A)                  ((A) + LENGTH(A))
+
+static void die(const char *fmt, ...);
+static void *ecalloc(size_t nmemb, size_t size);
+static int fd_set_nonblock(int fd);
+
+void
+die(const char *fmt, ...) {
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	if (fmt[0] && fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	} else {
+		fputc('\n', stderr);
+	}
+
+	exit(1);
+}
+
+void *
+ecalloc(size_t nmemb, size_t size)
+{
+	void *p;
+
+	if (!(p = calloc(nmemb, size)))
+		die("calloc:");
+	return p;
+}
+
+int
+fd_set_nonblock(int fd) {
+	int flags = fcntl(fd, F_GETFL);
+	if (flags < 0) {
+		perror("fcntl(F_GETFL):");
+		return -1;
+	}
+	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) < 0) {
+		perror("fcntl(F_SETFL):");
+		return -1;
+	}
+
+	return 0;
+}