Rework the build system (#19)

* Added simple configure script

Added simple script to autodetect if optional dependencies are installed
and enable/disable them as needed. Note this solution uses the compiler
directly instead of an external program like pkgconfig so it doesn't
require any extra dependencies. It is intended to work with any
arbitrary compiler; it has been tested with tcc and gcc.

There are some "breaking" changes hidden here
- HAVE_GIFLIB was renamed to HAVE_LIBGIF to match HAVE_LIBEXIF
- Simply typing `make` will no longer try to build with optional
  dependencies

* use implicit RM variable

* General clean-up in configure

- Use printf instead of echo
- Format style

* honor env PREFIX, use LDLIBS

* Revert "General clean-up in configure"

This reverts commit 8683c179dbf273a330f9a224a4d481a7bea42c5f.

* honor env LDFLAGS if set

* Don't set OPTIONAL_LIBS in configure

* make OBJ all caps

* follow suckless style build system

- remove configure script.
- HAVE_LIBGIF and HAVE_LIBEXIF defaults back to 1
- unload several varibales onto config.mk
- make version all-caps
- add -O2 optimization
- use CPPFLAGS for includes and defines

* Revert "follow suckless style build system"

This reverts commit 8bf75b1f68d72df349edba8d998d4659dd956dd8.

* Generate config.mk from make

* Inlined configure in Makefile

* update docs

* cleanups

- changes to config.mk should trigger a rebuild
- remove potentially confusing variables form Makefile

* Use install instead of mkdir/cp/chmod when sensible

* fixup! Inlined configure in Makefile

* Don't generate config.mk on rm -f *.o sxiv

* update docs and cleanups

- make config.mk silent
- mention editing config.mk in README

* fallback to 0 if user edits config.mk in unexpected way

* add comment on config.mk

* remove invalid comment

configure script is removed

* slight restructure

- make version all caps
- restructure variables that users may want to edit to top
- use CPPFLAGS for defines
- add some comments
- remove needless echos since we have verbose output now

* add echos back

Co-authored-by: NRK <nrk@disroot.org>
Co-authored-by: Berke Kocaoğlu <berke.kocaoglu@metu.edu.tr>

4 files changed, 66 insertions, 48 deletions

diff --git a/.gitignore b/.gitignore
index 3ab271b..17c4f3c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ version.h
 *.d
 *.o
 sxiv
+config.mk
diff --git a/Makefile b/Makefile
index da6c209..23ed7b8 100644
--- a/Makefile
+++ b/Makefile
@@ -1,82 +1,90 @@
-version = 26
+# Include configure options
+ifneq (clean,$(filter clean,$(MAKECMDGOALS)))
+-include config.mk
+endif
 
-srcdir = .
-VPATH = $(srcdir)
+# sxiv version
+VERSION = 26
 
-PREFIX = /usr/local
+# PREFIX for install
+PREFIX ?= /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
 # autoreload backend: inotify/nop
 AUTORELOAD = inotify
 
-# enable features requiring giflib (-lgif)
-HAVE_GIFLIB = 1
-
-# enable features requiring libexif (-lexif)
-HAVE_LIBEXIF = 1
-
-cflags = -std=c99 -Wall -pedantic $(CFLAGS)
-cppflags = -I. $(CPPFLAGS) -D_XOPEN_SOURCE=700 \
-  -DHAVE_GIFLIB=$(HAVE_GIFLIB) -DHAVE_LIBEXIF=$(HAVE_LIBEXIF) \
+# CFLAGS, any optimization flags goes here
+CFLAGS ?= -std=c99 -Wall -pedantic
+
+ifeq ($(HAVE_LIBEXIF), 1)
+	OPTIONAL_LIBS += -lexif
+else
+	HAVE_LIBEXIF = 0
+endif
+ifeq ($(HAVE_LIBGIF), 1)
+	OPTIONAL_LIBS += -lgif
+else
+	HAVE_LIBGIF = 0
+endif
+
+CPPFLAGS = -D_XOPEN_SOURCE=700 \
+  -DHAVE_LIBGIF=$(HAVE_LIBGIF) -DHAVE_LIBEXIF=$(HAVE_LIBEXIF) \
   -I/usr/include/freetype2 -I$(PREFIX)/include/freetype2
 
-lib_exif_0 =
-lib_exif_1 = -lexif
-lib_gif_0 =
-lib_gif_1 = -lgif
-ldlibs = $(LDLIBS) -lImlib2 -lX11 -lXft -lfontconfig \
-  $(lib_exif_$(HAVE_LIBEXIF)) $(lib_gif_$(HAVE_GIFLIB))
+LDLIBS = -lImlib2 -lX11 -lXft -lfontconfig $(OPTIONAL_LIBS)
 
-objs = autoreload_$(AUTORELOAD).o commands.o image.o main.o options.o \
+OBJS = autoreload_$(AUTORELOAD).o commands.o image.o main.o options.o \
   thumbs.o util.o window.o
 
-all: sxiv
-
 .PHONY: all clean install uninstall
 .SUFFIXES:
 .SUFFIXES: .c .o
-$(V).SILENT:
 
-sxiv: $(objs)
+all: sxiv
+
+sxiv: $(OBJS)
 	@echo "LINK $@"
-	$(CC) $(LDFLAGS) -o $@ $(objs) $(ldlibs)
+	$(CC) $(LDFLAGS) -o $@ $^ $(LDLIBS)
 
-$(objs): Makefile sxiv.h commands.lst config.h
+.c.o:
+	@echo "CC $@"
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
+
+$(OBJS): Makefile sxiv.h commands.lst config.h config.mk
 options.o: version.h
 window.o: icon/data.h
 
-.c.o:
-	@echo "CC $@"
-	$(CC) $(cflags) $(cppflags) -c -o $@ $<
+config.mk:
+	@echo "GEN $@"
+	@echo "# 0 = disable, 1 = enable" > config.mk
+	@for lib in exif gif; do \
+		if echo "int main(){}" | $(CC) "-l$$lib" -o /dev/null -x c - 2>/dev/null ; then \
+			echo "HAVE_LIB$$lib=1" | tr '[:lower:]' '[:upper:]' >> config.mk ; \
+		fi \
+	done
 
 config.h:
 	@echo "GEN $@"
-	cp $(srcdir)/config.def.h $@
+	cp config.def.h $@
 
 version.h: Makefile .git/index
 	@echo "GEN $@"
-	v="$$(cd $(srcdir); git describe 2>/dev/null)"; \
-	echo "#define VERSION \"$${v:-$(version)}\"" >$@
-
-.git/index:
+	v="$$(git describe 2>/dev/null)"; \
+	echo "#define VERSION \"$${v:-$(VERSION)}\"" >$@
 
 clean:
-	rm -f *.o sxiv
+	$(RM) *.o sxiv
 
 install: all
 	@echo "INSTALL bin/sxiv"
-	mkdir -p $(DESTDIR)$(PREFIX)/bin
-	cp sxiv $(DESTDIR)$(PREFIX)/bin/
-	chmod 755 $(DESTDIR)$(PREFIX)/bin/sxiv
+	install -Dt $(DESTDIR)$(PREFIX)/bin sxiv
 	@echo "INSTALL sxiv.1"
 	mkdir -p $(DESTDIR)$(MANPREFIX)/man1
-	sed "s!PREFIX!$(PREFIX)!g; s!VERSION!$(version)!g" sxiv.1 \
+	sed "s!PREFIX!$(PREFIX)!g; s!VERSION!$(VERSION)!g" sxiv.1 \
 		>$(DESTDIR)$(MANPREFIX)/man1/sxiv.1
 	chmod 644 $(DESTDIR)$(MANPREFIX)/man1/sxiv.1
 	@echo "INSTALL share/sxiv/"
-	mkdir -p $(DESTDIR)$(PREFIX)/share/sxiv/exec
-	cp exec/* $(DESTDIR)$(PREFIX)/share/sxiv/exec/
-	chmod 755 $(DESTDIR)$(PREFIX)/share/sxiv/exec/*
+	install -Dt $(DESTDIR)$(PREFIX)/share/sxiv/exec exec/*
 
 uninstall:
 	@echo "REMOVE bin/sxiv"
diff --git a/README.md b/README.md
index 8795fb5..f2aba7a 100644
--- a/README.md
+++ b/README.md
@@ -42,8 +42,8 @@ sxiv requires the following software to be installed:
   * Xft
   * freetype2
   * fontconfig
-  * giflib (optional, disabled with `HAVE_GIFLIB=0`)
-  * libexif (optional, disabled with `HAVE_LIBEXIF=0`)
+  * giflib (optional, automatically enabled if installed)
+  * libexif (optional, automatically enabled if installed)
 
 Please make sure to install the corresponding development packages in case that
 you want to build sxiv on a distribution with separate runtime and development
@@ -62,6 +62,15 @@ Please note, that the latter one requires root privileges.
 By default, sxiv is installed using the prefix "/usr/local", so the full path
 of the executable will be "/usr/local/bin/sxiv".
 
+Running make will automatically detect if libexif and libgif are available and
+enable them if so. CLI arguments will override any automatic detection.
+For example:
+
+	$ make HAVE_LIBGIF=0
+
+will always disable libgif.
+Alternatively, they can be disabled via editing `config.mk`.
+
 You can install sxiv into a directory of your choice by changing the second
 command to:
 
diff --git a/image.c b/image.c
index 6f37f44..1c1e4d2 100644
--- a/image.c
+++ b/image.c
@@ -31,7 +31,7 @@
 #include <libexif/exif-data.h>
 #endif
 
-#if HAVE_GIFLIB
+#if HAVE_LIBGIF
 #include <gif_lib.h>
 enum { DEF_GIF_DELAY = 75 };
 #endif
@@ -115,7 +115,7 @@ void exif_auto_orientate(const fileinfo_t *file)
 }
 #endif
 
-#if HAVE_GIFLIB
+#if HAVE_LIBGIF
 bool img_load_gif(img_t *img, const fileinfo_t *file)
 {
 	GifFileType *gif;
@@ -295,7 +295,7 @@ bool img_load_gif(img_t *img, const fileinfo_t *file)
 
 	return !err;
 }
-#endif /* HAVE_GIFLIB */
+#endif /* HAVE_LIBGIF */
 
 Imlib_Image img_open(const fileinfo_t *file)
 {
@@ -333,7 +333,7 @@ bool img_load(img_t *img, const fileinfo_t *file)
 #endif
 
 	if ((fmt = imlib_image_format()) != NULL) {
-#if HAVE_GIFLIB
+#if HAVE_LIBGIF
 		if (STREQ(fmt, "gif"))
 			img_load_gif(img, file);
 #endif