Rework build system v2 (#71)

* Remove non-POSIX extensions and commands
* Drop autodetection in favor of OPT_DEP_DEFAULT
* Use += for LDLIBS as some BSD distros need to add extra flags
* Change DOCPREFIX -> EGPREFIX
* Use ?= for MANPREFIX and EGPREFIX
* Update docs

With this, we should have a stable build system. No further significant
changes should be needed.

4 files changed, 52 insertions, 55 deletions

diff --git a/.gitignore b/.gitignore
index d2d77f1..41ab2e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,3 @@ version.h
 *.d
 *.o
 nsxiv
-config.mk
diff --git a/Makefile b/Makefile
index e126211..45971dd 100644
--- a/Makefile
+++ b/Makefile
@@ -1,18 +1,21 @@
-# Include configure options
-ifneq (clean,$(filter clean,$(MAKECMDGOALS)))
--include config.mk
-endif
-
 # nsxiv version
 VERSION = 27.1
 
 # PREFIX for install
 PREFIX ?= /usr/local
-MANPREFIX = $(PREFIX)/share/man
-DOCPREFIX = $(PREFIX)/share/doc/nsxiv
+MANPREFIX ?= $(PREFIX)/share/man
+EGPREFIX ?= $(PREFIX)/share/doc/nsxiv/examples
+
+# default value for optional dependencies. 1 = enabled, 0 = disabled
+OPT_DEP_DEFAULT ?= 1
 
-# autoreload backend: inotify/nop
-AUTORELOAD = inotify
+# autoreload backend: 1 = inotify, 0 = none
+HAVE_INOTIFY ?= $(OPT_DEP_DEFAULT)
+
+# optional dependencies, see README for more info
+HAVE_LIBGIF ?= $(OPT_DEP_DEFAULT)
+HAVE_LIBEXIF ?= $(OPT_DEP_DEFAULT)
+HAVE_LIBWEBP ?= $(OPT_DEP_DEFAULT)
 
 # CFLAGS, any optimization flags goes here
 CFLAGS ?= -std=c99 -Wall -pedantic
@@ -20,30 +23,25 @@ CFLAGS ?= -std=c99 -Wall -pedantic
 # icons that will be installed via `make icon`
 ICONS = 16x16.png 32x32.png 48x48.png 64x64.png 128x128.png
 
-ifeq ($(HAVE_LIBEXIF), 1)
-	OPTIONAL_LIBS += -lexif
-else
-	HAVE_LIBEXIF = 0
-endif
-ifeq ($(HAVE_LIBGIF), 1)
-	OPTIONAL_LIBS += -lgif
-else
-	HAVE_LIBGIF = 0
-endif
-ifeq ($(HAVE_LIBWEBP), 1)
-	OPTIONAL_LIBS += -lwebpdemux -lwebp
-else
-	HAVE_LIBWEBP = 0
-endif
-
 CPPFLAGS = -D_XOPEN_SOURCE=700 \
   -DHAVE_LIBGIF=$(HAVE_LIBGIF) -DHAVE_LIBEXIF=$(HAVE_LIBEXIF) \
   -DHAVE_LIBWEBP=$(HAVE_LIBWEBP) \
   -I/usr/include/freetype2 -I$(PREFIX)/include/freetype2
 
-LDLIBS = -lImlib2 -lX11 -lXft -lfontconfig $(OPTIONAL_LIBS)
-
-OBJS = autoreload_$(AUTORELOAD).o commands.o image.o main.o options.o \
+lib_exif_0 =
+lib_exif_1 = -lexif
+lib_gif_0 =
+lib_gif_1 = -lgif
+lib_webp_0 =
+lib_webp_1 = -lwebpdemux -lwebp
+autoreload_0 = nop
+autoreload_1 = inotify
+# using += because certain *BSD distros may need to add additional flags
+LDLIBS += -lImlib2 -lX11 -lXft -lfontconfig \
+  $(lib_exif_$(HAVE_LIBEXIF)) $(lib_gif_$(HAVE_LIBGIF)) \
+  $(lib_webp_$(HAVE_LIBWEBP))
+
+OBJS = autoreload_$(autoreload_$(HAVE_INOTIFY)).o commands.o image.o main.o options.o \
   thumbs.o util.o window.o
 
 .PHONY: all clean install uninstall install-all install-icon uninstall-icon install-desktop
@@ -60,19 +58,10 @@ nsxiv: $(OBJS)
 	@echo "CC $@"
 	$(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
 
-$(OBJS): Makefile nsxiv.h commands.lst config.h config.mk
+$(OBJS): Makefile nsxiv.h commands.lst config.h
 options.o: version.h
 window.o: icon/data.h
 
-config.mk:
-	@echo "GEN $@"
-	@echo "# 0 = disable, 1 = enable" > config.mk
-	@for lib in exif gif webp; 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 config.def.h $@
@@ -85,7 +74,7 @@ version.h: Makefile .git/index
 .git/index:
 
 clean:
-	$(RM) *.o nsxiv
+	rm -f *.o nsxiv version.h
 
 install-all: install install-desktop install-icon
 
@@ -112,14 +101,18 @@ uninstall-icon:
 
 install: all
 	@echo "INSTALL bin/nsxiv"
-	install -Dt $(DESTDIR)$(PREFIX)/bin nsxiv
+	mkdir -p $(DESTDIR)$(PREFIX)/bin
+	cp nsxiv $(DESTDIR)$(PREFIX)/bin/
+	chmod 755 $(DESTDIR)$(PREFIX)/bin/nsxiv
 	@echo "INSTALL nsxiv.1"
 	mkdir -p $(DESTDIR)$(MANPREFIX)/man1
-	sed "s!DOCPREFIX!$(DOCPREFIX)!g; s!PREFIX!$(PREFIX)!g; s!VERSION!$(VERSION)!g" nsxiv.1 \
+	sed "s!EGPREFIX!$(EGPREFIX)!g; s!PREFIX!$(PREFIX)!g; s!VERSION!$(VERSION)!g" nsxiv.1 \
 		>$(DESTDIR)$(MANPREFIX)/man1/nsxiv.1
 	chmod 644 $(DESTDIR)$(MANPREFIX)/man1/nsxiv.1
 	@echo "INSTALL share/nsxiv/"
-	install -Dt $(DESTDIR)$(DOCPREFIX)/examples examples/*
+	mkdir -p $(DESTDIR)$(EGPREFIX)
+	cp examples/* $(DESTDIR)$(EGPREFIX)
+	chmod 755 $(DESTDIR)$(EGPREFIX)/*
 
 uninstall: uninstall-icon
 	@echo "REMOVE bin/nsxiv"
@@ -129,5 +122,5 @@ uninstall: uninstall-icon
 	@echo "REMOVE nsxiv.desktop"
 	rm -f $(DESTDIR)$(PREFIX)/share/applications/nsxiv.desktop
 	@echo "REMOVE share/nsxiv/"
-	rm -rf $(DESTDIR)$(DOCPREFIX)
+	rm -rf $(DESTDIR)$(EGPREFIX)
 
diff --git a/README.md b/README.md
index 2ffeebc..1c9d58f 100644
--- a/README.md
+++ b/README.md
@@ -49,11 +49,16 @@ nsxiv requires the following software to be installed:
   * freetype2
   * fontconfig
 
-The following libraries are optional. They are automatically enabled if installed.
+The following dependencies are optional.
 
+  * inotify : Used for auto-reloading images on change.
+    Disabled via `HAVE_INOTIFY=0`
   * giflib : Used for animated gif playback.
+    Disabled via `HAVE_LIBGIF=0`.
   * libexif : Used for auto-orientation and exif thumbnails.
+    Disable via `HAVE_LIBEXIF=0`
   * libwebp : Used for animated webp playback.
+    Disabled via `HAVE_LIBWEBP=0`.
 
 Please make sure to install the corresponding development packages in case that
 you want to build nsxiv on a distribution with separate runtime and development
@@ -67,14 +72,14 @@ nsxiv is built using the commands:
 
     $ make
 
-Running make will automatically detect if libexif and libgif are available and
-enable them if so. CLI arguments will override any automatic detection.
+You can pass `HAVE_X=0` to `make` to disable an optional dependency.
 For example:
 
-    $ make HAVE_LIBGIF=0
+    $ make HAVE_LIBEXIF=0
 
-will always disable libgif.
-Alternatively, they can be disabled via editing `config.mk`.
+will disable `libexif` support. Alternatively they can be disabled via editing
+the `Makefile` directly. `OPT_DEP_DEFAULT=0` can be used to disable all
+optional dependencies.
 
 Installing nsxiv:
 
@@ -102,9 +107,9 @@ You can install nsxiv into a directory of your choice by changing this command t
 
     $ make PREFIX="/your/dir" install
 
-Example scripts are installed using `DOCPREFIX` which defaults to
-`/usr/local/share/doc/nsxiv`. You can change `DOCPREFIX` the same way you can
-change `PREFIX` shown above.
+Example scripts are installed using `EGPREFIX` which defaults to
+`/usr/local/share/doc/nsxiv/examples`. You can change `EGPREFIX` the same way
+you can change `PREFIX` shown above.
 
 The build-time specific settings of nsxiv can be found in the file *config.h*.
 Please check and change them, so that they fit your needs.
diff --git a/nsxiv.1 b/nsxiv.1
index c9d971e..27b0914 100644
--- a/nsxiv.1
+++ b/nsxiv.1
@@ -428,7 +428,7 @@ and the arguments given to it are: 1) path to image file, 2) image width,
 3) image height.
 .P
 There is also an example script installed together with nsxiv as
-.IR DOCPREFIX/examples/image-info .
+.IR EGPREFIX/image-info .
 .SH EXTERNAL KEY HANDLER
 Additional external keyboard commands can be defined using a handler program
 located in
@@ -446,7 +446,7 @@ where C/M/S indicate Ctrl/Meta(Alt)/Shift modifier states and KEY is the X
 keysym as listed in /usr/include/X11/keysymdef.h without the "XK_" prefix.
 
 There is also an example script installed together with nsxiv as
-.IR DOCPREFIX/examples/key-handler .
+.IR EGPREFIX/key-handler .
 .SH THUMBNAIL CACHING
 nsxiv stores all thumbnails under
 .IR $XDG_CACHE_HOME/nsxiv/ .