linux: Enable PIE

PIE (position-independent executables) is a security feature
that has been made reasonably cheap by recent improvements in
GCC; as a result, more and more Linux distributions are pushing
for its adoption.

Unfortunately, PIE and PIC are not compatible, so we have to
manage the CFLAGS and LDFLAGS used to compile the library and
the executable indipendently.

diff --git a/linux/Makefile b/linux/Makefile
index 74f648a87ab1292ef0269b9540dbe29004e5ca5b..bad2b0b8aae73fd0cfc90d1dca537da935aac599 100644 (file)
--- a/linux/Makefile
+++ b/linux/Makefile
@@ -17,27 +17,31 @@ ifneq ("${BUILDVERSION}", "")
 MAINT_CPPFLAGS += -DSPECTRWM_BUILDSTR=\"$(BUILDVERSION)\"
 endif
 
+BIN_CFLAGS   = -fPIE
+BIN_LDFLAGS  = -fPIE -pie
 BIN_CPPFLAGS = $(shell pkg-config --cflags x11 x11-xcb xcb-icccm xcb-keysyms xcb-randr xcb-util xcb-xtest xcursor xft)
 BIN_LDLIBS   = $(shell pkg-config --libs   x11 x11-xcb xcb-icccm xcb-keysyms xcb-randr xcb-util xcb-xtest xcursor xft)
+LIB_CFLAGS   = -fPIC
+LIB_LDFLAGS  = -fPIC -shared
 LIB_CPPFLAGS = $(shell pkg-config --cflags x11)
 LIB_LDLIBS   = $(shell pkg-config --libs   x11) -ldl
 
 all: spectrwm libswmhack.so.$(LIBVERSION)
 
 spectrwm: spectrwm.o linux.o
-       $(CC) $(MAINT_LDFLAGS) $(LDFLAGS) -o $@ $+ $(BIN_LDLIBS) $(LDLIBS)
+       $(CC) $(MAINT_LDFLAGS) $(BIN_LDFLAGS) $(LDFLAGS) -o $@ $+ $(BIN_LDLIBS) $(LDLIBS)
 
 spectrwm.o: ../spectrwm.c ../version.h tree.h util.h
-       $(CC) $(MAINT_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(BIN_CPPFLAGS) $(CPPFLAGS) -c -o $@ $<
+       $(CC) $(MAINT_CFLAGS) $(BIN_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(BIN_CPPFLAGS) $(CPPFLAGS) -c -o $@ $<
 
 linux.o: linux.c util.h
-       $(CC) $(MAINT_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(BIN_CPPFLAGS) $(CPPFLAGS) -c -o $@ $<
+       $(CC) $(MAINT_CFLAGS) $(BIN_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(BIN_CPPFLAGS) $(CPPFLAGS) -c -o $@ $<
 
 libswmhack.so.$(LIBVERSION): swm_hack.so
-       $(CC) $(MAINT_LDFLAGS) $(LDFLAGS) -Wl,-soname,$@ -shared -fPIC -o $@ $+ $(LIB_LDLIBS) $(LDLIBS)
+       $(CC) $(MAINT_LDFLAGS) $(LIB_LDFLAGS) $(LDFLAGS) -Wl,-soname,$@ -o $@ $+ $(LIB_LDLIBS) $(LDLIBS)
 
 swm_hack.so: ../lib/swm_hack.c
-       $(CC) $(MAINT_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(LIB_CPPFLAGS) $(CPPFLAGS) -fPIC -c -o $@ $<
+       $(CC) $(MAINT_CFLAGS) $(LIB_CFLAGS) $(CFLAGS) $(MAINT_CPPFLAGS) $(LIB_CPPFLAGS) $(CPPFLAGS) -c -o $@ $<
 
 clean:
        rm -f spectrwm *.o libswmhack.so.* *.so