#
# somewhat elaborate makefile illustrating various ways of putting 
# code into a library and using it
#
# more info in comments preceding targets for executables 
#
EXECUTABLES=\
			main \
			main-with-static \
			main-with-shared main-with-shared-rpath \
			main-dynamic main-dynamic-rpath
CC = gcc
CFLAGS = -Wall -std=c99 -pedantic

OBJ_S=foo.o bar.o
OBJ_L=foo-pic.o bar-pic.o

LIB_S=test
LIB_S_FILE=lib$(LIB_S).a
LIB_L=test_s
LIB_L_NAME=lib$(LIB_L).so
LIB_L_SONAME=$(LIB_L_NAME).1
LIB_L_FILE=$(LIB_L_SONAME).0

all: $(EXECUTABLES)

clean:
	rm -v *.o $(LIB_S_FILE) $(LIB_L_NAME)* $(EXECUTABLES) 

# 
# rules for creating libraries
#

# generate executable by compiling separately and linking
# (uses makefile implicit rules)
main: main.o foo.o bar.o

# generate executable using static library
main-with-static: main.o $(LIB_S_FILE)
	$(CC) -o $@ $< -L. -l$(LIB_S)

# generate executable using shared library
# must set LD_LIBRARY_PATH at runtime
main-with-shared: main.o $(LIB_L_NAME)
	$(CC) -o $@ $< -L. -l$(LIB_L)

# generate executable using shared library, in a way that includes
#   its location in executable
main-with-shared-rpath: main.o $(LIB_L_NAME)
	$(CC) -Wl,-rpath=. -o $@ $< -L. -l$(LIB_L)

# generate executable for example using runtime loading
# must set LD_LIBRARY_PATH at runtime
main-dynamic: main-dynamic.o $(LIB_L_NAME)
	gcc -rdynamic -o $@ $< -ldl

# generate executable for example using runtime loading, in a way
#   that includes its location in executable
main-dynamic-rpath: main-dynamic.o $(LIB_L_NAME)
	gcc -Wl,-rpath=. -rdynamic -o $@ $< -ldl

#
# rules for generating libraries
# (also takes advantage of implicit rules for compiling C)

%-pic.o : %.c
	$(CC) $(CFLAGS) -fPIC -c $< -o $@

$(LIB_S_FILE): $(OBJ_S)
	ar -cvq $@ $^

$(LIB_L_FILE): $(OBJ_L)
	$(CC) -shared -Wl,-soname=$(LIB_L_SONAME) -o $@ $^

$(LIB_L_SONAME): $(LIB_L_FILE)
	ln -s $< $@

$(LIB_L_NAME): $(LIB_L_SONAME)
	ln -s $< $@