CODEWITHSUNDEEP
c++cmakefile
Tony
Tony

Reputation: 1869

Building multiple shared libraries with one Makefile

I'm trying to build multiple shared libraries in one makefile. This is what I'm using to build one shared library:

CC = gcc # C compiler
PWD := $(shell pwd)
CFLAGS = -fPIC -Wall -Wextra -O2 -g # C flags
LDFLAGS = -shared  # linking flags

RM = rm -f  # rm command

CFLAGS += $(DFLAGS)

TARGET_LIB := lib1.so # target lib
#TARGET_LIB += lib2.so

SRCS := lib1.c # source files
#SRCS += lib2.c # source files

OBJS = $(SRCS:.c=.o)

.PHONY: all
all: $(TARGET_LIB)

$(TARGET_LIB): $(OBJS)
    $(CC) $(INC) $(LDFLAGS) $(CFLAGS) -o $@ $^

However, I can't just uncomment the lines for lib2 and have it being built as well. It's likely because $(TARGET_LIB): $(OBJS) expands to lib1.so lib2.so : lib1.o lib2.o which isn't what I want.

Instead, I want something like 

lib1.so : lib1.o

lib2.so : lib2.o

But I'm not sure how to do so or what it is called. Can someone tell me what to do to achieve what I'm looking for?

EDIT: I should have been more clear. I realize you can add more targets to build these. But is there a way to do it without having to write a new target everytime I want to add a new library?

Thanks.

Upvotes: 0

Views: 4555

Answers (4)

Mark Galeck
Mark Galeck

Reputation: 6395

The implicit rules are for that. Read about them in the GNU Make manual.

Replace

$(TARGET_LIB): $(OBJS)

with

%.so: %.c

Upvotes: 0

SHR
SHR

Reputation: 8333

You can do it by separating targets like this:

CC = gcc # C compiler
PWD := $(shell pwd)
CFLAGS = -fPIC -Wall -Wextra -O2 -g # C flags
LDFLAGS = -shared  # linking flags

RM = rm -f  # rm command

CFLAGS += $(DFLAGS)


TARGET_LIB1 = lib1.so # target lib
TARGET_LIB2 = lib2.so
TARGET_LIBS = $(TARGET_LIB1) $(TARGET_LIB2)

SRCS1 = lib1.c # source files
SRCS2 = lib2.c # source files
SRCS = $(SRCS1) $(SRCS2) 

OBJS1 = $(SRCS1:.c=.o)
OBJS2 = $(SRCS2:.c=.o)
OBJS = $(OBJS1) $(OBJS2)

.PHONY: all
all: $(TARGET_LIBS)

$(TARGET_LIB1): $(OBJS1)
    $(CC) $(INC) $(LDFLAGS) $(CFLAGS) -o $@ $^

$(TARGET_LIB2): $(OBJS2)
    $(CC) $(INC) $(LDFLAGS) $(CFLAGS) -o $@ $^

Upvotes: 0

pugnator
pugnator

Reputation: 725

You can separate sources of two libraries into different directories. It also may help in further maintenance of your libraries. Then use one make file which will trigger corresponding sub-makefiles. I may be better than one big makefile

Upvotes: 0

John_Avi_09
John_Avi_09

Reputation: 338

You can do something like this -

all : lib1.so lib2.so

and provide rules to make lib1.so and lib2.so

Upvotes: 2

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