Question

当我尝试编译单元测试文件时，我得到'未定义的引用`dlsym'错误。我在Unix系统上读到了（我在Ubuntu 12.04上）将-ldl添加到编译器中，但我尝试使用Zed的Shaw Makefile但仍然没有发生任何事情。这是代码：

CFLAGS=-g -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG $(OPTFLAGS)
LIBS=-ldl $(OPTLIBS)
PREFIX?=/usr/local

SOURCES=$(wildcard src/**/*.c src/*.c)
OBJECTS=$(patsubst %.c,%.o,$(SOURCES))

TEST_SRC=$(wildcard tests/*_tests.c)
TESTS=$(patsubst %.c,%,$(TEST_SRC))

TARGET=build/libex29.a
SO_TARGET=$(patsubst %.a,%.so,$(TARGET))

# The Target Build
all: $(TARGET) $(SO_TARGET) tests

dev:    CFLAGS=-g -Wall -Isrc -Wall -Wextra $(OPTFLAGS)
dev:    all

$(TARGET): CFLAGS += -fPIC
$(TARGET): build $(OBJECTS)
    ar rcs $@ $(OBJECTS)
    ranlib $@

$(SO_TARGET): $(TARGET) $(OBJECTS)
    $(CC) -shared -o $@ $(OBJECTS)

build:
    @mkdir -p build
    @mkdir -p bin

# The Unit Tests
.PHONY: tests
tests: CFLAGS += $(TARGET) 
tests: $(TESTS)
    sh ./tests/runtests.sh

valgrind:
    VALGRIND="valgrind --log-file=/tmp/valgrind-%p.log" $(MAKE)

# The Cleaner
clean:
    rm -rf build $(OBJECTS) $(TESTS)
    rm -f tests/tests.log
    find . -name "*.gc*" -exec rm {} \;
    rm -rf `find . -name "*.dSYM" -print`

# The Install
install: all
    install -d $(DESTDIR)/$(PREFIX)/lib/
    install $(TARGET) $(DESTDIR)/$(PREFIX)/lib/

记录的错误：

michal@ubuntu:~/Documents/projectsc/c-skeleton$ make
ar rcs build/libex29.a src/libex29.o
ranlib build/libex29.a
cc -shared -o build/libex29.so src/libex29.o
cc -g -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG -LIBS  build/libex29.a     tests/libex29_tests.c   -o tests/libex29_tests
tests/libex29_tests.c: In function ‘main’:
tests/libex29_tests.c:66:1: warning: parameter ‘argc’ set but not used [-Wunused-but-set-parameter]
/tmp/ccRX6ddf.o: In function `check_function':
/home/michal/Documents/projectsc/c-skeleton/tests/libex29_tests.c:10: undefined reference to `dlsym'
/home/michal/Documents/projectsc/c-skeleton/tests/libex29_tests.c:11: undefined reference to `dlerror'
/tmp/ccRX6ddf.o: In function `test_dlopen':
/home/michal/Documents/projectsc/c-skeleton/tests/libex29_tests.c:24: undefined reference to `dlopen'
/tmp/ccRX6ddf.o: In function `test_dlclose':
/home/michal/Documents/projectsc/c-skeleton/tests/libex29_tests.c:49: undefined reference to `dlclose'
collect2: ld returned 1 exit status
make: *** [tests/libex29_tests] Error 1

正如我所说，我试图将'-ldl-添加到CFLAGS，SO_TARGET变量，几乎所有的东西，根据我的分析，这可能会有所帮助，但这并没有改变任何东西。

Answer 1

阅读此问题后：Library Linking

我将LIBS更改为LDLIBS，这对我有用。

LDLIBS=-ldl $(OPTLIBS)

Answer 2

我认为这不是makefile的问题。您可能在libex29_tests.c中有错误的链接文件。在您的目录中发布此文件和文件树中的标题。

Answer 3

对于同样的问题，对我有用的是添加-Wl,--no-as-needed作为链接器参数。

未明确引用`dlsym'学习C艰难之路

3 个答案: