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I am trying to compile a bunch of .c files and make them into an executable. One of these files(image.c) uses functions from the libcurl library, which is installed.

The problem arises when I hit the command

make

and I get the error message

undefined reference to 'curl_global_init'

I suspect that it's got something to do with the linker and the external library, as suggested in Undefined reference in make

But I don't know how to solve this.

Here's the Makefile

GPU=0
CUDNN=0
OPENCV=0
OPENMP=0
DEBUG=0

ARCH= -gencode arch=compute_30,code=sm_30 \
      -gencode arch=compute_35,code=sm_35 \
      -gencode arch=compute_50,code=[sm_50,compute_50] \
      -gencode arch=compute_52,code=[sm_52,compute_52]
#      -gencode arch=compute_20,code=[sm_20,sm_21] \ This one is deprecated?

# This is what I use, uncomment if you know your arch and want to specify
# ARCH= -gencode arch=compute_52,code=compute_52

VPATH=./src/:./examples
SLIB=libdarknet.so
ALIB=libdarknet.a
EXEC=darknet
OBJDIR=./obj/

CC=gcc
NVCC=nvcc
AR=ar
ARFLAGS=rcs
OPTS=-Ofast
LDFLAGS= -lm -pthread
COMMON= -Iinclude/ -Isrc/
CFLAGS=-Wall -Wno-unknown-pragmas -Wfatal-errors -fPIC

ifeq ($(OPENMP), 1)
CFLAGS+= -fopenmp
endif

ifeq ($(DEBUG), 1)
OPTS=-O0 -g
endif

CFLAGS+=$(OPTS)

ifeq ($(OPENCV), 1)
COMMON+= -DOPENCV
CFLAGS+= -DOPENCV
LDFLAGS+= `pkg-config --libs opencv`
COMMON+= `pkg-config --cflags opencv`
endif

ifeq ($(GPU), 1)
COMMON+= -DGPU -I/usr/local/cuda/include/
CFLAGS+= -DGPU
LDFLAGS+= -L/usr/local/cuda/lib64 -lcuda -lcudart -lcublas -lcurand
endif

ifeq ($(CUDNN), 1)
COMMON+= -DCUDNN
CFLAGS+= -DCUDNN
LDFLAGS+= -lcudnn
endif

OBJ=gemm.o utils.o cuda.o deconvolutional_layer.o convolutional_layer.o list.o image.o activations.o im2col.o col2im.o blas.o crop_layer.o dropout_layer.o maxpool_layer.o softmax_layer.o data.o matrix.o network.o connected_layer.o cost_layer.o parser.o option_list.o detection_layer.o route_layer.o box.o normalization_layer.o avgpool_layer.o layer.o local_layer.o shortcut_layer.o activation_layer.o rnn_layer.o gru_layer.o crnn_layer.o demo.o batchnorm_layer.o region_layer.o reorg_layer.o tree.o  lstm_layer.o
EXECOBJA=captcha.o lsd.o super.o art.o tag.o cifar.o go.o rnn.o segmenter.o regressor.o classifier.o coco.o yolo.o detector.o nightmare.o attention.o darknet.o
ifeq ($(GPU), 1)
LDFLAGS+= -lstdc++
OBJ+=convolutional_kernels.o deconvolutional_kernels.o activation_kernels.o im2col_kernels.o col2im_kernels.o blas_kernels.o crop_layer_kernels.o dropout_layer_kernels.o maxpool_layer_kernels.o avgpool_layer_kernels.o
endif

EXECOBJ = $(addprefix $(OBJDIR), $(EXECOBJA))
OBJS = $(addprefix $(OBJDIR), $(OBJ))
DEPS = $(wildcard src/*.h) Makefile include/darknet.h

#all: obj backup results $(SLIB) $(ALIB) $(EXEC)
all: obj  results $(SLIB) $(ALIB) $(EXEC)


$(EXEC): $(EXECOBJ) $(ALIB)
        $(CC) $(COMMON) $(CFLAGS) $^ -o $@ $(LDFLAGS) $(ALIB)

$(ALIB): $(OBJS)
        $(AR) $(ARFLAGS) $@ $^

$(SLIB): $(OBJS)
        $(CC) $(CFLAGS) -shared $^ -o $@ $(LDFLAGS)

$(OBJDIR)%.o: %.c $(DEPS)
        $(CC) $(COMMON) $(CFLAGS) -c $< -o $@

$(OBJDIR)%.o: %.cu $(DEPS)
        $(NVCC) $(ARCH) $(COMMON) --compiler-options "$(CFLAGS)" -c $< -o $@

obj:
        mkdir -p obj
backup:
        mkdir -p backup
results:
        mkdir -p results

.PHONY: clean

clean:
        rm -rf $(OBJS) $(SLIB) $(ALIB) $(EXEC) $(EXECOBJ)
XRZ
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  • Did you use the linker flag `-lcurl` in make file ? – ntshetty Feb 27 '18 at 03:25
  • Please share the content of your makefile rather than the one in the other question. – Ahmed Masud Feb 27 '18 at 03:25
  • @Thiru Shetty yes, same error shows up – XRZ Feb 27 '18 at 03:32
  • *libcurl library, which is installed* - there's no such a thing as *installed* library when you compile, only if it exists or not – SHG Feb 27 '18 at 03:32
  • @XRZ where did you install `libcurl`, if you installed into different location than standard, link with absolute path `-L/path/to/libcurl` – ntshetty Feb 27 '18 at 03:45
  • @ThiruShetty I tried make -L/usr/lib64 and make -L/usr/lib64/libcurl.so.4 but then I get a different error: make: invalid option -- '/' ... – XRZ Feb 27 '18 at 03:51
  • Please [edit] your code to reduce it to a [mcve] of your problem. You should be able to create something that doesn't need OpenMP, OpenCV and the rest. I see no reference to `curl` in that makefile (and at least some confusion of the roles of `LDFLAGS` and `LIBS`). A simple clear example would help us to see the problem. – Toby Speight Feb 27 '18 at 16:24

1 Answers1

0

Add the following lines after DEPS = $(wildcard src/*.h) Makefile include/darknet.h

CFLAGS+= -lcurl
LDFLAGS+= -lcurl

Hope it works for you.

ntshetty
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