在go项目中使用cgo包含libsodium失败

Question

I am trying to include the libsodium into my Go project. For that, I've copied the repo inside my project

// #cgo CFLAGS: -I/mypath/libsodium/src/libsodium/include/sodium
// #include <stdlib.h>
// #include "crypto_sign_ed25519.h"
import "C"

When trying to build the project I get the following error:

/tmp/go-build/cgo-gcc-prolog:53: undefined reference to `crypto_sign_ed25519_pk_to_curve25519'
collect2: error: ld returned 1 exit status

The file can be found but the error is there. I've also tried to reference the '.c' file as well as to copy the crypto_sign_ed25519.h into the src folder but it does not work. My question is do I have to add LDFLAGS and therefore generate a .so file from the library or that is not needed and there is another possible way of doing it?

UPDATE: I've achieved to make it running by installing the library on my local ubuntu:

$ ./configure
$ make && make check
$ sudo make install

and adding // #cgo LDFLAGS: -L/usr/local/lib -lsodium But how can I do it without adding the local path?

Answer 1

You indeed need to link the library, the headers themselves are only the interface to the library and don't link the actual libsodium code to your binary.

Assuming libsodium ships a pkg-config file (it seems to be the case), you can use something like

// #cgo pkg-config: libsodium
// #include "crypto_sign_ed25519.h"

See https://golang.org/cmd/cgo/ for more information about pkg-config support.

To see what cflags/libs you'd be getting (so what cgo will use), run:

pkg-config --cflags --libs libsodium