在C Ruby扩展中使用curl / libcurl

#include <string.h>
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include \"ruby.h\"

VALUE Test = Qnil;

void Init_test();

VALUE download_file(VALUE self, VALUE from, VALUE to);

void Init_test()
{
    Test = rb_define_class(\"Test\", rb_cObject);
    rb_define_method(Test, \"download_file\", download_file, 2);
}

VALUE download_file(VALUE self, VALUE from, VALUE to)
{
    CURL *curl;
    FILE *fp;
    CURLcode res;

    char *url = STR2CSTR(from);
    char outfilename[FILENAME_MAX] = STR2CSTR(to);

    curl = curl_easy_init();
    if (curl) {
        fp = fopen(outfilename,\"wb\");
        curl_easy_setopt(curl, CURLOPT_URL, url);
        // curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
        res = curl_easy_perform(curl);
        curl_easy_cleanup(curl);
        fclose(fp);
    }
    return 0;
}

$ ruby test.rb
dyld: lazy symbol binding failed: Symbol not found: _curl_easy_init
  Referenced from: /path/to/test.bundle
  Expected in: flat namespace

dyld: Symbol not found: _curl_easy_init
  Referenced from: /path/to/test.bundle
  Expected in: flat namespace

Trace/BPT trap

require \'mkmf\'
extension_name = \'test\'
dir_config(extension_name)
create_makefile(extension_name)

curl-config --cflags

$  curl-config --cflags
-I/usr/local/include

/usr/local/include/curl/
/usr/local/lib/libcurl.dylib