Enterprise LibCurl with Zigler

enterprise_curl.exs

Mix.install([
  {:zigler, "~> 0.13"}
])

Logger.configure(level: :warning)

defmodule Main do
  use Zig,
    otp_app: :zigler,
    c: [link_lib: {:system, "curl"}],
    nifs: [example: [:dirty_io]]

  ~Z"""
  const std = @import("std");
  const curl = @cImport({
    @cInclude("curl/curl.h");
  });
  const beam = @import("beam");

  const EzOptions = enum (c_int) {
    user_agent = curl.CURLOPT_USERAGENT,
    url = curl.CURLOPT_URL,
  };

  const ExampleOptions = struct{
    user_agent: ?[]const u8 = "libcurl",
    url: ?[]const u8 = null
  };

  pub fn example(opts: ExampleOptions) !void {
    const c = curl.curl_easy_init() orelse return error.initialization_failure;
    const tags = comptime std.meta.tags(EzOptions);
    inline for (tags) | field | {
       if (@field(opts, @tagName(field))) | opt | {
         // annoying, perform null termination, better support for null-terminated
         // slices will drop in zigler 0.14

         const opt_str: [:0]u8 = try beam.allocator.allocWithOptions(u8, opt.len + 1, null, 0);
         defer beam.allocator.free(opt_str);

         @memcpy(opt_str[0..opt.len], opt);
         opt_str[opt.len] = 0;

         _ = curl.curl_easy_setopt(c, @intFromEnum(field), opt_str.ptr);
       }
    }

    _ = curl.curl_easy_perform(c);
  }
  """
end

Main.example(url: "https://httpbin.org/user-agent")
Main.example(url: "https://httpbin.org/user-agent", user_agent: "foobarbaz")