init

This builds a very basic version of the nats.c client (no TLS, no
streaming/jetstream/whatever, since those bring in complex
dependencies and I do not need them at the moment). Right now it
contains a simple test program that demonstrates the functionality
(cool!), but the plan is for the nats.zig to bind the API into a
nicer, zig-like shape and re-export it. Then this becomes a package.
The current function could become a test, though it's a bit complex
for a unit test (and requires connecting to an externally-running NATS
server in order to work).

nats-c.build.zig

@@ -0,0 +1,124 @@
+const std = @import("std");
+
+const NatsCOptions = struct {
+    name: []const u8,
+    target: std.zig.CrossTarget,
+    optimize: std.builtin.OptimizeMode,
+};
+
+pub fn nats_c_lib(
+    b: *std.Build,
+    options: NatsCOptions,
+) *std.Build.Step.Compile {
+    const lib = b.addStaticLibrary(.{
+        .name = options.name,
+        .target = options.target,
+        .optimize = options.optimize,
+    });
+
+    lib.disable_sanitize_c = true;
+
+    lib.linkLibC();
+    lib.addCSourceFiles(&common_sources, &.{"-fno-sanitize=undefined"});
+    lib.addIncludePath(.{ .path = nats_src_prefix ++ "include" });
+    // if building with streaming support
+    // lib.addIncludePath(.{ .path = nats_src_prefix ++ "stan" });
+    // lib.addCSourceFiles(&streaming_sources, &.{"-fno-sanitize=undefined"});
+
+    switch (lib.target_info.target.os.tag) {
+        .windows => {
+            lib.addCSourceFiles(&win_sources, &.{"-fno-sanitize=undefined"});
+            lib.defineCMacro("_WIN32", null);
+            lib.linkSystemLibrary("Ws2_32");
+        },
+        .macos => {
+            lib.addCSourceFiles(&unix_sources, &.{"-fno-sanitize=undefined"});
+            lib.defineCMacro("DARWIN", null);
+        },
+        else => {
+            lib.addCSourceFiles(&unix_sources, &.{"-fno-sanitize=undefined"});
+            lib.defineCMacro("_GNU_SOURCE", null);
+            lib.defineCMacro("LINUX", null);
+            // may need to link pthread and rt. Not sure if those are inluded with linkLibC
+            lib.linkSystemLibrary("pthread");
+            lib.linkSystemLibrary("rt");
+        },
+    }
+
+    lib.defineCMacro("_REENTRANT", null);
+
+    inline for (install_headers) |header| {
+        lib.installHeader(nats_src_prefix ++ header, "nats/" ++ header);
+    }
+
+    b.installArtifact(lib);
+
+    return lib;
+}
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    _ = nats_c_lib(b, .{ .name = "nats-c", .target = target, .optimize = optimize });
+}
+
+const nats_src_prefix = "deps/nats.c/src/";
+
+const install_headers = [_][]const u8{
+    "nats.h",
+    "status.h",
+    "version.h",
+};
+
+const common_sources = [_][]const u8{
+    nats_src_prefix ++ "asynccb.c",
+    nats_src_prefix ++ "comsock.c",
+    nats_src_prefix ++ "crypto.c",
+    nats_src_prefix ++ "js.c",
+    nats_src_prefix ++ "kv.c",
+    nats_src_prefix ++ "nats.c",
+    nats_src_prefix ++ "nkeys.c",
+    nats_src_prefix ++ "opts.c",
+    nats_src_prefix ++ "pub.c",
+    nats_src_prefix ++ "stats.c",
+    nats_src_prefix ++ "sub.c",
+    nats_src_prefix ++ "url.c",
+    nats_src_prefix ++ "buf.c",
+    nats_src_prefix ++ "conn.c",
+    nats_src_prefix ++ "hash.c",
+    nats_src_prefix ++ "jsm.c",
+    nats_src_prefix ++ "msg.c",
+    nats_src_prefix ++ "natstime.c",
+    nats_src_prefix ++ "nuid.c",
+    nats_src_prefix ++ "parser.c",
+    nats_src_prefix ++ "srvpool.c",
+    nats_src_prefix ++ "status.c",
+    nats_src_prefix ++ "timer.c",
+    nats_src_prefix ++ "util.c",
+};
+
+const unix_sources = [_][]const u8{
+    nats_src_prefix ++ "unix/cond.c",
+    nats_src_prefix ++ "unix/mutex.c",
+    nats_src_prefix ++ "unix/sock.c",
+    nats_src_prefix ++ "unix/thread.c",
+};
+
+const win_sources = [_][]const u8{
+    nats_src_prefix ++ "win/cond.c",
+    nats_src_prefix ++ "win/mutex.c",
+    nats_src_prefix ++ "win/sock.c",
+    nats_src_prefix ++ "win/strings.c",
+    nats_src_prefix ++ "win/thread.c",
+};
+
+const streaming_sources = [_][]const u8{
+    nats_src_prefix ++ "stan/conn.c",
+    nats_src_prefix ++ "stan/copts.c",
+    nats_src_prefix ++ "stan/msg.c",
+    nats_src_prefix ++ "stan/protocol.pb-c.c",
+    nats_src_prefix ++ "stan/pub.c",
+    nats_src_prefix ++ "stan/sopts.c",
+    nats_src_prefix ++ "stan/sub.c",
+};