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|
const std = @import("std");
const builtin = @import("builtin");
pub fn build(_: *std.Build) !void {}
// Configure the step to point to the Android NDK for libc and include
// paths. This requires the Android NDK installed in the system and
// setting the appropriate environment variables or installing the NDK
// in the default location.
//
// The environment variables can be set as follows:
// - `ANDROID_NDK_HOME`: Directly points to the NDK path, including the version.
// - `ANDROID_HOME` or `ANDROID_SDK_ROOT`: Points to the Android SDK path;
// latest available NDK will be automatically selected.
//
// NB: This is a workaround until zig natively supports bionic
// cross-compilation (ziglang/zig#23906).
pub fn addPaths(b: *std.Build, step: *std.Build.Step.Compile) !void {
const Cache = struct {
const Key = struct {
arch: std.Target.Cpu.Arch,
abi: std.Target.Abi,
api_level: u32,
};
var map: std.AutoHashMapUnmanaged(Key, ?struct {
libc: std.Build.LazyPath,
cpp_include: std.Build.LazyPath,
lib: std.Build.LazyPath,
}) = .empty;
};
const target = step.rootModuleTarget();
const gop = try Cache.map.getOrPut(b.allocator, .{
.arch = target.cpu.arch,
.abi = target.abi,
.api_level = target.os.version_range.linux.android,
});
if (!gop.found_existing) {
const ndk_path = findNDKPath(b) orelse return error.AndroidNDKNotFound;
const ndk_triple = ndkTriple(target) orelse {
gop.value_ptr.* = null;
return error.AndroidNDKUnsupportedTarget;
};
const host = hostTag() orelse {
gop.value_ptr.* = null;
return error.AndroidNDKUnsupportedHost;
};
const sysroot = b.pathJoin(&.{
ndk_path,
"toolchains",
"llvm",
"prebuilt",
host,
"sysroot",
});
const include_dir = b.pathJoin(&.{
sysroot,
"usr",
"include",
});
const sys_include_dir = b.pathJoin(&.{
sysroot,
"usr",
"include",
ndk_triple,
});
const c_runtime_dir = b.pathJoin(&.{
sysroot,
"usr",
"lib",
ndk_triple,
b.fmt("{d}", .{target.os.version_range.linux.android}),
});
const lib = b.pathJoin(&.{
sysroot,
"usr",
"lib",
ndk_triple,
});
const cpp_include = b.pathJoin(&.{
sysroot,
"usr",
"include",
"c++",
"v1",
});
const libc_txt = b.fmt(
\\include_dir={s}
\\sys_include_dir={s}
\\crt_dir={s}
\\msvc_lib_dir=
\\kernel32_lib_dir=
\\gcc_dir=
, .{ include_dir, sys_include_dir, c_runtime_dir });
const wf = b.addWriteFiles();
const libc_path = wf.add("libc.txt", libc_txt);
gop.value_ptr.* = .{
.libc = libc_path,
.cpp_include = .{ .cwd_relative = cpp_include },
.lib = .{ .cwd_relative = lib },
};
}
const value = gop.value_ptr.* orelse return error.AndroidNDKNotFound;
step.setLibCFile(value.libc);
step.root_module.addSystemIncludePath(value.cpp_include);
step.root_module.addLibraryPath(value.lib);
}
fn findNDKPath(b: *std.Build) ?[]const u8 {
// Check if user has set the environment variable for the NDK path.
if (b.graph.environ_map.get("ANDROID_NDK_HOME")) |value| {
if (value.len == 0) return null;
var dir = std.Io.Dir.openDirAbsolute(b.graph.io, value, .{}) catch return null;
defer dir.close(b.graph.io);
return value;
}
// Check the common environment variables for the Android SDK path and look for the NDK inside it.
inline for (.{ "ANDROID_HOME", "ANDROID_SDK_ROOT" }) |env| {
if (b.graph.environ_map.get(env)) |sdk| {
if (sdk.len > 0) {
if (findLatestNDK(b, sdk)) |ndk| return ndk;
}
}
}
// As a fallback, we assume the most common/default SDK path based on the OS.
const home = b.graph.environ_map.get(
if (builtin.os.tag == .windows) "LOCALAPPDATA" else "HOME",
) orelse return null;
const default_sdk_path = b.pathJoin(
&.{
home,
switch (builtin.os.tag) {
.linux, .windows => "Android/Sdk",
.macos => "Library/Android/Sdk",
else => return null,
},
},
);
return findLatestNDK(b, default_sdk_path);
}
fn findLatestNDK(b: *std.Build, sdk_path: []const u8) ?[]const u8 {
const ndk_dir = b.pathJoin(&.{ sdk_path, "ndk" });
var dir = std.Io.Dir.openDirAbsolute(b.graph.io, ndk_dir, .{ .iterate = true }) catch return null;
defer dir.close(b.graph.io);
var latest_: ?struct {
name: []const u8,
version: std.SemanticVersion,
} = null;
var iterator = dir.iterate();
while (iterator.next(b.graph.io) catch null) |file| {
if (file.kind != .directory) continue;
const version = std.SemanticVersion.parse(file.name) catch continue;
if (latest_) |latest| {
if (version.order(latest.version) != .gt) continue;
}
latest_ = .{
.name = file.name,
.version = version,
};
}
const latest = latest_ orelse return null;
return b.pathJoin(&.{ sdk_path, "ndk", latest.name });
}
fn hostTag() ?[]const u8 {
return switch (builtin.os.tag) {
.linux => "linux-x86_64",
// All darwin hosts use the same prebuilt binaries
// (https://developer.android.com/ndk/guides/other_build_systems).
.macos => "darwin-x86_64",
.windows => "windows-x86_64",
else => null,
};
}
// We must map the target architecture to the corresponding NDK triple following the NDK
// documentation: https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md#architectures
fn ndkTriple(target: std.Target) ?[]const u8 {
return switch (target.cpu.arch) {
.arm => "arm-linux-androideabi",
.aarch64 => "aarch64-linux-android",
.x86 => "i686-linux-android",
.x86_64 => "x86_64-linux-android",
else => null,
};
}
|
