turbonss/lib/libnss.zig

const std = @import("std");
const os = std.os;
const fmt = std.fmt;
const mem = std.mem;
const process = std.process;

const DB = @import("DB.zig");
const File = @import("File.zig");
const CGroup = @import("Group.zig").CGroup;
const PackedGroup = @import("PackedGroup.zig");
const CUser = @import("User.zig").CUser;
const PackedUser = @import("PackedUser.zig");

const c = @cImport({
    @cInclude("nss.h");
});

const TURBONSS_DB = "DB";
const TURBONSS_VERBOSE = "TURBONSS_VERBOSE";
const TURBONSS_OMIT_MEMBERS = "TURBONSS_OMIT_MEMBERS";

extern fn putenv(name: [*:0]const u8, value: [*:0]const u8, overwrite: c_int) c_int;
extern fn getenv(name: [*:0]const u8) ?[*:0]const u8;

export const turbonss_default_path: [:0]const u8 = "/etc/turbonss/db.turbo";

// State is a type of the global variable holding the process state:
// the DB handle and all the iterators.
const State = struct {
    file: ?File,
    getpwent_iterator: ?PackedUser.Iterator,
    getgrent_iterator: ?PackedGroup.Iterator,
    omit_members: bool,
    verbose: bool = false,

    fn debug(self: *const State, comptime format: []const u8, args: anytype) void {
        self.log(.debug, format, args);
    }
    fn info(self: *const State, comptime format: []const u8, args: anytype) void {
        self.log(.info, format, args);
    }
    fn err(self: *const State, comptime format: []const u8, args: anytype) void {
        self.log(.err, format, args);
    }
    fn log(
        self: *const State,
        comptime level: std.log.Level,
        comptime format: []const u8,
        args: anytype,
    ) void {
        if (!self.verbose) return;
        const stderr = std.io.getStdErr().writer();
        std.debug.getStderrMutex().lock();
        defer std.debug.getStderrMutex().unlock();
        stderr.print("[" ++ level.asText() ++ "] " ++ format ++ "\n", args) catch return;
    }
};

// state is initialized on library startup.
var state: State = undefined;

// constructor
export fn _turbo_init() void {
    //if (os.getenvZ(TURBONSS_VERBOSE)) |env|
    //    state.verbose = mem.eql(u8, env, "1");

    if (getenv(TURBONSS_VERBOSE)) |env| {
        const envZ = mem.sliceTo(env, 0);
        state.verbose = mem.eql(u8, envZ, "1");
    }

    //std.debug.print("TURBONSS_VERBOSE: {s}\n", .{os.getenv(TURBONSS_VERBOSE)});
    std.debug.print("TURBONSS_VERBOSE: {s}\n", .{getenv(TURBONSS_VERBOSE)});
    std.debug.print("verbose: {any}\n", .{state.verbose});

    const fname = os.getenvZ(TURBONSS_DB) orelse turbonss_default_path[0..];
    state.debug("opening {s}", .{fname});
    state.file = File.open(fname) catch |err| {
        state.err("open {s}: {s}", .{ fname, @errorName(err) });
        return;
    };
    state.debug("turbonss database opened", .{});

    const omit_members_env = os.getenvZ(TURBONSS_OMIT_MEMBERS) orelse "auto";
    state.omit_members = shouldOmitMembers(omit_members_env, os.argv);
    state.debug("omitting members from getgr* calls: {any}\n", .{state.omit_members});

    return;
}

fn shouldOmitMembers(env: []const u8, argv: [][*:0]u8) bool {
    if (mem.eql(u8, env, "1")) return true;
    if (mem.eql(u8, env, "0")) return false;
    if (argv.len == 0) return false;

    return mem.eql(u8, mem.sliceTo(argv[0], 0), "id");
}

// destructor
export fn _turbo_fini() void {
    if (state.file) |*fooo|
        fooo.close();
}

export fn _nss_turbo_getpwuid_r(
    uid: c_uint,
    res: *CUser,
    buf: [*]u8,
    len: usize,
    errnop: *c_int,
) c.enum_nss_status {
    if (state.file == null) {
        errnop.* = @enumToInt(os.E.AGAIN);
        return c.NSS_STATUS_UNAVAIL;
    }
    const cuser = state.file.?.db.getpwuid(uid, &buf[0..len]) catch |err| switch (err) {
        error.OutOfMemory => {
            errnop.* = @enumToInt(os.E.RANGE);
            return c.NSS_STATUS_TRYAGAIN;
        },
    };

    if (cuser == null) {
        errnop.* = @enumToInt(os.E.NOENT);
        return c.NSS_STATUS_NOTFOUND;
    }
    res.* = cuser.?;

    return c.NSS_STATUS_SUCCESS;
}

const testing = std.testing;

test "nss_turbo_getpwuid_r" {
    var tf = try File.TestFile.init(testing.allocator);
    defer tf.deinit(testing.allocator);

    var env = try process.getEnvMap(testing.allocator);
    defer env.deinit();

    try testing.expectEqual(putenv(TURBONSS_VERBOSE, "1", 1), 0);
    try testing.expectEqual(putenv(TURBONSS_DB, tf.path, 1), 0);
    _turbo_init();
    try testing.expect(state.file != null);

    var buf = try testing.allocator.alloc(u8, state.file.?.db.getpwBufsize());
    var user: CUser = undefined;
    var errno: c_int = undefined;
    const ret = _nss_turbo_getpwuid_r(128, &user, buf.ptr, buf.len, &errno);
    try testing.expectEqual(ret, c.NSS_STATUS_SUCCESS);
}