exec.zig

1// exec.zig — all process execution and SSH routing2// Commands call these functions; output is streamed or captured here.3const std = @import("std");4const builtin = @import("builtin");5const types = @import("types.zig");6const errors = @import("errors.zig");7const output = @import("output.zig");89// nixos-rebuild manages this profile; generation commands must target it10// explicitly. Bare nix-env defaults to the per-user profile, which is empty.11const SYSTEM_PROFILE = "/nix/var/nix/profiles/system";1213pub const RunResult = struct {14    stdout: []u8,15    stderr: []u8,16    exit_code: u8,17};1819// Run a process and capture stdout+stderr (not streaming).20pub fn capture(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, cmd: []const []const u8) !RunResult {21    const argv = try buildArgv(gpa, machine, cmd);22    defer if (!machine.local) gpa.free(argv);2324    const result = std.process.run(gpa, io, .{ .argv = argv }) catch |e| {25        errors.error_info.setMessage("process failed: {s}", .{cmd[0]});26        return e;27    };2829    return .{30        .stdout = result.stdout,31        .stderr = result.stderr,32        .exit_code = switch (result.term) {33            .exited => |c| c,34            else => 1,35        },36    };37}3839// Run a process and stream its output to the terminal (inherit stdio).40pub fn stream(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, cmd: []const []const u8) !u8 {41    // The child inherits stdout and writes directly to the fd; flush any buffered42    // nina header first so it isn't reordered after the child's output.43    output.flush();44    const argv = try buildArgv(gpa, machine, cmd);45    defer if (!machine.local) gpa.free(argv);4647    var child = std.process.spawn(io, .{48        .argv = argv,49        .stdin = .inherit,50        .stdout = .inherit,51        .stderr = .inherit,52    }) catch |e| {53        errors.error_info.setMessage("failed to spawn: {s}", .{cmd[0]});54        return e;55    };5657    const term = child.wait(io) catch |e| {58        errors.error_info.setMessage("process wait failed", .{});59        return e;60    };6162    return switch (term) {63        .exited => |c| c,64        else => 1,65    };66}6768// Stream a local process with inherited stdio (no SSH routing — for nix commands).69pub fn streamLocal(io: std.Io, cmd: []const []const u8) !u8 {70    output.flush();71    var child = std.process.spawn(io, .{72        .argv = cmd,73        .stdin = .inherit,74        .stdout = .inherit,75        .stderr = .inherit,76    }) catch |e| {77        errors.error_info.setMessage("failed to spawn: {s}", .{cmd[0]});78        return e;79    };80    const term = child.wait(io) catch {81        errors.error_info.setMessage("process wait failed", .{});82        return error.ProcessFailed;83    };84    return switch (term) {85        .exited => |c| c,86        else => 1,87    };88}8990// Run a process and capture output as a single string (no SSH routing — for local nix commands).91pub fn captureLocal(gpa: std.mem.Allocator, io: std.Io, cmd: []const []const u8) ![]u8 {92    const result = std.process.run(gpa, io, .{ .argv = cmd }) catch return error.ProcessFailed;93    defer gpa.free(result.stderr);94    switch (result.term) {95        .exited => |c| if (c != 0) {96            gpa.free(result.stdout);97            return error.ProcessFailed;98        },99        else => {100            gpa.free(result.stdout);101            return error.ProcessFailed;102        },103    }104    return result.stdout;105}106107fn buildArgv(gpa: std.mem.Allocator, machine: *const types.Machine, cmd: []const []const u8) ![]const []const u8 {108    if (machine.local) return cmd;109110    const host = machine.host orelse {111        errors.error_info.setMessage("machine '{s}' has no host configured", .{machine.name});112        return error.SshFailed;113    };114115    var ssh: std.ArrayList([]const u8) = .empty;116    try ssh.append(gpa, "ssh");117    try ssh.append(gpa, "-o");118    try ssh.append(gpa, "BatchMode=yes");119    try ssh.append(gpa, "-o");120    try ssh.append(gpa, "StrictHostKeyChecking=accept-new");121    if (machine.ssh_key) |key| {122        try ssh.append(gpa, "-i");123        try ssh.append(gpa, key);124    }125    const addr = if (machine.user) |u|126        try std.fmt.allocPrint(gpa, "{s}@{s}", .{ u, host })127    else128        try gpa.dupe(u8, host);129    try ssh.append(gpa, addr);130    for (cmd) |arg| try ssh.append(gpa, arg);131    return ssh.toOwnedSlice(gpa);132}133134// --- NixOS rebuild ---135136pub fn nixosRebuildSwitch(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {137    const cmd = &.{ "sudo", "nixos-rebuild", "switch" };138    output.printSubstep("nixos-rebuild switch", .{});139    return stream(io, machine, gpa, cmd);140}141142pub fn nixosRebuildDryActivate(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {143    return stream(io, machine, gpa, &.{ "sudo", "nixos-rebuild", "dry-activate" });144}145146pub fn nixosRebuildBuild(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {147    return stream(io, machine, gpa, &.{ "sudo", "nixos-rebuild", "build" });148}149150// --- Generations ---151152// Read system-profile generations WITHOUT root. `nix-env --list-generations -p153// /nix/var/nix/profiles/system` takes a profile lock and fails as a normal user154// ("system.lock: Permission denied"). The generation symlinks themselves are155// world-readable, so list them directly: parse `system-N-link` names, take each156// link's own mtime for the date/time, and mark the one the `system` symlink157// points at as current. Output matches the `nix-env --list-generations` columns158// (num date time [current]) so parseGenerations is unchanged.159const GEN_LIST_SCRIPT =160    \\cur=$(readlink /nix/var/nix/profiles/system 2>/dev/null | sed 's/.*system-\([0-9]*\)-link/\1/'); find /nix/var/nix/profiles -maxdepth 1 -name 'system-*-link' -printf '%f %TY-%Tm-%Td %TH:%TM\n' 2>/dev/null | sed 's/system-\([0-9]*\)-link/\1/' | sort -n | awk -v c="$cur" '{ if ($1==c) print $0" current"; else print $0 }'161;162163pub fn getGenerations(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]types.GenerationInfo {164    const r = try capture(gpa, io, machine, &.{ "sh", "-c", GEN_LIST_SCRIPT });165    defer gpa.free(r.stderr);166    defer gpa.free(r.stdout);167    if (r.exit_code != 0) return error.ProcessFailed;168    return parseGenerations(gpa, r.stdout);169}170171fn parseGenerations(gpa: std.mem.Allocator, output_str: []const u8) ![]types.GenerationInfo {172    var gens: std.ArrayList(types.GenerationInfo) = .empty;173    var lines = std.mem.splitScalar(u8, output_str, '\n');174    while (lines.next()) |line| {175        const trimmed = std.mem.trim(u8, line, " \t");176        if (trimmed.len == 0) continue;177        var parts = std.mem.tokenizeAny(u8, trimmed, " \t");178        const num_str = parts.next() orelse continue;179        const date_str = parts.next() orelse continue;180        const time_str = parts.next() orelse continue;181        const rest = parts.rest();182        const current = std.mem.indexOf(u8, rest, "current") != null;183        const num = std.fmt.parseInt(u32, num_str, 10) catch continue;184        try gens.append(gpa, .{185            .number = num,186            .date = try gpa.dupe(u8, date_str),187            .time = try gpa.dupe(u8, time_str),188            .current = current,189        });190    }191    return gens.toOwnedSlice(gpa);192}193194pub fn getCurrentGeneration(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) !u32 {195    const gens = try getGenerations(gpa, io, machine);196    defer gpa.free(gens);197    for (gens) |g| {198        if (g.current) return g.number;199    }200    return 0;201}202203pub fn switchGeneration(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, n: u32) !u8 {204    // Switch the system profile to generation n, then activate it (bootloader +205    // services). Without switch-to-configuration the change isn't applied.206    const cmd = try std.fmt.allocPrint(gpa, "nix-env -p {s} --switch-generation {d} && {s}/bin/switch-to-configuration switch", .{ SYSTEM_PROFILE, n, SYSTEM_PROFILE });207    defer gpa.free(cmd);208    return stream(io, machine, gpa, &.{ "sudo", "sh", "-c", cmd });209}210211pub fn rollback(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {212    return stream(io, machine, gpa, &.{ "sudo", "nixos-rebuild", "switch", "--rollback" });213}214215pub fn deleteGeneration(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, n: u32) !u8 {216    const n_str = try std.fmt.allocPrint(gpa, "{d}", .{n});217    defer gpa.free(n_str);218    return stream(io, machine, gpa, &.{ "sudo", "nix-env", "-p", SYSTEM_PROFILE, "--delete-generations", n_str });219}220221pub fn deleteOldGenerations(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {222    return stream(io, machine, gpa, &.{ "sudo", "nix-env", "-p", SYSTEM_PROFILE, "--delete-generations", "old" });223}224225// --- Garbage collection ---226227pub fn collectGarbage(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, delete_old: bool, keep: u32) !u8 {228    if (delete_old) {229        return stream(io, machine, gpa, &.{ "sudo", "nix-collect-garbage", "-d" });230    }231    // Keep the `keep` most recent system generations (+N deletes all but N),232    // then collect now-unreferenced store paths. `--delete-older-than` wants a233    // duration (e.g. 14d), not a generation count.234    const cmd = try std.fmt.allocPrint(gpa, "nix-env -p {s} --delete-generations +{d} && nix-collect-garbage", .{ SYSTEM_PROFILE, keep });235    defer gpa.free(cmd);236    return stream(io, machine, gpa, &.{ "sudo", "sh", "-c", cmd });237}238239// --- Channels ---240241pub fn channelList(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]types.ChannelInfo {242    const r = try capture(gpa, io, machine, &.{ "nix-channel", "--list" });243    defer gpa.free(r.stderr);244    defer gpa.free(r.stdout);245    if (r.exit_code != 0) return error.ProcessFailed;246    return parseChannels(gpa, r.stdout);247}248249fn parseChannels(gpa: std.mem.Allocator, output_str: []const u8) ![]types.ChannelInfo {250    var channels: std.ArrayList(types.ChannelInfo) = .empty;251    var lines = std.mem.splitScalar(u8, output_str, '\n');252    while (lines.next()) |line| {253        const trimmed = std.mem.trim(u8, line, " \t\r");254        if (trimmed.len == 0) continue;255        const space = std.mem.indexOfScalar(u8, trimmed, ' ') orelse continue;256        try channels.append(gpa, .{257            .name = try gpa.dupe(u8, trimmed[0..space]),258            .url = try gpa.dupe(u8, std.mem.trim(u8, trimmed[space + 1 ..], " \t")),259        });260    }261    return channels.toOwnedSlice(gpa);262}263264pub fn channelUpdate(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {265    return stream(io, machine, gpa, &.{ "sudo", "nix-channel", "--update" });266}267268pub fn channelAdd(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, url: []const u8, name: []const u8) !u8 {269    return stream(io, machine, gpa, &.{ "sudo", "nix-channel", "--add", url, name });270}271272pub fn channelRemove(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, name: []const u8) !u8 {273    return stream(io, machine, gpa, &.{ "sudo", "nix-channel", "--remove", name });274}275276// --- Services ---277278pub fn serviceList(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]types.ServiceInfo {279    const r = try capture(gpa, io, machine, &.{ "systemctl", "list-units", "--type=service", "--no-legend", "--no-pager" });280    defer gpa.free(r.stderr);281    defer gpa.free(r.stdout);282    if (r.exit_code != 0) return error.ProcessFailed;283    return parseServices(gpa, r.stdout);284}285286fn parseServices(gpa: std.mem.Allocator, output_str: []const u8) ![]types.ServiceInfo {287    var svcs: std.ArrayList(types.ServiceInfo) = .empty;288    var lines = std.mem.splitScalar(u8, output_str, '\n');289    while (lines.next()) |line| {290        const trimmed = std.mem.trim(u8, line, " \t\r");291        if (trimmed.len == 0 or trimmed[0] == 0xE2) continue; // skip UTF-8 bullet lines292        var parts = std.mem.tokenizeAny(u8, trimmed, " \t");293        const name = parts.next() orelse continue;294        _ = parts.next(); // load295        const active_str = parts.next() orelse continue;296        const sub_str = parts.next() orelse "unknown";297298        const state: types.ServiceState = if (std.mem.eql(u8, active_str, "active"))299            (if (std.mem.eql(u8, sub_str, "running") or std.mem.eql(u8, sub_str, "exited")) .active else .active)300        else if (std.mem.eql(u8, active_str, "failed"))301            .failed302        else303            .inactive;304305        try svcs.append(gpa, .{306            .name = try gpa.dupe(u8, name),307            .state = state,308            .uptime = null,309        });310    }311    return svcs.toOwnedSlice(gpa);312}313314pub fn serviceCtl(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, verb: []const u8, name: []const u8) !u8 {315    // --no-pager: `systemctl status` pipes to a pager on a tty and would block.316    return stream(io, machine, gpa, &.{ "sudo", "systemctl", "--no-pager", verb, name });317}318319pub fn serviceLogs(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, name: []const u8, last: u32, follow: bool) !u8 {320    const n_str = try std.fmt.allocPrint(gpa, "{d}", .{last});321    defer gpa.free(n_str);322    if (follow) {323        return stream(io, machine, gpa, &.{ "journalctl", "-u", name, "-f" });324    }325    return stream(io, machine, gpa, &.{ "journalctl", "-u", name, "-n", n_str, "--no-pager" });326}327328// --- Profile ---329330pub fn profileInstall(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, attr: []const u8) !u8 {331    const pkg_ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{attr});332    defer gpa.free(pkg_ref);333    // `nix profile add` is the current verb; `install` is a deprecated alias that334    // prints a warning on modern nix.335    return stream(io, machine, gpa, &.{ "nix", "profile", "add", pkg_ref });336}337338pub fn profileRemove(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, attr: []const u8) !u8 {339    // `nix profile remove` matches by profile element name (e.g. "ripgrep"), not340    // by flake ref — passing nixpkgs#ripgrep matches nothing.341    return stream(io, machine, gpa, &.{ "nix", "profile", "remove", attr });342}343344pub fn profileList(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {345    const r = try capture(gpa, io, machine, &.{ "nix", "profile", "list" });346    defer gpa.free(r.stderr);347    if (r.exit_code != 0) return error.ProcessFailed;348    return r.stdout;349}350351// Machine-readable profile listing — caller parses elements -> name + version.352pub fn profileListJson(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {353    const r = try capture(gpa, io, machine, &.{ "nix", "profile", "list", "--json" });354    defer gpa.free(r.stderr);355    if (r.exit_code != 0) {356        gpa.free(r.stdout);357        return error.ProcessFailed;358    }359    return r.stdout;360}361362// The store paths that make up the running system environment. Each reference is363// a <hash>-<name>-<version> path, so the caller can list system packages with364// versions — there is no cleaner per-package list for environment.systemPackages.365pub fn systemPackagePaths(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {366    const r = try capture(gpa, io, machine, &.{ "nix-store", "-q", "--references", "/run/current-system/sw" });367    defer gpa.free(r.stderr);368    if (r.exit_code != 0) {369        gpa.free(r.stdout);370        return error.ProcessFailed;371    }372    return r.stdout;373}374375pub fn profileUpgrade(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {376    return stream(io, machine, gpa, &.{ "nix", "profile", "upgrade", ".*" });377}378379// --- Store ---380381pub fn storeGc(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {382    return stream(io, machine, gpa, &.{ "sudo", "nix-collect-garbage" });383}384385pub fn storeVerify(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {386    return stream(io, machine, gpa, &.{ "nix", "store", "verify", "--all" });387}388389pub const SystemStatus = struct { size: []u8, age: []u8 };390391// One read-only pass for `nina status`: the current system's closure size (a392// single `path-info -S` of /run/current-system — fast, unlike -S over the whole393// store) and seconds since the system profile was last switched (its symlink394// mtime). Both are world-readable; no root needed.395const STATUS_SCRIPT =396    \\sz=$(nix path-info -S /run/current-system 2>/dev/null | awk '{print $NF}'); mt=$(stat -c %Y /nix/var/nix/profiles/system 2>/dev/null); now=$(date +%s); echo "${sz:-0} $(( ${now:-0} - ${mt:-0} ))"397;398399pub fn systemStatus(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) SystemStatus {400    const unknown = SystemStatus{401        .size = gpa.dupe(u8, "") catch return .{ .size = "", .age = "" },402        .age = gpa.dupe(u8, "") catch return .{ .size = "", .age = "" },403    };404    const r = capture(gpa, io, machine, &.{ "sh", "-c", STATUS_SCRIPT }) catch return unknown;405    defer gpa.free(r.stdout);406    defer gpa.free(r.stderr);407    if (r.exit_code != 0) return unknown;408409    var it = std.mem.tokenizeAny(u8, r.stdout, " \t\n\r");410    const sz_str = it.next() orelse return unknown;411    const age_str = it.next() orelse return unknown;412    const bytes = std.fmt.parseInt(u64, sz_str, 10) catch 0;413    const age_secs = std.fmt.parseInt(u64, age_str, 10) catch 0;414415    gpa.free(unknown.size);416    gpa.free(unknown.age);417    return .{418        .size = humanSize(gpa, bytes) catch (gpa.dupe(u8, "") catch ""),419        .age = humanAgo(gpa, age_secs) catch (gpa.dupe(u8, "") catch ""),420    };421}422423// `systemctl is-system-running` -> "running" / "degraded" / "starting" ... A424// one-word health signal; exits non-zero when degraded, so we read stdout, not425// the code. Caller owns the returned slice.426pub fn systemRunningState(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {427    const r = capture(gpa, io, machine, &.{ "systemctl", "is-system-running" }) catch428        return gpa.dupe(u8, "unknown");429    defer gpa.free(r.stderr);430    const state = std.mem.trim(u8, r.stdout, " \t\n\r");431    const owned = try gpa.dupe(u8, if (state.len > 0) state else "unknown");432    gpa.free(r.stdout);433    return owned;434}435436fn humanAgo(gpa: std.mem.Allocator, secs: u64) ![]u8 {437    if (secs < 60) return std.fmt.allocPrint(gpa, "{d}s ago", .{secs});438    if (secs < 3600) return std.fmt.allocPrint(gpa, "{d}m ago", .{secs / 60});439    if (secs < 86400) return std.fmt.allocPrint(gpa, "{d}h ago", .{secs / 3600});440    return std.fmt.allocPrint(gpa, "{d}d ago", .{secs / 86400});441}442443pub fn storeRepair(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {444    return stream(io, machine, gpa, &.{ "sudo", "nix", "store", "repair", "--all" });445}446447pub fn storeInfo(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) !types.StoreInfo {448    // `nix path-info -S --all` computes the CLOSURE size of every path — O(paths^2)449    // graph work that takes minutes on a real store (59k+ paths) and hangs the450    // command. We don't need closures: `--all --json` (no -S) carries each path's451    // own narSize, so one fast pass gives the path count and the summed store size.452    // `du -sh /nix/store` is just as slow on a big store, so it's gone too.453    // timeout-wrapped so a pathological store degrades to "?" instead of hanging.454    const pi = try capture(gpa, io, machine, &.{ "sh", "-c", "timeout 90 nix path-info --all --json 2>/dev/null" });455    defer gpa.free(pi.stdout);456    defer gpa.free(pi.stderr);457458    const scan = scanStoreJson(pi.stdout);459    const total_owned = try humanSize(gpa, scan.total_bytes);460461    return .{462        .total_size = total_owned,463        .live_paths = scan.count,464        .reclaimable_paths = 0,465    };466}467468const StoreScan = struct { count: u64, total_bytes: u64 };469470// One linear pass over `nix path-info --json`: each path object has exactly one471// "narSize": field, so counting them gives the true path count and summing the472// values gives the total store size — no per-path closure walk.473fn scanStoreJson(json_str: []const u8) StoreScan {474    const needle = "\"narSize\":";475    var count: u64 = 0;476    var total: u64 = 0;477    var i: usize = 0;478    while (std.mem.indexOfPos(u8, json_str, i, needle)) |pos| {479        var j = pos + needle.len;480        while (j < json_str.len and json_str[j] == ' ') : (j += 1) {}481        var val: u64 = 0;482        var any = false;483        while (j < json_str.len and json_str[j] >= '0' and json_str[j] <= '9') : (j += 1) {484            val = val * 10 + (json_str[j] - '0');485            any = true;486        }487        if (any) {488            count += 1;489            total += val;490        }491        i = j;492    }493    return .{ .count = count, .total_bytes = total };494}495496fn humanSize(gpa: std.mem.Allocator, bytes: u64) ![]u8 {497    const units = [_][]const u8{ "B", "KB", "MB", "GB", "TB" };498    var val: f64 = @floatFromInt(bytes);499    var unit: usize = 0;500    while (val >= 1024.0 and unit + 1 < units.len) : (unit += 1) val /= 1024.0;501    if (unit == 0) return std.fmt.allocPrint(gpa, "{d} {s}", .{ bytes, units[0] });502    return std.fmt.allocPrint(gpa, "{d:.1} {s}", .{ val, units[unit] });503}504505pub fn storePath(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, attr: []const u8) ![]u8 {506    // nixpkgs#<attr>, not .#<attr>: the package lives in nixpkgs (resolved via the507    // flake registry), not a flake in the current directory.508    const expr = try std.fmt.allocPrint(gpa, "nixpkgs#{s}.outPath", .{attr});509    defer gpa.free(expr);510    const r = try capture(gpa, io, machine, &.{ "nix", "eval", "--raw", expr });511    defer gpa.free(r.stderr);512    if (r.exit_code != 0) {513        gpa.free(r.stdout);514        return error.ProcessFailed;515    }516    return r.stdout;517}518519// --- Flake ---520521pub fn flakeUpdate(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, input: ?[]const u8) !u8 {522    if (input) |inp| {523        return stream(io, machine, gpa, &.{ "nix", "flake", "update", inp });524    }525    return stream(io, machine, gpa, &.{ "nix", "flake", "update" });526}527528pub fn flakeCheck(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {529    return stream(io, machine, gpa, &.{ "nix", "flake", "check" });530}531532pub fn flakeInit(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {533    return stream(io, machine, gpa, &.{ "nix", "flake", "init" });534}535536pub fn flakeLock(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {537    return stream(io, machine, gpa, &.{ "nix", "flake", "lock" });538}539540pub fn flakeClone(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, url: []const u8) !u8 {541    return stream(io, machine, gpa, &.{ "nix", "flake", "clone", url });542}543544pub fn flakeShow(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {545    const r = try capture(gpa, io, machine, &.{ "nix", "flake", "show", "--json" });546    defer gpa.free(r.stderr);547    if (r.exit_code != 0) {548        gpa.free(r.stdout);549        return error.ProcessFailed;550    }551    return r.stdout;552}553554// --- Build / Run / Develop ---555556pub fn nixBuild(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, attr: ?[]const u8) !u8 {557    if (attr) |a| {558        const ref = try std.fmt.allocPrint(gpa, ".#{s}", .{a});559        defer gpa.free(ref);560        return stream(io, machine, gpa, &.{ "nix", "build", ref });561    }562    return stream(io, machine, gpa, &.{ "nix", "build" });563}564565pub fn nixRun(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {566    // nix run always gets --no-write-lock-file for remote URLs567    const is_url = std.mem.startsWith(u8, pkg, "http://") or std.mem.startsWith(u8, pkg, "https://") or std.mem.startsWith(u8, pkg, "github:");568    if (is_url) {569        return stream(io, machine, gpa, &.{ "nix", "run", pkg, "--no-write-lock-file" });570    }571    // Already a flake ref (contains '#') → use as-is; bare name → default to nixpkgs#.572    if (std.mem.indexOfScalar(u8, pkg, '#') != null) {573        return stream(io, machine, gpa, &.{ "nix", "run", pkg });574    }575    const ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{pkg});576    defer gpa.free(ref);577    return stream(io, machine, gpa, &.{ "nix", "run", ref });578}579580pub fn nixShell(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {581    const ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{pkg});582    defer gpa.free(ref);583    return stream(io, machine, gpa, &.{ "nix", "shell", ref });584}585586pub fn nixDevelop(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, run_cmd: ?[]const u8) !u8 {587    if (run_cmd) |cmd| {588        // sh -c so a multi-word command isn't treated as a single executable name.589        return stream(io, machine, gpa, &.{ "nix", "develop", "--command", "sh", "-c", cmd });590    }591    return stream(io, machine, gpa, &.{ "nix", "develop" });592}593594pub fn nixRepl(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator) !u8 {595    return stream(io, machine, gpa, &.{ "nix", "repl", "--expr", "import <nixpkgs> {}" });596}597598// --- Format ---599600pub fn nixpkgsFmt(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, path: []const u8, check: bool) !u8 {601    if (check) {602        return stream(io, machine, gpa, &.{ "nixpkgs-fmt", "--check", path });603    }604    return stream(io, machine, gpa, &.{ "nixpkgs-fmt", path });605}606607// --- Info ---608609pub fn systemInfo(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {610    const r = try capture(gpa, io, machine, &.{"nixos-version"});611    defer gpa.free(r.stderr);612    if (r.exit_code != 0) {613        gpa.free(r.stdout);614        return error.ProcessFailed;615    }616    return r.stdout;617}618619pub fn kernelInfo(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {620    const r = try capture(gpa, io, machine, &.{ "uname", "-r" });621    defer gpa.free(r.stderr);622    if (r.exit_code != 0) {623        gpa.free(r.stdout);624        return error.ProcessFailed;625    }626    return r.stdout;627}628629pub fn uptimeInfo(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]u8 {630    const r = try capture(gpa, io, machine, &.{"uptime"});631    defer gpa.free(r.stderr);632    if (r.exit_code != 0) {633        gpa.free(r.stdout);634        return error.ProcessFailed;635    }636    return r.stdout;637}638639// --- Boot ---640641pub fn bootEntries(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]types.BootEntry {642    const r = try capture(gpa, io, machine, &.{ "bootctl", "list" });643    defer gpa.free(r.stderr);644    defer gpa.free(r.stdout);645    if (r.exit_code != 0) return error.ProcessFailed;646    return parseBootEntries(gpa, r.stdout);647}648649fn parseBootEntries(gpa: std.mem.Allocator, output_str: []const u8) ![]types.BootEntry {650    var entries: std.ArrayList(types.BootEntry) = .empty;651    var lines = std.mem.splitScalar(u8, output_str, '\n');652    while (lines.next()) |line| {653        const trimmed = std.mem.trim(u8, line, " \t\r");654        if (std.mem.startsWith(u8, trimmed, "title:")) {655            const title = std.mem.trim(u8, trimmed[6..], " \t");656            const current = std.mem.indexOf(u8, title, "(current)") != null;657            try entries.append(gpa, .{658                .title = try gpa.dupe(u8, title),659                .current = current,660            });661        }662    }663    return entries.toOwnedSlice(gpa);664}665666// --- Pkg info ---667668pub fn pkgWhy(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {669    return stream(io, machine, gpa, &.{ "nix", "why-depends", ".#", pkg });670}671672pub fn pkgDeps(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {673    return stream(io, machine, gpa, &.{ "nix-store", "--query", "--requisites", pkg });674}675676pub fn pkgSize(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, pkg: []const u8) ![]u8 {677    // A bare name ("ripgrep") isn't a valid installable; resolve via nixpkgs# like678    // `pkg path` does. -S -h gives closure size, human-readable. Output is679    // "<store-path>   <size>"; return just the size.680    const ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{pkg});681    defer gpa.free(ref);682    const r = try capture(gpa, io, machine, &.{ "nix", "path-info", "-S", "-h", ref });683    defer gpa.free(r.stderr);684    defer gpa.free(r.stdout);685    if (r.exit_code != 0) return error.ProcessFailed;686687    const line = std.mem.trim(u8, r.stdout, " \t\n\r");688    var it = std.mem.tokenizeAny(u8, line, " \t");689    _ = it.next(); // store path690    const size = std.mem.trim(u8, it.rest(), " \t");691    if (size.len == 0) return error.ProcessFailed;692    return gpa.dupe(u8, size);693}694695pub fn pkgClosure(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, pkg: []const u8) !u8 {696    return stream(io, machine, gpa, &.{ "nix", "path-info", "-rS", pkg });697}698699// --- Hash / Fetch ---700701pub fn nixHash(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, path: []const u8) ![]u8 {702    const r = try capture(gpa, io, machine, &.{ "nix", "hash", "path", path });703    defer gpa.free(r.stderr);704    if (r.exit_code != 0) {705        gpa.free(r.stdout);706        return error.ProcessFailed;707    }708    return r.stdout;709}710711pub fn nixFetch(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine, url: []const u8) ![]u8 {712    const r = try capture(gpa, io, machine, &.{ "nix-prefetch-url", url });713    defer gpa.free(r.stderr);714    if (r.exit_code != 0) {715        gpa.free(r.stdout);716        return error.ProcessFailed;717    }718    return r.stdout;719}720721// --- Pin ---722723pub fn editFlakeLock(_: std.mem.Allocator, _: []const u8, _: []const u8) !void {724    // Stub: full implementation would parse and edit flake.lock JSON725    // The pin/unpin flow works via nix flake update which regenerates flake.lock726}727728pub fn openEditor(io: std.Io, gpa: std.mem.Allocator, editor: []const u8, path: []const u8, line: ?u32) !u8 {729    if (line) |l| {730        const line_arg = try std.fmt.allocPrint(gpa, "+{d}", .{l});731        defer gpa.free(line_arg);732        return stream(io, &types.Machine{}, gpa, &.{ editor, path, line_arg });733    }734    return stream(io, &types.Machine{}, gpa, &.{ editor, path });735}736737pub fn diffClosures(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, a: u32, b: u32) !u8 {738    const a_str = try std.fmt.allocPrint(gpa, "/nix/var/nix/profiles/system-{d}-link", .{a});739    defer gpa.free(a_str);740    const b_str = try std.fmt.allocPrint(gpa, "/nix/var/nix/profiles/system-{d}-link", .{b});741    defer gpa.free(b_str);742    // On a tty, the child's own color is fine — stream it directly.743    if (output.colorEnabled()) {744        return stream(io, machine, gpa, &.{ "nix", "store", "diff-closures", a_str, b_str });745    }746    // Piped/redirected: nix store diff-closures colorizes regardless of NO_COLOR,747    // so we can't ask it to stop — capture its output and strip the ANSI ourselves.748    const r = try capture(gpa, io, machine, &.{ "nix", "store", "diff-closures", a_str, b_str });749    defer gpa.free(r.stdout);750    defer gpa.free(r.stderr);751    const cleaned = try stripAnsi(gpa, r.stdout);752    defer gpa.free(cleaned);753    output.raw(cleaned);754    return r.exit_code;755}756757// Strip CSI escape sequences (ESC '[' ... final-byte) from text. Used to clean a758// child process's color when it writes ANSI unconditionally.759fn stripAnsi(gpa: std.mem.Allocator, input: []const u8) ![]u8 {760    var out: std.ArrayList(u8) = .empty;761    errdefer out.deinit(gpa);762    var i: usize = 0;763    while (i < input.len) {764        if (input[i] == 0x1b and i + 1 < input.len and input[i + 1] == '[') {765            i += 2;766            while (i < input.len and !(input[i] >= 0x40 and input[i] <= 0x7e)) : (i += 1) {}767            if (i < input.len) i += 1; // consume the final byte768            continue;769        }770        try out.append(gpa, input[i]);771        i += 1;772    }773    return out.toOwnedSlice(gpa);774}775776test "stripAnsi removes CSI color sequences" {777    const cleaned = try stripAnsi(std.testing.allocator, "kepr: \x1b[31;1m13.1 KiB\x1b[0m");778    defer std.testing.allocator.free(cleaned);779    try std.testing.expectEqualStrings("kepr: 13.1 KiB", cleaned);780}781782// --- Doctor checks ---783784pub fn runDoctorChecks(gpa: std.mem.Allocator, io: std.Io, machine: *const types.Machine) ![]types.DoctorCheck {785    var checks: std.ArrayList(types.DoctorCheck) = .empty;786787    // Check nix daemon788    {789        const r = try capture(gpa, io, machine, &.{ "systemctl", "is-active", "nix-daemon" });790        defer gpa.free(r.stdout);791        defer gpa.free(r.stderr);792        const active = std.mem.indexOf(u8, r.stdout, "active") != null;793        try checks.append(gpa, .{ .name = "nix daemon", .status = if (active) .ok else .fail });794    }795796    // Check config syntax797    {798        const r = try capture(gpa, io, machine, &.{ "sudo", "nixos-rebuild", "dry-build" });799        defer gpa.free(r.stdout);800        defer gpa.free(r.stderr);801        try checks.append(gpa, .{ .name = "config syntax", .status = if (r.exit_code == 0) .ok else .fail });802    }803804    // Check channel805    {806        const r = try capture(gpa, io, machine, &.{ "nix-channel", "--list" });807        defer gpa.free(r.stdout);808        defer gpa.free(r.stderr);809        const has_channel = r.exit_code == 0 and r.stdout.len > 0;810        try checks.append(gpa, .{ .name = "channel", .status = if (has_channel) .ok else .warn });811    }812813    return checks.toOwnedSlice(gpa);814}815816// --- Log ---817818pub fn readNinaLog(gpa: std.mem.Allocator, io: std.Io, environ: *const std.process.Environ.Map, last: u32) ![]u8 {819    const home = environ.get("HOME") orelse return error.FileNotFound;820    const path = try std.fmt.allocPrint(gpa, "{s}/.nina.log", .{home});821    defer gpa.free(path);822    const content = std.Io.Dir.readFileAlloc(.cwd(), io, path, gpa, .unlimited) catch return error.FileNotFound;823    if (last == 0) return content;824825    // Collect non-empty lines, then keep only the final `last`. Slices point into826    // `content`, so copy them out before freeing it.827    var lines: std.ArrayList([]const u8) = .empty;828    defer lines.deinit(gpa);829    var it = std.mem.splitScalar(u8, content, '\n');830    while (it.next()) |line| {831        if (std.mem.trim(u8, line, " \t\r").len == 0) continue;832        try lines.append(gpa, line);833    }834    if (lines.items.len <= last) return content;835836    var out: std.ArrayList(u8) = .empty;837    errdefer out.deinit(gpa);838    for (lines.items[lines.items.len - last ..]) |line| {839        try out.appendSlice(gpa, line);840        try out.append(gpa, '\n');841    }842    gpa.free(content);843    return out.toOwnedSlice(gpa);844}845846// nina is a one-shot process, so "did the last apply fail this session?" can't847// live in memory — it's persisted as a ~/.nina-apply-failed flag, mirroring the848// other ~/.nina-* state files. This lets a later successful apply earn the849// excited kaomoji. mark sets it; take reads-and-clears so it fires exactly once.850pub fn markApplyFailed(io: std.Io, environ: *const std.process.Environ.Map) void {851    const home = environ.get("HOME") orelse return;852    var buf: [512]u8 = undefined;853    const path = std.fmt.bufPrint(&buf, "{s}/.nina-apply-failed", .{home}) catch return;854    const file = std.Io.Dir.createFile(.cwd(), io, path, .{}) catch return;855    file.close(io);856}857858pub fn takeApplyFailed(io: std.Io, environ: *const std.process.Environ.Map) bool {859    const home = environ.get("HOME") orelse return false;860    var buf: [512]u8 = undefined;861    const path = std.fmt.bufPrint(&buf, "{s}/.nina-apply-failed", .{home}) catch return false;862    if (std.Io.Dir.openFile(.cwd(), io, path, .{})) |f| {863        f.close(io);864        std.Io.Dir.deleteFile(.cwd(), io, path) catch {};865        return true;866    } else |_| {867        return false;868    }869}870871pub fn appendNinaLog(io: std.Io, environ: *const std.process.Environ.Map, entry: []const u8) void {872    const home = environ.get("HOME") orelse return;873    var path_buf: [512]u8 = undefined;874    const path = std.fmt.bufPrint(&path_buf, "{s}/.nina.log", .{home}) catch return;875    const file = std.Io.Dir.openFile(.cwd(), io, path, .{ .mode = .read_write }) catch876        (std.Io.Dir.createFile(.cwd(), io, path, .{}) catch return);877    defer file.close(io);878    const size = file.length(io) catch 0;879    file.writePositionalAll(io, entry, size) catch {};880}881882// --- Update helpers ---883884// Fetch a URL with curl and return the response body. Caller must free.885// error.NetworkError = DNS/connect failure; error.HttpError = non-2xx response.886pub fn fetchUrl(gpa: std.mem.Allocator, io: std.Io, url: []const u8) ![]u8 {887    const argv = [_][]const u8{888        "curl", "-s", "-L", "-w", "\nHTTP_STATUS:%{http_code}", "-m", "30", "--", url,889    };890    const result = std.process.run(gpa, io, .{ .argv = &argv }) catch return error.NetworkError;891    defer gpa.free(result.stderr);892893    const marker = "\nHTTP_STATUS:";894    const mark_idx = std.mem.lastIndexOf(u8, result.stdout, marker) orelse {895        gpa.free(result.stdout);896        return error.NetworkError;897    };898    const status_str = std.mem.trim(u8, result.stdout[mark_idx + marker.len ..], " \r\n");899    const status = std.fmt.parseInt(u16, status_str, 10) catch {900        gpa.free(result.stdout);901        return error.NetworkError;902    };903    if (status == 0) { gpa.free(result.stdout); return error.NetworkError; }904    if (status < 200 or status >= 300) { gpa.free(result.stdout); return error.HttpError; }905    const body = gpa.dupe(u8, result.stdout[0..mark_idx]) catch |e| {906        gpa.free(result.stdout);907        return e;908    };909    gpa.free(result.stdout);910    return body;911}912913// Download a URL to a temp file. Returns the temp path (caller must gpa.free).914// The file is written to /tmp/nina-update-<pid> and left for the caller to use.915pub fn downloadToTemp(gpa: std.mem.Allocator, io: std.Io, url: []const u8) ![]u8 {916    const tmp_path = try gpa.dupe(u8, "/tmp/nina-update.bin");917    errdefer gpa.free(tmp_path);918919    var child = std.process.spawn(io, .{920        .argv = &.{ "curl", "-fsSL", "-m", "300", "-o", tmp_path, "--", url },921        .stdin = .close,922        .stdout = .close,923        .stderr = .inherit,924    }) catch return error.NetworkError;925    const term = child.wait(io) catch return error.NetworkError;926    switch (term) {927        .exited => |c| if (c != 0) return error.NetworkError,928        else => return error.NetworkError,929    }930    return tmp_path;931}932933// Get the current executable path into buf. Returns slice of buf.934pub fn selfExePath(io: std.Io, buf: *[std.Io.Dir.max_path_bytes]u8) ![]const u8 {935    const len = try std.process.executablePath(io, buf);936    return buf[0..len];937}938939// Verify blake3 of tmp_path against expected_hex (raw hex, no prefix), then940// atomically install the binary to install_path. Errors: ChecksumMismatch,941// AccessDenied (with error_info set), or underlying I/O errors.942pub fn verifyAndInstall(gpa: std.mem.Allocator, io: std.Io, tmp_path: []const u8, expected_hex: []const u8, install_path: []const u8) !void {943    const bytes = std.Io.Dir.readFileAlloc(.cwd(), io, tmp_path, gpa, .unlimited) catch {944        errors.error_info.setMessage("downloaded file not found: {s}", .{tmp_path});945        return error.FileNotFound;946    };947    defer gpa.free(bytes);948949    var hasher = std.crypto.hash.Blake3.init(.{});950    hasher.update(bytes);951    var raw: [32]u8 = undefined;952    hasher.final(&raw);953    const hex = std.fmt.bytesToHex(raw, .lower);954    if (!std.mem.eql(u8, &hex, expected_hex)) return error.ChecksumMismatch;955956    var inst_tmp_buf: [std.Io.Dir.max_path_bytes + 8]u8 = undefined;957    const inst_tmp = std.fmt.bufPrint(&inst_tmp_buf, "{s}.new", .{install_path}) catch958        return error.NameTooLong;959960    {961        const f = std.Io.Dir.createFileAbsolute(io, inst_tmp, .{}) catch {962            errors.error_info.setMessage("cannot write to {s}", .{install_path});963            errors.error_info.setSuggestion("try: sudo nina update", .{});964            return error.AccessDenied;965        };966        defer f.close(io);967        f.writePositionalAll(io, bytes, 0) catch {968            errors.error_info.setMessage("cannot write to {s}", .{install_path});969            return error.AccessDenied;970        };971        try f.setPermissions(io, .fromMode(0o755));972    }973    errdefer std.Io.Dir.deleteFileAbsolute(io, inst_tmp) catch {};974975    if (comptime builtin.os.tag == .macos) {976        _ = captureLocal(gpa, io, &.{ "codesign", "-f", "-s", "-", inst_tmp }) catch {};977    }978979    std.Io.Dir.renameAbsolute(inst_tmp, install_path, io) catch |e| switch (e) {980        error.AccessDenied => {981            errors.error_info.setMessage("cannot replace {s}", .{install_path});982            errors.error_info.setSuggestion("try: sudo nina update", .{});983            return error.AccessDenied;984        },985        else => return e,986    };987}988989// --- Nix feature setup ---990991pub const NixFeatureStatus = struct {992    nix_command: bool = false,993    flakes: bool = false,994995    pub fn allEnabled(self: NixFeatureStatus) bool {996        return self.nix_command and self.flakes;997    }998};9991000fn scanConfFeatures(conf: []const u8, status: *NixFeatureStatus) void {1001    var lines = std.mem.splitScalar(u8, conf, '\n');1002    while (lines.next()) |line| {1003        const trimmed = std.mem.trim(u8, line, " \t");1004        if (!std.mem.startsWith(u8, trimmed, "experimental-features")) continue;1005        if (std.mem.indexOf(u8, trimmed, "nix-command") != null) status.nix_command = true;1006        if (std.mem.indexOf(u8, trimmed, "flakes") != null) status.flakes = true;1007    }1008}10091010pub fn checkNixFeatures(gpa: std.mem.Allocator, io: std.Io, environ: *const std.process.Environ.Map) NixFeatureStatus {1011    var status = NixFeatureStatus{};10121013    if (std.Io.Dir.readFileAlloc(.cwd(), io, "/etc/nix/nix.conf", gpa, .unlimited) catch null) |conf| {1014        defer gpa.free(conf);1015        scanConfFeatures(conf, &status);1016    }10171018    if (environ.get("HOME")) |home| {1019        var buf: [512]u8 = undefined;1020        const path = std.fmt.bufPrint(&buf, "{s}/.config/nix/nix.conf", .{home}) catch return status;1021        if (std.Io.Dir.readFileAlloc(.cwd(), io, path, gpa, .unlimited) catch null) |conf| {1022            defer gpa.free(conf);1023            scanConfFeatures(conf, &status);1024        }1025    }10261027    return status;1028}10291030pub fn isNixOS(io: std.Io) bool {1031    const file = std.Io.Dir.openFile(.cwd(), io, "/etc/NIXOS", .{}) catch return false;1032    file.close(io);1033    return true;1034}10351036// Appends `experimental-features = nix-command flakes` to ~/.config/nix/nix.conf.1037// Returns the path written (caller must free).1038pub fn enableNixFeatures(gpa: std.mem.Allocator, io: std.Io, environ: *const std.process.Environ.Map) ![]const u8 {1039    const home = environ.get("HOME") orelse {1040        errors.error_info.setMessage("HOME not set", .{});1041        return error.ConfigNotFound;1042    };10431044    const dir_path = try std.fmt.allocPrint(gpa, "{s}/.config/nix", .{home});1045    defer gpa.free(dir_path);1046    const file_path = try std.fmt.allocPrint(gpa, "{s}/.config/nix/nix.conf", .{home});1047    errdefer gpa.free(file_path);10481049    _ = captureLocal(gpa, io, &.{ "mkdir", "-p", dir_path }) catch {};10501051    const line = "experimental-features = nix-command flakes\n";1052    const file = std.Io.Dir.openFile(.cwd(), io, file_path, .{ .mode = .read_write }) catch1053        (std.Io.Dir.createFile(.cwd(), io, file_path, .{}) catch {1054        errors.error_info.setMessage("could not write {s}", .{file_path});1055        return error.FileNotFound;1056    });1057    defer file.close(io);10581059    const size = file.length(io) catch 0;1060    file.writePositionalAll(io, line, size) catch {1061        errors.error_info.setMessage("could not write {s}", .{file_path});1062        return error.FileNotFound;1063    };10641065    return file_path;1066}10671068// --- NixOS: declarative experimental-features ---1069//1070// On NixOS the permanent, declarative home for these flags is configuration.nix,1071// not ~/.config/nix/nix.conf. nina offers to add this one line and then leaves1072// the `nixos-rebuild switch` to the user.10731074pub const NIXOS_FEATURES_LINE =1075    "nix.settings.experimental-features = [ \"nix-command\" \"flakes\" ];";10761077// Best-effort, non-sudo check (configuration.nix is 0644 by default). Returns1078// false on any read error so the caller still offers to add the line.1079pub fn nixosConfigEnablesFeatures(gpa: std.mem.Allocator, io: std.Io, path: []const u8) bool {1080    const conf = std.Io.Dir.readFileAlloc(.cwd(), io, path, gpa, .unlimited) catch return false;1081    defer gpa.free(conf);1082    return std.mem.indexOf(u8, conf, "experimental-features") != null and1083        std.mem.indexOf(u8, conf, "nix-command") != null and1084        std.mem.indexOf(u8, conf, "flakes") != null;1085}10861087fn readMaybeSudo(gpa: std.mem.Allocator, io: std.Io, path: []const u8) ![]u8 {1088    if (std.Io.Dir.readFileAlloc(.cwd(), io, path, gpa, .unlimited) catch null) |data| return data;1089    return captureLocal(gpa, io, &.{ "sudo", "cat", path });1090}10911092// Insert NIXOS_FEATURES_LINE just before the final `}` of configuration.nix1093// (i.e. inside the top-level attribute set) and write it back via a single1094// `sudo cp`, which prompts for the password on the terminal. Returns an error1095// for the caller to fall back to printed manual instructions.1096pub fn appendFeaturesToNixosConfig(1097    gpa: std.mem.Allocator,1098    io: std.Io,1099    environ: *const std.process.Environ.Map,1100    path: []const u8,1101) !void {1102    const conf = readMaybeSudo(gpa, io, path) catch {1103        errors.error_info.setMessage("could not read {s}", .{path});1104        return error.ConfigNotFound;1105    };1106    defer gpa.free(conf);11071108    if (std.mem.indexOf(u8, conf, "experimental-features") != null) return; // already declared11091110    const brace = std.mem.lastIndexOfScalar(u8, conf, '}') orelse {1111        errors.error_info.setMessage("no closing brace in {s} — add the line by hand", .{path});1112        return error.MalformedConfig;1113    };11141115    const home = environ.get("HOME") orelse {1116        errors.error_info.setMessage("HOME not set", .{});1117        return error.ConfigNotFound;1118    };1119    const tmp_path = try std.fmt.allocPrint(gpa, "{s}/.nina-configuration.nix", .{home});1120    defer gpa.free(tmp_path);11211122    var buf: std.ArrayList(u8) = .empty;1123    defer buf.deinit(gpa);1124    try buf.appendSlice(gpa, conf[0..brace]);1125    if (brace == 0 or conf[brace - 1] != '\n') try buf.append(gpa, '\n');1126    try buf.appendSlice(gpa, "  # added by nina setup — flakes + the new nix CLI\n");1127    try buf.appendSlice(gpa, "  ");1128    try buf.appendSlice(gpa, NIXOS_FEATURES_LINE);1129    try buf.append(gpa, '\n');1130    try buf.appendSlice(gpa, conf[brace..]);11311132    const tmp = std.Io.Dir.createFile(.cwd(), io, tmp_path, .{}) catch {1133        errors.error_info.setMessage("could not write {s}", .{tmp_path});1134        return error.FileNotFound;1135    };1136    tmp.writePositionalAll(io, buf.items, 0) catch {1137        tmp.close(io);1138        std.Io.Dir.deleteFile(.cwd(), io, tmp_path) catch {};1139        errors.error_info.setMessage("could not write {s}", .{tmp_path});1140        return error.FileNotFound;1141    };1142    tmp.close(io);11431144    // Back up the existing config, then replace it — in one sudo call so the1145    // password is asked for at most once. Paths travel as positional args ($0,1146    // $1) to sidestep shell quoting.1147    const code = streamLocal(io, &.{1148        "sudo", "sh", "-c", "cp -- \"$0\" \"$0.nina-bak\" && cp -- \"$1\" \"$0\"", path, tmp_path,1149    }) catch {1150        std.Io.Dir.deleteFile(.cwd(), io, tmp_path) catch {};1151        errors.error_info.setMessage("could not write {s}", .{path});1152        return error.ProcessFailed;1153    };1154    std.Io.Dir.deleteFile(.cwd(), io, tmp_path) catch {};1155    if (code != 0) {1156        errors.error_info.setMessage("sudo cp into {s} failed", .{path});1157        return error.ProcessFailed;1158    }1159}