const builtin = @import("builtin"); const Os = builtin.Os; const os = @import("index.zig"); const io = @import("../io.zig"); pub const UserInfo = struct { uid: u32, gid: u32, }; /// POSIX function which gets a uid from username. pub fn getUserInfo(name: []const u8) !UserInfo { return switch (builtin.os) { Os.linux, Os.macosx, Os.ios => posixGetUserInfo(name), else => @compileError("Unsupported OS"), }; } const State = enum { Start, WaitForNextLine, SkipPassword, ReadUserId, ReadGroupId, }; // TODO this reads /etc/passwd. But sometimes the user/id mapping is in something else // like NIS, AD, etc. See `man nss` or look at an strace for `id myuser`. pub fn posixGetUserInfo(name: []const u8) !UserInfo { var in_stream = try io.InStream.open("/etc/passwd", null); defer in_stream.close(); var buf: [os.page_size]u8 = undefined; var name_index: usize = 0; var state = State.Start; var uid: u32 = 0; var gid: u32 = 0; while (true) { const amt_read = try in_stream.read(buf[0..]); for (buf[0..amt_read]) |byte| { switch (state) { State.Start => switch (byte) { ':' => { state = if (name_index == name.len) State.SkipPassword else State.WaitForNextLine; }, '\n' => return error.CorruptPasswordFile, else => { if (name_index == name.len or name[name_index] != byte) { state = State.WaitForNextLine; } name_index += 1; }, }, State.WaitForNextLine => switch (byte) { '\n' => { name_index = 0; state = State.Start; }, else => continue, }, State.SkipPassword => switch (byte) { '\n' => return error.CorruptPasswordFile, ':' => { state = State.ReadUserId; }, else => continue, }, State.ReadUserId => switch (byte) { ':' => { state = State.ReadGroupId; }, '\n' => return error.CorruptPasswordFile, else => { const digit = switch (byte) { '0'...'9' => byte - '0', else => return error.CorruptPasswordFile, }; if (@mulWithOverflow(u32, uid, 10, *uid)) return error.CorruptPasswordFile; if (@addWithOverflow(u32, uid, digit, *uid)) return error.CorruptPasswordFile; }, }, State.ReadGroupId => switch (byte) { '\n', ':' => { return UserInfo{ .uid = uid, .gid = gid, }; }, else => { const digit = switch (byte) { '0'...'9' => byte - '0', else => return error.CorruptPasswordFile, }; if (@mulWithOverflow(u32, gid, 10, *gid)) return error.CorruptPasswordFile; if (@addWithOverflow(u32, gid, digit, *gid)) return error.CorruptPasswordFile; }, }, } } if (amt_read < buf.len) return error.UserNotFound; } }