shellEscape

fn shellEscape(writer: *Io.Writer, string: []const u8, is_argv0: bool) !void {
    for (string) |c| {
        if (switch (c) {
            else => true,
            '%', '+'...':', '@'...'Z', '_', 'a'...'z' => false,
            '=' => is_argv0,
        }) break;
    } else return writer.writeAll(string);

    try writer.writeByte('"');
    for (string) |c| {
        if (switch (c) {
            std.ascii.control_code.nul => break,
            '!', '"', '$', '\\', '`' => true,
            else => !std.ascii.isPrint(c),
        }) try writer.writeByte('\\');
        switch (c) {
            std.ascii.control_code.nul => unreachable,
            std.ascii.control_code.bel => try writer.writeByte('a'),
            std.ascii.control_code.bs => try writer.writeByte('b'),
            std.ascii.control_code.ht => try writer.writeByte('t'),
            std.ascii.control_code.lf => try writer.writeByte('n'),
            std.ascii.control_code.vt => try writer.writeByte('v'),
            std.ascii.control_code.ff => try writer.writeByte('f'),
            std.ascii.control_code.cr => try writer.writeByte('r'),
            std.ascii.control_code.esc => try writer.writeByte('E'),
            ' '...'~' => try writer.writeByte(c),
            else => try writer.print("{o:0>3}", .{c}),
        }
    }
    try writer.writeByte('"');
}