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const std = @import("std");
const build_options = @import("terminal_options");
const Allocator = std.mem.Allocator;
const kitty_gfx = @import("kitty/graphics.zig");
const log = std.log.scoped(.terminal_apc);
/// APC command handler. This should be hooked into a terminal.Stream handler.
/// The start/feed/end functions are meant to be called from the terminal.Stream
/// apcStart, apcPut, and apcEnd functions, respectively.
pub const Handler = struct {
state: State = .inactive,
/// Maximum bytes each APC protocol can buffer. This is to prevent
/// malicious input from causing us to allocate too much memory.
/// If you want to be lazy and set a single value for all protocols,
/// use `.initFull`.
max_bytes: std.EnumMap(Protocol, usize) = .initFullWith(.{
.kitty = Protocol.defaultMaxBytes(.kitty),
}),
pub fn deinit(self: *Handler) void {
self.state.deinit();
}
pub fn start(self: *Handler) void {
self.state.deinit();
self.state = .{ .identify = {} };
}
pub fn feed(self: *Handler, alloc: Allocator, byte: u8) void {
switch (self.state) {
.inactive => unreachable,
// We're ignoring this APC command, likely because we don't
// recognize it so there is no need to store the data in memory.
.ignore => return,
// We identify the APC command by the first byte.
.identify => {
switch (byte) {
// Kitty graphics protocol
'G' => self.state = if (comptime build_options.kitty_graphics)
.{ .kitty = .init(
alloc,
self.max_bytes.get(.kitty) orelse
Protocol.defaultMaxBytes(.kitty),
) }
else
.ignore,
// Unknown
else => self.state = .ignore,
}
},
.kitty => |*p| if (comptime build_options.kitty_graphics) {
p.feed(byte) catch |err| {
log.warn("kitty graphics protocol error: {}", .{err});
p.deinit();
self.state = .ignore;
};
} else unreachable,
}
}
pub fn end(self: *Handler) ?Command {
defer {
self.state.deinit();
self.state = .inactive;
}
return switch (self.state) {
.inactive => unreachable,
.ignore, .identify => null,
.kitty => |*p| kitty: {
if (comptime !build_options.kitty_graphics) unreachable;
// Use the same allocator that was used to create the parser.
const alloc = p.arena.child_allocator;
const command = p.complete(alloc) catch |err| {
log.warn("kitty graphics protocol error: {}", .{err});
break :kitty null;
};
break :kitty .{ .kitty = command };
},
};
}
};
pub const State = union(enum) {
/// We're not in the middle of an APC command yet.
inactive: void,
/// We got an unrecognized APC sequence or the APC sequence we
/// recognized became invalid. We're just dropping bytes.
ignore: void,
/// We're waiting to identify the APC sequence. This is done by
/// inspecting the first byte of the sequence.
identify: void,
/// Kitty graphics protocol
kitty: if (build_options.kitty_graphics)
kitty_gfx.CommandParser
else
void,
pub fn deinit(self: *State) void {
switch (self.*) {
.inactive, .ignore, .identify => {},
.kitty => |*v| if (comptime build_options.kitty_graphics)
v.deinit()
else
unreachable,
}
}
};
/// Possible APC command types.
pub const Protocol = enum {
kitty,
/// Returns the default maximum bytes for the given protocol.
pub fn defaultMaxBytes(self: Protocol) usize {
return switch (self) {
// Kitty graphics payloads can be very large (e.g. full images
// encoded as base64), so the default is set to 65 MiB.
.kitty => 65 * 1024 * 1024,
};
}
};
/// Possible APC commands.
pub const Command = union(Protocol) {
kitty: if (build_options.kitty_graphics)
kitty_gfx.Command
else
void,
pub fn deinit(self: *Command, alloc: Allocator) void {
switch (self.*) {
.kitty => |*v| if (comptime build_options.kitty_graphics)
v.deinit(alloc)
else
unreachable,
}
}
};
test "unknown APC command" {
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{};
h.start();
for ("Xabcdef1234") |c| h.feed(alloc, c);
try testing.expect(h.end() == null);
}
test "garbage Kitty command" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{};
h.start();
for ("Gabcdef1234") |c| h.feed(alloc, c);
try testing.expect(h.end() == null);
}
test "Kitty command with overflow u32" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{};
h.start();
for ("Ga=p,i=10000000000") |c| h.feed(alloc, c);
try testing.expect(h.end() == null);
}
test "Kitty command with overflow i32" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{};
h.start();
for ("Ga=p,i=1,z=-9999999999") |c| h.feed(alloc, c);
try testing.expect(h.end() == null);
}
test "kitty feed error deinits parser" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
// Feed a valid kitty command start to allocate parser state, then
// trigger an error during feed via an integer overflow. The testing
// allocator will detect leaks if deinit is not called.
var h: Handler = .{};
defer h.deinit();
h.start();
for ("Ga=p,i=10000000000;") |c| h.feed(alloc, c);
try testing.expect(h.state == .ignore);
}
test "kitty max bytes exceeded" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{ .max_bytes = .init(.{ .kitty = 4 }) };
defer h.deinit();
h.start();
// 'G' identifies kitty, 'a=t;' moves to data state, then feed exceeds max_bytes.
for ("Ga=t;") |c| h.feed(alloc, c);
try testing.expect(h.state != .ignore);
for ("abcd") |c| h.feed(alloc, c);
try testing.expect(h.state != .ignore);
// The 5th data byte exceeds the 4-byte limit.
h.feed(alloc, 'e');
try testing.expect(h.state == .ignore);
}
test "valid Kitty command" {
if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
const testing = std.testing;
const alloc = testing.allocator;
var h: Handler = .{};
h.start();
const input = "Gf=24,s=10,v=20,hello=world";
for (input) |c| h.feed(alloc, c);
var cmd = h.end().?;
defer cmd.deinit(alloc);
try testing.expect(cmd == .kitty);
}
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