From 0069e28cc6f681797f1424317f46d52da9d9e635 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Mon, 20 Apr 2026 08:56:40 -0700
Subject: [PATCH] libghostty: expose the APC max byte limits

---
 include/ghostty/vt/terminal.h | 19 +++++++++++++++++++
 src/terminal/c/terminal.zig   | 17 +++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/ghostty/vt/terminal.h b/include/ghostty/vt/terminal.h
index 433308c84..0e6d048e1 100644
--- a/include/ghostty/vt/terminal.h
+++ b/include/ghostty/vt/terminal.h
@@ -573,6 +573,25 @@ typedef enum GHOSTTY_ENUM_TYPED {
    * Input type: bool*
    */
   GHOSTTY_TERMINAL_OPT_KITTY_IMAGE_MEDIUM_SHARED_MEM = 18,
+
+  /**
+   * Set the maximum bytes the APC handler will buffer for all protocols.
+   * This prevents malicious input from causing unbounded memory allocation.
+   * A NULL value pointer removes all overrides, reverting to the built-in
+   * defaults.
+   *
+   * Input type: size_t*
+   */
+  GHOSTTY_TERMINAL_OPT_APC_MAX_BYTES = 19,
+
+  /**
+   * Set the maximum bytes the APC handler will buffer for Kitty graphics
+   * protocol data. A NULL value pointer removes the override, reverting
+   * to the built-in default.
+   *
+   * Input type: size_t*
+   */
+  GHOSTTY_TERMINAL_OPT_APC_MAX_BYTES_KITTY = 20,
   GHOSTTY_TERMINAL_OPT_MAX_VALUE = GHOSTTY_ENUM_MAX_VALUE,
 } GhosttyTerminalOption;
 
diff --git a/src/terminal/c/terminal.zig b/src/terminal/c/terminal.zig
index 0931b1685..670c2aea3 100644
--- a/src/terminal/c/terminal.zig
+++ b/src/terminal/c/terminal.zig
@@ -7,6 +7,7 @@ const ZigTerminal = @import("../Terminal.zig");
 const Stream = @import("../stream_terminal.zig").Stream;
 const ScreenSet = @import("../ScreenSet.zig");
 const PageList = @import("../PageList.zig");
+const apc = @import("../apc.zig");
 const kitty = @import("../kitty/key.zig");
 const kitty_gfx_c = @import("kitty_graphics.zig");
 const modes = @import("../modes.zig");
@@ -310,6 +311,8 @@ pub const Option = enum(c_int) {
     kitty_image_medium_file = 16,
     kitty_image_medium_temp_file = 17,
     kitty_image_medium_shared_mem = 18,
+    apc_max_bytes = 19,
+    apc_max_bytes_kitty = 20,
 
     /// Input type expected for setting the option.
     pub fn InType(comptime self: Option) type {
@@ -331,6 +334,7 @@ pub const Option = enum(c_int) {
             .kitty_image_medium_temp_file,
             .kitty_image_medium_shared_mem,
             => ?*const bool,
+            .apc_max_bytes, .apc_max_bytes_kitty => ?*const usize,
         };
     }
 };
@@ -425,6 +429,19 @@ fn setTyped(
                 }
             }
         },
+        .apc_max_bytes => {
+            wrapper.stream.handler.apc_handler.max_bytes = if (value) |ptr|
+                .initFull(ptr.*)
+            else
+                .{};
+        },
+        .apc_max_bytes_kitty => {
+            if (value) |ptr| {
+                wrapper.stream.handler.apc_handler.max_bytes.put(.kitty, ptr.*);
+            } else {
+                wrapper.stream.handler.apc_handler.max_bytes.remove(.kitty);
+            }
+        },
     }
     return .success;
 }