Harden display apply and recovery

config/dot/hypr/monitors.lua

@@ -27,25 +27,78 @@ local prefs = require("prefs")
 -- (see the header) rather than preferences, and a settings page has no way to
 -- explain the screencopy tradeoff at the moment you would be changing it.
 local displays = prefs.get("displays", {})
+if type(displays) ~= "table" then
+    displays = {}
+end
 
-local function override(output, field, fallback)
+local function mode_dimensions(mode)
+    if type(mode) ~= "string" then
+        return nil, nil
+    end
+    local width, height, refresh = mode:match("^(%d+)x(%d+)@(%d+%.%d+)$")
+    if width == nil then
+        width, height, refresh = mode:match("^(%d+)x(%d+)@(%d+)$")
+    end
+    width, height, refresh = tonumber(width), tonumber(height), tonumber(refresh)
+    if width == nil or height == nil or refresh == nil
+        or width <= 0 or height <= 0 or refresh <= 0 then
+        return nil, nil
+    end
+    return width, height
+end
+
+local function valid_mode(mode)
+    local width = mode_dimensions(mode)
+    return width ~= nil
+end
+
+local function valid_scale(mode, scale)
+    local width, height = mode_dimensions(mode)
+    if width == nil or type(scale) ~= "number" or scale ~= scale
+        or scale <= 0 or scale > 4 then
+        return false
+    end
+    local logical_width = width / scale
+    local logical_height = height / scale
+    return math.abs(logical_width - math.floor(logical_width + 0.5)) < 0.0001
+        and math.abs(logical_height - math.floor(logical_height + 0.5)) < 0.0001
+end
+
+local function valid_transform(transform)
+    return type(transform) == "number"
+        and transform == math.floor(transform)
+        and transform >= 0
+        and transform <= 3
+end
+
+local function display_entry(output)
+    if type(output) ~= "string" or output == ""
+        or output:match("^[%w_.-]+$") == nil then
+        return nil
+    end
     local entry = displays[output]
     if type(entry) ~= "table" then
-        return fallback
+        return nil
     end
-    local value = entry[field]
-    if value == nil or type(value) ~= type(fallback) then
-        return fallback
+    if not valid_mode(entry.mode)
+        or not valid_scale(entry.mode, entry.scale)
+        or not valid_transform(entry.transform) then
+        return nil
     end
-    return value
+    return entry
 end
 
+local shipped_mode = "4500x3000@60"
+local shipped_scale = 1.5
+local shipped_transform = 0
+local dp2 = display_entry("DP-2")
+
 hl.monitor({
     output   = "DP-2",
-    mode     = override("DP-2", "mode", "4500x3000@60"),
+    mode     = dp2 and dp2.mode or shipped_mode,
     position = "0x0",
-    scale    = override("DP-2", "scale", 1.5),
-    transform = override("DP-2", "transform", 0),
+    scale    = dp2 and dp2.scale or shipped_scale,
+    transform = dp2 and dp2.transform or shipped_transform,
 
     -- 10-bit output. 4500x3000@60 at 10bpc is ~24 Gbps, right at the edge of
     -- DP 1.4 HBR3, so this relies on DSC. If the display fails to light up or
@@ -56,6 +109,24 @@ hl.monitor({
     cm = "auto",
 })
 
+-- Other connected outputs use the same validated per-output store. They keep
+-- automatic placement and the compositor's normal colour policy; DP-2 alone
+-- carries the panel-specific 10-bit policy documented above.
+for output, _ in pairs(displays) do
+    if output ~= "DP-2" then
+        local entry = display_entry(output)
+        if entry ~= nil then
+            hl.monitor({
+                output = output,
+                mode = entry.mode,
+                position = "auto",
+                scale = entry.scale,
+                transform = entry.transform,
+            })
+        end
+    end
+end
+
 -- Any monitor not named above: sane defaults rather than nothing.
 hl.monitor({
     output   = "",