fix: stop the widgets from stalling or raising the draw

Memoize hwmon_dir by chip name so sensor reads no longer popen grep on
every frame, cache misses included. Floor fractional byte counts in
card.human so it cannot raise. Drop the GPU package-temperature row,
which duplicated the headline. Set umask before mkdir in both samplers
so a fresh cache directory is not world-readable. Make render.lua exit
non-zero on a draw error and tolerate an unset HOME.

6 files changed, 33 insertions, 14 deletions

diff --git a/bin/cache-sample.sh b/bin/cache-sample.sh
index cac8911..202bc63 100755
--- a/bin/cache-sample.sh
+++ b/bin/cache-sample.sh
@@ -11,11 +11,11 @@ CACHE_DIR="${XDG_CACHE_HOME:-$HOME/.cache}/udt"
 CACHE="$CACHE_DIR/cachesize.txt"
 TARGET="${XDG_CACHE_HOME:-$HOME/.cache}"
 
+umask 077
 mkdir -p "$CACHE_DIR"
 
 TMP="$CACHE.tmp.$$"
 trap 'rm -f "$TMP"' EXIT
-umask 077
 
 # Total first, then the four largest children. `sort -h` compares human sizes
 # numerically; the Lua side converts them again because it needs the ratio to
diff --git a/bin/disks-sample.sh b/bin/disks-sample.sh
index 83b8a62..5291bcf 100755
--- a/bin/disks-sample.sh
+++ b/bin/disks-sample.sh
@@ -16,11 +16,11 @@ CACHE="$CACHE_DIR/disks.txt"
 
 MOUNTS=(/ /home /data /mnt/nfs/Library /mnt/nfs/shared)
 
+umask 077
 mkdir -p "$CACHE_DIR"
 
 TMP="$CACHE.tmp.$$"
 trap 'rm -f "$TMP"' EXIT
-umask 077
 
 # /usr/bin/df by absolute path with -P -B1, deliberately:
 #   - the user's shell aliases df to `df -h`, and an alias or a function would
diff --git a/lib/card.lua b/lib/card.lua
index 48a7f2e..185703c 100644
--- a/lib/card.lua
+++ b/lib/card.lua
@@ -213,7 +213,7 @@ function M.human(bytes)
   local units = { 'B', 'K', 'M', 'G', 'T', 'P' }
   local i = 1
   while n >= 1024 and i < #units do n = n / 1024; i = i + 1 end
-  if i == 1 then return string.format('%d%s', n, units[i]) end
+  if i == 1 then return string.format('%d%s', math.floor(n), units[i]) end
   if n >= 100 then return string.format('%.0f%s', n, units[i]) end
   return string.format('%.1f%s', n, units[i])
 end
diff --git a/lib/data.lua b/lib/data.lua
index acf7a0f..2047ef8 100644
--- a/lib/data.lua
+++ b/lib/data.lua
@@ -62,14 +62,28 @@ end
 -- Globbing by name, never by a fixed hwmon index: indices drift across kernel
 -- and hardware reorders, and a stale index silently reports a different chip.
 -- Carried over from the previous conky config, where this was the hard-won bit.
+--
+-- The result is memoized per chip name, hits and misses alike. A chip's hwmon
+-- directory is stable for the process's life, and the draw hook calls this
+-- several times per frame: without the cache every sensor read popens grep,
+-- which is exactly the subprocess-per-draw the samplers exist to avoid. A miss
+-- is cached too, so an absent chip is not re-globbed on every frame.
+local hwmon_cache = {}
+
 function M.hwmon_dir(name)
-  local p = io.popen('grep -lx ' .. ("%q"):format(name)
-    .. ' /sys/class/hwmon/hwmon*/name 2>/dev/null')
-  if not p then return nil end
-  local hit = p:read('*l')
-  p:close()
-  if not hit then return nil end
-  return hit:match('^(.*)/name$')
+  if type(name) ~= 'string' then return nil end
+  if hwmon_cache[name] == nil then
+    local p = io.popen('grep -lx ' .. ("%q"):format(name)
+      .. ' /sys/class/hwmon/hwmon*/name 2>/dev/null')
+    local dir = false
+    if p then
+      local hit = p:read('*l')
+      p:close()
+      if hit then dir = hit:match('^(.*)/name$') end
+    end
+    hwmon_cache[name] = dir
+  end
+  return hwmon_cache[name] or nil
 end
 
 -- A stateful CPU-load counter.
diff --git a/test/render.lua b/test/render.lua
index 7d48d0e..3ed5f7e 100644
--- a/test/render.lua
+++ b/test/render.lua
@@ -29,7 +29,9 @@ local sw, sh = 2560, 1080
 -- The palette, read from the rendered conky.conf exactly as dashboard.lua
 -- does, so the PNG uses the real scheme rather than invented colours.
 local function config_colors()
-  local path = os.getenv('HOME') .. '/.config/conky/conky.conf'
+  local home = os.getenv('HOME')
+  if not home then return {} end
+  local path = home .. '/.config/conky/conky.conf'
   local f = io.open(path, 'r')
   if not f then return {} end
   local src = f:read('*a')
@@ -79,7 +81,10 @@ if not ok then
   os.exit(1)
 end
 local drew, err = pcall(mod.draw, cr, rect, colors)
-if not drew then print('DRAW ERROR: ' .. tostring(err)) end
+if not drew then
+  print('DRAW ERROR: ' .. tostring(err))
+  os.exit(1)
+end
 
 cairo_destroy(cr)
 cairo_surface_write_to_png(surf, out)
diff --git a/widgets/gpu.lua b/widgets/gpu.lua
index 5f289a0..87e22f3 100644
--- a/widgets/gpu.lua
+++ b/widgets/gpu.lua
@@ -14,9 +14,9 @@ local data = require 'lib.data'
 
 local M = {}
 
--- chip, file, label, warn, crit
+-- chip, file, label, warn, crit. Package (temp2) is the headline above, so it
+-- is not repeated here; these are the rows drawn under it.
 local TEMPS = {
-  { 'xe', 'temp2_input', 'PKG',  75, 85 },
   { 'xe', 'temp3_input', 'VRAM', 80, 90 },
 }