feat: add the disks and cache samplers

1 files changed, 40 insertions, 0 deletions

diff --git a/bin/disks-sample.sh b/bin/disks-sample.sh
new file mode 100755
index 0000000..83b8a62
--- /dev/null
+++ b/bin/disks-sample.sh
@@ -0,0 +1,40 @@
+#!/bin/bash
+# Sample filesystem usage into a cache file, for widgets/disks.lua.
+#
+# This exists so the draw hook never calls statfs on an NFS path. An
+# unreachable server blocks that call, and blocking the Cairo draw freezes the
+# whole dashboard; here it costs a stale cache and nothing else.
+#
+# One NFS mount per server: Library and Slackware are the same export on one
+# server, shared and backup_danix the same on another, so showing all four
+# printed every number twice.
+
+set -u
+
+CACHE_DIR="${XDG_CACHE_HOME:-$HOME/.cache}/udt"
+CACHE="$CACHE_DIR/disks.txt"
+
+MOUNTS=(/ /home /data /mnt/nfs/Library /mnt/nfs/shared)
+
+mkdir -p "$CACHE_DIR"
+
+TMP="$CACHE.tmp.$$"
+trap 'rm -f "$TMP"' EXIT
+umask 077
+
+# /usr/bin/df by absolute path with -P -B1, deliberately:
+#   - the user's shell aliases df to `df -h`, and an alias or a function would
+#     hand the parser '1.6G' where it expects an integer
+#   - -P is the POSIX format, one line per filesystem, mountpoint last
+#   - -B1 is bytes, so the widget does the formatting and the parser never
+#     has to interpret a suffix
+if ! /usr/bin/df -P -B1 "${MOUNTS[@]}" > "$TMP" 2>/dev/null; then
+    # A single unreachable mount must not discard the others: df still reports
+    # the ones it could stat, so keep the output if it has any data rows.
+    if [ "$(wc -l < "$TMP")" -lt 2 ]; then
+        echo "disks-sample: df produced nothing usable" >&2
+        exit 1
+    fi
+fi
+
+mv -f "$TMP" "$CACHE"