Rewrite enumerate-displays in python

Looking at the /sys filesystem gets the mapping wrong for some reason.
XRandr sees DP-2-8 whereas /sys sees DP-5 or DP-3 (for which there are
no physical analogs) and doesn't contain any file mapping the two. The
long-term correct answer is to rewrite this in C and use the XRandr APIs
directly but I need this to work right now for some presentations so
Python it is.

1 files changed, 75 insertions, 16 deletions

diff --git a/bin/enumerate-displays b/bin/enumerate-displays
index 996a135..40aea68 100755
--- a/bin/enumerate-displays
+++ b/bin/enumerate-displays
@@ -1,21 +1,80 @@
-#!/bin/bash
+#!/usr/bin/env python3
 #
-# Simple script to do all the ugly munging or connected displays on a Dell XPS
-# 13. Is used by a Lua function within Awesome that actually determines what to
-# do with those displays.
+# TODO: Rewrite this in C and just use the XRandr APIs directly
 #
 
-for output in /sys/class/drm/card*-*; do
-    if [ "$(cat $output/status)" == "connected" ]; then
-        card=$(basename $output); card=${card##card?-}
-        edid=$(cat $output/edid | parse-edid 2>&1 | grep Identifier | cut -d '"' -f2)
-        edid_sum=$(md5sum -b $output/edid | cut -f1 -d' ')
+import re
+import sys
+import subprocess
 
-        # The EDID data is corrupt on the Dell XPS panels for some reason
-        if [ "$edid_sum" == "99030a11512deeb0371adf0a6c6a8a06" ] || [ "$edid_sum" == "31a6481b493cdfcd9e50c67290644eed" ]; then
-            edid="DELL_XPS_13"
-        fi
 
-        echo "$card:$edid"
-    fi
-done
+def is_host_xps():
+    try:
+        with open("/sys/class/dmi/id/product_name", "r") as fp:
+            product = fp.read()
+
+        return bool(re.match("XPS 13 93[78]0", product))
+    except FileNotFoundError:
+        return False
+
+
+def parse_edid(hex_list):
+        proc = subprocess.Popen(
+            ["parse-edid"], stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+
+        out, _ = proc.communicate(bytes.fromhex("".join(hex_list)))
+
+        identifier = re.findall(
+            '\tIdentifier "([^"]+)"\n',
+            out.decode("us-ascii", errors="backslashreplace"))
+
+        if identifier:
+            return identifier[0]
+        else:
+            return None
+
+
+def get_connected_displays():
+    out = subprocess.check_output(["xrandr", "--verbose", "--query"])
+
+    current_display = None
+    in_edid = False
+    current_edid = []
+
+    all_edids = {}
+
+    for line in out.decode("us-ascii").split("\n"):
+        if ' connected ' in line:
+            current_display = line.split(" ")[0]
+
+        if current_display and 'EDID:' in line:
+            in_edid = True
+            continue
+
+        if in_edid and line[:2] == "\t\t":
+            current_edid.append(line.strip())
+        elif in_edid and line[:2] != "\t\t":
+            all_edids[current_display] = parse_edid(current_edid)
+            in_edid = False
+            current_display = None
+            current_edid = []
+
+    return all_edids
+
+
+def main():
+    is_xps = is_host_xps()
+
+    for display, edid in get_connected_displays().items():
+        # The EDID data is corrupted on all Dell XPSes
+        if is_xps and display == "eDP-1":
+            edid = "DELL_XPS_13"
+
+        print("{display}:{edid}".format(**locals()))
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())