From 3839eb15d65163f30c9c5859a361302fcb4c447a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Mon, 11 Apr 2022 10:20:36 +0200
Subject: [PATCH] Also check the NixOS specific files

---
 src/nix-find-roots/nix-find-roots.cc | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/nix-find-roots/nix-find-roots.cc b/src/nix-find-roots/nix-find-roots.cc
index 06b5f272f..8ceb92521 100644
--- a/src/nix-find-roots/nix-find-roots.cc
+++ b/src/nix-find-roots/nix-find-roots.cc
@@ -197,6 +197,9 @@ TraceResult followPathsToStore(GlobalOpts opts, set<fs::path> roots)
  */
 void scanFileContent(const GlobalOpts & opts, const fs::path & fileToScan, Roots & res)
 {
+    if (!fs::exists(fileToScan))
+        return;
+
     std::ostringstream contentStream;
     {
         std::ifstream fs;
@@ -218,6 +221,9 @@ void scanFileContent(const GlobalOpts & opts, const fs::path & fileToScan, Roots
  */
 void scanMapsFile(const GlobalOpts & opts, const fs::path & mapsFile, Roots & res)
 {
+    if (!fs::exists(mapsFile))
+        return;
+
     static auto mapRegex = std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
     std::stringstream mappedFile;
     {
@@ -275,6 +281,13 @@ Roots getRuntimeRoots(GlobalOpts opts)
         scanFileContent(opts, procEntry.path()/"environ", res);
         scanMapsFile(opts, procEntry.path()/"maps", res);
     }
+
+    // Mostly useful for NixOS, but doesn’t hurt to check on other systems
+    // anyways
+    scanFileContent(opts, "/proc/sys/kernel/modprobe", res);
+    scanFileContent(opts, "/proc/sys/kernel/fbsplash", res);
+    scanFileContent(opts, "/proc/sys/kernel/poweroff_cmd", res);
+
     return res;
 }