From 5a23a24ba275ca78d9f1e0d1dfdb7757a720707d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Mon, 27 Mar 2023 19:18:00 +0200
Subject: [PATCH 1/2] nixos/grub-install: don't rely on shell to run commands

data passed to these programs might be accidentially interpreted as
shell. Discovered in https://github.com/Mic92/envfs/issues/111
---
 .../modules/system/boot/loader/grub/install-grub.pl | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index aea426c7fdf..4a8983b1bb1 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -47,10 +47,9 @@ sub writeFile {
 }
 
 sub runCommand {
-    my ($cmd) = @_;
-    open FILE, "$cmd 2>/dev/null |" or die "Failed to execute: $cmd\n";
-    my @ret = <FILE>;
-    close FILE;
+    open(my $fh, "-|", @_) or die "Failed to execute: $@_\n";
+    my @ret = $fh->getlines();
+    close $fh;
     return ($?, @ret);
 }
 
@@ -200,7 +199,7 @@ sub GrubFs {
                 $search = $types{$fsIdentifier} . ' ';
 
                 # Based on the type pull in the identifier from the system
-                my ($status, @devInfo) = runCommand("@utillinux@/bin/blkid -o export @{[$fs->device]}");
+                my ($status, @devInfo) = runCommand("@utillinux@/bin/blkid", "-o", "export", @{[$fs->device]});
                 if ($status != 0) {
                     die "Failed to get blkid info (returned $status) for @{[$fs->mount]} on @{[$fs->device]}";
                 }
@@ -213,7 +212,7 @@ sub GrubFs {
 
             # BTRFS is a special case in that we need to fix the referrenced path based on subvolumes
             if ($fs->type eq 'btrfs') {
-                my ($status, @id_info) = runCommand("@btrfsprogs@/bin/btrfs subvol show @{[$fs->mount]}");
+                my ($status, @id_info) = runCommand("@btrfsprogs@/bin/btrfs", "subvol", "show", @{[$fs->mount]});
                 if ($status != 0) {
                     die "Failed to retrieve subvolume info for @{[$fs->mount]}\n";
                 }
@@ -221,7 +220,7 @@ sub GrubFs {
                 if ($#ids > 0) {
                     die "Btrfs subvol name for @{[$fs->device]} listed multiple times in mount\n"
                 } elsif ($#ids == 0) {
-                    my ($status, @path_info) = runCommand("@btrfsprogs@/bin/btrfs subvol list @{[$fs->mount]}");
+                    my ($status, @path_info) = runCommand("@btrfsprogs@/bin/btrfs", "subvol", "list", @{[$fs->mount]});
                     if ($status != 0) {
                         die "Failed to find @{[$fs->mount]} subvolume id from btrfs\n";
                     }

From d9c92360a8454c6735b0a53e49fdedaa69862162 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Mon, 27 Mar 2023 19:19:41 +0200
Subject: [PATCH 2/2] nixos/install-grub: stop using bare file handles for
 readFile/WriteFile

---
 .../system/boot/loader/grub/install-grub.pl   | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index 4a8983b1bb1..2779f26aa1b 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -34,16 +34,23 @@ sub getList {
 }
 
 sub readFile {
-    my ($fn) = @_; local $/ = undef;
-    open FILE, "<$fn" or return undef; my $s = <FILE>; close FILE;
-    local $/ = "\n"; chomp $s; return $s;
+    my ($fn) = @_;
+    # enable slurp mode: read entire file in one go
+    local $/ = undef;
+    open my $fh, "<$fn" or return undef;
+    my $s = <$fh>;
+    close $fh;
+    # disable slurp mode
+    local $/ = "\n";
+    chomp $s;
+    return $s;
 }
 
 sub writeFile {
     my ($fn, $s) = @_;
-    open FILE, ">$fn" or die "cannot create $fn: $!\n";
-    print FILE $s or die;
-    close FILE or die;
+    open my $fh, ">$fn" or die "cannot create $fn: $!\n";
+    print $fh $s or die "cannot write to $fn: $!\n";
+    close $fh or die "cannot close $fn: $!\n";
 }
 
 sub runCommand {