From d996e4687d9f554bd35091838b85f723b9eec08f Mon Sep 17 00:00:00 2001
From: Petr Tesarik <[email protected]>
Date: Mon, 1 Apr 2024 16:20:40 +0800
Subject: [PATCH 043/272] Unquote parameters written to Xen EFI config file

The GRUB_CMDLINE_* value is copied verbatim to grub.conf, so it is first
parsed by GRUB2 before being passed down to the kernel. OTOH Xen EFI loader
takes the config file options verbatim. This means that any special GRUB2
syntax must be evaluated when generating that file.

Of course, some things are not even possible (e.g. substituting GRUB runtime
variables), but let's call them known limitations.

Signed-off-by: Petr Tesarik <[email protected]>
---
 util/grub.d/20_linux_xen.in | 52 +++++++++++++++++++++++++++++++++++--
 1 file changed, 50 insertions(+), 2 deletions(-)

diff --git a/util/grub.d/20_linux_xen.in b/util/grub.d/20_linux_xen.in
index 21ac71bb8..7641f8b27 100644
--- a/util/grub.d/20_linux_xen.in
+++ b/util/grub.d/20_linux_xen.in
@@ -139,6 +139,52 @@ else
   is_efi=false
 fi
 
+grub2_unquote ()
+{
+  awk '
+    BEGIN   {
+      bare = "[^{}|&$;<> \t\n'\''\"\\\\]+"
+      esc = "\\\\."
+      id = "[[:alpha:]_][[:alnum:]_]*|[[:digit:]]+|[?#*@]"
+      var = "\\$("id")|\\$\\{("id")\\}"
+      dqesc = "\\\\[$\"\\\\]"
+      dqstr = "\\$?\"([^\"]|"var"|"dqesc")*\""
+      sqstr = "'\''[^'\'']*'\''"
+      pat = bare"|"esc"|"var"|"dqstr"|"sqstr
+      ORS = ""
+    }
+    {
+      patsplit($0, words, pat, sep)
+      print sep[0]
+      for (i in words) {
+        w = words[i]
+        if (w ~ /^\$?"/) {
+          # Double-quoted string
+          patsplit(w, segs, var"|"dqesc, ssep)
+          print ssep[0]
+          for (j in segs) {
+            if (segs[j] ~ /^\\/)
+              print substr(segs[j], 2)
+            print ssep[j]
+          }
+        } else if (w ~ /^'\''/) {
+          # Single-quoted string
+          print substr(w, 2, length(w)-2)
+        } else if (w ~ /^\\/) {
+          # Escape sequence
+          print substr(w, 2)
+        } else if (w ~ /^\$/) {
+          # Variable expansion
+        } else {
+          # Bare word
+          print w
+        }
+        print sep[i]
+      }
+      print "\n"
+    }'
+}
+
 linux_entry ()
 {
   linux_entry_xsm "$@" false
@@ -209,11 +255,13 @@ linux_entry_xsm ()
     else
       section="failsafe.$section_count"
     fi
+    xen_args_unq=$(echo $xen_args | grub2_unquote)
+    args_unq=$(echo $args | grub2_unquote)
     cat <<-EOF >> $grub_dir/$xen_cfg
 
 	[$section]
-	options=${xen_args}
-	kernel=${basename} root=${linux_root_device_thisversion} ${args}
+	options=${xen_args_unq}
+	kernel=${basename} root=${linux_root_device_thisversion} ${args_unq}
 	ramdisk=${initrd_real}
 	EOF
     message="$(gettext_printf "Loading Xen %s with Linux %s ..." ${xen_version} ${version})"
-- 
2.41.0