From 492d9953fa2a2bfe961e3f361462f0a97bec1ee7 Mon Sep 17 00:00:00 2001
From: Jose Luis Duran <jlduran@gmail.com>
Date: Wed, 23 Feb 2022 14:04:02 -0300
Subject: [PATCH] libefivar: Handle AcpiExp device path when optional para is
 not specified

AcpiExp text device path: AcpiExp(HID,CID,UIDSTR)
And according to UEFI spec, the CID parameter is optional
and has a default value of 0. But current implementation
miss to check following cases for the AcpiExp.
FromText: when text device is AcpiExp(HID,,UIDSTR)/AcpiExp(HID,0,UIDSTR)
ToText: when the CID is 0 in the node structure

This commit is to do the enhancement.

Upstream Bug:	https://bugzilla.tianocore.org/show_bug.cgi?id=1243
Obtained from:	https://github.com/tianocore/edk2/commit/a8b5750901faa63ff5570634851e648b8e335e5a
Pull Request:   https://github.com/freebsd/freebsd-src/pull/581
---
 lib/libefivar/efivar-dp-format.c | 23 ++++++++++++++++-------
 lib/libefivar/efivar-dp-parse.c  | 11 ++++++++++-
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/lib/libefivar/efivar-dp-format.c b/lib/libefivar/efivar-dp-format.c
index e2a5e666ce7b..0062216ac307 100644
--- a/lib/libefivar/efivar-dp-format.c
+++ b/lib/libefivar/efivar-dp-format.c
@@ -539,13 +539,22 @@ DevPathToTextAcpiEx (
     //
     // use AcpiExp()
     //
-    UefiDevicePathLibCatPrint (
-      Str,
-      "AcpiExp(%s,%s,%s)",
-      HIDText,
-      CIDText,
-      UIDStr
-      );
+    if (AcpiEx->CID == 0) {
+      UefiDevicePathLibCatPrint (
+         Str,
+         "AcpiExp(%s,0,%s)",
+         HIDText,
+         UIDStr
+        );
+    } else {
+      UefiDevicePathLibCatPrint (
+        Str,
+        "AcpiExp(%s,%s,%s)",
+        HIDText,
+        CIDText,
+        UIDStr
+        );
+    }
   } else {
     if (AllowShortcuts) {
       //
diff --git a/lib/libefivar/efivar-dp-parse.c b/lib/libefivar/efivar-dp-parse.c
index a4c7cff57c06..c6ea7bc00a57 100644
--- a/lib/libefivar/efivar-dp-parse.c
+++ b/lib/libefivar/efivar-dp-parse.c
@@ -1014,7 +1014,16 @@ DevPathFromTextAcpiExp (
                                                   );
 
   AcpiEx->HID = EisaIdFromText (HIDStr);
-  AcpiEx->CID = EisaIdFromText (CIDStr);
+  //
+  // According to UEFI spec, the CID parameter is optional and has a default value of 0.
+  // So when the CID parameter is not specified or specified as 0 in the text device node.
+  // Set the CID to 0 in the ACPI extension device path structure.
+  //
+  if (*CIDStr == '\0' || *CIDStr == '0') {
+    AcpiEx->CID = 0;
+  } else {
+    AcpiEx->CID = EisaIdFromText (CIDStr);
+  }
   AcpiEx->UID = 0;
 
   AsciiStr = (CHAR8 *) ((UINT8 *)AcpiEx + sizeof (ACPI_EXTENDED_HID_DEVICE_PATH));