[win-pv-devel] [PATCH 1/2] Don't use C runtime versions of toupper() and tolower()

[Paul Durrant <pdurrant@xxxxxxxxx>]

It seems that, despite their trivial functionality, the runtime
implementation insists on converting to Unicode! This means those functions
are actually only safe at PASSIVE_LEVEL.
This patch implements __toupper() and __tolower() as replacements with
no such hidden nastiness and modifies callers to use those.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
 src/common/util.h | 22 ++++++++++++++++++++++
 src/xen/module.c  |  2 +-
 src/xenbus/fdo.c  |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/common/util.h b/src/common/util.h
index 1a2bb86..c772b1e 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -278,4 +278,26 @@ __strtok_r(
     return Token;
 }
 
+static FORCEINLINE CHAR
+__toupper(
+    IN  CHAR    Character
+    )
+{
+    if (Character < 'a' || Character > 'z')
+        return Character;
+
+    return 'A' + Character - 'a';
+}
+
+static FORCEINLINE CHAR
+__tolower(
+    IN  CHAR    Character
+    )
+{
+    if (Character < 'A' || Character > 'Z')
+        return Character;
+
+    return 'a' + Character - 'A';
+}
+
 #endif  // _COMMON_UTIL_H
diff --git a/src/xen/module.c b/src/xen/module.c
index ed8838a..a5bf3c7 100644
--- a/src/xen/module.c
+++ b/src/xen/module.c
@@ -155,7 +155,7 @@ ModuleAdd(
         if (Name[Index] == '\0')
             break;
 
-        New->Name[Index] = (CHAR)tolower(Name[Index]);
+        New->Name[Index] = __tolower(Name[Index]);
     }
 
     New->Start = Start;
diff --git a/src/xenbus/fdo.c b/src/xenbus/fdo.c
index 00801c9..d079928 100644
--- a/src/xenbus/fdo.c
+++ b/src/xenbus/fdo.c
@@ -1129,7 +1129,7 @@ FdoMultiSzToUpcaseAnsi(
             if (Buffer[Index] == '\0')
                 break;
         } else {
-            Buffer[Index] = (CHAR)toupper(Buffer[Index]);
+            Buffer[Index] = __toupper(Buffer[Index]);
             Index++;
         }
     }
-- 
2.1.1


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