From: Qin Long <qin.long@intel.com>

The compiler (visual studio) may optimize some explicit strcmp call
in openssl source to use the intrinsic memcmp call.
In CrtLibSupport.h, we just use #define to mapping memcmp to
CompareMem API. So in Link phase, this kind of intrinsic optimization
will cause the "unresolved external symbol" error. For example:
    OpensslLib.lib(v3_utl.obj) : error LNK2001:
                               unresolved external symbol _memcmp

This patch will keep the memcmp mapping, and provide extra Intrinsic
memcmp wrapper to satisfy the symbol link.

Cc: Ting Ye <ting.ye@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qin Long <qin.long@intel.com>
---
 CryptoPkg/Include/CrtLibSupport.h                 |  1 +
 CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/CryptoPkg/Include/CrtLibSupport.h b/CryptoPkg/Include/CrtLibSupport.h
index ddf7784a37..7f1ec12302 100644
--- a/CryptoPkg/Include/CrtLibSupport.h
+++ b/CryptoPkg/Include/CrtLibSupport.h
@@ -133,6 +133,7 @@ void           *malloc     (size_t);
 void           *realloc    (void *, size_t);
 void           free        (void *);
 void           *memset     (void *, int, size_t);
+int            memcmp      (const void *, const void *, size_t);
 int            isdigit     (int);
 int            isspace     (int);
 int            isxdigit    (int);
diff --git a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
index e8a76d07ff..bf485d680d 100644
--- a/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
+++ b/CryptoPkg/Library/IntrinsicLib/MemoryIntrinsics.c
@@ -17,12 +17,14 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/BaseMemoryLib.h>
 #include <Library/BaseLib.h>
 
+typedef UINTN  size_t;
+
 /* OpenSSL will use floating point support, and C compiler produces the _fltused
    symbol by default. Simply define this symbol here to satisfy the linker. */
 int _fltused = 1;
 
 /* Sets buffers to a specified character */
-void * memset (void *dest, char ch, unsigned int count)
+void * memset (void *dest, char ch, size_t count)
 {
   //
   // NOTE: Here we use one base implementation for memset, instead of the direct
@@ -46,6 +48,12 @@ void * memset (void *dest, char ch, unsigned int count)
   return dest;
 }
 
+/* Compare bytes in two buffers. */
+int memcmp (const void *buf1, const void *buf2, size_t count)
+{
+  return (int)CompareMem(buf1, buf2, count);
+}
+
 int strcmp (const char *s1, const char *s2)
 {
   return (int)AsciiStrCmp(s1, s2);
-- 
2.12.2.windows.1

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