From 33c5d979ce47943d931bd75bdbb6fc019d4c6e1d Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Mon, 23 Feb 2015 23:32:33 +0100
Subject: [PATCH] warc.c: native uuid generation on Windows

* warc.c (windows_uuid_str) [WINDOWS]: New function specific to
MS-Windows.
(warc_uuid_str) [WINDOWS]: If windows_uuid_str succeeds, use its
result; otherwise use the fallback method.
---
 src/warc.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 65 insertions(+), 1 deletion(-)

diff --git a/src/warc.c b/src/warc.c
index 5ae21a51..55884e0b 100644
--- a/src/warc.c
+++ b/src/warc.c
@@ -60,7 +60,8 @@ as that of the covered work.  */
 
 #ifdef WINDOWS
 /* we need this on Windows to have O_TEMPORARY defined */
-#include <fcntl.h>
+# include <fcntl.h>
+# include <rpc.h>
 #endif
 
 #ifndef O_TEMPORARY
@@ -632,6 +633,61 @@ warc_uuid_str (char *urn_str)
   xfree (uuid_str);
 }
 #else
+# ifdef WINDOWS
+
+typedef RPC_STATUS (RPC_ENTRY * UuidCreate_proc) (UUID *);
+typedef RPC_STATUS (RPC_ENTRY * UuidToString_proc) (UUID *, unsigned char **);
+typedef RPC_STATUS (RPC_ENTRY * RpcStringFree_proc) (unsigned char **);
+
+static int
+windows_uuid_str (char *urn_str)
+{
+  static UuidCreate_proc pfn_UuidCreate = NULL;
+  static UuidToString_proc pfn_UuidToString = NULL;
+  static RpcStringFree_proc pfn_RpcStringFree = NULL;
+  static int rpc_uuid_avail = -1;
+
+  /* Rpcrt4.dll is not available on older versions of Windows, so we
+     need to test its availability at run time.  */
+  if (rpc_uuid_avail == -1)
+    {
+      HMODULE hm_rpcrt4 = LoadLibrary ("Rpcrt4.dll");
+
+      if (hm_rpcrt4)
+	{
+	  pfn_UuidCreate =
+	    (UuidCreate_proc) GetProcAddress (hm_rpcrt4, "UuidCreate");
+	  pfn_UuidToString =
+	    (UuidToString_proc) GetProcAddress (hm_rpcrt4, "UuidToStringA");
+	  pfn_RpcStringFree =
+	    (RpcStringFree_proc) GetProcAddress (hm_rpcrt4, "RpcStringFreeA");
+	  if (pfn_UuidCreate && pfn_UuidToString && pfn_RpcStringFree)
+	    rpc_uuid_avail = 1;
+	  else
+	    rpc_uuid_avail = 0;
+	}
+      else
+	rpc_uuid_avail = 0;
+    }
+
+  if (rpc_uuid_avail)
+    {
+      BYTE *uuid_str;
+      UUID  uuid;
+
+      if (pfn_UuidCreate (&uuid) == RPC_S_OK)
+	{
+	  if (pfn_UuidToString (&uuid, &uuid_str) == RPC_S_OK)
+	    {
+	      sprintf (urn_str, "<urn:uuid:%s>", uuid_str);
+	      pfn_RpcStringFree (&uuid_str);
+	      return 1;
+	    }
+	}
+    }
+  return 0;
+}
+#endif
 /* Fills urn_str with a UUID based on random numbers in the format
    required for the WARC-Record-Id header.
    (See RFC 4122, UUID version 4.)
@@ -647,6 +703,14 @@ warc_uuid_str (char *urn_str)
 
   unsigned char uuid_data[16];
   int i;
+
+#ifdef WINDOWS
+  /* If the native method fails (expected on older Windows versions),
+     use the fallback below.  */
+  if (windows_uuid_str (urn_str))
+    return;
+#endif
+
   for (i=0; i<16; i++)
     uuid_data[i] = random_number (255);