Index: src/agent.c
===================================================================
--- src/agent.c	(revision 1622)
+++ src/agent.c	(working copy)
@@ -274,10 +274,14 @@
     return LIBSSH2_ERROR_NONE;
 }
 
+static SECURITY_ATTRIBUTES *SharpSvn_CreateSecurityAttributes(HWND forWindow);
+static void SharpSvn_DestroySecurityAttributes(SECURITY_ATTRIBUTES *sa);
+
 static int
 agent_transact_pageant(LIBSSH2_AGENT *agent, agent_transaction_ctx_t transctx)
 {
     HWND hwnd;
+    SECURITY_ATTRIBUTES *psa;
     char mapname[23];
     HANDLE filemap;
     unsigned char *p;
@@ -294,10 +298,14 @@
         return _libssh2_error(agent->session, LIBSSH2_ERROR_AGENT_PROTOCOL,
                               "found no pageant");
 
+    psa = SharpSvn_CreateSecurityAttributes(hwnd);
+
     sprintf(mapname, "PageantRequest%08x", (unsigned)GetCurrentThreadId());
-    filemap = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE,
+    filemap = CreateFileMapping(INVALID_HANDLE_VALUE, psa, PAGE_READWRITE,
                                 0, PAGEANT_MAX_MSGLEN, mapname);
 
+    SharpSvn_DestroySecurityAttributes(psa);
+
     if (filemap == NULL || filemap == INVALID_HANDLE_VALUE)
         return _libssh2_error(agent->session, LIBSSH2_ERROR_AGENT_PROTOCOL,
                               "failed setting up pageant filemap");
@@ -791,3 +799,101 @@
     agent_free_identities(agent);
     LIBSSH2_FREE(agent->session, agent);
 }
+
+/* SharpSvn patch */
+PSID get_user_sid(void)
+{
+    HANDLE proc = NULL, tok = NULL;
+    TOKEN_USER *user = NULL;
+    DWORD toklen, sidlen;
+    PSID sid = NULL, ret = NULL;
+
+    if ((proc = OpenProcess(MAXIMUM_ALLOWED, FALSE,
+                            GetCurrentProcessId())) == NULL)
+        goto cleanup;
+
+    if (!OpenProcessToken(proc, TOKEN_QUERY, &tok))
+        goto cleanup;
+
+    if (!GetTokenInformation(tok, TokenUser, NULL, 0, &toklen) &&
+        GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+        goto cleanup;
+
+    if ((user = (TOKEN_USER *)LocalAlloc(LPTR, toklen)) == NULL)
+        goto cleanup;
+
+    if (!GetTokenInformation(tok, TokenUser, user, toklen, &toklen))
+        goto cleanup;
+
+    sidlen = GetLengthSid(user->User.Sid);
+
+    sid = (PSID)LocalAlloc(LPTR, sidlen);
+
+    if (!CopySid(sidlen, sid, user->User.Sid))
+        goto cleanup;
+
+    /* Success. Move sid into the return value slot, and null it out
+     * to stop the cleanup code freeing it. */
+    ret = sid;
+    sid = NULL;
+
+  cleanup:
+    if (proc != NULL)
+        CloseHandle(proc);
+    if (tok != NULL)
+        CloseHandle(tok);
+    if (user != NULL)
+        LocalFree(user);
+    if (sid != NULL)
+        free(sid);
+
+    return ret;
+}
+
+static SECURITY_ATTRIBUTES *SharpSvn_CreateSecurityAttributes(HWND forWindow)
+{
+    SECURITY_ATTRIBUTES *psa;
+    SECURITY_DESCRIPTOR *psd;
+    PSID usersid;
+    if (!forWindow)
+        return NULL;
+
+    /*
+     * Make the file mapping we create for communication with
+     * Pageant owned by the user SID rather than the default. This
+     * should make communication between processes with slightly
+     * different contexts more reliable: in particular, command
+     * prompts launched as administrator should still be able to
+     * run PSFTPs which refer back to the owning user's
+     * unprivileged Pageant.
+     */
+    usersid = get_user_sid();
+
+    if (usersid) {
+        psd = (SECURITY_DESCRIPTOR*)LocalAlloc(LPTR, sizeof(*psd));
+        psa = (SECURITY_ATTRIBUTES*)LocalAlloc(LPTR, sizeof(*psa));
+        if (psa && psd) {
+            if (InitializeSecurityDescriptor(psd, SECURITY_DESCRIPTOR_REVISION) &&
+                SetSecurityDescriptorOwner(psd, usersid, FALSE)) {
+                psa->nLength = sizeof(*psa);
+                psa->bInheritHandle = FALSE;
+                psa->lpSecurityDescriptor = psd;
+                return psa;
+            } else {
+                LocalFree(psd);
+                LocalFree(psa);
+            }
+        }
+        LocalFree(usersid);
+    }
+
+    return NULL;
+}
+
+static void SharpSvn_DestroySecurityAttributes(SECURITY_ATTRIBUTES *sa)
+{
+  if (sa) {
+      LocalFree(sa->lpSecurityDescriptor);
+      LocalFree(sa);
+  }
+}