--- /dev/null
+++ dyld/dyld-519.2.1/dyld3/Logging.cpp
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2017 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+#include <string.h>
+#include <stdint.h>
+#include <_simple.h>
+
+#include "Logging.h"
+
+
+namespace dyld3 {
+
+
+static bool sVerboseLoading         = false;
+static bool sVerboseInitializers    = false;
+static bool sVerboseSegments        = false;
+static bool sVerboseAPIs            = false;
+static bool sVerboseNotifications   = false;
+static bool sVerboseFixups          = false;
+static bool sVerboseDOFs          = false;
+
+static void vlog_default(const char* format, va_list list)
+{
+    _simple_vdprintf(2, format, list);
+}
+
+static void (*sLogFunction)(const char* format, va_list list) = &vlog_default;
+static void (*sHaltFunction)(const char* message) __attribute__((noreturn)) = nullptr;
+
+void halt(const char* message)
+{
+    (*sHaltFunction)(message);
+}
+
+static void vlog(const char* format, va_list list)
+{
+    (*sLogFunction)(format, list);
+}
+
+bool log_loads(const char* format, ...)
+{
+    if ( !sVerboseLoading )
+        return false;
+    va_list  list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_segments(const char* format, ...)
+{
+    if ( !sVerboseSegments )
+        return false;
+    va_list  list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_fixups(const char* format, ...)
+{
+    if ( !sVerboseFixups )
+        return false;
+    va_list    list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_initializers(const char* format, ...)
+{
+    if ( !sVerboseInitializers )
+        return false;
+    va_list  list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_apis(const char* format, ...)
+{
+    if ( !sVerboseAPIs )
+        return false;
+    va_list  list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_notifications(const char* format, ...)
+{
+    if ( !sVerboseNotifications )
+        return false;
+    va_list  list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+bool log_dofs(const char* format, ...)
+{
+    if ( !sVerboseDOFs )
+        return false;
+    va_list    list;
+    va_start(list, format);
+    vlog(format, list);
+    va_end(list);
+    return true;
+}
+
+
+
+void setLoggingFromEnvs(const char* envp[])
+{
+    for(const char** p = envp; *p != NULL; p++) {
+        const char* keyEqualsValue = *p;
+        const char* equals = strchr(keyEqualsValue, '=');
+        if ( equals != NULL ) {
+            //const char* value = &equals[1];
+            const size_t keyLen = equals-keyEqualsValue;
+            char key[keyLen+1];
+            strncpy(key, keyEqualsValue, keyLen);
+            key[keyLen] = '\0';
+            if ( strcmp(key, "DYLD_PRINT_LIBRARIES") == 0 ) {
+                sVerboseLoading = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_SEGMENTS") == 0 ) {
+                sVerboseSegments = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_INITIALIZERS") == 0 ) {
+                sVerboseInitializers = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_APIS") == 0 ) {
+                sVerboseAPIs = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_NOTIFICATIONS") == 0 ) {
+                sVerboseNotifications = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_BINDINGS") == 0 ) {
+                sVerboseFixups = true;
+            }
+            else if ( strcmp(key, "DYLD_PRINT_DOFS") == 0 ) {
+                sVerboseDOFs = true;
+            }
+        }
+    }
+}
+
+void setLoggingFunction(void (*func)(const char* format, va_list list))
+{
+    sLogFunction = func;
+}
+
+void setHaltFunction(void (*func)(const char* message) __attribute__((noreturn)))
+{
+    sHaltFunction = func;
+}
+
+
+} // namespace dyld3
+