--- /dev/null
+++ dyld/dyld-1340/mach_o/FunctionStarts.cpp
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2021 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 <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "FunctionStarts.h"
+#include "Misc.h"
+
+
+namespace mach_o {
+
+
+FunctionStarts::FunctionStarts(const uint8_t* start, size_t size)
+  : _funcStartsBegin(start), _funcStartsEnd(start+size)
+{
+}
+
+Error FunctionStarts::valid(uint64_t maxFuncOffset) const
+{
+    uint64_t runtimeOffset = 0;
+    for (const uint8_t* p=_funcStartsBegin; p < _funcStartsEnd; ) {
+        bool malformed;
+        uint64_t value = read_uleb128(p, _funcStartsEnd, malformed);
+        if ( malformed )
+            return Error("malformed uleb128 in function-starts data");
+        // a delta of zero marks end of functionStarts stream
+        if ( value == 0 ) {
+            while ( p < _funcStartsEnd ) {
+                if ( *p++ != 0 )
+                    return Error("padding at end of function-starts not all zeros");
+            }
+            return Error::none();
+        }
+        runtimeOffset += value;
+        if ( runtimeOffset > maxFuncOffset )
+            return Error("functions-starts has entry beyond end of TEXT");
+    };
+    return Error("functions-starts not zero terminated");
+}
+
+void FunctionStarts::forEachFunctionStart(uint64_t loadAddr, void (^callback)(uint64_t funcAddr)) const
+{
+    uint64_t runtimeOffset = 0;
+    for (const uint8_t* p=_funcStartsBegin; p < _funcStartsEnd; ) {
+        bool malformed;
+        uint64_t value = read_uleb128(p, _funcStartsEnd, malformed);
+        // a delta of zero marks end of functionStarts stream
+        if ( malformed || (value == 0) )
+            return;
+        runtimeOffset += value;
+        callback(loadAddr+runtimeOffset);
+    };
+}
+
+
+
+
+} // namespace mach_o