[compiler-rt] [compiler-rt][rtsan] mremap for Linux interception. (PR #124234)

[Chris Apple via llvm-commits]

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@@ -850,6 +851,32 @@ INTERCEPTOR(void *, mmap64, void *addr, size_t length, int prot, int flags,
 #define RTSAN_MAYBE_INTERCEPT_MMAP64
 #endif // SANITIZER_INTERCEPT_MMAP64
 
+#if SANITIZER_LINUX
+// Note that even if rtsan is ported to netbsd, it has a different signature
+// still
+INTERCEPTOR(void *, mremap, void *oaddr, size_t olength, size_t nlength,
+            int flags, ...) {
+  __rtsan_notify_intercepted_call("mremap");
+
+  void *naddr = nullptr;
+
+  // the last optional argument is only used in this case
+  // as the new page region will be assigned to. Is ignored otherwise.
+  if (flags & MREMAP_FIXED) {
+    va_list args;
+
+    va_start(args, flags);
+    naddr = va_arg(args, void *);
+    va_end(args);
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cjappl wrote:

For this will you follow the pattern set forth in our `open`/`openat` interceptor? that is, call REAL in two places so we don't have to pass in nullptr on 873?

https://github.com/llvm/llvm-project/pull/124234