[compiler-rt] [llvm] [sanitizer_common] Add experimental flag to tweak dlopen(<main program>) (PR #71715)

[Vitaly Buka via llvm-commits]

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@@ -6307,7 +6308,36 @@ INTERCEPTOR(int, fclose, __sanitizer_FILE *fp) {
 INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER_NOIGNORE(ctx, dlopen, filename, flag);
-  if (filename) COMMON_INTERCEPTOR_READ_STRING(ctx, filename, 0);
+
+  if (filename) {
+    COMMON_INTERCEPTOR_READ_STRING(ctx, filename, 0);
+
+#  if !SANITIZER_DYNAMIC
+    // We care about a very specific use-case: dladdr on
+    // statically-linked ASan may return <main program>
+    // instead of the library.
+    // We therefore only take effect if the sanitizer is statically
+    // linked, and we don't bother canonicalizing paths because
+    // dladdr should return the same address both times (we assume
+    // the user did not canonicalize the result from dladdr).
+    if (common_flags()->test_only_replace_dlopen_main_program) {
+      VPrintf(1, "dlopen interceptor: filename: %s\n", filename);
+
+      const char *selfFName = dladdrSelfFName();
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vitalybuka wrote:

dladdrSelfFName -> DladdrSelfFName

https://github.com/llvm/llvm-project/pull/71715