[compiler-rt] PR#39514 Support versioned llvm-symbolizer binaries

[ahunt]

Summary

Some linux distributions produce versioned llvm-symbolizer binaries,
e.g. my llvm-11 installation puts the symbolizer binary at
/usr/bin/llvm-symbolizer-11.0.0 . However if you then try to run
a binary containing ASAN with
ASAN_SYMBOLIZER_PATH=..../llvm-symbolizer-FOO , it will fail on startup
with "isn't a known symbolizer".

Although it is possible to work around this by setting up symlinks,
that's kindof ugly - supporting versioned binaries is a nicer solution.
(There are now multiple stack overflow and blog posts talking about
this exact issue :) .)

Originally added in:
https://reviews.llvm.org/D8285

[eugenis]

LGTM

Do you have commit access? I can land this for you.

[ahunt]

In D97682#2617649, @eugenis wrote:

Do you have commit access? I can land this for you.

Yes please - I would appreciate if you could commit this. I do not have commit access - thank you for offering!

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp

static SymbolizerTool *ChooseExternalSymbolizer(LowLevelAllocator *allocator) {
 
   if (path && internal_strchr(path, '%')) {
     char *new_path = (char *)InternalAlloc(kMaxPathLength);
     SubstituteForFlagValue(path, new_path, kMaxPathLength);
     path = new_path;
   }
 
   const char *binary_name = path ? StripModuleName(path) : "";
+  static const char kLLVMSymbolizerPrefix[] = "llvm-symbolizer";
   if (path && path[0] == '\0') {
     VReport(2, "External symbolizer is explicitly disabled.\n");
     return nullptr;
-  } else if (!internal_strcmp(binary_name, "llvm-symbolizer")) {
+  } else if (!internal_strncmp(binary_name, kLLVMSymbolizerPrefix,
+                               internal_strlen(kLLVMSymbolizerPrefix))) {
     VReport(2, "Using llvm-symbolizer at user-specified path: %s\n", path);
     return new(*allocator) LLVMSymbolizer(path, allocator);
   } else if (!internal_strcmp(binary_name, "atos")) {
 #if SANITIZER_MAC
     VReport(2, "Using atos at user-specified path: %s\n", path);
     return new(*allocator) AtosSymbolizer(path, allocator);
 #else  // SANITIZER_MAC
     Report("ERROR: Using `atos` is only supported on Darwin.\n");