commit 1eb4325dc17cb80255e6eeed91d261dc1672f56c
author Jonas Devlieghere <jonas@devlieghere.com> Wed Aug 03 15:45:18 2022 -0700
committer Copybara-Service <copybara-worker@google.com> Wed Aug 03 15:51:27 2022 -0700
tree 5b07fe3ecc2c44b5d5bd5774936babff88e62f75
parent f845af992bafbd7964092f780b5fed85b042101c

[lldb] Make LLDB resilient against failing dyld introspection SPIs

Make LLDB resilient against failing dyld introspection SPIs:

 - dyld_process_create_for_current_task
 - dyld_process_snapshot_create_for_process
 - dyld_process_snapshot_get_shared_cache

These can all fail and return a nullptr. Instead of having an assert,
which doesn't really make sense, as we have no control over whether
these calls succeed or not, bail out gracefully and use the fallback
logic.

rdar://98070414

Differential revision: https://reviews.llvm.org/D131110

GitOrigin-RevId: 71ebcd3348061de2fde3a13f1adb56059aca5997

source/Host/macosx/objcxx/HostInfoMacOSX.mm

diff --git a/source/Host/macosx/objcxx/HostInfoMacOSX.mm b/source/Host/macosx/objcxx/HostInfoMacOSX.mm
index 74a4fb2..4cb9f5d 100644
--- a/source/Host/macosx/objcxx/HostInfoMacOSX.mm
+++ b/source/Host/macosx/objcxx/HostInfoMacOSX.mm
@@ -16,6 +16,7 @@
 #include "lldb/Utility/Timer.h"
 #include "Utility/UuidCompatibility.h"
 
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/FileSystem.h"
@@ -520,20 +521,33 @@
   SharedCacheInfo();
 
 private:
+  bool CreateSharedCacheInfoWithInstrospectionSPIs();
+
   llvm::StringMap<SharedCacheImageInfo> m_images;
   UUID m_uuid;
 };
 }
 
-SharedCacheInfo::SharedCacheInfo() {
+bool SharedCacheInfo::CreateSharedCacheInfoWithInstrospectionSPIs() {
 #if defined(SDK_HAS_NEW_DYLD_INTROSPECTION_SPIS)
   if (__builtin_available(macOS 12, *)) {
     if (dyld_process_create_for_current_task) {
-      auto dyld_process = dyld_process_create_for_current_task();
-      auto snapshot =
+      dyld_process_t dyld_process = dyld_process_create_for_current_task();
+      if (!dyld_process)
+        return false;
+
+      dyld_process_snapshot_t snapshot =
           dyld_process_snapshot_create_for_process(dyld_process, nullptr);
-      auto shared_cache = dyld_process_snapshot_get_shared_cache(snapshot);
-      assert(dyld_process && snapshot && shared_cache);
+      if (!snapshot)
+        return false;
+
+      auto on_exit = llvm::make_scope_exit(
+          [&]() { dyld_process_snapshot_dispose(snapshot); });
+
+      dyld_shared_cache_t shared_cache =
+          dyld_process_snapshot_get_shared_cache(snapshot);
+      if (!shared_cache)
+        return false;
 
       dyld_shared_cache_for_each_image(shared_cache, ^(dyld_image_t image) {
         __block uint64_t minVmAddr = UINT64_MAX;
@@ -555,11 +569,16 @@
             std::make_shared<DataBufferUnowned>((uint8_t *)minVmAddr,
                                                 maxVmAddr - minVmAddr)};
       });
-      dyld_process_snapshot_dispose(snapshot);
-      return;
+      return true;
     }
   }
 #endif
+  return false;
+}
+
+SharedCacheInfo::SharedCacheInfo() {
+  if (CreateSharedCacheInfoWithInstrospectionSPIs())
+    return;
 
   size_t shared_cache_size;
   uint8_t *shared_cache_start =