[scudo][standalone] Get statistics in a char buffer

Summary:
Following up on D68471, this CL introduces some `getStats` APIs to
gather statistics in char buffers (`ScopedString` really) instead of
printing them out right away. Ultimately `printStats` will just
output the buffer, but that allows us to potentially do some work
on the intermediate buffer, and can be used for a `mallocz` type
of functionality. This allows us to pretty much get rid of all the
`Printf` calls around, but I am keeping the function in for
debugging purposes.

This changes the existing tests to use the new APIs when required.

I will add new tests as suggested in D68471 in another CL.

Reviewers: morehouse, hctim, vitalybuka, eugenis, cferris

Reviewed By: morehouse

Subscribers: delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D68653

llvm-svn: 374173

1 files changed, 15 insertions, 1 deletions

diff --git a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
index 3f971a30428..d74c07e8458 100644
--- a/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
@@ -136,7 +136,21 @@ template <class Config> static void testAllocator() {
   }
 
   Allocator->releaseToOS();
-  Allocator->printStats();
+
+  scudo::uptr BufferSize = 8192;
+  std::vector<char> Buffer(BufferSize);
+  scudo::uptr ActualSize = Allocator->getStats(Buffer.data(), BufferSize);
+  while (ActualSize > BufferSize) {
+    BufferSize = ActualSize + 1024;
+    Buffer.resize(BufferSize);
+    ActualSize = Allocator->getStats(Buffer.data(), BufferSize);
+  }
+  std::string Stats(Buffer.begin(), Buffer.end());
+  // Basic checks on the contents of the statistics output, which also allows us
+  // to verify that we got it all.
+  EXPECT_NE(Stats.find("Stats: SizeClassAllocator"), std::string::npos);
+  EXPECT_NE(Stats.find("Stats: MapAllocator"), std::string::npos);
+  EXPECT_NE(Stats.find("Stats: Quarantine"), std::string::npos);
 }
 
 TEST(ScudoCombinedTest, BasicCombined) {