[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

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@374173 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 3 deletions

diff --git a/lib/scudo/standalone/combined.h b/lib/scudo/standalone/combined.h
index b2dc25f78..60be1dd20 100644
--- a/lib/scudo/standalone/combined.h
+++ b/lib/scudo/standalone/combined.h
@@ -369,12 +369,31 @@ public:
     Primary.enable();
   }
 
+  // The function returns the amount of bytes required to store the statistics,
+  // which might be larger than the amount of bytes provided. Note that the
+  // statistics buffer is not necessarily constant between calls to this
+  // function. This can be called with a null buffer or zero size for buffer
+  // sizing purposes.
+  uptr getStats(char *Buffer, uptr Size) {
+    ScopedString Str(1024);
+    disable();
+    const uptr Length = getStats(&Str) + 1;
+    enable();
+    if (Length < Size)
+      Size = Length;
+    if (Buffer && Size) {
+      memcpy(Buffer, Str.data(), Size);
+      Buffer[Size - 1] = '\0';
+    }
+    return Length;
+  }
+
   void printStats() {
+    ScopedString Str(1024);
     disable();
-    Primary.printStats();
-    Secondary.printStats();
-    Quarantine.printStats();
+    getStats(&Str);
     enable();
+    Str.output();
   }
 
   void releaseToOS() { Primary.releaseToOS(); }
@@ -563,6 +582,13 @@ private:
       *Size = getSize(Ptr, &Header);
     return P;
   }
+
+  uptr getStats(ScopedString *Str) {
+    Primary.getStats(Str);
+    Secondary.getStats(Str);
+    Quarantine.getStats(Str);
+    return Str->length();
+  }
 };
 
 } // namespace scudo