[scudo][standalone] Make malloc_info return a minimal XML

Summary:
Initially, our malloc_info was returning ENOTSUP, but Android would
rather have it return successfully and write a barebone XML to the
stream, so we will oblige.

Add an associated test.

Reviewers: cferris, morehouse, hctim, eugenis, vitalybuka

Reviewed By: morehouse

Subscribers: delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D68427

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@373754 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 16 insertions, 4 deletions

diff --git a/lib/scudo/standalone/tests/combined_test.cpp b/lib/scudo/standalone/tests/combined_test.cpp
index c9c65690a..3f971a304 100644
--- a/lib/scudo/standalone/tests/combined_test.cpp
+++ b/lib/scudo/standalone/tests/combined_test.cpp
@@ -101,7 +101,7 @@ template <class Config> static void testAllocator() {
   // returns the same chunk. This requires that all the sizes we iterate on use
   // the same block size, but that should be the case for 2048 with our default
   // class size maps.
-  P  = Allocator->allocate(DataSize, Origin);
+  P = Allocator->allocate(DataSize, Origin);
   memset(P, Marker, DataSize);
   for (scudo::sptr Delta = -32; Delta < 32; Delta += 8) {
     const scudo::uptr NewSize = DataSize + Delta;
diff --git a/lib/scudo/standalone/tests/wrappers_c_test.cpp b/lib/scudo/standalone/tests/wrappers_c_test.cpp
index 28c21ebc8..cb651f265 100644
--- a/lib/scudo/standalone/tests/wrappers_c_test.cpp
+++ b/lib/scudo/standalone/tests/wrappers_c_test.cpp
@@ -281,3 +281,14 @@ TEST(ScudoWrappersCTest, MallocIterateBoundary) {
 
   free(P);
 }
+
+TEST(ScudoWrappersCTest, MallocInfo) {
+  char Buffer[64];
+  FILE *F = fmemopen(Buffer, sizeof(Buffer), "w+");
+  EXPECT_NE(F, nullptr);
+  errno = 0;
+  EXPECT_EQ(malloc_info(0, F), 0);
+  EXPECT_EQ(errno, 0);
+  fclose(F);
+  EXPECT_EQ(strncmp(Buffer, "<malloc version=\"scudo-", 23), 0);
+}
diff --git a/lib/scudo/standalone/wrappers_c.inc b/lib/scudo/standalone/wrappers_c.inc
index cb2202dce..a9adbc835 100644
--- a/lib/scudo/standalone/wrappers_c.inc
+++ b/lib/scudo/standalone/wrappers_c.inc
@@ -179,7 +179,8 @@ INTERFACE WEAK void *SCUDO_PREFIX(aligned_alloc)(size_t alignment,
       SCUDO_ALLOCATOR.allocate(size, scudo::Chunk::Origin::Malloc, alignment));
 }
 
-INTERFACE WEAK int SCUDO_PREFIX(malloc_info)(int, FILE *) {
-  errno = ENOTSUP;
-  return -1;
+INTERFACE WEAK int SCUDO_PREFIX(malloc_info)(UNUSED int options, FILE *stream) {
+  fputs("<malloc version=\"scudo-1\">", stream);
+  fputs("</malloc>", stream);
+  return 0;
 }