[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

llvm-svn: 373754

1 files changed, 4 insertions, 3 deletions

diff --git a/compiler-rt/lib/scudo/standalone/wrappers_c.inc b/compiler-rt/lib/scudo/standalone/wrappers_c.inc
index cb2202dcedf..a9adbc83588 100644
--- a/compiler-rt/lib/scudo/standalone/wrappers_c.inc
+++ b/compiler-rt/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;
 }