[msan] Switch the pvalloc overflow test to a lit test

[cryptoad]

Summary

The test was not passing in google3 due to allocator_may_return_null being
true there. Change the test to a lit test so that we can test both situations.

[bkramer]

lgtm

lib/msan/tests/msan_test.cc

TEST(MemorySanitizer, pvalloc) {
   EXPECT_EQ(0U, (uintptr_t)p % PageSize);
   EXPECT_EQ(2 * PageSize, __sanitizer_get_allocated_size(p));
   free(p);
 
   p = pvalloc(0);  // pvalloc(0) should allocate at least one page.
   EXPECT_EQ(0U, (uintptr_t)p % PageSize);
   EXPECT_EQ(PageSize, __sanitizer_get_allocated_size(p));
   free(p);
-
-  // Overflows should be caught.
-  EXPECT_DEATH(p = pvalloc((uintptr_t)-1),
-               "allocator is terminating the process instead of returning 0");
-  EXPECT_DEATH(p = pvalloc((uintptr_t)-(PageSize - 1)),
-               "allocator is terminating the process instead of returning 0");
 }
 #endif
 
 TEST(MemorySanitizer, inet_pton) {
   const char *s = "1:0:0:0:0:0:0:8";
   unsigned char buf[sizeof(struct in6_addr)];
   int res = inet_pton(AF_INET6, s, buf);
   ASSERT_EQ(1, res);

test/msan/pvalloc.cc

+// RUN: %clangxx_msan -O0 %s -o %t
+// RUN: MSAN_OPTIONS=allocator_may_return_null=0 not %run %t m1 2>&1 | FileCheck %s
+// RUN: MSAN_OPTIONS=allocator_may_return_null=1     %run %t m1 2>&1
+// RUN: MSAN_OPTIONS=allocator_may_return_null=0 not %run %t psm1 2>&1 | FileCheck %s
+// RUN: MSAN_OPTIONS=allocator_may_return_null=1     %run %t psm1 2>&1
+
+// UNSUPPORTED: win32, freebsd
+
+// Checks that pvalloc overflows are caught. If the allocator is allowed to
+// return null, the errno should be set to ENOMEM.
+
+#include <assert.h>
+#include <errno.h>
+#include <malloc.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+  void *p;
+  size_t page_size;
+
+  assert(argc == 2);
+
+  page_size = sysconf(_SC_PAGESIZE);
+  // Check that the page size is a power of two.
+  assert((page_size & (page_size - 1)) == 0);
+
+  if (!strcmp(argv[1], "m1")) {
+    p = pvalloc((uintptr_t)-1);
+    assert(!p);
+    assert(errno == ENOMEM);
+  }
+  if (!strcmp(argv[1], "psm1")) {
+    p = pvalloc((uintptr_t)-(page_size - 1));
+    assert(!p);
+    assert(errno == ENOMEM);
+  }
+
+  return 0;
+}
+
+// CHECK: MemorySanitizer's allocator is terminating the process