libcutils: test: increase use of ashmem_valid(fd)

There may be evidence of ashmem_valid(fd) reporting that the file
descriptor is an ashmem node.  Increase testing of ashmem_valid(fd),
reporting that the node _is_ ashmem, to inspire confidence in the
positive result.  Scan all file descriptors in the system, and for
those that pass ashmem_valid, get a non-zero size reference back.

Some clang-format-isms applied.

Test: libcutils-test --gtest_filter=AshmemTest.*
Bug: 72021458
Change-Id: I77d746b57a89a6afa1b829dddfdc4dd319f6b684

1 files changed, 48 insertions, 22 deletions

diff --git a/libcutils/tests/AshmemTest.cpp b/libcutils/tests/AshmemTest.cpp
index a87e23e30..b37d020fb 100644
--- a/libcutils/tests/AshmemTest.cpp
+++ b/libcutils/tests/AshmemTest.cpp
@@ -14,11 +14,18 @@
  * limitations under the License.
  */
 
+#include <errno.h>
+#include <linux/fs.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <android-base/macros.h>
 #include <android-base/unique_fd.h>
 #include <cutils/ashmem.h>
 #include <gtest/gtest.h>
-#include <linux/fs.h>
-#include <sys/mman.h>
 
 using android::base::unique_fd;
 
@@ -31,15 +38,21 @@ void TestCreateRegion(size_t size, unique_fd &fd, int prot) {
 }
 
 void TestMmap(const unique_fd& fd, size_t size, int prot, void** region, off_t off = 0) {
+    ASSERT_TRUE(fd >= 0);
+    ASSERT_TRUE(ashmem_valid(fd));
     *region = mmap(nullptr, size, prot, MAP_SHARED, fd, off);
     ASSERT_NE(MAP_FAILED, *region);
 }
 
 void TestProtDenied(const unique_fd &fd, size_t size, int prot) {
+    ASSERT_TRUE(fd >= 0);
+    ASSERT_TRUE(ashmem_valid(fd));
     EXPECT_EQ(MAP_FAILED, mmap(nullptr, size, prot, MAP_SHARED, fd, 0));
 }
 
 void TestProtIs(const unique_fd& fd, int prot) {
+    ASSERT_TRUE(fd >= 0);
+    ASSERT_TRUE(ashmem_valid(fd));
     EXPECT_EQ(prot, ioctl(fd, ASHMEM_GET_PROT_MASK));
 }
 
@@ -86,18 +99,23 @@ TEST(AshmemTest, ForkTest) {
     ASSERT_EQ(0, memcmp(region1, &data, size));
     EXPECT_EQ(0, munmap(region1, size));
 
-    ASSERT_EXIT({
-        void *region2 = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-        if (region2 == MAP_FAILED) {
-            _exit(1);
-        }
-        if (memcmp(region2, &data, size) != 0) {
-            _exit(2);
-        }
-        memset(region2, 0, size);
-        munmap(region2, size);
-        _exit(0);
-    }, ::testing::ExitedWithCode(0),"");
+    ASSERT_EXIT(
+        {
+            if (!ashmem_valid(fd)) {
+                _exit(3);
+            }
+            void* region2 = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+            if (region2 == MAP_FAILED) {
+                _exit(1);
+            }
+            if (memcmp(region2, &data, size) != 0) {
+                _exit(2);
+            }
+            memset(region2, 0, size);
+            munmap(region2, size);
+            _exit(0);
+        },
+        ::testing::ExitedWithCode(0), "");
 
     memset(&data, 0, size);
     void *region2;
@@ -146,6 +164,7 @@ TEST(AshmemTest, FileOperationsTest) {
     };
     for (const auto& cfg : seeks) {
         errno = 0;
+        ASSERT_TRUE(ashmem_valid(fd));
         auto off = lseek(fd, cfg.offset, cfg.whence);
         ASSERT_EQ(cfg.ret, off) << "lseek(" << cfg.offset << ", " << cfg.whence << ") failed"
                                 << (errno ? ": " : "") << (errno ? strerror(errno) : "");
@@ -196,15 +215,19 @@ TEST(AshmemTest, ForkProtTest) {
     constexpr size_t size = PAGE_SIZE;
 
     int protFlags[] = { PROT_READ, PROT_WRITE };
-    for (int i = 0; i < 2; i++) {
+    for (size_t i = 0; i < arraysize(protFlags); i++) {
         ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_WRITE));
-        ASSERT_EXIT({
-            if (ashmem_set_prot_region(fd, protFlags[i]) >= 0) {
-                _exit(0);
-            } else {
-                _exit(1);
-            }
-        }, ::testing::ExitedWithCode(0), "");
+        ASSERT_EXIT(
+            {
+                if (!ashmem_valid(fd)) {
+                    _exit(3);
+                } else if (ashmem_set_prot_region(fd, protFlags[i]) >= 0) {
+                    _exit(0);
+                } else {
+                    _exit(1);
+                }
+            },
+            ::testing::ExitedWithCode(0), "");
         ASSERT_NO_FATAL_FAILURE(TestProtDenied(fd, size, protFlags[1-i]));
     }
 }
@@ -227,6 +250,9 @@ TEST(AshmemTest, ForkMultiRegionTest) {
 
     ASSERT_EXIT({
         for (int i = 0; i < nRegions; i++) {
+            if (!ashmem_valid(fd[i])) {
+                _exit(3);
+            }
             void *region = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd[i], 0);
             if (region == MAP_FAILED) {
                 _exit(1);