manager: add hard-coded read checks

The host-client cannot try to read back more than this number of bytes
without hitting a memory overflow in phosphor-host-ipmid.  The method we
can call to dynamically receive that number isn't currently linking out
of the userlayer library.

Note: Once the configure_ac can find and provide the userlayer library
from phosphor-host-ipmid, we can remove the hard-coded 64 and 0xe.

Change-Id: I08f6bb59ce44279f76a494dccaa477ae75d532c4
Signed-off-by: Patrick Venture <venture@google.com>

1 files changed, 32 insertions, 1 deletions

diff --git a/test/manager_read_unittest.cpp b/test/manager_read_unittest.cpp
index 1d40f5d..73e198b 100644
--- a/test/manager_read_unittest.cpp
+++ b/test/manager_read_unittest.cpp
@@ -60,7 +60,7 @@ TEST(ManagerReadTest, ReadFromHandlerReturnsData)
 
     uint16_t sess = 1;
     uint32_t ofs = 0x54;
-    uint32_t requested = 0x100;
+    uint32_t requested = 0x10;
     uint16_t flags = OpenFlags::read;
     std::string path = "/asdf/asdf";
     std::vector<uint8_t> data = {0x12, 0x14, 0x15, 0x16};
@@ -75,4 +75,35 @@ TEST(ManagerReadTest, ReadFromHandlerReturnsData)
     EXPECT_EQ(data.size(), result.size());
     EXPECT_EQ(result, data);
 }
+
+TEST(ManagerReadTest, ReadTooManyBytesTruncates)
+{
+    // For now, the hard-coded maximum transfer size is 64 bytes on read
+    // commands, due to a hard-coded buffer in ipmid among other future
+    // challenges.
+
+    BlobManager mgr;
+    std::unique_ptr<BlobMock> m1 = std::make_unique<BlobMock>();
+    auto m1ptr = m1.get();
+    EXPECT_TRUE(mgr.registerHandler(std::move(m1)));
+
+    uint16_t sess = 1;
+    uint32_t ofs = 0x54;
+    uint32_t requested = 0x100;
+    uint16_t flags = OpenFlags::read;
+    std::string path = "/asdf/asdf";
+    std::vector<uint8_t> data = {0x12, 0x14, 0x15, 0x16};
+
+    EXPECT_CALL(*m1ptr, canHandleBlob(path)).WillOnce(Return(true));
+    EXPECT_CALL(*m1ptr, open(_, flags, path)).WillOnce(Return(true));
+    EXPECT_TRUE(mgr.open(flags, path, &sess));
+
+    EXPECT_CALL(*m1ptr, read(sess, ofs, maximumReadSize))
+        .WillOnce(Return(data));
+
+    std::vector<uint8_t> result = mgr.read(sess, ofs, requested);
+    EXPECT_EQ(data.size(), result.size());
+    EXPECT_EQ(result, data);
+}
+
 } // namespace blobs