From 747253a531b6f0e2e62138ee12edadc0235456be Mon Sep 17 00:00:00 2001
From: Harrison Cook <harrison.cook@ecmwf.int>
Date: Mon, 7 Jul 2025 16:17:32 +0000
Subject: [PATCH 1/3] fix: Update MemoryReader to read more than one field

---
 eccodes/highlevel/reader.py |  8 +++--
 tests/test_highlevel.py     | 59 +++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/eccodes/highlevel/reader.py b/eccodes/highlevel/reader.py
index e0ca516..5dd747e 100644
--- a/eccodes/highlevel/reader.py
+++ b/eccodes/highlevel/reader.py
@@ -74,12 +74,16 @@ class MemoryReader(ReaderBase):
     def __init__(self, buf, kind=eccodes.CODES_PRODUCT_GRIB):
         super().__init__(kind=kind)
         self.buf = buf
+        self._index = 0
 
     def _next_handle(self):
         if self.buf is None:
             return None
-        handle = eccodes.codes_new_from_message(self.buf)
-        self.buf = None
+        handle = eccodes.codes_new_from_message(self.buf[self._index :])
+        self._index += eccodes.codes_get(handle, "totalLength")
+
+        if self._index >= len(self.buf):
+            self.buf = None
         return handle
 
 
diff --git a/tests/test_highlevel.py b/tests/test_highlevel.py
index 4647d3e..480f215 100644
--- a/tests/test_highlevel.py
+++ b/tests/test_highlevel.py
@@ -1,4 +1,5 @@
 import collections
+import io
 import itertools
 import pathlib
 
@@ -179,3 +180,61 @@ def test_grib_message_from_samples():
 def test_bufr_message_from_samples():
     message = eccodes.BUFRMessage.from_samples("BUFR4")
     assert message["edition"] == 4
+
+def test_read_memory():
+    buffer = io.BytesIO()
+    with eccodes.FileReader(TEST_GRIB_DATA2) as reader1:
+        written = []
+        for message in itertools.islice(reader1, 15):
+            message.write_to(buffer)
+            written.append(message)
+
+    with eccodes.MemoryReader(buffer.getvalue()) as reader2:
+        for message1, message2 in itertools.zip_longest(written, reader2):
+            assert message1 is not None
+            assert message2 is not None
+            for key in [
+                "edition",
+                "centre",
+                "typeOfLevel",
+                "level",
+                "dataDate",
+                "stepRange",
+                "dataType",
+                "shortName",
+                "packingType",
+                "gridType",
+                "number",
+            ]:
+                assert message1[key] == message2[key]
+            assert np.all(message1.data == message2.data)
+
+def test_read_stream():
+    buffer = io.BytesIO()
+    with eccodes.FileReader(TEST_GRIB_DATA2) as reader1:
+        written = []
+        for message in itertools.islice(reader1, 15):
+            message.write_to(buffer)
+            written.append(message)
+
+    buffer.seek(0, 0)
+
+    with eccodes.StreamReader(buffer) as reader2:
+        for message1, message2 in itertools.zip_longest(written, reader2):
+            assert message1 is not None
+            assert message2 is not None
+            for key in [
+                "edition",
+                "centre",
+                "typeOfLevel",
+                "level",
+                "dataDate",
+                "stepRange",
+                "dataType",
+                "shortName",
+                "packingType",
+                "gridType",
+                "number",
+            ]:
+                assert message1[key] == message2[key]
+            assert np.all(message1.data == message2.data)
\ No newline at end of file

From 9fc5f7e11f6238860955a26fb204f56e180e74a4 Mon Sep 17 00:00:00 2001
From: Harrison Cook <harrison.cook@ecmwf.int>
Date: Mon, 7 Jul 2025 16:21:00 +0000
Subject: [PATCH 2/3] Ran black

---
 tests/test_highlevel.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/test_highlevel.py b/tests/test_highlevel.py
index 480f215..680a1fc 100644
--- a/tests/test_highlevel.py
+++ b/tests/test_highlevel.py
@@ -181,6 +181,7 @@ def test_bufr_message_from_samples():
     message = eccodes.BUFRMessage.from_samples("BUFR4")
     assert message["edition"] == 4
 
+
 def test_read_memory():
     buffer = io.BytesIO()
     with eccodes.FileReader(TEST_GRIB_DATA2) as reader1:
@@ -209,6 +210,7 @@ def test_read_memory():
                 assert message1[key] == message2[key]
             assert np.all(message1.data == message2.data)
 
+
 def test_read_stream():
     buffer = io.BytesIO()
     with eccodes.FileReader(TEST_GRIB_DATA2) as reader1:
@@ -237,4 +239,4 @@ def test_read_stream():
                 "number",
             ]:
                 assert message1[key] == message2[key]
-            assert np.all(message1.data == message2.data)
\ No newline at end of file
+            assert np.all(message1.data == message2.data)

From 712147ff23d82ca3268ee4cdececcbff8480083a Mon Sep 17 00:00:00 2001
From: Harrison Cook <harrison.cook@ecmwf.int>
Date: Mon, 7 Jul 2025 17:56:04 +0000
Subject: [PATCH 3/3] Return None on failure of `totalLength`

---
 eccodes/highlevel/reader.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/eccodes/highlevel/reader.py b/eccodes/highlevel/reader.py
index 5dd747e..751c455 100644
--- a/eccodes/highlevel/reader.py
+++ b/eccodes/highlevel/reader.py
@@ -80,8 +80,13 @@ def _next_handle(self):
         if self.buf is None:
             return None
         handle = eccodes.codes_new_from_message(self.buf[self._index :])
-        self._index += eccodes.codes_get(handle, "totalLength")
 
+        try:
+            handle_length = eccodes.codes_get(handle, "totalLength")
+        except eccodes.GribInternalError:
+            return None
+
+        self._index += handle_length
         if self._index >= len(self.buf):
             self.buf = None
         return handle