tests/ports/qemu: Add arch flags MPY import checks test.

This commit introduces a test file (along with its necessary data) to
test MPY files pass/reject cases, due to either mismatching architecture
flag requirements or unneeded "no-flags" values set.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

tests/ports/qemu/mpy_arch_flags_test.py

@@ -0,0 +1,128 @@
+try:
+    import sys, io, vfs
+
+    sys.implementation._mpy
+    io.IOBase
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+sys_implementation_mpy = sys.implementation._mpy
+arch = (sys_implementation_mpy >> 10) & 0x0F
+
+# RV32-only for now.
+if arch != 11:
+    print("SKIP")
+    raise SystemExit
+
+
+class UserFile(io.IOBase):
+    def __init__(self, data):
+        self.data = memoryview(data)
+        self.pos = 0
+
+    def readinto(self, buf):
+        n = min(len(buf), len(self.data) - self.pos)
+        buf[:n] = self.data[self.pos : self.pos + n]
+        self.pos += n
+        return n
+
+    def ioctl(self, req, arg):
+        if req == 4:  # MP_STREAM_CLOSE
+            return 0
+        return -1
+
+
+class UserFS:
+    def __init__(self, files):
+        self.files = files
+
+    def mount(self, readonly, mksfs):
+        pass
+
+    def umount(self):
+        pass
+
+    def stat(self, path):
+        if path in self.files:
+            return (32768, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+        raise OSError
+
+    def open(self, path, mode):
+        return UserFile(self.files[path])
+
+
+def mp_encode_uint(val):
+    encoded = [val & 0x7F]
+    val >>= 7
+    while val != 0:
+        encoded.insert(0, 0x80 | (val & 0x7F))
+        val >>= 7
+    return bytes(encoded)
+
+
+def add_flags(module, flags):
+    output = bytearray()
+    output.extend(module[:4])
+    output[2] |= 0x40
+    output.extend(mp_encode_uint(flags))
+    output.extend(module[4:])
+    return output
+
+
+arch_flags = sys_implementation_mpy >> 16
+can_test_partial_flags = arch_flags not in [1 << i for i in range(16)]
+
+# To recreate this string run:
+# echo "hello=1" | mpy-cross -s module.py - | python -c 'import sys; print(sys.stdin.buffer.read())'
+MPY_FILE_BASE = b"M\x06\x00\x1f\x03\x00\x12module.py\x00\x0f\nhello\x00@\x00\x02\x01\x81\x16\x02Qc"
+
+user_files = {
+    "/matching_flags.mpy": add_flags(MPY_FILE_BASE, arch_flags),
+    "/invalid_flags.mpy": add_flags(MPY_FILE_BASE, (~arch_flags & 0xFFFF)),
+    "/explicit_no_flags.mpy": add_flags(MPY_FILE_BASE, 0),
+}
+if can_test_partial_flags:
+    user_files["/partial_flags_more.mpy"] = add_flags(
+        MPY_FILE_BASE, (arch_flags | (arch_flags << 1)) & 0xFFFF
+    )
+    user_files["/partial_flags_less.mpy"] = add_flags(
+        MPY_FILE_BASE, (arch_flags >> 1) & arch_flags
+    )
+
+vfs.mount(UserFS(user_files), "/userfs")
+sys.path.append("/userfs")
+
+import matching_flags
+
+if not hasattr(matching_flags, "hello"):
+    print("Improper matching_flags import")
+
+import explicit_no_flags
+
+if not hasattr(explicit_no_flags, "hello"):
+    print("Improper explicit_no_flags import")
+
+try:
+    import invalid_flags
+
+    print("Unexpected invalid_flags import")
+except ValueError as e:
+    if str(e) != "incompatible .mpy file":
+        print("Unexpected invalid_flags import error:", str(e))
+
+if can_test_partial_flags:
+    import partial_flags_less
+
+    if not hasattr(partial_flags_less, "hello"):
+        print("Improper partial_flags_less import")
+
+    try:
+        import partial_flags_more
+
+        print("Unexpected partial_flags_more import")
+    except ValueError as e:
+        if str(e) != "incompatible .mpy file":
+            print("Unexpected partial_flags_more import error:", str(e))
+
+print("OK")

tests/ports/qemu/mpy_arch_flags_test.py.exp

@@ -0,0 +1 @@
+OK