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envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The migration stream lacks magic numbers at some key points. It's easy to mis-parse data. Unfortunately, the VMS_NULLPTR_MARKER continues with the trend. A '0' byte is ambiguous and could be interpreted as a valid 0x30. It is maybe not worth trying to change this while keeping backward compatibility, so add some words of documentation to clarify. Signed-off-by: Fabiano Rosas --- migration/vmstate-types.c | 6 ++++++ scripts/analyze-migration.py | 9 +++++++++ 2 files changed, 15 insertions(+) diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c index e83bfccb9e..08ed059f87 100644 --- a/migration/vmstate-types.c +++ b/migration/vmstate-types.c @@ -339,6 +339,12 @@ static int put_nullptr(QEMUFile *f, void *pv, size_t size, const VMStateInfo vmstate_info_nullptr = { .name = "uint64", + + /* + * Ideally these would actually read/write the size of a pointer, + * but we're stuck with just a byte now for backward + * compatibility. + */ .get = get_nullptr, .put = put_nullptr, }; diff --git a/scripts/analyze-migration.py b/scripts/analyze-migration.py index f2457b1dde..4292fde424 100755 --- a/scripts/analyze-migration.py +++ b/scripts/analyze-migration.py @@ -388,12 +388,21 @@ def read(self): return self.data class VMSDFieldUInt(VMSDFieldInt): + NULL_PTR_MARKER = 0x30 + def __init__(self, desc, file): super(VMSDFieldUInt, self).__init__(desc, file) def read(self): super(VMSDFieldUInt, self).read() self.data = self.udata + + if self.data == self.NULL_PTR_MARKER: + # The migration stream encodes NULL pointers as '0' so any + # 0x30 in the stream could be a NULL. There's not much we + # can do without breaking backward compatibility. + pass + return self.data class VMSDFieldIntLE(VMSDFieldInt):