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Function 60 - Inter Process Communication (IPC)

IPC is used to send messages from one process / thread to another. In doing so, you must first agree on how to interpret a particular message.

Subfunction 1 - set the area to get IPC

Called by a receiver process.

Options:

· eax = 60 - function number

· ebx = 1 - number of subfunction

· ecx = pointer to buffer

· edx = buffer size

Return value:

· eax = 0 - always successful

IPC buffer format:

· +0: dword: if here is not 0, then the buffer is considered blocked; block / unlock the buffer when you are actively working with it and you need to prevent the buffer data from being changed from the outside (no new messages were received)

· +4: dword: buffer space occupied (bytes)

· +8: first post

· +8 + n: second message

· ...

Message format:

· +0: dword: PID of the process / thread that sent the message

· +4: dword: message length (not counting this header)

· +8: n * byte: message data

Subfunction 2 - send IPC message

Called by the initiator process.

Options:

· eax = 60 - function number

· ebx = 2 - subfunction number

· ecx = PID receiver

· edx = pointer to the message data

· esi = message length (in bytes)

Return value:

· eax = 0 - successful

· eax = 1 - the receiver has not defined a buffer for IPC messages (maybe not yet had time, and maybe this is not the flow which is needed)

· eax = 2 - the receiver has blocked the IPC buffer; try to wait a bit

· eax = 3 - receiver IPC buffer overflow

· eax = 4 - there is no process / thread with such a PID

Remarks:

· The system immediately after writing the IPC message to the buffer sends event 7 to the receiving stream (see event codes).

Constants for registers:

eax - SF_IPC (60)

ebx - SSF_SET_AREA (1), SSF_SEND_MESSAGE (2)