45 lines
1.8 KiB
C
45 lines
1.8 KiB
C
#ifndef IPC_H
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#define IPC_H
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/* This header file defines constants for MINIX inter-process communication.
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* These definitions are used in the file proc.c.
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*/
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#include <minix/com.h>
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#include <minix/ipcconst.h>
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/* Masks and flags for system calls. */
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#define NON_BLOCKING 0x0080 /* do not block if target not ready */
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#define FROM_KERNEL 0x0100 /* message from kernel on behalf of a process */
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#define WILLRECEIVE(target, source_ep) \
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((RTS_ISSET(target, RTS_RECEIVING) && !RTS_ISSET(target, RTS_SENDING)) && \
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(target->p_getfrom_e == ANY || target->p_getfrom_e == source_ep))
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/* IPC status code macros. */
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#define IPC_STATUS_GET(p) ((p)->p_reg.IPC_STATUS_REG)
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#define IPC_STATUS_CLEAR(p) ((p)->p_reg.IPC_STATUS_REG = 0)
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/*
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* XXX: the following check is used to set the status code only on RECEIVE.
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* SENDREC is not currently atomic for user processes. A process can return
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* from SENDREC in a different context than the original when a Posix signal
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* handler gets executed. For this reason, it is not safe to manipulate
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* the context (i.e. registers) when a process is blocked on a SENDREC.
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* Unfortunately, avoiding setting the status code for SENDREC doesn't solve
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* the problem entirely because in rare situations it is still necessary to
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* override retreg dynamically (and possibly in a different context).
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* A possible reliable solution is to improve our Posix signal handling
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* implementation and guarantee SENDREC atomicity w.r.t. the process context.
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*/
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#define IPC_STATUS_ADD(p, m) do { \
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if(!((p)->p_misc_flags & MF_REPLY_PEND)) { \
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(p)->p_reg.IPC_STATUS_REG |= (m); \
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} \
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} while(0)
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#define IPC_STATUS_ADD_CALL(p, call) \
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IPC_STATUS_ADD(p, IPC_STATUS_CALL_TO(call))
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#define IPC_STATUS_ADD_FLAGS(p, flags) \
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IPC_STATUS_ADD(p, IPC_STATUS_FLAGS(flags))
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#endif /* IPC_H */
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