Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

System Functions (t) tdm_spawn(2)
Shared Memory
Any attached shared memory segments are detached from the child process by a successful call
to the tdm_spawn( ) function. See the shmat(2) reference page for additional information about
shared memory segment use.
Semaphores
Semaphore set IDs attached to a parent process are also attached to the child process if the child
process executes in the same processor as the parent.
A semaphore set cannot be shared when a semadj value exists for the parent process and the
child process is created in a different processor. When that condition exists, a call to the
tdm_spawn() function fails and errno is set to [EHLDSEM].
See the semget(2) reference page for additional information about semaphore use.
Signals
The setting of signaling attributes in the new process depends on the information provided in the
inheritance structure (pointed to by the inherit parameter).
This default signal information applies to the child process unless modified by the information in
the inheritance structure:
• Signals set to the default action (SIG_DFL) in the parent process are set to the default
action in the child process.
• Signals set to be ignored (SIG_IGN) by the parent process are set to be ignored by the
child process.
• Signals that cause abnormal termination (SIG_ABORT) in the calling process image are
set to that action in the new process image.
• Signals that cause entry into the debugger (SIG_DEBUG) in the calling process image
are set to that action in the new process image.
• Signals set to be caught by the parent process are set to the default action in the child
process (see the signal(4) reference page).
• The signal mask in the child process is inherited from the parent process.
• Signals pending in the parent process are disregarded by the child process.
The inheritance structure can modify the default signal information as listed:
• If the SPAWN_SETSIGMASK bit is set in
inherit->flags, then inherit->sigmask contains the signal mask for the child process.
• If the SPAWN_SETSIGDEF bit is set in
inherit->flags, then inherit->sigdefault specifies the signal set that is forced to the
default action in the child process. Additional signals that are set to the default action in
the parent process, or for which the parent process has a signal-catching function
installed, are also set to the default action in the child process.
Process Group
By default, the child process is a member of the same process group as the parent. However, the
new process can be designated a member of some other process group by setting the
SPAWN_SETPGROUP bit in inherit->flags. The inherit->pgroup field specifies the process
group number, or it contains the SPAWN_NEWPGROUP symbolic constant if the new process
is to be the leader of a new process group.
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