NAME¶
psignal
,
pgsignal
,
gsignal
,
tdsignal
—
post signal to a thread, process, or process
group
SYNOPSIS¶
#include
<sys/types.h>
#include
<sys/signalvar.h>
void
psignal
(
struct
proc *p,
int
signum);
void
pgsignal
(
struct
pgrp *pgrp,
int
signum,
int
checkctty);
void
gsignal
(
int
pgid,
int
signum);
void
tdsignal
(
struct
thread *td,
int
signum);
DESCRIPTION¶
These functions post a signal to a thread or one or more processes. The argument
signum common to all three functions should
be in the range [1-
NSIG
].
The
psignal
() function posts signal number
signum to the process represented by the
process structure
p. With a few exceptions
noted below, the target process signal disposition is updated and is marked as
runnable, so further handling of the signal is done in the context of the
target process after a context switch. Note that
psignal
() does not by itself cause a
context switch to happen.
The target process is not marked as runnable in the following cases:
- The target process is sleeping uninterruptibly. The signal will be noticed
when the process returns from the system call or trap.
- The target process is currently ignoring the signal.
- If a stop signal is sent to a sleeping process that takes the default
action (see sigaction(2)), the process is
stopped without awakening it.
SIGCONT
restarts a stopped process (or puts them back to sleep) regardless of the
signal action (e.g., blocked or ignored).
If the target process is being traced
psignal
() behaves as if the target process
were taking the default action for
signum.
This allows the tracing process to be notified of the signal.
The
pgsignal
() function posts signal number
signum to each member of the process group
described by
pgrp. If
checkctty is non-zero, the signal will be
posted only to processes that have a controlling terminal.
pgsignal
() is implemented by walking along
the process list headed by the field
pg_members
of the
process group structure pointed at by
pgrp
and calling
psignal
() as appropriate. If
pgrp is
NULL
no action is taken.
The
gsignal
() function posts signal number
signum to each member of the process group
identified by the group id
pgid.
gsignal
() first finds the group structure
associated with
pgid, then invokes
pgsignal
() with the argument
checkctty set to zero. If
pgid is zero no action is taken.
The
tdsignal
() function posts signal number
signum to the thread represented by the
thread structure
td.
SEE ALSO¶
sigaction(2),
signal(9),
tsleep(9)