man/man3proc/Plwp_stack.3proc

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 Copyright 2015 Joyent, Inc.

.Dd May 11, 2016
.Dt PLWP_STACK 3PROC
.Os
.Sh NAME
.Nm Plwp_stack ,
.Nm Plwp_alt_stack ,
.Nm Plwp_main_stack ,
.Nm Lstack ,
.Nm Lalt_stack ,
.Nm Lmain_stack
.Nd get thread stack information
.Sh SYNOPSIS
.Lb libproc
n libproc.h .Ft int
.Fo Plwp_stack
.Fa "struct ps_prochandle *P"
.Fa "lwpid_t lwpid"
.Fa "stack_t *stkp"
.Fc
.Ft int
.Fo Plwp_alt_stack
.Fa "struct ps_prochandle *P"
.Fa "lwpid_t lwpid"
.Fa "stack_t *stkp"
.Fc
.Ft int
.Fo Plwp_main_stack
.Fa "struct ps_prochandle *P"
.Fa "lwpid_t lwpid"
.Fa "stack_t *stkp"
.Fc
.Ft int
.Fo Lalt_stack
.Fa "struct ps_lwphandle *L"
.Fa "stack_t *stkp"
.Fc
.Ft int
.Fo Lmain_stack
.Fa "struct ps_lwphandle *L"
.Fa "stack_t *stkp"
.Fc
.Ft int
.Fo Lstack
.Fa "struct ps_lwphandle *L"
.Fa "stack_t *stkp"
.Fc
.Sh DESCRIPTION
The
.Fn Plwp_stack ,
.Fn Plwp_alt_stack ,
and
.Fn Plwp_main_stack
functions obtain information about the size and address of the stacks
for the thread identified by
.Fa lwpid
in the process handle
.Fa P .
p
Each thread in a process has its own stack which is used both for
maintaining function call sequences and the storing of local variables.
A thread may also configure a different stack to handle specific
signals. This stack is often called the
.Em alternate stack .
Whether or not the alternate stack is used may be controlled through the
.Xr sigaction 2
and
.Xr sigaltstack 2
functions .
p
The
.Fn Plwp_stack
function fills in
.Fa stkp
with the information about the thread's currently executing stack,
whether the alternate or main one.
p
The
.Fn Plwp_alt_stack
function fills in
.Fa stkp
with the information about the thread's alternate stack, if it's
configured.
p
The
.Fn Plwp_main_stack
function fills in
.Fa stkp
with the information about the thread's main stack, regardless of if there
is an alternate stack or it is executing one.
p
Process handles that refer to files, obtained through
.Xr Pgrab_file 3PROC ,
do not have any stack information and these functions will always fail
on them.
p
The
.Fn Lalt_stack ,
.Fn Lmain_stack ,
and
.Fn Lstack
functions are identical to the
.Fn Plwp_alt_stack ,
.Fn Plwp_main_stack ,
and
.Fn Plwp_main_stack
functions, except rather than specifying a thread to operate on, they
operate on the thread handle
.Fa L ,
which specifies the thread to operate on.
.Sh RETURN VALUES
Upon successful completion, the
.Fn Plwp_stack ,
.Fn Plwp_alt_stack ,
.Fn Plwp_main_stack ,
.Fn Lalt_stack ,
.Fn Lmain_stack ,
and
.Fn Lstack
functions return
.Sy 0
and fills in
.Fa stkp
with information about the appropriate stack. Otherwise,
.Sy -1
is returned,
.Sy errno
is updated with the error, and
.Fa stkp
is not modified.
.Sh ERRORS
For a full list of possible errors also see the
.Sy DIAGNOSTICS
section in
.Xr proc 4 .
p
The
.Fn Plwp_stack ,
.Fn Plwp_alt_stack ,
and
.Fn Plwp_main_stack
function will fail if:
l -tag -width Er t Er ENODATA The process handle
.Fa P
refers to a grabbed file, not an active process or core.
t Er EINVAL The process handle
.Fa P
refers to a core file and the specified thread does not exist.
t Er ENOENT The process handle
.Fa P
refers to an active process and the specified thread does not exist.
.El
p
The
.Fn Plwp_alt_stack
and
.Fn Lalt_stack
functions will fail if:
l -tag -width Er t Er ENODATA The thread identified by
.Fa lwpid
did not have an alternate stack enabled.
.El
.Sh INTERFACE STABILITY
.Sy Uncommitted
.Sh MT-LEVEL
See
.Sy LOCKING
in
.Xr libproc 3LIB .
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr sigaltstack 2 ,
.Xr libproc 3LIB ,
.Xr proc 4