NAME

pthread_attr_getstack, pthread_attr_setstack - get and set stack attributes

SYNOPSIS

[THR] #include <pthread.h>

[TSA TSS] int pthread_attr_getstack(const pthread_attr_t *restrict attr,
       void **restrict stackaddr, size_t *restrict stacksize);
int pthread_attr_setstack(pthread_attr_t *attr, void *stackaddr,
       size_t stacksize);


DESCRIPTION

The pthread_attr_getstack() and pthread_attr_setstack() functions, respectively, shall get and set the thread creation stack attributes stackaddr and stacksize in the attr object.

The stack attributes specify the area of storage to be used for the created thread's stack. The base (lowest addressable byte) of the storage shall be stackaddr, and the size of the storage shall be stacksize bytes. The stacksize shall be at least {PTHREAD_STACK_MIN}. The stackaddr shall be aligned appropriately to be used as a stack; for example, pthread_attr_setstack() may fail with [EINVAL] if ( stackaddr & 0x7) is not 0. All pages within the stack described by stackaddr and stacksize shall be both readable and writable by the thread.

RETURN VALUE

Upon successful completion, these functions shall return a value of 0; otherwise, an error number shall be returned to indicate the error.

The pthread_attr_getstack() function shall store the stack attribute values in stackaddr and stacksize if successful.

ERRORS

The pthread_attr_setstack() function shall fail if:

[EINVAL]

The value of stacksize is less than {PTHREAD_STACK_MIN} or exceeds an implementation-defined limit.

The pthread_attr_getstack() function may fail if:

[EINVAL]

The value specified by addr does not refer to an initialized thread attribute object.

The pthread_attr_setstack() function may fail if:

[EINVAL]

The value of stackaddr does not have proper alignment to be used as a stack, or ( stackaddr + stacksize) lacks proper alignment, or the value specified by attr does not refer to an initialized thread attribute object.

[EACCES]

The stack page(s) described by stackaddr and stacksize are not both readable and writable by the thread.

These functions shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

These functions are appropriate for use by applications in an environment where the stack for a thread must be placed in some particular region of memory.

While it might seem that an application could detect stack overflow by providing a protected page outside the specified stack region, this cannot be done portably. Implementations are free to place the thread's initial stack pointer anywhere within the specified region to accommodate the machine's stack pointer behavior and allocation requirements. Furthermore, on some architectures, such as the IA-64, "overflow" might mean that two separate stack pointers allocated within the region will overlap somewhere in the middle of the region.

After a successful call to pthread_attr_setstack(), the storage area specified by the stackaddr parameter is under the control of the implementation, as described in Use of Application-Managed Thread Stacks.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_attr_init(), pthread_attr_setdetachstate(), pthread_attr_setstacksize(), pthread_create() , the Base Definitions volume of IEEE Std 1003.1-2001, <limits.h>, <pthread.h>

CHANGE HISTORY

First released in Issue 6. Developed as an XSI extension and brought into the BASE by IEEE PASC Interpretation 1003.1 #101.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/83 is applied, updating the APPLICATION USAGE section to refer to Use of Application-Managed Thread Stacks.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC/D6/84 is applied, updating the ERRORS section to include optional errors for the case when attr refers to an uninitialized thread attribute object.