NAME

posix_spawnattr_destroy, posix_spawnattr_init — destroy and initialize spawn attributes object (ADVANCED REALTIME)

SYNOPSIS

[SPN] #include <spawn.h>

int posix_spawnattr_destroy(posix_spawnattr_t *attr);
int posix_spawnattr_init(posix_spawnattr_t *attr);

DESCRIPTION

The posix_spawnattr_destroy() function shall destroy a spawn attributes object. A destroyed attr attributes object can be reinitialized using posix_spawnattr_init(); the results of otherwise referencing the object after it has been destroyed are undefined. An implementation may cause posix_spawnattr_destroy() to set the object referenced by attr to an invalid value.

The posix_spawnattr_init() function shall initialize a spawn attributes object attr with the default value for all of the individual attributes used by the implementation. Results are undefined if posix_spawnattr_init() is called specifying an already initialized attr attributes object.

A spawn attributes object is of type posix_spawnattr_t (defined in <spawn.h>) and is used to specify the inheritance of process attributes across a spawn operation. POSIX.1-2024 does not define comparison or assignment operators for the type posix_spawnattr_t.

Each implementation shall document the individual attributes it uses and their default values unless these values are defined by POSIX.1-2024. Attributes not defined by POSIX.1-2024, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined.

The resulting spawn attributes object (possibly modified by setting individual attribute values), is used to modify the behavior of posix_spawn() or posix_spawnp(). After a spawn attributes object has been used to spawn a process by a call to a posix_spawn() or posix_spawnp(), any function affecting the attributes object (including destruction) shall not affect any process that has been spawned in this way.

RETURN VALUE

Upon successful completion, posix_spawnattr_destroy() and posix_spawnattr_init() shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The posix_spawnattr_init() function shall fail if:

[ENOMEM]

Insufficient memory exists to initialize the spawn attributes object.

The posix_spawnattr_destroy() function may fail if:

[EINVAL]

The value specified by attr is invalid.

EXAMPLES

None.

APPLICATION USAGE

These functions are part of the Spawn option and need not be provided on all implementations.

RATIONALE

The original spawn interface proposed in POSIX.1-2024 defined the attributes that specify the inheritance of process attributes across a spawn operation as a structure. In order to be able to separate optional individual attributes under their appropriate options (that is, the spawn-schedparam and spawn-schedpolicy attributes depending upon the Process Scheduling option), and also for extensibility and consistency with the newer POSIX interfaces, the attributes interface has been changed to an opaque data type. This interface now consists of the type posix_spawnattr_t, representing a spawn attributes object, together with associated functions to initialize or destroy the attributes object, and to set or get each individual attribute. Although the new object-oriented interface is more verbose than the original structure, it is simple to use, more extensible, and easy to implement.

FUTURE DIRECTIONS

None.

SEE ALSO

posix_spawn, posix_spawnattr_getsigdefault, posix_spawnattr_getflags, posix_spawnattr_getpgroup, posix_spawnattr_getschedparam, posix_spawnattr_getschedpolicy, posix_spawnattr_getsigmask

XBD <spawn.h>

CHANGE HISTORY

First released in Issue 6. Derived from IEEE Std 1003.1d-1999.

IEEE PASC Interpretation 1003.1 #106 is applied, noting that the effect of initializing an already initialized spawn attributes option is undefined.