NAME

sys/types.h - data types

SYNOPSIS

#include <sys/types.h>

DESCRIPTION

The <sys/types.h> header shall include definitions for at least the following types:

blkcnt_t

Used for file block counts.

blksize_t

Used for block sizes.

clock_t

^[XSI] Used for system times in clock ticks or CLOCKS_PER_SEC; see <time.h>.

clockid_t

^[TMR] Used for clock ID type in the clock and timer functions.

dev_t

Used for device IDs.

fsblkcnt_t

^[XSI] Used for file system block counts.

fsfilcnt_t

^[XSI] Used for file system file counts.

gid_t

Used for group IDs.

id_t

^[XSI] Used as a general identifier; can be used to contain at least a pid_t, uid_t, or gid_t.

ino_t

Used for file serial numbers.

key_t

^[XSI] Used for XSI interprocess communication.

mode_t

Used for some file attributes.

nlink_t

Used for link counts.

off_t

Used for file sizes.

pid_t

Used for process IDs and process group IDs.

pthread_attr_t

^[THR] Used to identify a thread attribute object.

pthread_barrier_t

^[BAR] Used to identify a barrier.

pthread_barrierattr_t

^[BAR] Used to define a barrier attributes object.

pthread_cond_t

^[THR] Used for condition variables.

pthread_condattr_t

^[THR] Used to identify a condition attribute object.

pthread_key_t

^[THR] Used for thread-specific data keys.

pthread_mutex_t

^[THR] Used for mutexes.

pthread_mutexattr_t

^[THR] Used to identify a mutex attribute object.

pthread_once_t

^[THR] Used for dynamic package initialization.

pthread_rwlock_t

^[THR] Used for read-write locks.

pthread_rwlockattr_t

^[THR] Used for read-write lock attributes.

pthread_spinlock_t

^[SPI] Used to identify a spin lock.

pthread_t

^[THR] Used to identify a thread.

size_t

Used for sizes of objects.

ssize_t

Used for a count of bytes or an error indication.

suseconds_t

^[XSI] Used for time in microseconds.

time_t

Used for time in seconds.

timer_t

^[TMR] Used for timer ID returned by timer_create().

trace_attr_t

^[TRC] Used to identify a trace stream attributes object.

trace_event_id_t

^[TRC] Used to identify a trace event type.

trace_event_set_t

^{[TRC TEF]} Used to identify a trace event type set.

trace_id_t

^[TRC] Used to identify a trace stream.

uid_t

Used for user IDs.

useconds_t

^[XSI] Used for time in microseconds.

All of the types shall be defined as arithmetic types of an appropriate length, with the following exceptions:

^[XSI]
key_t

^[THR]
pthread_attr_t

^[BAR]
pthread_barrier_t
pthread_barrierattr_t

^[THR]
pthread_cond_t
pthread_condattr_t
pthread_key_t
pthread_mutex_t
pthread_mutexattr_t
pthread_once_t
pthread_rwlock_t
pthread_rwlockattr_t

^[SPI]
pthread_spinlock_t

^[THR]
pthread_t

^[TRC]
trace_attr_t
trace_event_id_t

^{[TRC TEF]}
trace_event_set_t

^[TRC]
trace_id_t

Additionally:

• mode_t shall be an integer type.

• nlink_t, uid_t, gid_t, and id_t shall be integer types.

• blkcnt_t and off_t shall be signed integer types.

• ^[XSI] fsblkcnt_t, fsfilcnt_t,  and ino_t shall be defined as unsigned integer types.

• size_t shall be an unsigned integer type.

• blksize_t, pid_t, and ssize_t shall be signed integer types.

• time_t and clock_t shall be integer or real-floating types.

The type ssize_t shall be capable of storing values at least in the range [-1, {SSIZE_MAX}]. ^[XSI]  The type useconds_t shall be an unsigned integer type capable of storing values at least in the range [0, 1000000]. The type suseconds_t shall be a signed integer type capable of storing values at least in the range [-1, 1000000].

The implementation shall support one or more programming environments in which the widths of blksize_t, pid_t, size_t, ssize_t, suseconds_t, and useconds_t are no greater than the width of type long. The names of these programming environments can be obtained using the confstr() function or the getconf utility.

There are no defined comparison or assignment operators for the following types:

^[THR]
pthread_attr_t

^[BAR]
pthread_barrier_t
pthread_barrierattr_t

^[THR]
pthread_cond_t
pthread_condattr_t
pthread_mutex_t
pthread_mutexattr_t
pthread_rwlock_t
pthread_rwlockattr_t

^[SPI]
pthread_spinlock_t

^[TRC]
trace_attr_t

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<time.h>, the System Interfaces volume of IEEE Std 1003.1-2001, confstr(), the Shell and Utilities volume of IEEE Std 1003.1-2001, getconf

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 5

The clockid_t and timer_t types are defined for alignment with the POSIX Realtime Extension.

The types blkcnt_t, blksize_t, fsblkcnt_t, fsfilcnt_t, and suseconds_t are added.

Large File System extensions are added.

Updated for alignment with the POSIX Threads Extension.

Issue 6

The pthread_barrier_t, pthread_barrierattr_t, and pthread_spinlock_t types are added for alignment with IEEE Std 1003.1j-2000.

The margin code is changed from XSI to THR for the pthread_rwlock_t and pthread_rwlockattr_t types as Read-Write Locks have been absorbed into the POSIX Threads option. The threads types are marked THR.

IEEE Std 1003.1-2001/Cor 2-2004, item XBD/TC2/D6/26 is applied, adding pthread_t to the list of types that are not required to be arithmetic types, thus allowing pthread_t to be defined as a structure.