The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group

NAME

sys/types.h — data types

SYNOPSIS

#include <sys/types.h>

DESCRIPTION

The <sys/types.h> header shall define at least the following types:

blkcnt_t
Used for file block counts.
blksize_t
Used for block sizes.
clock_t
Used for system times in clock ticks or CLOCKS_PER_SEC; see <time.h>.
clockid_t
Used for clock ID type in the clock and timer functions.
dev_t
Used for device IDs.
fsblkcnt_t
Used for file system block counts.
fsfilcnt_t
Used for file system file counts.
gid_t
Used for group IDs.
id_t
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] [Option Start] Used for XSI interprocess communication. [Option End]
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
Used to identify a thread attribute object.
pthread_barrier_t
Used to identify a barrier.
pthread_barrierattr_t
Used to define a barrier attributes object.
pthread_cond_t
Used for condition variables.
pthread_condattr_t
Used to identify a condition attribute object.
pthread_key_t
Used for thread-specific data keys.
pthread_mutex_t
Used for mutexes.
pthread_mutexattr_t
Used to identify a mutex attribute object.
pthread_once_t
Used for dynamic package initialization.
pthread_rwlock_t
Used for read-write locks.
pthread_rwlockattr_t
Used for read-write lock attributes.
pthread_spinlock_t
Used to identify a spin lock.
pthread_t
Used to identify a thread.
reclen_t
Used for directory entry lengths.
size_t
Used for sizes of objects.
ssize_t
Used for a count of bytes or an error indication.
suseconds_t
Used for time in microseconds.
time_t
Used for time in seconds.
timer_t
Used for timer ID returned by timer_create().
uid_t
Used for user IDs.

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


pthread_attr_t
pthread_barrier_t
pthread_barrierattr_t
pthread_cond_t
pthread_condattr_t
pthread_key_t
pthread_mutex_t
pthread_mutexattr_t
pthread_once_t
pthread_rwlock_t
pthread_rwlockattr_t
pthread_spinlock_t
pthread_t
timer_t

Additionally:

The type ssize_t shall be capable of storing values at least in the range [-1, {SSIZE_MAX}].

[XSI] [Option Start] The type suseconds_t shall be a signed integer type capable of storing values at least in the range [-1, 1000000]. [Option End]

The implementation shall support one or more programming environments in which the widths of blksize_t, pid_t, size_t, ssize_t, and suseconds_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:


pthread_attr_t
pthread_barrier_t
pthread_barrierattr_t
pthread_cond_t
pthread_condattr_t
pthread_mutex_t
pthread_mutexattr_t
pthread_rwlock_t
pthread_rwlockattr_t
pthread_spinlock_t
timer_t


The following sections are informative.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<stdint.h> , <time.h>

XSH confstr

XCU 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.

Issue 7

Austin Group Interpretation 1003.1-2001 #033 is applied, requiring key_t to be an arithmetic type.

The Trace option types are marked obsolescent.

The clock_t and id_t types are moved from the XSI option to the Base.

The pthread_barrier_t and pthread_barrierattr_t types are moved from the Barriers option to the Base.

The pthread_spinlock_t type is moved from the Spin Locks option to the Base.

Functionality relating to the Timers and Threads options is moved to the Base.

POSIX.1-2008, Technical Corrigendum 1, XBD/TC1-2008/0069 [210], XBD/TC1-2008/0070 [28], XBD/TC1-2008/0071 [376], XBD/TC1-2008/0072 [210], and XBD/TC1-2008/0073 [327] are applied.

POSIX.1-2008, Technical Corrigendum 2, XBD/TC2-2008/0079 [856] and XBD/TC2-2008/0080 [659] are applied.

Issue 8

Austin Group Defect 697 is applied, adding reclen_t.

Austin Group Defect 1330 is applied, removing obsolescent interfaces.

Austin Group Defect 1462 is applied, changing time_t to have a width of at least 64 bits.

End of informative text.

 

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