Defines primitive system data types.
The /usr/include/sys/types.h file defines data types used in system source code. Since some system data types are accessible to user code, they can be used to enhance portability across different machines and operating systems. For example, the pid_t type allows for more processes than the unsigned short (ushort_t) type, and the dev_t type can be 16 bits rather than 32 bits.
Standard Type Definitions
The types.h file includes the following standard type definitions, which are defined with a typedef statement:
| Item | Description |
|---|---|
| daddr_t | Used for disk addresses, except in i-nodes on disk. The /usr/include/sys/filsys.h file format describes the format of disk addresses used in i-nodes. |
| caddr_t | Core (memory) address. |
| clock_t | Used for system times as specified in CLK_TCKs. |
| ino_t | File system i-node number. |
| cnt_t | File system reference count type. |
| dev_t | Major and minor parts of a device code specify the kind of device and unit number of the device and depend on how the system is customized. |
| chan_t | Channel number (the minor's minor). |
| off_t | File offset, measured in bytes from the beginning of a file or device. off_t is normally defined as a signed, 32-bit integer. In the programming environment which enables large files, off_t is defined to be a signed, 64-bit integer. |
| offset_t | 64-bit file offset, measured in bytes from the beginning of a file or device. |
| off64_t | 64-bit file offset, measured in bytes from the beginning of a file or device. |
| soff_t | 32-bit file offset, measured in bytes from the beginning of a file or device. |
| paddr_t | Real address. |
| key_t | IPC key. |
| time_t | Timer ID. Times are encoded in seconds, since 00:00:00 UCT, January 1, 1970. |
| nlink_t | Number of file links. |
| mode_t | File mode. |
| uid_t | User ID. |
| gid_t | Group ID. |
| mid_t | Module ID. |
| pid_t | Process ID. |
| slab_t | Security label. |
| mtyp_t | Interprocess communication (IPC) message type. |
| size_t | Data type is used for sizes of objects. |
| ssize_t | Data type is used for a count of bytes or an error indication. |
| uchar_t | Unsigned char. |
| ushort_t | Unsigned short. |
| uint_t | Unsigned int. |
| ulong_t | Unsigned long. |
| trace_attr_t | Trace attributes object. |
| trace_id_t | Trace stream identifier. |
| trace_event_id_t | Trace-event-type identifier. |
| trace_event_set_t | Trace-event-type set. |
Unsigned Integers and Addresses
The types.h file also includes the following type definitions for unsigned integers and addresses:
typedef struct _quad { long val[2]; } quad;
typedef long swblk_t;
typedef unsigned long size_t;The following type definitions are for BSD compatibility only:
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;