fchown (BPX1FCO, BPX4FCO) — Change the owner and group of a file or directory by descriptor

Function

The fchown callable service changes the owner, group, or both owner and group of a file. You identify the file by its file descriptor.

For the corresponding service using a pathname, see chown (BPX1CHO, BPX4CHO) — Change the owner or group of a file or directory.

Requirements

Parameters

File_descriptor

Supplied parameter

Type:

Integer

Length:

Fullword

The name of a fullword that contains the file descriptor of the file for which you wish to change the owner, group, or both owner and group.

Owner_UID

Supplied parameter

Type:

Integer

Length:

Fullword

The name of a fullword field that contains the new owner UID assigned to the file, or the present value or -1 if there is no change. This parameter must be specified.

Group_ID

Supplied parameter

Type:

Integer

Length:

Fullword

The name of a fullword field that contains the new group ID (GID) to be assigned to the file, or the present value or -1 if there is no change. This parameter must be specified.

Return_value

Returned parameter

Type:

Integer

Length:

Fullword

The name of a fullword to which the fchown service returns 0 if the request is successful, or -1 if it is unsuccessful.

Return_code

Returned parameter

Type:

Integer

Length:

Fullword

The name of a fullword in which the fchown service stores the return code. The fchown service returns Return_code only if Return_value is -1. See z/OS UNIX System Services Messages and Codes for a complete list of possible return code values. The fchown service can return one of the following values in the Return_code parameter:

Return_code	Explanation
EBADF	The File_descriptor parameter is not a valid file descriptor.
EINVAL	The Owner_UID or Group_ID parameter is incorrect; or File_descriptor refers to an unnamed pipe, and fchown is not allowed on such a file.
EPERM	The calling process does not have appropriate privileges (see Authorization).
EROFS	The specified file is on a read-only file system. The following reason code can accompany the return code: JRReadOnlyFS.

Reason_code

Returned parameter

Type:

Integer

Length:

Fullword

The name of a fullword in which the fchown service stores the reason code. The fchown service returns a Reason_code only if Return_value is -1. Reason_code further qualifies the Return_code value. See z/OS UNIX System Services Messages and Codes for the reason codes.

Usage notes

1. The fchown service changes the owner UID and owner GID of a file. Only a process with appropriate privileges (see Authorization) can change the owner UID of a file.
2. The owner GID of a file can be changed by a process if the process has appropriate privileges, or if a process meets all of these conditions:
   • The effective UID of the process matches the file's owner UID.
   • The Owner_UID value specified in the change request matches the file's owner UID.
   • The Group_ID value specified in the change request is the effective GID, or one of the supplementary GIDs, of the calling process.
3. The set-user-ID-on-execution and set-group-ID-on-execution permissions of the file mode are automatically turned off.
4. If the change request is successful, the change time for the file is updated.
5. Values for both Owner_UID and Group_ID must be specified. If you want to change only one of these values, you must set the other to its present value or to -1 in order for it to remain unchanged.

Related services

• chown (BPX1CHO, BPX4CHO) — Change the owner or group of a file or directory
• fchmod (BPX1FCM, BPX4FCM) — Change the mode of a file or directory by descriptor
• fstat (BPX1FST, BPX4FST) — Get status information about a file by descriptor

Characteristics and restrictions

There are no restrictions on the use of the fchown service.