iofunc_chown()

Handle an _IO_CHOWN message

Synopsis:

#include <sys/iofunc.h>

int iofunc_chown ( resmgr_context_t *ctp,
                   io_chown_t *msg,
                   iofunc_ocb_t *ocb,
                   iofunc_attr_t *attr );

Arguments:

ctp

A pointer to a resmgr_context_t structure that the resource-manager library uses to pass context information between functions.

msg

A pointer to the io_chown_t structure that contains the message that the resource manager received; see below.

ocb

A pointer to the iofunc_ocb_t structure for the Open Control Block that was created when the client opened the resource.

attr

A pointer to the iofunc_attr_t structure that describes the characteristics of the device that's associated with your resource manager.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The iofunc_chown() helper function implements POSIX semantics for the client's chown() call, which is received as an _IO_CHOWN message by the resource manager.

The iofunc_chown() function verifies that the client has the necessary permissions to effect a chown on the attribute. If so, the chown is performed, modifying elements of the ocb->attr structure. As per POSIX 1003.1, if the client isn't root, iofunc_chown() clears the set-user-id and set-group-id bits in the ocb->attr->mode member.

This function takes care of updating the IOFUNC_ATTR_CTIME, IOFUNC_ATTR_DIRTY_TIME, and IOFUNC_ATTR_DIRTY_MODE bits in ocb->attr->flags. You can use iofunc_time_update(), to update the appropriate time fields in ocb->attr.

io_chown_t structure

The io_chown_t structure holds the _IO_CHOWN message received by the resource manager:

struct _io_chown {
    uint16_t                    type;
    uint16_t                    combine_len;
    int32_t                     gid;
    int32_t                     uid;
};

typedef union {
    struct _io_chown            i;
} io_chown_t;

The I/O message structures are unions of an input message (coming to the resource manager) and an output or reply message (going back to the client). In this case, there's only an input message, i.

The i member is a structure of type _io_chown that contains the following members:

type

_IO_CHOWN.

combine_len

If the message is a combine message, _IO_COMBINE_FLAG is set in this member. For more information, see Combine Messages chapter of Writing a Resource Manager.

gid

The new group ID.

uid

The new user ID.

Returns:

EOK

Successful completion.

EROFS

An attempt was made to chown on a read-only filesystem.

EACCES

The client doesn't have permissions to do the operation.

EPERM

The group ID or owner ID didn't match.

Classification:

QNX Neutrino

See also:

iofunc_attr_t, iofunc_chmod(), iofunc_chown_default(), iofunc_ocb_t, iofunc_time_update(), resmgr_attach(), resmgr_context_t

Writing a Resource Manager

Resource Managers chapter of Getting Started with QNX Neutrino