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Increment count and locking flags
#include <sys/iofunc.h>
int iofunc_openfd( resmgr_context_t *ctp,
io_openfd_t *msg,
iofunc_ocb_t *ocb,
iofunc_attr_t *attr );
- 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_openfd_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.
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
The iofunc_openfd() helper function
examines the mode specified
by the _IO_OPENFD message, and increments the
read and write count flags
(ocb->attr->rcount and
ocb->attr->wcount), and the locking flags
(ocb->attr->rlocks and
ocb->attr->wlocks), as specified by the open mode.
The function does what's needed to support the
openfd()
function.
The io_openfd_t structure holds the _IO_OPENFD
message received by the resource manager:
struct _io_openfd {
uint16_t type;
uint16_t combine_len;
uint32_t ioflag;
uint16_t sflag;
uint16_t xtype;
struct _msg_info info;
uint32_t reserved2;
uint32_t key;
};
typedef union {
struct _io_openfd i;
} io_openfd_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_openfd that
contains the following members:
- type
- _IO_OPENFD.
- 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.
- ioflag
- How the client wants to open the file; a combination of the following bits:
- _IO_FLAG_RD — permit the file to be read.
- _IO_FLAG_WR — permit the file to be written.
- O_APPEND — cause each record that's written to
be written at the end of the file.
- O_TRUNC — if the file exists, truncate it to
contain no data.
This flag has no effect if the file doesn't exist.
- sflag
- How the client wants the file to be shared; a combination of the
following bits:
- SH_COMPAT — set compatibility mode.
- SH_DENYRW — prevent read or write access to the
file.
- SH_DENYWR — prevent write access to the file.
- SH_DENYRD — prevent read access to the file.
- SH_DENYNO — permit both read and write access
to the file.
- xtype
- Extended type information that can change the behavior of an I/O function.
One of:
- _IO_OPENFD_NONE — no extended type information.
- _IO_OPENFD_PIPE — a pipe is being opened.
- _IO_OPENFD_RESERVED — reserved
- info
- A pointer to a
_msg_info
structure that contains
information about the message received by the resource manager.
- key
- Reserved for future use.
- EOK
- Success.
- EACCES
- You don't have permission to open the file.
- EBUSY
- The file has shared locks that are in use.
QNX Neutrino
Safety: | |
Cancellation point |
No |
Interrupt handler |
No |
Signal handler |
Yes |
Thread |
Yes |
iofunc_ocb_attach(),
iofunc_openfd_default(),
_msg_info,
openfd()
Writing a Resource Manager
Resource Managers
chapter of Getting Started with QNX Neutrino
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