Getting Started with QNX Neutrino - QNX Software Systems

Alphabetical listing of connect and I/O functions
© 2009, QNX Software Systems GmbH & Co. KG.
Helper functions: iofunc_unblock()
Client function: none — kernel action due to signal or timeout
Messages: none — synthesized by library
Data structure: pointer to message structure being interrupted
Description: This is the I/O message version of the unblock outcall, synthesized by the
library as a result of a kernel pulse due to the client’s attempt to unblock during the I/O
message phase. The connect message phase io_unblock() handler is substantially the
same (see the preceding section).
Common to both unblock handlers (connect and I/O) is the characteristic that the
client wishes to unblock, but is at the mercy of the resource manager. The resource
manager must reply to the client’s message in order to unblock the client. (This is
discussed in the Message Passing chapter when we looked at the ChannelCreate()
flags, particularly the _NTO_CHF_UNBLOCK flag).
Returns: The status via the helper macro _RESMGR_STATUS.
See the section in the Message Passing chapter, titled “Using the
_NTO_MI_UNBLOCK_REQ” for a detailed discussion of unblocking strategies.
io_unlink()
int io_unlink (resmgr_context_t *ctp, io_unlink_t *msg,
RESMGR_HANDLE_T *handle, void *reserved)
Classification: Connect
Default handler: none
Helper functions: iofunc_unlink()
Client function: unlink()
Messages: _IO_CONNECT with subtype _IO_CONNECT_UNLINK
Data structure:
struct _io_connect {
// internal fields (as described above)
uint16_t path_len;
uint8_t extra_type;
uint16_t extra_len;
char path [1];
};
struct _io_connect_link_reply {
uint32_t reserved1 [2];
uint8_t eflag;
uint8_t reserved2 [3];
uint32_t umask;
uint16_t nentries;
uint16_t path_len;
};
typedef union {
250 Chapter 5 • Resource Managers April 30, 2009