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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Utilities & Libraries
C Library Reference
I
iofunc_unblock()
Unblock OCBs

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
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  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
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- Utilities & Libraries
  - C Library Reference
    - What's in a Function Description?
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      - ilogb(), ilogbf(), ilogbl()
        Compute the integral part of a logarithm
      - in6addr_*
        Variables for IPv6 addresses
      - in8()
        Read an 8-bit value from a port
      - in8s()
        Read 8-bit values from a port
      - in16(), inbe16(), inle16()
        Read a 16-bit value from a port
      - in16s()
        Read 16-bit values from a port
      - in32(), inbe32(), inle32()
        Read a 32-bit value from a port
      - in32s()
        Read 32-bit values from a port
      - initgroups()
        Initialize the supplementary group access list
      - initstate()
        Initialize a pseudo-random number generator
      - inotify_add_watch()
        Add or update a watch for filesystem events associated with a path
      - inotify_event
        Structure that describes a watched filesystem event
      - inotify_init()
        Initialize the inode notify system
      - inotify_rm_watch()
        Remove the watch associated with the given watch descriptor
      - inotify_qnx_ext()
        Enable QNX OS-specific extensions to the inotify interface
      - insque()
        Insert an element into a doubly linked queue
      - InterruptAttachEvent(), InterruptAttachEvent_r(), InterruptAttachEventPriority(), InterruptAttachEventPriority_r()
        Attach an event to an interrupt source
      - InterruptAttachThread(), InterruptAttachThread_r()
        Attach a thread to an interrupt source
      - InterruptDetach(), InterruptDetach_r()
        Detach an interrupt thread by ID
      - InterruptDisable()
        Disables all external interrupts on the current CPU core of the calling thread
      - InterruptEnable()
        Enables external interrupts on the current CPU core of the calling thread
      - InterruptLock()
        Attempt to acquire a spinlock with interrupts disabled
      - InterruptMask()
        Disable a hardware interrupt
      - InterruptQuery(), InterruptQuery_r()
        Obtain data about an interrupt source or Interrupt Service Thread (IST)
      - InterruptStatus()
        Determine whether or not interrupts are enabled
      - InterruptUnblock(), InterruptUnblock_r()
        Calls to the kernel to post a semaphore associated with an interrupt handler
      - InterruptUnlock()
        Unlock a spinlock and re-enable interrupts
      - InterruptUnmask()
        Enable a hardware interrupt
      - InterruptWait(), InterruptWait_r()
        Wait for a hardware interrupt
      - _io_connect
        Structure of a resource manager's connect message
      - _io_connect_ftype_reply
        Structure of a connect message giving a status and a file type
      - _io_connect_link_reply
        Structure of a connect message that redirects a client to another resource
      - _IO_INPUT_PAYLOAD()
        Generate a pointer to the payload that follows the header represented by the i member of an I/O message object
      - _IO_LINK_REPLY_PAYLOAD()
        Generate a pointer to the payload that follows the header represented by the link_reply member of an I/O message object
      - _IO_OUTPUT_PAYLOAD()
        Generate a pointer to the payload that follows the header represented by the o member of an I/O message object
      - ioctl(), vioctl()
        Control a device
      - iofdinfo()
        Retrieve server attributes
      - iofunc_ability_check()
        Verify that the client has a given resource manager ability
      - iofunc_acl()
        Handle an _IO_ACL message
      - iofunc_acl_default()
        Default handler for the acl callout
      - iofunc_attr_init(), iofunc_attr_init_sized()
        Initialize the per-name attribute structure associated with a device
      - iofunc_attr_lock()
        Lock the attribute structure
      - iofunc_attr_t
        I/O attribute structure
      - iofunc_attr_trylock()
        Try to lock the attribute structure
      - iofunc_attr_unlock()
        Unlock the attribute structure
      - iofunc_check_access()
        Check access permissions
      - iofunc_check_msg_default()
        Check a message
      - iofunc_chmod()
        Handle an _IO_CHMOD message
      - iofunc_chmod_default()
        Default handler for _IO_CHMOD messages
      - iofunc_chown()
        Handle an _IO_CHOWN message
      - iofunc_chown_default()
        Default handler for _IO_CHOWN messages
      - iofunc_client_info_able()
        Return information about a client connection, including abilities
      - iofunc_client_info_ext()
        Return information about a client connection
      - iofunc_client_info_ext_free()
        Free the structure used for information about a client connection
      - iofunc_close_dup()
        Free all locks allocated for the client process
      - iofunc_close_dup_default()
        Default handler for _IO_CLOSE messages
      - iofunc_close_ocb()
        Return the memory allocated for an OCB
      - iofunc_close_ocb_default()
        Return the memory allocated for an OCB
      - iofunc_devctl()
        Handle an _IO_DEVCTL message
      - iofunc_devctl_default()
        Default handler for _IO_DEVCTL messages
      - iofunc_devctl_verify()
        Perform validation that's common to all handlers for _IO_DEVCTL messages
      - iofunc_fdinfo()
        Handle an _IO_FDINFO message
      - iofunc_fdinfo_default()
        Default handler for _IO_FDINFO messages
      - iofunc_func_init()
        Initialize the default POSIX-layer function tables
      - iofunc_link()
        Link two directory entries
      - iofunc_lock()
        Lock a resource
      - iofunc_lock_default()
        Default handler for _IO_LOCK messages
      - iofunc_lock_ocb_default()
        Default handler for the lock_ocb callout
      - iofunc_lseek()
        Handle an _IO_LSEEK message
      - iofunc_lseek_default()
        Default handler for _IO_LSEEK messages
      - iofunc_mknod()
        Verify a client's ability to make a new filesystem entry point
      - iofunc_mmap()
        Handle an _IO_MMAP message
      - iofunc_mmap_default(), iofunc_mmap_default_ext()
        Default handler for _IO_MMAP messages
      - iofunc_mmap_ext()
        Handle an _IO_MMAP message
      - iofunc_mount_fini()
        Clean up the IOFUNC_MOUNT_T structure
      - iofunc_mount_init()
        Initialize the IOFUNC_MOUNT_T structure
      - iofunc_mount_set_time()
        Set the timestamp resolution for iofunc functions and structures
      - iofunc_mount_t
        I/O mount structure
      - iofunc_notify()
        Add, poll, or remove a notification handler
      - iofunc_notify_remove(), iofunc_notify_remove_strict()
        Remove notification entries from a list
      - iofunc_notify_trigger(), iofunc_notify_trigger_strict()
        Send notifications to queued clients
      - iofunc_ocb_attach()
        Initialize an Open Control Block (OCB)
      - iofunc_ocb_calloc()
        Allocate an iofunc Open Control Block
      - iofunc_ocb_detach()
        Release Open Control Block resources
      - iofunc_ocb_free()
        Deallocate an iofunc Open Control Block's memory
      - iofunc_ocb_t
        Open Control Block structure
      - iofunc_open()
        Verify a client's ability to open or to create a resource
      - iofunc_open_default(), iofunc_open_default_cinfo()
        Default handler for _IO_CONNECT messages
      - iofunc_openfd()
        Increment count and locking flags
      - iofunc_openfd_default()
        Default handler for _IO_OPENFD messages
      - iofunc_pathconf()
        Support pathconf() requests
      - iofunc_pathconf_default()
        Default handler for _IO_PATHCONF messages
      - iofunc_read_default()
        Default handler for _IO_READ messages
      - iofunc_read_verify()
        Verify a client's read access to a resource
      - iofunc_readlink()
        Verify the attributes being used to read a link
      - iofunc_rename()
        Do permission checks for a _IO_CONNECT_RENAME message
      - iofunc_space_verify()
        Do permission checks for the _IO_SPACE message
      - iofunc_stat(), iofunc_stat_format()
        Populate a stat structure
      - iofunc_stat_default()
        Default handler for _IO_STAT messages
      - iofunc_sync()
        Indicate if synchronization is needed
      - iofunc_sync_default()
        Default handler for _IO_SYNC messages
      - iofunc_sync_verify()
        Verify permissions to sync
      - iofunc_time_update()
        Update time stamps
      - iofunc_unblock()
        Unblock OCBs
      - iofunc_unblock_default()
        Default unblock handler
      - iofunc_unlink()
        Verify that an entry can be unlinked
      - iofunc_unlock_ocb_default()
        Default handler for the unlock_ocb callout
      - iofunc_utime()
        Update time stamps
      - iofunc_utime_default()
        Default handler for _IO_UTIME messages
      - iofunc_write_default()
        Default handler for _IO_WRITE messages
      - iofunc_write_verify()
        Verify a client's write access to a resource
      - ionotify()
        Arm a resource manager
      - isalnum()
        Test a character to see if it's alphanumeric
      - isalpha()
        Test a character to see if it's alphabetic
      - isascii()
        Test a character to see if it's a 7-bit ASCII character
      - isatty()
        Test to see if a file descriptor is associated with a terminal
      - isblank()
        Test a character to see if it's a blank character
      - iscntrl()
        Test a character to see if it's a control character
      - isdigit()
        Test a character to see if it's a decimal digit
      - isfdtype()
        Test the file type of a file descriptor
      - isfinite()
        Determine if a number is finite
      - isgraph()
        Test a character to see if it's any printable character except a space
      - isgreater()
        Determine whether one floating-point number is greater than another
      - isgreaterequal()
        Determine whether one floating-point number is greater than or equal to another
      - isinf()
        Test for infinity
      - isless()
        Determine whether one floating-point number is less than another
      - islessequal()
        Determine whether one floating-point number is less than or equal to another
      - islessgreater()
        Determine whether one floating-point number is less than or greater than another
      - islower()
        Test a character to see if it's a lowercase letter
      - isnan()
        Test for not-a-number (NaN)
      - isnormal()
        Determine whether a floating-point number is normal
      - isprint()
        Test a character to see if it's any printable character, including a space
      - ispunct()
        Test a character to see if it's any punctuation character
      - isspace()
        Test a character to see if it's a whitespace character
      - isunordered()
        Determine whether two floating-point numbers are unordered
      - isupper()
        Test a character to see if it's an uppercase letter
      - iswalnum()
        Test a wide character to see if it's alphanumeric
      - iswalpha()
        Test a wide character to see if it's alphabetic
      - iswblank()
        Test a wide character to see if it's a blank character
      - iswcntrl()
        Test a wide character to see if it's a control character
      - iswctype()
        Test a wide character to see if it's a given character class
      - iswdigit()
        Test a wide character to see if it's a decimal digit
      - iswgraph()
        Test a wide character to see if it's any printable character except space
      - iswlower()
        Test a wide character to see if it's a lowercase letter
      - iswprint()
        Test a wide character to see if it's any printable character, including space
      - iswpunct()
        Test a wide character to see if it's any punctuation character
      - iswspace()
        Test a wide character to see if it's a whitespace character
      - iswupper()
        Test a character to see if it's an uppercase letter
      - iswxdigit()
        Test a wide character to see if it's a hexadecimal digit
      - isxdigit()
        Test a character to see if it's a hexadecimal digit
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    The QNX Cryptography Library (qcrypto) is a flexible cryptography framework that allows you to choose which cryptography provider responds to requests on a per-process basis.
  - QNX devcrypto Service
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

iofunc_unblock()

QNX SDP8.0C Library ReferenceAPIDeveloper

Unblock OCBs

Synopsis:

#include <sys/iofunc.h>

int iofunc_unblock( resmgr_context_t * ctp,
                    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.
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_unblock() function unblocks any clients that are blocked on any internal resource manager structures.

Note:

Currently, this involves only the advisory lock list that's maintained by the attribute.

If a client connection is found on the internal lists:

that client is unblocked, and is replied to with the error EINTR
iofunc_unblock() returns _RESMGR_NOREPLY

If no such client connection is found, iofunc_unblock() returns _RESMGR_DEFAULT. In this case, the user code must clean up and unblock the client.

Returns:

_RESMGR_DEFAULT: No client connection was found.
_RESMGR_NOREPLY: A client connection has been unblocked.

Classification:


Safety:
Cancellation point	No
Signal handler	Yes
Thread	Yes

Page updated: August 11, 2025