Getting Started with QNX Neutrino - QNX Software Systems

© 2009, QNX Software Systems GmbH & Co. KG. Alphabetical listing of connect and I/O functions
of struct dirent members in the directory case. For more information about
returning directory entries, see the example in the “Advanced topics” section under
“Returning directory entries.”
The helper function iofunc_read_verify() should be called to ascertain that the file was
opened in a mode compatible with reading. Also, the iofunc_sync_verify() function
should be called to verify if the data needs to be synchronized to the medium. (For a
read(), that means that the data returned is guaranteed to be on-media.)
Returns: The number of bytes read, or the status, via the helper macro
_IO_SET_READ_NBYTES, and the data itself via message reply.
For an example of returning just data, take a look at “A simple io_read() example”
below. For a more complicated example of returning both data and directory entries,
look in the “Advanced topics” section under “Returning directory entries.”
io_readlink()
int io_readlink (resmgr_context_t *ctp, io_readlink_t *msg,
RESMGR_HANDLE_T *handle, void *reserved)
Classification: Connect
Default handler: none
Helper functions: iofunc_readlink()
Client function: readlink()
Messages: _IO_CONNECT with subtype _IO_CONNECT_READLINK
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 {
struct _io_connect
connect;
struct _io_connect_link_reply link_reply;
} io_open_t;
Description: Responsible for reading the contents of a symbolic link as specified by
the path member of the input structure. The bytes returned are the contents of the
symbolic link; the status returned is the number of bytes in the reply. A valid return
should be done only for a symbolic link; all other accesses should return an error code.
April 30, 2009 Chapter 5 • Resource Managers 245