aio_read man page on SmartOS

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AIO_READ(3C)							  AIO_READ(3C)

NAME
       aio_read - asynchronous read from a file

SYNOPSIS
       #include <aio.h>

       int aio_read(struct aiocb *aiocbp);

DESCRIPTION
       The   aio_read()	  function   allows   the   calling  process  to  read
       aiocbp->aio_nbytes from the  file  associated  with  aiocbp->aio_fildes
       into  the  buffer  pointed  to  by  aiocbp->aio_buf.  The function call
       returns when the read request has been initiated or queued to the  file
       or  device  (even  when	the  data cannot be delivered immediately). If
       _POSIX_PRIORITIZED_IO is defined and prioritized I/O is	supported  for
       this  file,  then the asynchronous operation is submitted at a priority
       equal   to   the	  scheduling   priority	  of   the    process	 minus
       aiocbp->aio_reqprio.  The  aiocbp  value	 may be used as an argument to
       aio_error(3C) and aio_return(3C) in order to determine the error status
       and return status, respectively, of the asynchronous operation while it
       is proceeding. If an error condition is encountered during queuing, the
       function	 call  returns without having initiated or queued the request.
       The requested operation takes place at the  absolute  position  in  the
       file  as	 given	by  aio_offset, as if lseek(2) were called immediately
       prior to the operation with an offset equal to aio_offset and a	whence
       equal  to  SEEK_SET. After a successful call to enqueue an asynchronous
       I/O operation, the value of the file offset for the  file  is  unspeci‐
       fied.

       The  aiocbp->aio_sigevent structure defines what asynchronous notifica‐
       tion is to occur when the asynchronous operation completes,  as	speci‐
       fied in signal.h(3HEAD).

       The aiocbp->aio_lio_opcode field is ignored by aio_read().

       The aiocbp argument points to an aiocb structure. If the buffer pointed
       to by aiocbp->aio_buf or the control block pointed to by aiocbp becomes
       an  illegal  address  prior  to	asynchronous  I/O completion, then the
       behavior is undefined.

       Simultaneous asynchronous operations  using  the	 same  aiocbp  produce
       undefined results.

       If _POSIX_SYNCHRONIZED_IO is defined and synchronized I/O is enabled on
       the file associated with aiocbp->aio_fildes, the behavior of this func‐
       tion is according to the definitions of synchronized I/O data integrity
       completion and synchronized I/O file integrity completion.

       For any system action that changes the process memory  space  while  an
       asynchronous I/O is outstanding to the address range being changed, the
       result of that action is undefined.

       For regular files, no data transfer will occur past the offset  maximum
       established    in   the	 open	file   description   associated	  with
       aiocbp->aio_fildes.

RETURN VALUES
       The aio_read() function returns 0 to the calling	 process  if  the  I/O
       operation  is  successfully  queued; otherwise, the function returns −1
       and sets errno to indicate the error.

ERRORS
       The aio_read() function will fail if:

       EAGAIN
		 The requested asynchronous I/O operation was not  queued  due
		 to system resource limitations.

       Each  of	 the following conditions may be detected synchronously at the
       time of the call to aio_read(), or asynchronously. If any of the condi‐
       tions below are detected synchronously, the aio_read() function returns
       -1 and sets errno to the corresponding value. If any of the  conditions
       below  are  detected asynchronously, the return status of the asynchro‐
       nous operation is set to −1, and the error status of  the  asynchronous
       operation will be set to the corresponding value.

       EBADF
		 The  aiocbp->aio_fildes argument is not a valid file descrip‐
		 tor open for reading.

       EINVAL
		 The file offset value implied by aiocbp->aio_offset would  be
		 invalid,   aiocbp->aio_reqprio	 is  not  a  valid  value,  or
		 aiocbp->aio_nbytes is an invalid value.

       In the case that the aio_read() successfully queues the	I/O  operation
       but  the operation is subsequently canceled or encounters an error, the
       return status of the asynchronous operation is one of the  values  nor‐
       mally  returned	by  the	 read(2) function call. In addition, the error
       status of the asynchronous operation will be set to one	of  the	 error
       statuses	 normally  set by the read() function call, or one of the fol‐
       lowing values:

       EBADF
		    The	 aiocbp->aio_fildes  argument  is  not	a  valid  file
		    descriptor open for reading.

       ECANCELED
		    The	 requested  I/O	 was canceled before the I/O completed
		    due to an explicit aio_cancel(3C) request.

       EINVAL
		    The file offset value implied by aiocbp->aio_offset	 would
		    be invalid.

       The   following	condition  may	be  detected  synchronously  or	 asyn‐
       chronously:

       EOVERFLOW
		    The file is a regular file, aiobcp->aio_nbytes is  greater
		    than  0  and  the starting offset in aiobcp->aio_offset is
		    before the end-of-file and is at or beyond the offset max‐
		    imum   in	the  open  file	 description  associated  with
		    aiocbp->aio_fildes.

USAGE
       For portability, the application should set aiocb->aio_reqprio to 0.

       The aio_read() function has a transitional interface  for  64-bit  file
       offsets.	 See lf64(5).

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       ┌────────────────────┬───────────────────┐
       │  ATTRIBUTE TYPE    │  ATTRIBUTE VALUE	│
       ├────────────────────┼───────────────────┤
       │Interface Stability │ Committed		│
       ├────────────────────┼───────────────────┤
       │MT-Level	    │ MT-Safe		│
       ├────────────────────┼───────────────────┤
       │Standard	    │ See standards(5). │
       └────────────────────┴───────────────────┘

SEE ALSO
       close(2),  exec(2),  exit(2),  fork(2),	lseek(2),  read(2),  write(2),
       aio_cancel(3C),	aio_return(3C),	 aio.h(3HEAD),	lio_listio(3C),	  sig‐
       info.h(3HEAD), signal.h(3HEAD), attributes(5), lf64(5), standards(5)

				  Feb 5, 2008			  AIO_READ(3C)
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