man3/aio_write.3

   1 .\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
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  23 .TH AIO_WRITE 3 2010-10-02  "" "Linux Programmer's Manual"
  24 .SH NAME
  25 aio_write \- asynchronous write
  26 .SH SYNOPSIS
  27 .B "#include <aio.h>"
  28 .sp
  29 .BI "int aio_write(struct aiocb *" aiocbp );
  30 .sp
  31 Link with \fI\-lrt\fP.
  32 .SH DESCRIPTION
  33 The
  34 .BR aio_write ()
  35 function requests an asynchronous "n = write(fd, buf, count)"
  36 with fd, buf, count given by
  37 .IR aiocbp\->aio_fildes ,
  38 .IR aiocbp\->aio_buf ,
  39 .IR aiocbp\->aio_nbytes ,
  40 respectively.
  41 The return status n can be retrieved upon completion using
  42 .BR aio_return (3).
  43 (See
  44 .BR aio (7)
  45 for a description of the
  46 .I aiocb
  47 structure.)
  48 .LP
  49 If
  50 .B O_APPEND
  51 is not set, the data is written starting at the
  52 absolute file offset
  53 .IR aiocbp\->aio_offset ,
  54 regardless of the current file position.
  55 If
  56 .B O_APPEND
  57 is set, the data is written at the end of the file.
  58 After this request, the value of the current file position is unspecified.
  59 .LP
  60 The "asynchronous" means that this call returns as soon as the
  61 request has been enqueued; the write may or may not have completed
  62 when the call returns.
  63 One tests for completion using
  64 .BR aio_error (3).
  65 .LP
  66 If
  67 .B _POSIX_PRIORITIZED_IO
  68 is defined, and this file supports it,
  69 then the asynchronous operation is submitted at a priority equal
  70 to that of the calling process minus
  71 .IR aiocbp\->aio_reqprio .
  72 .LP
  73 The field
  74 .I aiocbp\->aio_lio_opcode
  75 is ignored.
  76 .LP
  77 No data is written to a regular file beyond its maximum offset.
  78 .SH "RETURN VALUE"
  79 On success, 0 is returned.
  80 On error the request is not enqueued, \-1
  81 is returned, and
  82 .I errno
  83 is set appropriately.
  84 If an error is first detected later, it will
  85 be reported via
  86 .BR aio_return (3)
  87 (returns status \-1) and
  88 .BR aio_error (3)
  89 (error status whatever one would have gotten in
  90 .IR errno ,
  91 such as
  92 .BR EBADF ).
  93 .SH ERRORS
  94 .TP
  95 .B EAGAIN
  96 Out of resources.
  97 .TP
  98 .B EBADF
  99 .I aio_fildes
 100 is not a valid file descriptor open for writing.
 101 .TP
 102 .B EFBIG
 103 The file is a regular file, we want to write at least one byte,
 104 but the starting position is at or beyond the maximum offset for this file.
 105 .TP
 106 .B EINVAL
 107 One or more of
 108 .IR aio_offset ,
 109 .IR aio_reqprio ,
 110 .I aio_nbytes
 111 are invalid.
 112 .TP
 113 .B ENOSYS
 114 This function is not supported.
 115 .SH VERSIONS
 116 The
 117 .BR aio_write ()
 118 function is available since glibc 2.1.
 119 .SH "CONFORMING TO"
 120 POSIX.1-2001, POSIX.1-2008.
 121 .SH NOTES
 122 It is a good idea to zero out the control block before use.
 123 This control block must not be changed while the write operation
 124 is in progress.
 125 The buffer area being written out
 126 .\" or the control block of the operation
 127 must not be accessed during the operation or undefined results may
 128 occur.
 129 The memory areas involved must remain valid.
 130 .SH "SEE ALSO"
 131 .BR aio_cancel (3),
 132 .BR aio_error (3),
 133 .BR aio_fsync (3),
 134 .BR aio_read (3),
 135 .BR aio_return (3),
 136 .BR aio_suspend (3),
 137 .BR aio (7)