aio_write(3)

1aio_write(3)               Library Functions Manual               aio_write(3)
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NAME

6       aio_write - asynchronous write
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LIBRARY

9       Real-time library (librt, -lrt)
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SYNOPSIS

12       #include <aio.h>
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14       int aio_write(struct aiocb *aiocbp);
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DESCRIPTION

17       The aio_write() function queues the I/O request described by the buffer
18       pointed to by aiocbp.  This function  is  the  asynchronous  analog  of
19       write(2).  The arguments of the call
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21           write(fd, buf, count)
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23       correspond (in order) to the fields aio_fildes, aio_buf, and aio_nbytes
24       of the structure pointed to by aiocbp.  (See aio(7) for  a  description
25       of the aiocb structure.)
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27       If  O_APPEND  is  not set, the data is written starting at the absolute
28       position aiocbp->aio_offset, regardless of the file offset.   If  O_AP‐
29       PEND  is  set, data is written at the end of the file in the same order
30       as aio_write() calls are made.  After the call, the value of  the  file
31       offset is unspecified.
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33       The  "asynchronous" means that this call returns as soon as the request
34       has been enqueued; the write may or may not  have  completed  when  the
35       call returns.  One tests for completion using aio_error(3).  The return
36       status of a completed I/O  operation  can  be  obtained  aio_return(3).
37       Asynchronous  notification of I/O completion can be obtained by setting
38       aiocbp->aio_sigevent appropriately; see sigevent(7) for details.
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40       If _POSIX_PRIORITIZED_IO is defined, and this file  supports  it,  then
41       the  asynchronous operation is submitted at a priority equal to that of
42       the calling process minus aiocbp->aio_reqprio.
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44       The field aiocbp->aio_lio_opcode is ignored.
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46       No data is written to a regular file beyond its maximum offset.
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RETURN VALUE

49       On success, 0 is returned.  On error, the request is not  enqueued,  -1
50       is  returned,  and  errno is set to indicate the error.  If an error is
51       detected only later, it will be  reported  via  aio_return(3)  (returns
52       status  -1) and aio_error(3) (error status—whatever one would have got‐
53       ten in errno, such as EBADF).
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ERRORS

56       EAGAIN Out of resources.
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58       EBADF  aio_fildes is not a valid file descriptor open for writing.
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60       EFBIG  The file is a regular file, we want to write at least one  byte,
61              but the starting position is at or beyond the maximum offset for
62              this file.
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64       EINVAL One or more of aio_offset, aio_reqprio, aio_nbytes are invalid.
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66       ENOSYS aio_write() is not implemented.
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ATTRIBUTES

69       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
70       tributes(7).
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72       ┌────────────────────────────────────────────┬───────────────┬─────────┐
73       │Interface                                   │ Attribute     │ Value   │
74       ├────────────────────────────────────────────┼───────────────┼─────────┤
75       │aio_write()                                 │ Thread safety │ MT-Safe │
76       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

79       POSIX.1-2008.
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HISTORY

82       glibc 2.1.  POSIX.1-2001.
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NOTES

85       It  is  a good idea to zero out the control block before use.  The con‐
86       trol block must  not  be  changed  while  the  write  operation  is  in
87       progress.   The buffer area being written out must not be accessed dur‐
88       ing the operation or undefined results may occur.  The memory areas in‐
89       volved must remain valid.
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91       Simultaneous I/O operations specifying the same aiocb structure produce
92       undefined results.
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