lio_listio(3)

1LIO_LISTIO(3)              Linux Programmer's Manual             LIO_LISTIO(3)
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NAME

6       lio_listio - initiate a list of I/O requests
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SYNOPSIS

9       #include <aio.h>
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11       int lio_listio(int mode, struct aiocb *restrict const aiocb_list[restrict],
12                      int nitems, struct sigevent *restrict sevp);
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14       Link with -lrt.
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DESCRIPTION

17       The  lio_listio()  function  initiates  the  list of I/O operations de‐
18       scribed by the array aiocb_list.
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20       The mode operation has one of the following values:
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22       LIO_WAIT
23              The call blocks until all operations are complete.  The sevp ar‐
24              gument is ignored.
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26       LIO_NOWAIT
27              The  I/O  operations  are queued for processing and the call re‐
28              turns immediately.  When all of  the  I/O  operations  complete,
29              asynchronous notification occurs, as specified by the sevp argu‐
30              ment; see sigevent(7) for details.  If sevp is  NULL,  no  asyn‐
31              chronous notification occurs.
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33       The  aiocb_list  argument  is  an array of pointers to aiocb structures
34       that describe I/O operations.  These operations are executed in an  un‐
35       specified  order.   The nitems argument specifies the size of the array
36       aiocb_list.  Null pointers in aiocb_list are ignored.
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38       In each control block in aiocb_list, the aio_lio_opcode field specifies
39       the I/O operation to be initiated, as follows:
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41       LIO_READ
42              Initiate  a  read  operation.   The operation is queued as for a
43              call to aio_read(3) specifying this control block.
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45       LIO_WRITE
46              Initiate a write operation.  The operation is queued  as  for  a
47              call to aio_write(3) specifying this control block.
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49       LIO_NOP
50              Ignore this control block.
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52       The  remaining  fields  in each control block have the same meanings as
53       for aio_read(3) and aio_write(3).  The aio_sigevent fields of each con‐
54       trol  block can be used to specify notifications for the individual I/O
55       operations (see sigevent(7)).
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RETURN VALUE

58       If mode is LIO_NOWAIT, lio_listio() returns 0 if all I/O operations are
59       successfully  queued.   Otherwise,  -1 is returned, and errno is set to
60       indicate the error.
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62       If mode is LIO_WAIT, lio_listio() returns 0 when all of the I/O  opera‐
63       tions  have completed successfully.  Otherwise, -1 is returned, and er‐
64       rno is set to indicate the error.
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66       The return status from lio_listio() provides information only about the
67       call  itself,  not about the individual I/O operations.  One or more of
68       the I/O operations may fail, but this does not prevent other operations
69       completing.   The status of individual I/O operations in aiocb_list can
70       be determined using aio_error(3).  When an operation has completed, its
71       return  status can be obtained using aio_return(3).  Individual I/O op‐
72       erations  can  fail  for  the  reasons  described  in  aio_read(3)  and
73       aio_write(3).
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ERRORS

76       The lio_listio() function may fail for the following reasons:
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78       EAGAIN Out of resources.
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80       EAGAIN The number of I/O operations specified by nitems would cause the
81              limit AIO_MAX to be exceeded.
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83       EINTR  mode was LIO_WAIT and a signal was caught before all I/O  opera‐
84              tions  completed;  see  signal(7).  (This may even be one of the
85              signals used for asynchronous I/O completion notification.)
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87       EINVAL mode is invalid, or nitems exceeds the limit AIO_LISTIO_MAX.
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89       EIO    One of more of the operations specified  by  aiocb_list  failed.
90              The  application  can  check  the status of each operation using
91              aio_return(3).
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93       If lio_listio() fails with the error EAGAIN, EINTR, or EIO,  then  some
94       of  the  operations in aiocb_list may have been initiated.  If lio_lis‐
95       tio() fails for any other reason, then none of the I/O  operations  has
96       been initiated.
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VERSIONS

99       The lio_listio() function is available since glibc 2.1.
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ATTRIBUTES

102       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
103       tributes(7).
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105       ┌────────────────────────────────────────────┬───────────────┬─────────┐
106       │Interface                                   │ Attribute     │ Value   │
107       ├────────────────────────────────────────────┼───────────────┼─────────┤
108       │lio_listio()                                │ Thread safety │ MT-Safe │
109       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

112       POSIX.1-2001, POSIX.1-2008.
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NOTES

115       It is a good idea to zero out the control blocks before use.  The  con‐
116       trol  blocks  must  not  be  changed  while  the  I/O operations are in
117       progress.  The buffer areas being read into or written from must not be
118       accessed  during  the  operations  or undefined results may occur.  The
119       memory areas involved must remain valid.
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121       Simultaneous I/O operations specifying the same aiocb structure produce
122       undefined results.
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COLOPHON

129       This page is part of release 5.12 of the Linux  man-pages  project.   A
130       description  of  the project, information about reporting bugs, and the
131       latest    version    of    this    page,    can     be     found     at
132       https://www.kernel.org/doc/man-pages/.
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136                                  2021-03-22                     LIO_LISTIO(3)