1 .\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
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23 .TH AIO_READ 3 2010-10-03 "" "Linux Programmer's Manual"
25 aio_read \- asynchronous read
29 .BI "int aio_read(struct aiocb *" aiocbp );
31 Link with \fI\-lrt\fP.
35 function queues the I/O request described by the buffer pointed to by
37 This function is the asynchronous analog of
39 The arguments of the call
43 correspond (in order) to the fields
48 of the structure pointed to by
52 for a description of the
56 The data is read starting at the absolute file offset
57 .IR aiocbp\->aio_offset ,
58 regardless of the current file offset.
60 the value of the current file offset is unspecified.
62 The "asynchronous" means that this call returns as soon as the
63 request has been enqueued; the read may or may not have completed
64 when the call returns.
65 One tests for completion using
67 The return status of a completed I/O operation can be obtained
69 Asynchronous notification of I/O completion can be obtained by setting
70 .IR aiocbp\->aio_sigevent
76 .B _POSIX_PRIORITIZED_IO
77 is defined, and this file supports it,
78 then the asynchronous operation is submitted at a priority equal
79 to that of the calling process minus
80 .IR aiocbp\->aio_reqprio .
83 .I aiocbp\->aio_lio_opcode
86 No data is read from a regular file beyond its maximum offset.
88 On success, 0 is returned.
89 On error the request is not enqueued, \-1
93 If an error is only detected later, it will
96 (returns status \-1) and
98 (error status\(emwhatever one would have gotten in
109 is not a valid file descriptor open for reading.
120 This function is not supported.
123 The file is a regular file, we start reading before end-of-file
124 and want at least one byte, but the starting position is past
125 the maximum offset for this file.
129 function is available since glibc 2.1.
131 POSIX.1-2001, POSIX.1-2008.
133 It is a good idea to zero out the control block before use.
134 The control block must not be changed while the read operation
136 The buffer area being read into
137 .\" or the control block of the operation
138 must not be accessed during the operation or undefined results may occur.
139 The memory areas involved must remain valid.
141 Simultaneous I/O operations specifying the same
143 structure produce undefined results.