1 .\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
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24 .TH AIO_READ 3 2017-09-15 "" "Linux Programmer's Manual"
26 aio_read \- asynchronous read
30 .BI "int aio_read(struct aiocb *" aiocbp );
32 Link with \fI\-lrt\fP.
36 function queues the I/O request described by the buffer pointed to by
38 This function is the asynchronous analog of
40 The arguments of the call
44 correspond (in order) to the fields
49 of the structure pointed to by
53 for a description of the
57 The data is read starting at the absolute position
58 .IR aiocbp\->aio_offset ,
59 regardless of the file offset.
61 the value of the file offset is unspecified.
63 The "asynchronous" means that this call returns as soon as the
64 request has been enqueued; the read may or may not have completed
65 when the call returns.
66 One tests for completion using
68 The return status of a completed I/O operation can be obtained by
70 Asynchronous notification of I/O completion can be obtained by setting
71 .IR aiocbp\->aio_sigevent
77 .B _POSIX_PRIORITIZED_IO
78 is defined, and this file supports it,
79 then the asynchronous operation is submitted at a priority equal
80 to that of the calling process minus
81 .IR aiocbp\->aio_reqprio .
84 .I aiocbp\->aio_lio_opcode
87 No data is read from a regular file beyond its maximum offset.
89 On success, 0 is returned.
90 On error, the request is not enqueued, \-1
94 If an error is detected only later, it will
97 (returns status \-1) and
99 (error status\(emwhatever one would have gotten in
110 is not a valid file descriptor open for reading.
125 The file is a regular file, we start reading before end-of-file
126 and want at least one byte, but the starting position is past
127 the maximum offset for this file.
131 function is available since glibc 2.1.
133 For an explanation of the terms used in this section, see
139 Interface Attribute Value
142 T} Thread safety MT-Safe
145 POSIX.1-2001, POSIX.1-2008.
147 It is a good idea to zero out the control block before use.
148 The control block must not be changed while the read operation
150 The buffer area being read into
151 .\" or the control block of the operation
152 must not be accessed during the operation or undefined results may occur.
153 The memory areas involved must remain valid.
155 Simultaneous I/O operations specifying the same
157 structure produce undefined results.