1LIO_LISTIO(3P) POSIX Programmer's Manual LIO_LISTIO(3P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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13 lio_listio — list directed I/O
14
16 #include <aio.h>
17 int lio_listio(int mode, struct aiocb *restrict const list[restrict],
19 int nent, struct sigevent *restrict sig);
20
22 The lio_listio() function shall initiate a list of I/O requests with a
23 single function call.
24 The mode argument takes one of the values LIO_WAIT or LIO_NOWAIT
26 declared in <aio.h> and determines whether the function returns when
27 the I/O operations have been completed, or as soon as the operations
28 have been queued. If the mode argument is LIO_WAIT, the function shall
29 wait until all I/O is complete and the sig argument shall be ignored.
30 If the mode argument is LIO_NOWAIT, the function shall return immedi‐
32 ately, and asynchronous notification shall occur, according to the sig
33 argument, when all the I/O operations complete. If sig is NULL, then no
34 asynchronous notification shall occur. If sig is not NULL, asynchronous
35 notification occurs as specified in Section 2.4.1, Signal Generation
36 and Delivery when all the requests in list have completed.
37 The I/O requests enumerated by list are submitted in an unspecified
39 order.
40 The list argument is an array of pointers to aiocb structures. The
42 array contains nent elements. The array may contain NULL elements,
43 which shall be ignored.
44 If the buffer pointed to by list or the aiocb structures pointed to by
46 the elements of the array list become illegal addresses before all
47 asynchronous I/O completed and, if necessary, the notification is sent,
48 then the behavior is undefined. If the buffers pointed to by the
49 aio_buf member of the aiocb structure pointed to by the elements of the
50 array list become illegal addresses prior to the asynchronous I/O asso‐
51 ciated with that aiocb structure being completed, the behavior is unde‐
52 fined.
53 The aio_lio_opcode field of each aiocb structure specifies the opera‐
55 tion to be performed. The supported operations are LIO_READ, LIO_WRITE,
56 and LIO_NOP; these symbols are defined in <aio.h>. The LIO_NOP opera‐
57 tion causes the list entry to be ignored. If the aio_lio_opcode element
58 is equal to LIO_READ, then an I/O operation is submitted as if by a
59 call to aio_read() with the aiocbp equal to the address of the aiocb
60 structure. If the aio_lio_opcode element is equal to LIO_WRITE, then an
61 I/O operation is submitted as if by a call to aio_write() with the
62 aiocbp equal to the address of the aiocb structure.
63 The aio_fildes member specifies the file descriptor on which the opera‐
65 tion is to be performed.
66 The aio_buf member specifies the address of the buffer to or from which
68 the data is transferred.
69 The aio_nbytes member specifies the number of bytes of data to be
71 transferred.
72 The members of the aiocb structure further describe the I/O operation
74 to be performed, in a manner identical to that of the corresponding
75 aiocb structure when used by the aio_read() and aio_write() functions.
76 The nent argument specifies how many elements are members of the list;
78 that is, the length of the array.
79 The behavior of this function is altered according to the definitions
81 of synchronized I/O data integrity completion and synchronized I/O file
82 integrity completion if synchronized I/O is enabled on the file associ‐
83 ated with aio_fildes.
84 For regular files, no data transfer shall occur past the offset maximum
86 established in the open file description associated with
87 aiocbp->aio_fildes.
88 If sig->sigev_notify is SIGEV_THREAD and sig->sigev_notify_attributes
90 is a non-null pointer and the block pointed to by this pointer becomes
91 an illegal address prior to all asynchronous I/O being completed, then
92 the behavior is undefined.
93
95 If the mode argument has the value LIO_NOWAIT, the lio_listio() func‐
96 tion shall return the value zero if the I/O operations are successfully
97 queued; otherwise, the function shall return the value −1 and set errno
98 to indicate the error.
99 If the mode argument has the value LIO_WAIT, the lio_listio() function
101 shall return the value zero when all the indicated I/O has completed
102 successfully. Otherwise, lio_listio() shall return a value of −1 and
103 set errno to indicate the error.
104 In either case, the return value only indicates the success or failure
106 of the lio_listio() call itself, not the status of the individual I/O
107 requests. In some cases one or more of the I/O requests contained in
108 the list may fail. Failure of an individual request does not prevent
109 completion of any other individual request. To determine the outcome of
110 each I/O request, the application shall examine the error status asso‐
111 ciated with each aiocb control block. The error statuses so returned
112 are identical to those returned as the result of an aio_read() or
113 aio_write() function.
114
116 The lio_listio() function shall fail if:
117 EAGAIN The resources necessary to queue all the I/O requests were not
119 available. The application may check the error status for each
120 aiocb to determine the individual request(s) that failed.
121 EAGAIN The number of entries indicated by nent would cause the system-
123 wide limit {AIO_MAX} to be exceeded.
124 EINVAL The mode argument is not a proper value, or the value of nent
126 was greater than {AIO_LISTIO_MAX}.
127 EINTR A signal was delivered while waiting for all I/O requests to
129 complete during an LIO_WAIT operation. Note that, since each I/O
130 operation invoked by lio_listio() may possibly provoke a signal
131 when it completes, this error return may be caused by the com‐
132 pletion of one (or more) of the very I/O operations being
133 awaited. Outstanding I/O requests are not canceled, and the
134 application shall examine each list element to determine whether
135 the request was initiated, canceled, or completed.
136 EIO One or more of the individual I/O operations failed. The appli‐
138 cation may check the error status for each aiocb structure to
139 determine the individual request(s) that failed.
140 In addition to the errors returned by the lio_listio() function, if the
142 lio_listio() function succeeds or fails with errors of [EAGAIN],
143 [EINTR], or [EIO], then some of the I/O specified by the list may have
144 been initiated. If the lio_listio() function fails with an error code
145 other than [EAGAIN], [EINTR], or [EIO], no operations from the list
146 shall have been initiated. The I/O operation indicated by each list
147 element can encounter errors specific to the individual read or write
148 function being performed. In this event, the error status for each
149 aiocb control block contains the associated error code. The error codes
150 that can be set are the same as would be set by a read() or write()
151 function, with the following additional error codes possible:
152 EAGAIN The requested I/O operation was not queued due to resource limi‐
154 tations.
155 ECANCELED
157 The requested I/O was canceled before the I/O completed due to
158 an explicit aio_cancel() request.
159 EFBIG The aiocbp->aio_lio_opcode is LIO_WRITE, the file is a regular
161 file, aiocbp->aio_nbytes is greater than 0, and the
162 aiocbp->aio_offset is greater than or equal to the offset maxi‐
163 mum in the open file description associated with
164 aiocbp->aio_fildes.
165 EINPROGRESS
167 The requested I/O is in progress.
168 EOVERFLOW
170 The aiocbp->aio_lio_opcode is LIO_READ, the file is a regular
171 file, aiocbp->aio_nbytes is greater than 0, and the
172 aiocbp->aio_offset is before the end-of-file and is greater than
173 or equal to the offset maximum in the open file description
174 associated with aiocbp->aio_fildes.
175 The following sections are informative.
177
179 None.
180
182 None.
183
185 Although it may appear that there are inconsistencies in the specified
186 circumstances for error codes, the [EIO] error condition applies when
187 any circumstance relating to an individual operation makes that opera‐
188 tion fail. This might be due to a badly formulated request (for exam‐
189 ple, the aio_lio_opcode field is invalid, and aio_error() returns [EIN‐
190 VAL]) or might arise from application behavior (for example, the file
191 descriptor is closed before the operation is initiated, and aio_error()
192 returns [EBADF]).
193 The limitation on the set of error codes returned when operations from
195 the list shall have been initiated enables applications to know when
196 operations have been started and whether aio_error() is valid for a
197 specific operation.
198
200 None.
201
203 aio_read(), aio_write(), aio_error(), aio_return(), aio_cancel(),
204 close(), exec, exit(), fork(), lseek(), read()
205 The Base Definitions volume of POSIX.1‐2008, <aio.h>
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209 Portions of this text are reprinted and reproduced in electronic form
210 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
211 -- Portable Operating System Interface (POSIX), The Open Group Base
212 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
213 cal and Electronics Engineers, Inc and The Open Group. (This is
214 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
215 event of any discrepancy between this version and the original IEEE and
216 The Open Group Standard, the original IEEE and The Open Group Standard
217 is the referee document. The original Standard can be obtained online
218 at http://www.unix.org/online.html .
219 Any typographical or formatting errors that appear in this page are
221 most likely to have been introduced during the conversion of the source
222 files to man page format. To report such errors, see https://www.ker‐
223 nel.org/doc/man-pages/reporting_bugs.html .
224IEEE/The Open Group 2013 LIO_LISTIO(3P)