1LIO_LISTIO(3P) POSIX Programmer's Manual LIO_LISTIO(3P)
2
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.
10
12 lio_listio — list directed I/O
13
15 #include <aio.h>
16 int lio_listio(int mode, struct aiocb *restrict const list[restrict],
18 int nent, struct sigevent *restrict sig);
19
21 The lio_listio() function shall initiate a list of I/O requests with a
22 single function call.
23 The mode argument takes one of the values LIO_WAIT or LIO_NOWAIT
25 declared in <aio.h> and determines whether the function returns when
26 the I/O operations have been completed, or as soon as the operations
27 have been queued. If the mode argument is LIO_WAIT, the function shall
28 wait until all I/O is complete and the sig argument shall be ignored.
29 If the mode argument is LIO_NOWAIT, the function shall return immedi‐
31 ately, and asynchronous notification shall occur, according to the sig
32 argument, when all the I/O operations complete. If sig is NULL, then no
33 asynchronous notification shall occur. If sig is not NULL, asynchronous
34 notification occurs as specified in Section 2.4.1, Signal Generation
35 and Delivery when all the requests in list have completed.
36 The I/O requests enumerated by list are submitted in an unspecified
38 order.
39 The list argument is an array of pointers to aiocb structures. The
41 array contains nent elements. The array may contain NULL elements,
42 which shall be ignored.
43 If the buffer pointed to by list or the aiocb structures pointed to by
45 the elements of the array list become illegal addresses before all
46 asynchronous I/O completed and, if necessary, the notification is sent,
47 then the behavior is undefined. If the buffers pointed to by the
48 aio_buf member of the aiocb structure pointed to by the elements of the
49 array list become illegal addresses prior to the asynchronous I/O asso‐
50 ciated with that aiocb structure being completed, the behavior is unde‐
51 fined.
52 The aio_lio_opcode field of each aiocb structure specifies the opera‐
54 tion to be performed. The supported operations are LIO_READ, LIO_WRITE,
55 and LIO_NOP; these symbols are defined in <aio.h>. The LIO_NOP opera‐
56 tion causes the list entry to be ignored. If the aio_lio_opcode element
57 is equal to LIO_READ, then an I/O operation is submitted as if by a
58 call to aio_read() with the aiocbp equal to the address of the aiocb
59 structure. If the aio_lio_opcode element is equal to LIO_WRITE, then an
60 I/O operation is submitted as if by a call to aio_write() with the
61 aiocbp equal to the address of the aiocb structure.
62 The aio_fildes member specifies the file descriptor on which the opera‐
64 tion is to be performed.
65 The aio_buf member specifies the address of the buffer to or from which
67 the data is transferred.
68 The aio_nbytes member specifies the number of bytes of data to be
70 transferred.
71 The members of the aiocb structure further describe the I/O operation
73 to be performed, in a manner identical to that of the corresponding
74 aiocb structure when used by the aio_read() and aio_write() functions.
75 The nent argument specifies how many elements are members of the list;
77 that is, the length of the array.
78 The behavior of this function is altered according to the definitions
80 of synchronized I/O data integrity completion and synchronized I/O file
81 integrity completion if synchronized I/O is enabled on the file associ‐
82 ated with aio_fildes.
83 For regular files, no data transfer shall occur past the offset maximum
85 established in the open file description associated with
86 aiocbp->aio_fildes.
87 If sig->sigev_notify is SIGEV_THREAD and sig->sigev_notify_attributes
89 is a non-null pointer and the block pointed to by this pointer becomes
90 an illegal address prior to all asynchronous I/O being completed, then
91 the behavior is undefined.
92
94 If the mode argument has the value LIO_NOWAIT, the lio_listio() func‐
95 tion shall return the value zero if the I/O operations are successfully
96 queued; otherwise, the function shall return the value -1 and set errno
97 to indicate the error.
98 If the mode argument has the value LIO_WAIT, the lio_listio() function
100 shall return the value zero when all the indicated I/O has completed
101 successfully. Otherwise, lio_listio() shall return a value of -1 and
102 set errno to indicate the error.
103 In either case, the return value only indicates the success or failure
105 of the lio_listio() call itself, not the status of the individual I/O
106 requests. In some cases one or more of the I/O requests contained in
107 the list may fail. Failure of an individual request does not prevent
108 completion of any other individual request. To determine the outcome of
109 each I/O request, the application shall examine the error status asso‐
110 ciated with each aiocb control block. The error statuses so returned
111 are identical to those returned as the result of an aio_read() or
112 aio_write() function.
113
115 The lio_listio() function shall fail if:
116 EAGAIN The resources necessary to queue all the I/O requests were not
118 available. The application may check the error status for each
119 aiocb to determine the individual request(s) that failed.
120 EAGAIN The number of entries indicated by nent would cause the system-
122 wide limit {AIO_MAX} to be exceeded.
123 EINVAL The mode argument is not a proper value, or the value of nent
125 was greater than {AIO_LISTIO_MAX}.
126 EINTR A signal was delivered while waiting for all I/O requests to
128 complete during an LIO_WAIT operation. Note that, since each I/O
129 operation invoked by lio_listio() may possibly provoke a signal
130 when it completes, this error return may be caused by the com‐
131 pletion of one (or more) of the very I/O operations being
132 awaited. Outstanding I/O requests are not canceled, and the
133 application shall examine each list element to determine whether
134 the request was initiated, canceled, or completed.
135 EIO One or more of the individual I/O operations failed. The appli‐
137 cation may check the error status for each aiocb structure to
138 determine the individual request(s) that failed.
139 In addition to the errors returned by the lio_listio() function, if the
141 lio_listio() function succeeds or fails with errors of [EAGAIN],
142 [EINTR], or [EIO], then some of the I/O specified by the list may have
143 been initiated. If the lio_listio() function fails with an error code
144 other than [EAGAIN], [EINTR], or [EIO], no operations from the list
145 shall have been initiated. The I/O operation indicated by each list
146 element can encounter errors specific to the individual read or write
147 function being performed. In this event, the error status for each
148 aiocb control block contains the associated error code. The error codes
149 that can be set are the same as would be set by a read() or write()
150 function, with the following additional error codes possible:
151 EAGAIN The requested I/O operation was not queued due to resource limi‐
153 tations.
154 ECANCELED
156 The requested I/O was canceled before the I/O completed due to
157 an explicit aio_cancel() request.
158 EFBIG The aiocbp->aio_lio_opcode is LIO_WRITE, the file is a regular
160 file, aiocbp->aio_nbytes is greater than 0, and the
161 aiocbp->aio_offset is greater than or equal to the offset maxi‐
162 mum in the open file description associated with
163 aiocbp->aio_fildes.
164 EINPROGRESS
166 The requested I/O is in progress.
167 EOVERFLOW
169 The aiocbp->aio_lio_opcode is LIO_READ, the file is a regular
170 file, aiocbp->aio_nbytes is greater than 0, and the
171 aiocbp->aio_offset is before the end-of-file and is greater than
172 or equal to the offset maximum in the open file description
173 associated with aiocbp->aio_fildes.
174 The following sections are informative.
176
178 None.
179
181 None.
182
184 Although it may appear that there are inconsistencies in the specified
185 circumstances for error codes, the [EIO] error condition applies when
186 any circumstance relating to an individual operation makes that opera‐
187 tion fail. This might be due to a badly formulated request (for exam‐
188 ple, the aio_lio_opcode field is invalid, and aio_error() returns [EIN‐
189 VAL]) or might arise from application behavior (for example, the file
190 descriptor is closed before the operation is initiated, and aio_error()
191 returns [EBADF]).
192 The limitation on the set of error codes returned when operations from
194 the list shall have been initiated enables applications to know when
195 operations have been started and whether aio_error() is valid for a
196 specific operation.
197
199 None.
200
202 aio_read(), aio_write(), aio_error(), aio_return(), aio_cancel(),
203 close(), exec, exit(), fork(), lseek(), read()
204 The Base Definitions volume of POSIX.1‐2017, <aio.h>
206
208 Portions of this text are reprinted and reproduced in electronic form
209 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
210 table Operating System Interface (POSIX), The Open Group Base Specifi‐
211 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
212 Electrical and Electronics Engineers, Inc and The Open Group. In the
213 event of any discrepancy between this version and the original IEEE and
214 The Open Group Standard, the original IEEE and The Open Group Standard
215 is the referee document. The original Standard can be obtained online
216 at http://www.opengroup.org/unix/online.html .
217 Any typographical or formatting errors that appear in this page are
219 most likely to have been introduced during the conversion of the source
220 files to man page format. To report such errors, see https://www.ker‐
221 nel.org/doc/man-pages/reporting_bugs.html .
222IEEE/The Open Group 2017 LIO_LISTIO(3P)