1LIO_LISTIO(P) POSIX Programmer's Manual LIO_LISTIO(P)
2
6 lio_listio - list directed I/O (REALTIME)
7
9 #include <aio.h>
10 int lio_listio(int mode, struct aiocb *restrict const list[restrict],
12 int nent, struct sigevent *restrict sig);
13
16 The lio_listio() function shall initiate a list of I/O requests with a
17 single function call.
18 The mode argument takes one of the values LIO_WAIT or LIO_NOWAIT
20 declared in <aio.h> and determines whether the function returns when
21 the I/O operations have been completed, or as soon as the operations
22 have been queued. If the mode argument is LIO_WAIT, the function shall
23 wait until all I/O is complete and the sig argument shall be ignored.
24 If the mode argument is LIO_NOWAIT, the function shall return immedi‐
26 ately, and asynchronous notification shall occur, according to the sig
27 argument, when all the I/O operations complete. If sig is NULL, then
28 no asynchronous notification shall occur. If sig is not NULL, asynchro‐
29 nous notification occurs as specified in Signal Generation and Delivery
30 when all the requests in list have completed.
31 The I/O requests enumerated by list are submitted in an unspecified
33 order.
34 The list argument is an array of pointers to aiocb structures. The
36 array contains nent elements. The array may contain NULL elements,
37 which shall be ignored.
38 The aio_lio_opcode field of each aiocb structure specifies the opera‐
40 tion to be performed. The supported operations are LIO_READ, LIO_WRITE,
41 and LIO_NOP; these symbols are defined in <aio.h>. The LIO_NOP opera‐
42 tion causes the list entry to be ignored. If the aio_lio_opcode element
43 is equal to LIO_READ, then an I/O operation is submitted as if by a
44 call to aio_read() with the aiocbp equal to the address of the aiocb
45 structure. If the aio_lio_opcode element is equal to LIO_WRITE, then an
46 I/O operation is submitted as if by a call to aio_write() with the
47 aiocbp equal to the address of the aiocb structure.
48 The aio_fildes member specifies the file descriptor on which the opera‐
50 tion is to be performed.
51 The aio_buf member specifies the address of the buffer to or from which
53 the data is transferred.
54 The aio_nbytes member specifies the number of bytes of data to be
56 transferred.
57 The members of the aiocb structure further describe the I/O operation
59 to be performed, in a manner identical to that of the corresponding
60 aiocb structure when used by the aio_read() and aio_write() functions.
61 The nent argument specifies how many elements are members of the list;
63 that is, the length of the array.
64 The behavior of this function is altered according to the definitions
66 of synchronized I/O data integrity completion and synchronized I/O file
67 integrity completion if synchronized I/O is enabled on the file associ‐
68 ated with aio_fildes.
69 For regular files, no data transfer shall occur past the offset maximum
71 established in the open file description associated with
72 aiocbp->aio_fildes.
73
75 If the mode argument has the value LIO_NOWAIT, the lio_listio() func‐
76 tion shall return the value zero if the I/O operations are successfully
77 queued; otherwise, the function shall return the value -1 and set errno
78 to indicate the error.
79 If the mode argument has the value LIO_WAIT, the lio_listio() function
81 shall return the value zero when all the indicated I/O has completed
82 successfully. Otherwise, lio_listio() shall return a value of -1 and
83 set errno to indicate the error.
84 In either case, the return value only indicates the success or failure
86 of the lio_listio() call itself, not the status of the individual I/O
87 requests. In some cases one or more of the I/O requests contained in
88 the list may fail. Failure of an individual request does not prevent
89 completion of any other individual request. To determine the outcome
90 of each I/O request, the application shall examine the error status
91 associated with each aiocb control block. The error statuses so
92 returned are identical to those returned as the result of an aio_read()
93 or aio_write() function.
94
96 The lio_listio() function shall fail if:
97 EAGAIN The resources necessary to queue all the I/O requests were not
99 available. The application may check the error status for each
100 aiocb to determine the individual request(s) that failed.
101 EAGAIN The number of entries indicated by nent would cause the system-
103 wide limit {AIO_MAX} to be exceeded.
104 EINVAL The mode argument is not a proper value, or the value of nent
106 was greater than {AIO_LISTIO_MAX}.
107 EINTR A signal was delivered while waiting for all I/O requests to
109 complete during an LIO_WAIT operation. Note that, since each I/O
110 operation invoked by lio_listio() may possibly provoke a signal
111 when it completes, this error return may be caused by the com‐
112 pletion of one (or more) of the very I/O operations being
113 awaited. Outstanding I/O requests are not canceled, and the
114 application shall examine each list element to determine whether
115 the request was initiated, canceled, or completed.
116 EIO One or more of the individual I/O operations failed. The appli‐
118 cation may check the error status for each aiocb structure to
119 determine the individual request(s) that failed.
120 In addition to the errors returned by the lio_listio() function, if the
123 lio_listio() function succeeds or fails with errors of [EAGAIN],
124 [EINTR], or [EIO], then some of the I/O specified by the list may have
125 been initiated. If the lio_listio() function fails with an error code
126 other than [EAGAIN], [EINTR], or [EIO], no operations from the list
127 shall have been initiated. The I/O operation indicated by each list
128 element can encounter errors specific to the individual read or write
129 function being performed. In this event, the error status for each
130 aiocb control block contains the associated error code. The error
131 codes that can be set are the same as would be set by a read() or
132 write() function, with the following additional error codes possible:
133 EAGAIN The requested I/O operation was not queued due to resource limi‐
135 tations.
136 ECANCELED
138 The requested I/O was canceled before the I/O completed due to
139 an explicit aio_cancel() request.
140 EFBIG The aiocbp->aio_lio_opcode is LIO_WRITE, the file is a regular
142 file, aiocbp->aio_nbytes is greater than 0, and the
143 aiocbp->aio_offset is greater than or equal to the offset maxi‐
144 mum in the open file description associated with
145 aiocbp->aio_fildes.
146 EINPROGRESS
148 The requested I/O is in progress.
149 EOVERFLOW
151 The aiocbp->aio_lio_opcode is LIO_READ, the file is a regular
152 file, aiocbp->aio_nbytes is greater than 0, and the
153 aiocbp->aio_offset is before the end-of-file and is greater than
154 or equal to the offset maximum in the open file description
155 associated with aiocbp->aio_fildes.
156 The following sections are informative.
159
161 None.
162
164 None.
165
167 Although it may appear that there are inconsistencies in the specified
168 circumstances for error codes, the [EIO] error condition applies when
169 any circumstance relating to an individual operation makes that opera‐
170 tion fail. This might be due to a badly formulated request (for exam‐
171 ple, the aio_lio_opcode field is invalid, and aio_error() returns [EIN‐
172 VAL]) or might arise from application behavior (for example, the file
173 descriptor is closed before the operation is initiated, and aio_error()
174 returns [EBADF]).
175 The limitation on the set of error codes returned when operations from
177 the list shall have been initiated enables applications to know when
178 operations have been started and whether aio_error() is valid for a
179 specific operation.
180
182 None.
183
185 aio_read() , aio_write() , aio_error() , aio_return() , aio_cancel() ,
186 close() , exec() , exit() , fork() , lseek() , read() , the Base Defi‐
187 nitions volume of IEEE Std 1003.1-2001, <aio.h>
188
190 Portions of this text are reprinted and reproduced in electronic form
191 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
192 -- Portable Operating System Interface (POSIX), The Open Group Base
193 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
194 Electrical and Electronics Engineers, Inc and The Open Group. In the
195 event of any discrepancy between this version and the original IEEE and
196 The Open Group Standard, the original IEEE and The Open Group Standard
197 is the referee document. The original Standard can be obtained online
198 at http://www.opengroup.org/unix/online.html .
199IEEE/The Open Group 2003 LIO_LISTIO(P)