1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.shmop-open" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>shmop_open</refname>
<refpurpose>Create or open shared memory block</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type class="union"><type>Shmop</type><type>false</type></type><methodname>shmop_open</methodname>
<methodparam><type>int</type><parameter>key</parameter></methodparam>
<methodparam><type>string</type><parameter>mode</parameter></methodparam>
<methodparam><type>int</type><parameter>permissions</parameter></methodparam>
<methodparam><type>int</type><parameter>size</parameter></methodparam>
</methodsynopsis>
<para>
<function>shmop_open</function> can create or open a shared memory block.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>key</parameter></term>
<listitem>
<para>
System's id for the shared memory block.
Can be passed as a decimal or hex.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>mode</parameter></term>
<listitem>
<para>
The flags that you can use:
<itemizedlist>
<listitem>
<simpara>
"a" for access (sets SHM_RDONLY for shmat)
use this flag when you need to open an existing shared memory
segment for read only
</simpara>
</listitem>
<listitem>
<simpara>
"c" for create (sets IPC_CREATE)
use this flag when you need to create a new shared memory segment
or if a segment with the same key exists, try to open it for read
and write
</simpara>
</listitem>
<listitem>
<simpara>
"w" for read & write access
use this flag when you need to read and write to a shared memory
segment, use this flag in most cases.
</simpara>
</listitem>
<listitem>
<simpara>
"n" create a new memory segment (sets IPC_CREATE|IPC_EXCL)
use this flag when you want to create a new shared memory segment
but if one already exists with the same flag, fail. This is useful
for security purposes, using this you can prevent race condition
exploits.
</simpara>
</listitem>
</itemizedlist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>permissions</parameter></term>
<listitem>
<para>
The permissions that you wish to assign to your memory segment, those
are the same as permission for a file. Permissions need to be passed
in octal form, like for example <literal>0644</literal>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>size</parameter></term>
<listitem>
<para>
The size of the shared memory block you wish to create in bytes
</para>
</listitem>
</varlistentry>
</variablelist>
<note>
<para>
Note: the 3rd and 4th should be entered as 0 if you are opening an
existing memory segment.
</para>
</note>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
On success <function>shmop_open</function> will return a <classname>Shmop</classname> instance that you can
use to access the shared memory segment you've created. &false; is
returned on failure.
</para>
</refsect1>
<refsect1 role="errors">
&reftitle.errors;
<para>
If <parameter>mode</parameter> is invalid, or <parameter>size</parameter> is less than or equal to zero,
a <classname>ValueError</classname> is thrown.
On other failures, <constant>E_WARNING</constant> is emitted.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>8.0.0</entry>
<entry>
On success, this function returns an <classname>Shmop</classname> instance now;
previously, a <type>resource</type> was returned.
</entry>
</row>
<row>
<entry>8.0.0</entry>
<entry>
If <parameter>mode</parameter> is invalid, or <parameter>size</parameter> is less than or equal to zero,
a <classname>ValueError</classname> is thrown; previously <constant>E_WARNING</constant> was emitted instead,
and the function returned &false;.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Create a new shared memory block</title>
<programlisting role="php">
<![CDATA[
<?php
$shm_key = ftok(__FILE__, 't');
$shm_id = shmop_open($shm_key, "c", 0644, 100);
?>
]]>
</programlisting>
</example>
</para>
<para>
This example opened a shared memory block with a system id returned by
<function>ftok</function>.
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>shmop_close</function></member>
<member><function>shmop_delete</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
