1 LIBPICLTREE(3PICLTREE) PICL Plug-In Library Functions LIBPICLTREE(3PICLTREE)
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3
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5 NAME
6 libpicltree - PTree and Plug-in Registration interface library
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8 SYNOPSIS
9 cc [flag ...] file ... -lpicltree [library ...]
10 #include <picltree.h>
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12
13 DESCRIPTION
14 The PTree interface is the set of functions and data structures to
15 access and manipulate the PICL tree. The daemon and the plug-in modules
16 use the PTree interface.
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18
19 The Plug-in Registration interface is used by the plug-in modules to
20 register themselves with the daemon.
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23 The plug-in modules create the nodes and properties of the tree. At the
24 time of creating a property, the plug-ins specify the property
25 information in the ptree_propinfo_t structure defined as:
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27 typedef struct {
28 int version; /* version */
29 picl_propinfo_t piclinfo; /* info to clients */
30 int (*read)(ptree_rarg_t *arg, void *buf);
31 /* read access function for */
32 /* volatile prop */
33 int (*write)(ptree_warg_t *arg, const void *buf);
34 /* write access function for */
35 /* volatile prop */
36 } ptree_propinfo_t;
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38
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40 See libpicl(3PICL) for more information on PICL tree nodes and
41 properties.
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44 The maximum size of a property value cannot exceed PICL_PROPSIZE_MAX.
45 It is currently set to 512KB.
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47 Volatile Properties
48 In addition to PICL_READ and PICL_WRITE property access modes, the
49 plug-in modules specify whether a property is volatile or not by
50 setting the bit PICL_VOLATILE.
51
52 #define PICL_VOLATILE 0x4
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56 For a volatile property, the plug-in module provides the access
57 functions to read and/or write the property in the ptree_propinfo_t
58 argument passed when creating the property.
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60
61 The daemon invokes the access functions of volatile properties when
62 clients access their values. Two arguments are passed to the read
63 access functions. The first argument is a pointer to ptree_rarg_t,
64 which contains the handle of the node, the handle of the accessed
65 property and the credentials of the caller. The second argument is a
66 pointer to the buffer where the value is to be copied.
67
68 typedef struct {
69 picl_nodehdl_t nodeh;
70 picl_prophdl_t proph;
71 door_cred_t cred;
72 } ptree_rarg_t;
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74
75
76 The prototype of the read access function for volatile property is:
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78 int read(ptree_rarg_t *rarg, void *buf);
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81
82 The read function returns PICL_SUCCESS to indicate successful
83 completion.
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86 Similarly, when a write access is performed on a volatile property, the
87 daemon invokes the write access function provided by the plug-in for
88 that property and passes it two arguments. The first argument is a
89 pointer to ptree_warg_t, which contains the handle to the node, the
90 handle of the accessed property and the credentials of the caller. The
91 second argument is a pointer to the buffer containing the value to be
92 written.
93
94 typedef struct {
95 picl_nodehdl_t nodeh;
96 picl_prophdl_t proph;
97 door_cred_t cred;
98 } ptree_warg_t;
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100
101
102 The prototype of the write access function for volatile property is:
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104 int write(ptree_warg_t *warg, const void *buf);
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107
108 The write function returns PICL_SUCCESS to indicate successful
109 completion.
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112 For all volatile properties, the 'size' of the property must be
113 specified to be the maximum possible size of the value. The maximum
114 size of the value cannot exceed PICL_PROPSIZE_MAX. This allows a client
115 to allocate a sufficiently large buffer before retrieving a volatile
116 property's value
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118 Plug-in Modules
119 Plug-in modules are shared objects that are located in well-known
120 directories for the daemon to locate and load them. Plug-in modules are
121 located in the one of the following plug-in directories depending on
122 the platform-specific nature of the data they collect and publish.
123
124 /usr/platform/picl/plugins/`uname -i`/
125 /usr/platform/picl/plugins/`uname -m`/
126 /usr/lib/picl/plugins/
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130 A plug-in module may specify its dependency on another plug-in module
131 using the -l linker option. The plug-ins are loaded by the PICL daemon
132 using dlopen(3C) according to the specified dependencies. Each plug-in
133 module must define a .init section, which is executed when the plug-in
134 module is loaded, to register themselves with the daemon. See
135 picld_plugin_register(3PICLTREE) for more information on plug-in
136 registration.
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139 The plug-in modules may use the picld_log(3PICLTREE) function to log
140 their messages to the system log file.
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142 ATTRIBUTES
143 See attributes(5) for descriptions of the following attributes:
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147
148 +---------------+-----------------+
149 |ATTRIBUTE TYPE | ATTRIBUTE VALUE |
150 +---------------+-----------------+
151 |MT-Level | MT-Safe |
152 +---------------+-----------------+
153
154 SEE ALSO
155 libpicl(3PICL), libpicltree(3LIB), picld_log(3PICLTREE),
156 picld_plugin_register(3PICLTREE), attributes(5)
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160 May 16, 2020 LIBPICLTREE(3PICLTREE)