nn_symbol_info(3)

1NN_SYMBOL_INFO(3)                nanomsg 1.1.5               NN_SYMBOL_INFO(3)
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NAME

6       nn_symbol_info - query the names and properties of nanomsg symbols
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SYNOPSIS

9       #include <nanomsg/nn.h>
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11       int nn_symbol_info (int i, struct nn_symbol_properties *buf, int
12       buflen);
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DESCRIPTION

15       Retrieves the symbol name and value at index i. Indices start at 0. An
16       index has no significance to its associated symbol; the mappings may
17       change between library versions.
18
19       The nn_symbol_properties has the following definition:
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21           struct nn_symbol_properties {
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23               /*  The constant value  */
24               int value;
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26               /*  The constant name  */
27               const char* name;
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29               /*  The constant namespace, or zero for namespaces themselves */
30               int ns;
31
32               /*  The option type for socket option constants  */
33               int type;
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35               /*  The unit for the option value for socket option constants  */
36               int unit;
37           };
38
39       More structure members may be added in future, but the input pointer
40       will be written only up to buflen so the ABI is forward-compatible.
41
42       Typically a client will iterate through the symbols until
43       nn_symbol_info returns NULL in order to collect all the symbols.
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45       All symbols exposed by nn_symbol_info are available directly in the C
46       API, generally as preprocessor macros. Thus, this function is useful
47       mostly for language bindings that can’t parse the header file and rely
48       on retrieving the symbols at runtime.
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50       Note that the NN_MSG symbol is not exported by the nn_symbol_info
51       function. First, it is a pointer rather than an integer; second, the
52       symbol is not supposed to be exported from language bindings to the
53       user. Instead, language bindings should provide the zero-copy
54       functionality in a language-specific way, if at all (zero-copy
55       functionality may not make sense for some languages/bindings).
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AVAILABLE NAMESPACES

58       NN_NS_NAMESPACE
59           Equals to zero and denotes the NN_NS_* constants themselves
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61       NN_NS_VERSION
62           Nanomsg version constants
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64       NN_NS_DOMAIN
65           Socket domain (or address family) constants AF_SP, AF_SP_RAW
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67       NN_NS_TRANSPORT
68           Transport name constants (used for socket options mainly)
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70       NN_NS_PROTOCOL
71           Socket protocol constants
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73       NN_NS_OPTION_LEVEL
74           Socket option level constants (NN_SOL_SOCKET)
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76       NN_NS_SOCKET_OPTION
77           Socket options for NN_SOL_SOCKET level
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79       NN_NS_TRANSPORT_OPTION
80           Socket options for transport level (used with transport constants)
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82       NN_NS_OPTION_TYPE
83           The option types (described below)
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85       NN_NS_FLAG
86           The nn_send/nn_recv flags (only NN_DONTWAIT for now)
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88       NN_NS_ERROR
89           The errno values
90
91       NN_NS_LIMIT
92           Various nanomsg limits (only NN_SOCKADDR_MAX for now)
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94       NN_NS_EVENT
95           Event flags (bit mask) for use with nn_poll (NN_POLLIN, NN_POLLOUT)
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AVAILABLE OPTION TYPES

98       NN_TYPE_NONE
99           No type, is returned for constants that are not socket options
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101       NN_TYPE_INT
102           The integer type
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104       NN_TYPE_STR
105           String (char *) type
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107       More types may be added in the future to nanomsg. You may enumerate all
108       of them using the nn_symbol_info itself by checking NN_NS_OPTION_TYPE
109       namespace.
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AVAILABLE OPTION UNITS

112       NN_UNIT_NONE
113           No unit, is returned for constants that are not socket options, or
114           do not have any meaningful unit (strings, integer values)
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116       NN_UNIT_BYTES
117           The option value is expressed in bytes
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119       NN_UNIT_MILLISECONDS
120           The option value is expressed in milliseconds
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122       NN_UNIT_PRIORITY
123           The option value is a priority, an integer from 1 to 16
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125       NN_UNIT_BOOLEAN
126           The option value is boolean, an integer 0 or 1
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128       More types may be added in the future to nanomsg. You may enumerate all
129       of them using the nn_symbol_info itself by checking NN_NS_OPTION_TYPE
130       namespace.
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RETURN VALUE

133       If i is valid, returns the number of bytes stored at the structure. The
134       maximum value that can be returned is buflen.
135
136       If i is out-of-range, nn_symbol_info returns zero.
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EXAMPLE

139           int i;
140           for (i = 0; ; ++i) {
141               struct nn_symbol_properties sym;
142               int rc = nn_symbol_info (i, &sym, sizeof (sym));
143               if(rc == 0)
144                   break;
145               assert (rc == sizeof (sym));
146               printf ("'%s' = %d\n", sym.name, sym.value);
147           }
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AUTHORS

153       Paul Colomiets <paul@colomiets.name> Garrett D’Amore
154       <garrett@damore.org>
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158                                  2020-01-29                 NN_SYMBOL_INFO(3)