1explain_getaddrinfo(3) Library Functions Manual explain_getaddrinfo(3)
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6 explain_getaddrinfo - explain getaddrinfo(3) errors
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9 #include <libexplain/getaddrinfo.h>
10 const char *explain_errcode_getaddrinfo(int errnum, const char *node,
11 const char *service, const struct addrinfo *hints, struct addrinfo
12 **res);
13 void explain_message_errcode_getaddrinfo(char *message, int mes‐
14 sage_size, int errnum, const char *node, const char *service, const
15 struct addrinfo *hints, struct addrinfo **res);
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18 These functions may be used to obtain explanations for errors returned
19 by the getaddrinfo(3) system call.
20 explain_errcode_getaddrinfo
22 const char *explain_errcode_getaddrinfo(int errnum, const char *node,
23 const char *service, const struct addrinfo *hints, struct addrinfo
24 **res);
25 The explain_errcode_getaddrinfo function is used to obtain an explana‐
27 tion of an error returned by the getaddrinfo(3) system call. The least
28 the message will contain is the value of gai_strerror(errcode), but
29 usually it will do much better, and indicate the underlying cause in
30 more detail.
31 This function is intended to be used in a fashion similar to the fol‐
33 lowing example:
34 int errcode = getaddrinfo(node, service, hints, res);
35 if (errncode == GAI_SYSTEM)
36 errcode = errno;
37 if (errcode)
38 {
39 fprintf(stderr, "%s\n", explain_errcode_getaddrinfo(errcode,
40 node, service, hints, res));
41 exit(EXIT_FAILURE);
42 }
43 The above code example is available as the explain_getad‐
45 drinfo_or_die(3) function.
46 errnum The error value to be decoded, usually obtained from the errno
48 global variable just before this function is called. This is
49 necessary if you need to call any code between the system call
50 to be explained and this function, because many libc functions
51 will alter the value of errno.
52 node The original node, exactly as passed to the getaddrinfo(3) sys‐
54 tem call.
55 service The original service, exactly as passed to the getaddrinfo(3)
57 system call.
58 hints The original hints, exactly as passed to the getaddrinfo(3)
60 system call.
61 res The original res, exactly as passed to the getaddrinfo(3) sys‐
63 tem call.
64 Returns:
66 The message explaining the error. This message buffer is
67 shared by all libexplain functions which do not supply a buffer
68 in their argument list. This will be overwritten by the next
69 call to any libexplain function which shares this buffer,
70 including other threads.
71 Note: This function is not thread safe, because it shares a return buf‐
73 fer across all threads, and many other functions in this library.
74 explain_message_errno_getaddrinfo
76 void explain_message_errno_getaddrinfo(char *message, int message_size,
77 int errnum, const char *node, const char *service, const struct
78 addrinfo *hints, struct addrinfo **res);
79 The explain_message_errno_getaddrinfo function may be used to obtain an
81 explanation of an error returned by the getaddrinfo(3) system call.
82 The least the message will contain is the value of strerror(errnum),
83 but usually it will do much better, and indicate the underlying cause
84 in more detail.
85 This function is intended to be used in a fashion similar to the fol‐
87 lowing example:
88 int errcode = getaddrinfo(node, service, hints, res);
89 if (errnode == EAI_SYSTEM)
90 errcode = errno;
91 if (errcode)
92 {
93 char message[3000];
94 explain_message_errcode_getaddrinfo(message, sizeof(message),
95 errcode, node, service, hints, res);
96 fprintf(stderr, "%s\n", message);
97 exit(EXIT_FAILURE);
98 }
99 The above code example is available pre‐packaged as the explain_getad‐
101 drinfo_or_die(3) function.
102 message The location in which to store the returned message. If a
104 suitable message return buffer is supplied, this function is
105 thread safe.
106 message_size
108 The size in bytes of the location in which to store the
109 returned message.
110 errnum The error value to be decoded, usually obtained from the errno
112 global variable just before this function is called. This is
113 necessary if you need to call any code between the system call
114 to be explained and this function, because many libc functions
115 will alter the value of errno.
116 node The original node, exactly as passed to the getaddrinfo(3) sys‐
118 tem call.
119 service The original service, exactly as passed to the getaddrinfo(3)
121 system call.
122 hints The original hints, exactly as passed to the getaddrinfo(3)
124 system call.
125 res The original res, exactly as passed to the getaddrinfo(3) sys‐
127 tem call.
128
130 getaddrinfo(3)
131 network address and
132 explain_getaddrinfo_or_die(3)
134 network address and and report errors
135
137 libexplain version 1.4
138 Copyright (C) 2008 Peter Miller
139 explain_getaddrinfo(3)