1explain_getsockopt(3) Library Functions Manual explain_getsockopt(3)
2
6 explain_getsockopt - explain getsockopt(2) errors
7
9 #include <libexplain/getsockopt.h>
10 const char *explain_getsockopt(int fildes, int level, int name, void
11 *data, socklen_t *data_size);
12 const char *explain_errno_getsockopt(int errnum, int fildes, int level,
13 int name, void *data, socklen_t *data_size);
14 void explain_message_getsockopt(char *message, int message_size, int
15 fildes, int level, int name, void *data, socklen_t *data_size);
16 void explain_message_errno_getsockopt(char *message, int message_size,
17 int errnum, int fildes, int level, int name, void *data, socklen_t
18 *data_size);
19
21 These functions may be used to obtain explanations for errors returned
22 by the getsockopt(2) system call.
23 explain_getsockopt
25 const char *explain_getsockopt(int fildes, int level, int name, void
26 *data, socklen_t *data_size);
27 The explain_getsockopt function is used to obtain an explanation of an
29 error returned by the getsockopt(2) system call. The least the message
30 will contain is the value of strerror(errno), but usually it will do
31 much better, and indicate the underlying cause in more detail.
32 The errno global variable will be used to obtain the error value to be
34 decoded.
35 This function is intended to be used in a fashion similar to the fol‐
37 lowing example:
38 if (getsockopt(fildes, level, name, data, data_size) < 0)
39 {
40 fprintf(stderr, "%s\n", explain_getsockopt(fildes,
41 level, name, data, data_size));
42 exit(EXIT_FAILURE);
43 }
44 The above code example is available pre‐packaged as the explain_get‐
46 sockopt_or_die(3) function.
47 fildes The original fildes, exactly as passed to the getsockopt(2)
49 system call.
50 level The original level, exactly as passed to the getsockopt(2) sys‐
52 tem call.
53 name The original name, exactly as passed to the getsockopt(2) sys‐
55 tem call.
56 data The original data, exactly as passed to the getsockopt(2) sys‐
58 tem call.
59 data_size
61 The original data_size, exactly as passed to the getsockopt(2)
62 system call.
63 Returns:
65 The message explaining the error. This message buffer is
66 shared by all libexplain functions which do not supply a buffer
67 in their argument list. This will be overwritten by the next
68 call to any libexplain function which shares this buffer,
69 including other threads.
70 Note: This function is not thread safe, because it shares a return buf‐
72 fer across all threads, and many other functions in this library.
73 explain_errno_getsockopt
75 const char *explain_errno_getsockopt(int errnum, int fildes, int level,
76 int name, void *data, socklen_t *data_size);
77 The explain_errno_getsockopt function is used to obtain an explanation
79 of an error returned by the getsockopt(2) system call. The least the
80 message will contain is the value of strerror(errnum), but usually it
81 will do much better, and indicate the underlying cause in more detail.
82 This function is intended to be used in a fashion similar to the fol‐
84 lowing example:
85 if (getsockopt(fildes, level, name, data, data_size) < 0)
86 {
87 int err = errno;
88 fprintf(stderr, "%s\n", explain_errno_getsockopt(err,
89 fildes, level, name, data, data_size));
90 exit(EXIT_FAILURE);
91 }
92 The above code example is available pre‐packaged as the explain_get‐
94 sockopt_or_die(3) function.
95 errnum The error value to be decoded, usually obtained from the errno
97 global variable just before this function is called. This is
98 necessary if you need to call any code between the system call
99 to be explained and this function, because many libc functions
100 will alter the value of errno.
101 fildes The original fildes, exactly as passed to the getsockopt(2)
103 system call.
104 level The original level, exactly as passed to the getsockopt(2) sys‐
106 tem call.
107 name The original name, exactly as passed to the getsockopt(2) sys‐
109 tem call.
110 data The original data, exactly as passed to the getsockopt(2) sys‐
112 tem call.
113 data_size
115 The original data_size, exactly as passed to the getsockopt(2)
116 system call.
117 Returns:
119 The message explaining the error. This message buffer is
120 shared by all libexplain functions which do not supply a buffer
121 in their argument list. This will be overwritten by the next
122 call to any libexplain function which shares this buffer,
123 including other threads.
124 Note: This function is not thread safe, because it shares a return buf‐
126 fer across all threads, and many other functions in this library.
127 explain_message_getsockopt
129 void explain_message_getsockopt(char *message, int message_size, int
130 fildes, int level, int name, void *data, socklen_t *data_size);
131 The explain_message_getsockopt function may be used to obtain an
133 explanation of an error returned by the getsockopt(2) system call. The
134 least the message will contain is the value of strerror(errno), but
135 usually it will do much better, and indicate the underlying cause in
136 more detail.
137 The errno global variable will be used to obtain the error value to be
139 decoded.
140 This function is intended to be used in a fashion similar to the fol‐
142 lowing example:
143 if (getsockopt(fildes, level, name, data, data_size) < 0)
144 {
145 char message[3000];
146 explain_message_getsockopt(message, sizeof(message),
147 fildes, level, name, data, data_size);
148 fprintf(stderr, "%s\n", message);
149 exit(EXIT_FAILURE);
150 }
151 The above code example is available pre‐packaged as the explain_get‐
153 sockopt_or_die(3) function.
154 message The location in which to store the returned message. If a
156 suitable message return buffer is supplied, this function is
157 thread safe.
158 message_size
160 The size in bytes of the location in which to store the
161 returned message.
162 fildes The original fildes, exactly as passed to the getsockopt(2)
164 system call.
165 level The original level, exactly as passed to the getsockopt(2) sys‐
167 tem call.
168 name The original name, exactly as passed to the getsockopt(2) sys‐
170 tem call.
171 data The original data, exactly as passed to the getsockopt(2) sys‐
173 tem call.
174 data_size
176 The original data_size, exactly as passed to the getsockopt(2)
177 system call.
178 explain_message_errno_getsockopt
180 void explain_message_errno_getsockopt(char *message, int message_size,
181 int errnum, int fildes, int level, int name, void *data, socklen_t
182 *data_size);
183 The explain_message_errno_getsockopt function may be used to obtain an
185 explanation of an error returned by the getsockopt(2) system call. The
186 least the message will contain is the value of strerror(errnum), but
187 usually it will do much better, and indicate the underlying cause in
188 more detail.
189 This function is intended to be used in a fashion similar to the fol‐
191 lowing example:
192 if (getsockopt(fildes, level, name, data, data_size) < 0)
193 {
194 int err = errno;
195 char message[3000];
196 explain_message_errno_getsockopt(message, sizeof(message),
197 err, fildes, level, name, data, data_size);
198 fprintf(stderr, "%s\n", message);
199 exit(EXIT_FAILURE);
200 }
201 The above code example is available pre‐packaged as the explain_get‐
203 sockopt_or_die(3) function.
204 message The location in which to store the returned message. If a
206 suitable message return buffer is supplied, this function is
207 thread safe.
208 message_size
210 The size in bytes of the location in which to store the
211 returned message.
212 errnum The error value to be decoded, usually obtained from the errno
214 global variable just before this function is called. This is
215 necessary if you need to call any code between the system call
216 to be explained and this function, because many libc functions
217 will alter the value of errno.
218 fildes The original fildes, exactly as passed to the getsockopt(2)
220 system call.
221 level The original level, exactly as passed to the getsockopt(2) sys‐
223 tem call.
224 name The original name, exactly as passed to the getsockopt(2) sys‐
226 tem call.
227 data The original data, exactly as passed to the getsockopt(2) sys‐
229 tem call.
230 data_size
232 The original data_size, exactly as passed to the getsockopt(2)
233 system call.
234
236 getsockopt(2)
237 get and set options on sockets
238 explain_getsockopt_or_die(3)
240 get and set options on sockets and report errors
241
243 libexplain version 1.4
244 Copyright (C) 2009 Peter Miller
245 explain_getsockopt(3)