1explain_adjtime(3) Library Functions Manual explain_adjtime(3)
2
6 explain_adjtime - explain adjtime(2) errors
7
9 #include <libexplain/adjtime.h>
10 const char *explain_adjtime(const struct timeval *delta, struct timeval
11 *olddelta);
12 const char *explain_errno_adjtime(int errnum, const struct timeval
13 *delta, struct timeval *olddelta);
14 void explain_message_adjtime(char *message, int message_size, const
15 struct timeval *delta, struct timeval *olddelta);
16 void explain_message_errno_adjtime(char *message, int message_size, int
17 errnum, const struct timeval *delta, struct timeval *olddelta);
18
20 These functions may be used to obtain explanations for errors returned
21 by the adjtime(2) system call.
22 explain_adjtime
24 const char *explain_adjtime(const struct timeval *delta, struct timeval
25 *olddelta);
26 The explain_adjtime function is used to obtain an explanation of an
28 error returned by the adjtime(2) system call. The least the message
29 will contain is the value of strerror(errno), but usually it will do
30 much better, and indicate the underlying cause in more detail.
31 The errno global variable will be used to obtain the error value to be
33 decoded.
34 delta The original delta, exactly as passed to the adjtime(2) system
36 call.
37 olddelta
39 The original olddelta, exactly as passed to the adjtime(2) sys‐
40 tem call.
41 Returns:
43 The message explaining the error. This message buffer is shared
44 by all libexplain functions which do not supply a buffer in
45 their argument list. This will be overwritten by the next call
46 to any libexplain function which shares this buffer, including
47 other threads.
48 Note: This function is not thread safe, because it shares a return buf‐
50 fer across all threads, and many other functions in this library.
51 Example: This function is intended to be used in a fashion similar to
53 the following example:
54 if (adjtime(delta, olddelta) < 0)
55 {
56 fprintf(stderr, "%s\n", explain_adjtime(delta, olddelta));
57 exit(EXIT_FAILURE);
58 }
59 The above code example is available pre‐packaged as the explain_adj‐
61 time_or_die(3) function.
62 explain_errno_adjtime
64 const char *explain_errno_adjtime(int errnum, const struct timeval
65 *delta, struct timeval *olddelta);
66 The explain_errno_adjtime function is used to obtain an explanation of
68 an error returned by the adjtime(2) system call. The least the message
69 will contain is the value of strerror(errno), but usually it will do
70 much better, and indicate the underlying cause in more detail.
71 errnum The error value to be decoded, usually obtained from the errno
73 global variable just before this function is called. This is
74 necessary if you need to call any code between the system call
75 to be explained and this function, because many libc functions
76 will alter the value of errno.
77 delta The original delta, exactly as passed to the adjtime(2) system
79 call.
80 olddelta
82 The original olddelta, exactly as passed to the adjtime(2) sys‐
83 tem call.
84 Returns:
86 The message explaining the error. This message buffer is shared
87 by all libexplain functions which do not supply a buffer in
88 their argument list. This will be overwritten by the next call
89 to any libexplain function which shares this buffer, including
90 other threads.
91 Note: This function is not thread safe, because it shares a return buf‐
93 fer across all threads, and many other functions in this library.
94 Example: This function is intended to be used in a fashion similar to
96 the following example:
97 if (adjtime(delta, olddelta) < 0)
98 {
99 int err = errno;
100 fprintf(stderr, "%s\n", explain_errno_adjtime(err, delta,
101 olddelta));
102 exit(EXIT_FAILURE);
103 }
104 The above code example is available pre‐packaged as the explain_adj‐
106 time_or_die(3) function.
107 explain_message_adjtime
109 void explain_message_adjtime(char *message, int message_size, const
110 struct timeval *delta, struct timeval *olddelta);
111 The explain_message_adjtime function is used to obtain an explanation
113 of an error returned by the adjtime(2) system call. The least the mes‐
114 sage will contain is the value of strerror(errno), but usually it will
115 do much better, and indicate the underlying cause in more detail.
116 The errno global variable will be used to obtain the error value to be
118 decoded.
119 message The location in which to store the returned message. If a suit‐
121 able message return buffer is supplied, this function is thread
122 safe.
123 message_size
125 The size in bytes of the location in which to store the
126 returned message.
127 delta The original delta, exactly as passed to the adjtime(2) system
129 call.
130 olddelta
132 The original olddelta, exactly as passed to the adjtime(2) sys‐
133 tem call.
134 Example: This function is intended to be used in a fashion similar to
136 the following example:
137 if (adjtime(delta, olddelta) < 0)
138 {
139 char message[3000];
140 explain_message_adjtime(message, sizeof(message), delta,
141 olddelta);
142 fprintf(stderr, "%s\n", message);
143 exit(EXIT_FAILURE);
144 }
145 The above code example is available pre‐packaged as the explain_adj‐
147 time_or_die(3) function.
148 explain_message_errno_adjtime
150 void explain_message_errno_adjtime(char *message, int message_size, int
151 errnum, const struct timeval *delta, struct timeval *olddelta);
152 The explain_message_errno_adjtime function is used to obtain an expla‐
154 nation of an error returned by the adjtime(2) system call. The least
155 the message will contain is the value of strerror(errno), but usually
156 it will do much better, and indicate the underlying cause in more
157 detail.
158 message The location in which to store the returned message. If a suit‐
160 able message return buffer is supplied, this function is thread
161 safe.
162 message_size
164 The size in bytes of the location in which to store the
165 returned message.
166 errnum The error value to be decoded, usually obtained from the errno
168 global variable just before this function is called. This is
169 necessary if you need to call any code between the system call
170 to be explained and this function, because many libc functions
171 will alter the value of errno.
172 delta The original delta, exactly as passed to the adjtime(2) system
174 call.
175 olddelta
177 The original olddelta, exactly as passed to the adjtime(2) sys‐
178 tem call.
179 Example: This function is intended to be used in a fashion similar to
181 the following example:
182 if (adjtime(delta, olddelta) < 0)
183 {
184 int err = errno;
185 char message[3000];
186 explain_message_errno_adjtime(message, sizeof(message), err,
187 delta, olddelta);
188 fprintf(stderr, "%s\n", message);
189 exit(EXIT_FAILURE);
190 }
191 The above code example is available pre‐packaged as the explain_adj‐
193 time_or_die(3) function.
194
196 adjtime(2)
197 smoothly tune kernel clock
198 explain_adjtime_or_die(3)
200 smoothly tune kernel clock and report errors
201
203 libexplain version 0.40
204 Copyright (C) 2009 Peter Miller
205 explain_adjtime(3)