1explain_settimeofday(3) Library Functions Manual explain_settimeofday(3)
2
6 explain_settimeofday - explain settimeofday(2) errors
7
9 #include <libexplain/settimeofday.h>
10 const char *explain_settimeofday(const struct timeval *tv, const struct
11 timezone *tz);
12 const char *explain_errno_settimeofday(int errnum, const struct timeval
13 *tv, const struct timezone *tz);
14 void explain_message_settimeofday(char *message, int message_size,
15 const struct timeval *tv, const struct timezone *tz);
16 void explain_message_errno_settimeofday(char *message, int mes‐
17 sage_size, int errnum, const struct timeval *tv, const struct timezone
18 *tz);
19
21 These functions may be used to obtain explanations for errors returned
22 by the settimeofday(2) system call.
23 explain_settimeofday
25 const char *explain_settimeofday(const struct timeval *tv, const struct
26 timezone *tz);
27 The explain_settimeofday function is used to obtain an explanation of
29 an error returned by the settimeofday(2) system call. The least the
30 message will contain is the value of strerror(errno), but usually it
31 will do 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 tv The original tv, exactly as passed to the settimeofday(2) sys‐
37 tem call.
38 tz The original tz, exactly as passed to the settimeofday(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 (settimeofday(tv, tz) < 0)
55 {
56 fprintf(stderr, "%s\n", explain_settimeofday(tv, tz));
57 exit(EXIT_FAILURE);
58 }
59 The above code example is available pre-packaged as the explain_set‐
61 timeofday_or_die(3) function.
62 explain_errno_settimeofday
64 const char *explain_errno_settimeofday(int errnum, const struct timeval
65 *tv, const struct timezone *tz);
66 The explain_errno_settimeofday function is used to obtain an explana‐
68 tion of an error returned by the settimeofday(2) system call. The least
69 the message will contain is the value of strerror(errno), but usually
70 it will do much better, and indicate the underlying cause in more
71 detail.
72 errnum The error value to be decoded, usually obtained from the errno
74 global variable just before this function is called. This is
75 necessary if you need to call any code between the system call
76 to be explained and this function, because many libc functions
77 will alter the value of errno.
78 tv The original tv, exactly as passed to the settimeofday(2) sys‐
80 tem call.
81 tz The original tz, exactly as passed to the settimeofday(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 (settimeofday(tv, tz) < 0)
98 {
99 int err = errno;
100 fprintf(stderr, "%s\n", explain_errno_settimeofday(err, tv,
101 tz));
102 exit(EXIT_FAILURE);
103 }
104 The above code example is available pre-packaged as the explain_set‐
106 timeofday_or_die(3) function.
107 explain_message_settimeofday
109 void explain_message_settimeofday(char *message, int message_size,
110 const struct timeval *tv, const struct timezone *tz);
111 The explain_message_settimeofday function is used to obtain an explana‐
113 tion of an error returned by the settimeofday(2) system call. The least
114 the message will contain is the value of strerror(errno), but usually
115 it will do much better, and indicate the underlying cause in more
116 detail.
117 The errno global variable will be used to obtain the error value to be
119 decoded.
120 message The location in which to store the returned message. If a suit‐
122 able message return buffer is supplied, this function is thread
123 safe.
124 message_size
126 The size in bytes of the location in which to store the
127 returned message.
128 tv The original tv, exactly as passed to the settimeofday(2) sys‐
130 tem call.
131 tz The original tz, exactly as passed to the settimeofday(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 (settimeofday(tv, tz) < 0)
138 {
139 char message[3000];
140 explain_message_settimeofday(message, sizeof(message), tv,
141 tz);
142 fprintf(stderr, "%s\n", message);
143 exit(EXIT_FAILURE);
144 }
145 The above code example is available pre-packaged as the explain_set‐
147 timeofday_or_die(3) function.
148 explain_message_errno_settimeofday
150 void explain_message_errno_settimeofday(char *message, int mes‐
151 sage_size, int errnum, const struct timeval *tv, const struct timezone
152 *tz);
153 The explain_message_errno_settimeofday function is used to obtain an
155 explanation of an error returned by the settimeofday(2) system call.
156 The least the message will contain is the value of strerror(errno), but
157 usually it will do much better, and indicate the underlying cause in
158 more detail.
159 message The location in which to store the returned message. If a suit‐
161 able message return buffer is supplied, this function is thread
162 safe.
163 message_size
165 The size in bytes of the location in which to store the
166 returned message.
167 errnum The error value to be decoded, usually obtained from the errno
169 global variable just before this function is called. This is
170 necessary if you need to call any code between the system call
171 to be explained and this function, because many libc functions
172 will alter the value of errno.
173 tv The original tv, exactly as passed to the settimeofday(2) sys‐
175 tem call.
176 tz The original tz, exactly as passed to the settimeofday(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 (settimeofday(tv, tz) < 0)
183 {
184 int err = errno;
185 char message[3000];
186 explain_message_errno_settimeofday(message, sizeof(message),
187 err, tv, tz);
188 fprintf(stderr, "%s\n", message);
189 exit(EXIT_FAILURE);
190 }
191 The above code example is available pre-packaged as the explain_set‐
193 timeofday_or_die(3) function.
194
196 settimeofday(2)
197 sets system time
198 explain_settimeofday_or_die(3)
200 sets system time and report errors
201
203 libexplain version 1.4
204 Copyright (C) 2013 Peter Miller
205 explain_settimeofday(3)