1explain_gettimeofday(3)    Library Functions Manual    explain_gettimeofday(3)
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4

NAME

6       explain_gettimeofday - explain gettimeofday(2) errors
7

SYNOPSIS

9       #include <libexplain/gettimeofday.h>
10       const  char  *explain_gettimeofday(struct  timeval *tv, struct timezone
11       *tz);
12       const char *explain_errno_gettimeofday(int errnum, struct timeval  *tv,
13       struct timezone *tz);
14       void   explain_message_gettimeofday(char  *message,  int  message_size,
15       struct timeval *tv, struct timezone *tz);
16       void   explain_message_errno_gettimeofday(char   *message,   int   mes‐
17       sage_size, int errnum, struct timeval *tv, struct timezone *tz);
18

DESCRIPTION

20       These  functions may be used to obtain explanations for errors returned
21       by the gettimeofday(2) system call.
22
23   explain_gettimeofday
24       const char *explain_gettimeofday(struct timeval  *tv,  struct  timezone
25       *tz);
26
27       The  explain_gettimeofday  function is used to obtain an explanation of
28       an error returned by the gettimeofday(2) system call.   The  least  the
29       message  will  contain  is the value of strerror(errno), but usually it
30       will do much better, and indicate the underlying cause in more detail.
31
32       The errno global variable will be used to obtain the error value to  be
33       decoded.
34
35       This  function  is intended to be used in a fashion similar to the fol‐
36       lowing example:
37              if (gettimeofday(tv, tz) < 0)
38              {
39                  fprintf(stderr, "%s\n", explain_gettimeofday(tv, tz));
40                  exit(EXIT_FAILURE);
41              }
42
43       tv      The original tv, exactly as passed to the gettimeofday(2)  sys‐
44               tem call.
45
46       tz      The  original tz, exactly as passed to the gettimeofday(2) sys‐
47               tem call.
48
49       Returns:
50               The message explaining  the  error.   This  message  buffer  is
51               shared by all libexplain functions which do not supply a buffer
52               in their argument list.  This will be overwritten by  the  next
53               call  to  any  libexplain  function  which  shares this buffer,
54               including other threads.
55
56       Note: This function is not thread safe, because it shares a return buf‐
57       fer across all threads, and many other functions in this library.
58
59   explain_errno_gettimeofday
60       const  char *explain_errno_gettimeofday(int errnum, struct timeval *tv,
61       struct timezone *tz);
62
63       The explain_errno_gettimeofday function is used to obtain  an  explana‐
64       tion  of  an  error  returned  by the gettimeofday(2) system call.  The
65       least the message will contain is the value  of  strerror(errnum),  but
66       usually  it  will  do much better, and indicate the underlying cause in
67       more detail.
68
69       This function is intended to be used in a fashion similar to  the  fol‐
70       lowing example:
71              if (gettimeofday(tv, tz) < 0)
72              {
73                  int err = errno;
74                  fprintf(stderr, "%s\n", explain_errno_gettimeofday(err, tv, tz));
75                  exit(EXIT_FAILURE);
76              }
77
78       errnum  The  error value to be decoded, usually obtained from the errno
79               global variable just before this function is called.   This  is
80               necessary  if you need to call any code between the system call
81               to be explained and this function, because many libc  functions
82               will alter the value of errno.
83
84       tv      The  original tv, exactly as passed to the gettimeofday(2) sys‐
85               tem call.
86
87       tz      The original tz, exactly as passed to the gettimeofday(2)  sys‐
88               tem call.
89
90       Returns:
91               The  message  explaining  the  error.   This  message buffer is
92               shared by all libexplain functions which do not supply a buffer
93               in  their  argument list.  This will be overwritten by the next
94               call to any  libexplain  function  which  shares  this  buffer,
95               including other threads.
96
97       Note: This function is not thread safe, because it shares a return buf‐
98       fer across all threads, and many other functions in this library.
99
100   explain_message_gettimeofday
101       void  explain_message_gettimeofday(char  *message,  int   message_size,
102       struct timeval *tv, struct timezone *tz);
103
104       The  explain_message_gettimeofday  function  may  be used to  obtain an
105       explanation of an error returned by the  gettimeofday(2)  system  call.
106       The least the message will contain is the value of strerror(errno), but
107       usually it will do much better, and indicate the  underlying  cause  in
108       more detail.
109
110       The  errno global variable will be used to obtain the error value to be
111       decoded.
112
113       This function is intended to be used in a fashion similar to  the  fol‐
114       lowing example:
115              if (gettimeofday(tv, tz) < 0)
116              {
117                  char message[3000];
118                  explain_message_gettimeofday(message, sizeof(message), tv, tz);
119                  fprintf(stderr, "%s\n", message);
120                  exit(EXIT_FAILURE);
121              }
122
123       message The  location  in  which  to  store the returned message.  If a
124               suitable message return buffer is supplied,  this  function  is
125               thread safe.
126
127       message_size
128               The  size  in  bytes  of  the  location  in  which to store the
129               returned message.
130
131       tv      The original tv, exactly as passed to the gettimeofday(2)  sys‐
132               tem call.
133
134       tz      The  original tz, exactly as passed to the gettimeofday(2) sys‐
135               tem call.
136
137   explain_message_errno_gettimeofday
138       void   explain_message_errno_gettimeofday(char   *message,   int   mes‐
139       sage_size, int errnum, struct timeval *tv, struct timezone *tz);
140
141       The  explain_message_errno_gettimeofday  function may be used to obtain
142       an explanation of an error returned by the gettimeofday(2) system call.
143       The  least  the  message will contain is the value of strerror(errnum),
144       but usually it will do much better, and indicate the  underlying  cause
145       in more detail.
146
147       This  function  is intended to be used in a fashion similar to the fol‐
148       lowing example:
149              if (gettimeofday(tv, tz) < 0)
150              {
151                  int err = errno;
152                  char message[3000];
153                  explain_message_errno_gettimeofday(message, sizeof(message), err,
154                      tv, tz);
155                  fprintf(stderr, "%s\n", message);
156                  exit(EXIT_FAILURE);
157              }
158
159       message The location in which to store  the  returned  message.   If  a
160               suitable  message  return  buffer is supplied, this function is
161               thread safe.
162
163       message_size
164               The size in bytes  of  the  location  in  which  to  store  the
165               returned message.
166
167       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
173       tv      The  original tv, exactly as passed to the gettimeofday(2) sys‐
174               tem call.
175
176       tz      The original tz, exactly as passed to the gettimeofday(2)  sys‐
177               tem call.
178

SEE ALSO

180       gettimeofday(2)
181               get time
182
183       explain_gettimeofday_or_die(3)
184               get time and report errors
185
187       libexplain version 1.4
188       Copyright (C) 2008 Peter Miller
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192                                                       explain_gettimeofday(3)
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