NAME¶
explain_gettimeofday - explain
gettimeofday(2) errors
SYNOPSIS¶
#include <libexplain/gettimeofday.h>
const char *explain_gettimeofday(struct timeval *tv, struct timezone *tz);
const char *explain_errno_gettimeofday(int errnum, struct timeval *tv, struct
timezone *tz);
void explain_message_gettimeofday(char *message, int message_size, struct
timeval *tv, struct timezone *tz);
void explain_message_errno_gettimeofday(char *message, int message_size, int
errnum, struct timeval *tv, struct timezone *tz);
DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the
gettimeofday(2) system call.
explain_gettimeofday¶
const char *explain_gettimeofday(struct timeval *tv, struct timezone *tz);
The
explain_gettimeofday function is used to obtain an explanation of an
error returned by the
gettimeofday(2) system call. The least the
message will contain is the value of strerror(errno), but usually it will do
much better, and indicate the underlying cause in more detail.
The
errno global variable will be used to obtain the error value to be
decoded.
This function is intended to be used in a fashion similar to the following
example:
if (gettimeofday(tv, tz) < 0)
{
fprintf(stderr, "%s\n", explain_gettimeofday(tv, tz));
exit(EXIT_FAILURE);
}
- tv
- The original tv, exactly as passed to the
gettimeofday(2) system call.
- tz
- The original tz, exactly as passed to the
gettimeofday(2) system call.
- Returns:
- The message explaining the error. This message buffer is
shared by all libexplain functions which do not supply a buffer in their
argument list. This will be overwritten by the next call to any libexplain
function which shares this buffer, including other threads.
Note: This function is
not thread safe, because it shares a return
buffer across all threads, and many other functions in this library.
explain_errno_gettimeofday¶
const char *explain_errno_gettimeofday(int errnum, struct timeval *tv, struct
timezone *tz);
The
explain_errno_gettimeofday function is used to obtain an explanation
of an error returned by the
gettimeofday(2) system call. The least the
message will contain is the value of strerror(errnum), but usually it will do
much better, and indicate the underlying cause in more detail.
This function is intended to be used in a fashion similar to the following
example:
if (gettimeofday(tv, tz) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_gettimeofday(err, tv, tz));
exit(EXIT_FAILURE);
}
- errnum
- The error value to be decoded, usually obtained from the
errno global variable just before this function is called. This is
necessary if you need to call any code between the system call to
be explained and this function, because many libc functions will alter the
value of errno.
- tv
- The original tv, exactly as passed to the
gettimeofday(2) system call.
- tz
- The original tz, exactly as passed to the
gettimeofday(2) system call.
- Returns:
- The message explaining the error. This message buffer is
shared by all libexplain functions which do not supply a buffer in their
argument list. This will be overwritten by the next call to any libexplain
function which shares this buffer, including other threads.
Note: This function is
not thread safe, because it shares a return
buffer across all threads, and many other functions in this library.
explain_message_gettimeofday¶
void explain_message_gettimeofday(char *message, int message_size, struct
timeval *tv, struct timezone *tz);
The
explain_message_gettimeofday function may be used to obtain an
explanation of an error returned by the
gettimeofday(2) system call.
The least the message will contain is the value of strerror(errno), but
usually it will do much better, and indicate the underlying cause in more
detail.
The
errno global variable will be used to obtain the error value to be
decoded.
This function is intended to be used in a fashion similar to the following
example:
if (gettimeofday(tv, tz) < 0)
{
char message[3000];
explain_message_gettimeofday(message, sizeof(message), tv, tz);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
- message
- The location in which to store the returned message. If a
suitable message return buffer is supplied, this function is thread
safe.
- message_size
- The size in bytes of the location in which to store the
returned message.
- tv
- The original tv, exactly as passed to the
gettimeofday(2) system call.
- tz
- The original tz, exactly as passed to the
gettimeofday(2) system call.
explain_message_errno_gettimeofday¶
void explain_message_errno_gettimeofday(char *message, int message_size, int
errnum, struct timeval *tv, struct timezone *tz);
The
explain_message_errno_gettimeofday function may be used to obtain an
explanation of an error returned by the
gettimeofday(2) system call.
The least the message will contain is the value of strerror(errnum), but
usually it will do much better, and indicate the underlying cause in more
detail.
This function is intended to be used in a fashion similar to the following
example:
if (gettimeofday(tv, tz) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_gettimeofday(message, sizeof(message), err,
tv, tz);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
- message
- The location in which to store the returned message. If a
suitable message return buffer is supplied, this function is thread
safe.
- message_size
- The size in bytes of the location in which to store the
returned message.
- errnum
- The error value to be decoded, usually obtained from the
errno global variable just before this function is called. This is
necessary if you need to call any code between the system call to
be explained and this function, because many libc functions will alter the
value of errno.
- tv
- The original tv, exactly as passed to the
gettimeofday(2) system call.
- tz
- The original tz, exactly as passed to the
gettimeofday(2) system call.
SEE ALSO¶
- gettimeofday(2)
- get time
- explain_gettimeofday_or_die(3)
- get time and report errors
COPYRIGHT¶
libexplain version 0.52
Copyright (C) 2008 Peter Miller
