NAME
explain_adjtime - explain adjtime(2) errors
SYNOPSIS
#include <libexplain/adjtime.h>
const char *explain_adjtime(const struct timeval *delta, struct timeval
*olddelta);
const char *explain_errno_adjtime(int errnum, const struct timeval
*delta, struct timeval *olddelta);
void explain_message_adjtime(char *message, int message_size, const
struct timeval *delta, struct timeval *olddelta);
void explain_message_errno_adjtime(char *message, int message_size, int
errnum, const struct timeval *delta, struct timeval *olddelta);
DESCRIPTION
These functions may be used to obtain explanations for errors returned
by the adjtime(2) system call.
explain_adjtime
const char *explain_adjtime(const struct timeval *delta, struct timeval
*olddelta);
The explain_adjtime function is used to obtain an explanation of an
error returned by the adjtime(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.
delta The original delta, exactly as passed to the adjtime(2) system
call.
olddelta
The original olddelta, exactly as passed to the adjtime(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.
Example: This function is intended to be used in a fashion similar to
the following example:
if (adjtime(delta, olddelta) < 0)
{
fprintf(stderr, "%s\n", explain_adjtime(delta, olddelta));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the
explain_adjtime_or_die(3) function.
explain_errno_adjtime
const char *explain_errno_adjtime(int errnum, const struct timeval
*delta, struct timeval *olddelta);
The explain_errno_adjtime function is used to obtain an explanation of
an error returned by the adjtime(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.
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.
delta The original delta, exactly as passed to the adjtime(2) system
call.
olddelta
The original olddelta, exactly as passed to the adjtime(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.
Example: This function is intended to be used in a fashion similar to
the following example:
if (adjtime(delta, olddelta) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_adjtime(err, delta,
olddelta));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the
explain_adjtime_or_die(3) function.
explain_message_adjtime
void explain_message_adjtime(char *message, int message_size, const
struct timeval *delta, struct timeval *olddelta);
The explain_message_adjtime function is used to obtain an explanation
of an error returned by the adjtime(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.
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.
delta The original delta, exactly as passed to the adjtime(2) system
call.
olddelta
The original olddelta, exactly as passed to the adjtime(2)
system call.
Example: This function is intended to be used in a fashion similar to
the following example:
if (adjtime(delta, olddelta) < 0)
{
char message[3000];
explain_message_adjtime(message, sizeof(message), delta,
olddelta);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the
explain_adjtime_or_die(3) function.
explain_message_errno_adjtime
void explain_message_errno_adjtime(char *message, int message_size, int
errnum, const struct timeval *delta, struct timeval *olddelta);
The explain_message_errno_adjtime function is used to obtain an
explanation of an error returned by the adjtime(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.
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.
delta The original delta, exactly as passed to the adjtime(2) system
call.
olddelta
The original olddelta, exactly as passed to the adjtime(2)
system call.
Example: This function is intended to be used in a fashion similar to
the following example:
if (adjtime(delta, olddelta) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_adjtime(message, sizeof(message), err,
delta, olddelta);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the
explain_adjtime_or_die(3) function.
SEE ALSO
adjtime(2)
smoothly tune kernel clock
explain_adjtime_or_die(3)
smoothly tune kernel clock and report errors
COPYRIGHT
libexplain version 0.19
Copyright (C) 2009 Peter Miller
explain_adjtime(3)