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