explain_nice(3)

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
Copyright (C) 2009 Peter Miller