explain_getpriority(3)

NAME
explain_getpriority - explain getpriority(2) errors

SYNOPSIS
#include <libexplain/getpriority.h>

const char *explain_getpriority(int which, int who);
const char *explain_errno_getpriority(int errnum, int which, int who);
void explain_message_getpriority(char *message, int message_size, int which, int who);
void explain_message_errno_getpriority(char *message, int message_size, int errnum, int which, int who);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the getpriority(2) system call.

  explain_getpriority
const char *explain_getpriority(int which, int who);

The explain_getpriority function is used to obtain an explanation of an error returned by the getpriority(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.

which
    The original which, exactly as passed to the getpriority(2) system call.

who The original who, exactly as passed to the getpriority(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 = getpriority(which, who);
    if (result < 0)
    {
    fprintf(stderr, "%s\n", explain_getpriority(which, who));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_getpriority_or_die(3) function.

  explain_errno_getpriority
const char *explain_errno_getpriority(int errnum, int which, int who);

The explain_errno_getpriority function is used to obtain an explanation of an error returned by the getpriority(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.

which
    The original which, exactly as passed to the getpriority(2) system call.

who The original who, exactly as passed to the getpriority(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 = getpriority(which, who);
    if (result < 0)
    {
        int err = errno;
    fprintf(stderr, "%s\n", explain_errno_getpriority(err, which, who));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_getpriority_or_die(3) function.

  explain_message_getpriority
void explain_message_getpriority(char *message, int message_size, int which, int who);

The explain_message_getpriority function is used to obtain an explanation of an error returned by the getpriority(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.

which
    The original which, exactly as passed to the getpriority(2) system call.

who The original who, exactly as passed to the getpriority(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    int result = getpriority(which, who);
    if (result < 0)
    {
        char message[3000];
    explain_message_getpriority(message, sizeof(message), which, who);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_getpriority_or_die(3) function.

  explain_message_errno_getpriority
void explain_message_errno_getpriority(char *message, int message_size, int errnum, int which, int who);

The explain_message_errno_getpriority function is used to obtain an explanation of an error returned by the getpriority(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.

which
    The original which, exactly as passed to the getpriority(2) system call.

who The original who, exactly as passed to the getpriority(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    int result = getpriority(which, who);
    if (result < 0)
    {
        int err = errno;
        char message[3000];
    explain_message_errno_getpriority(message, sizeof(message), err, which, who);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_getpriority_or_die(3) function.

SEE ALSO

getpriority(2)
    get program scheduling priority

explain_getpriority_or_die(3)
    get program scheduling priority and report errors

COPYRIGHT
libexplain version 1.4
Copyright (C) 2013 Peter Miller