Provided by: libexplain-dev_1.4.D001-8_amd64 bug

NAME

       explain_setpriority - explain setpriority(2) errors

SYNOPSIS

       #include <libexplain/setpriority.h>
       const char *explain_setpriority(int which, int who, int prio);
       const char *explain_errno_setpriority(int errnum, int which, int who, int prio);
       void explain_message_setpriority(char *message, int message_size, int which, int who, int
       prio);
       void explain_message_errno_setpriority(char *message, int message_size, int errnum, int
       which, int who, int prio);

DESCRIPTION

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

   explain_setpriority
       const char *explain_setpriority(int which, int who, int prio);

       The explain_setpriority function is used to obtain an explanation of an error returned  by
       the  setpriority(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 setpriority(2) system call.

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

       prio    The original prio, exactly as passed to the setpriority(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 (setpriority(which, who, prio) < 0)
              {
                  fprintf(stderr, "%s\n", explain_setpriority(which, who, prio));
                  exit(EXIT_FAILURE);
              }

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

   explain_errno_setpriority
       const char *explain_errno_setpriority(int errnum, int which, int who, int prio);

       The  explain_errno_setpriority  function  is  used  to  obtain  an explanation of an error
       returned by the setpriority(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 setpriority(2) system call.

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

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

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

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

       The explain_message_setpriority function is used to obtain  an  explanation  of  an  error
       returned  by  the  setpriority(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 setpriority(2) system call.

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

       prio    The original prio, exactly as passed to the setpriority(2) system call.

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

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

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

       The  explain_message_errno_setpriority  function  is  used  to obtain an explanation of an
       error returned by the setpriority(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 setpriority(2) system call.

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

       prio    The original prio, exactly as passed to the setpriority(2) system call.

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

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

SEE ALSO

       setpriority(2)
               set program scheduling priority

       explain_setpriority_or_die(3)
               set program scheduling priority and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2013 Peter Miller

                                                                           explain_setpriority(3)