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

NAME

       explain_gethostname - explain gethostname(2) errors

SYNOPSIS

       #include <libexplain/gethostname.h>
       const char *explain_gethostname(char *data, size_t data_size);
       const char *explain_errno_gethostname(int errnum, char *data, size_t data_size);
       void  explain_message_gethostname(char  *message,  int  message_size,  char  *data, size_t
       data_size);
       void explain_message_errno_gethostname(char *message, int message_size, int  errnum,  char
       *data, size_t data_size);

DESCRIPTION

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

   explain_gethostname
       const char *explain_gethostname(char *data, size_t data_size);

       The explain_gethostname function is used to obtain an explanation of an error returned  by
       the  gethostname(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.

       This function is intended to be used in a fashion similar to the following example:
              if (gethostname(data, data_size) < 0)
              {
                  fprintf(stderr, "%s\n", explain_gethostname(data, data_size));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available pre‐packaged as the explain_gethostname_or_die(3)
       function.

       data    The original data, exactly as passed to the gethostname(2) system call.

       data_size
               The original data_size, exactly as passed to the gethostname(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.

   explain_errno_gethostname
       const char *explain_errno_gethostname(int errnum, char *data, size_t data_size);

       The explain_errno_gethostname function is used  to  obtain  an  explanation  of  an  error
       returned  by  the  gethostname(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.

       This function is intended to be used in a fashion similar to the following example:
              if (gethostname(data, data_size) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_gethostname(err, data, data_size));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available pre‐packaged as the explain_gethostname_or_die(3)
       function.

       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.

       data    The original data, exactly as passed to the gethostname(2) system call.

       data_size
               The original data_size, exactly as passed to the gethostname(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.

   explain_message_gethostname
       void  explain_message_gethostname(char  *message,  int  message_size,  char  *data, size_t
       data_size);

       The explain_message_gethostname function is used to obtain  an  explanation  of  an  error
       returned  by  the  gethostname(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.

       This function is intended to be used in a fashion similar to the following example:
              if (gethostname(data, data_size) < 0)
              {
                  char message[3000];
                  explain_message_gethostname(message, sizeof(message), data, data_size);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available pre‐packaged as the explain_gethostname_or_die(3)
       function.

       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.

       data    The original data, exactly as passed to the gethostname(2) system call.

       data_size
               The original data_size, exactly as passed to the gethostname(2) system call.

   explain_message_errno_gethostname
       void  explain_message_errno_gethostname(char  *message, int message_size, int errnum, char
       *data, size_t data_size);

       The explain_message_errno_gethostname function is used to  obtain  an  explanation  of  an
       error  returned  by the gethostname(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.

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

       The  above  code  example  is  available pre‐packaged as the explain_gethostname_or_die(3)
       function.

       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.

       data    The original data, exactly as passed to the gethostname(2) system call.

       data_size
               The original data_size, exactly as passed to the gethostname(2) system call.

SEE ALSO

       gethostname(2)
               get/set hostname

       explain_gethostname_or_die(3)
               get/set hostname and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2009 Peter Miller

                                                                           explain_gethostname(3)