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

NAME

       explain_setsockopt - explain setsockopt(2) errors

SYNOPSIS

       #include <libexplain/setsockopt.h>
       const  char  *explain_setsockopt(int  fildes,  int  level, int name, void *data, socklen_t
       data_size);
       const char *explain_errno_setsockopt(int errnum, int fildes, int  level,  int  name,  void
       *data, socklen_t data_size);
       void  explain_message_setsockopt(char  *message,  int message_size, int fildes, int level,
       int name, void *data, socklen_t data_size);
       void explain_message_errno_setsockopt(char *message, int  message_size,  int  errnum,  int
       fildes, int level, int name, void *data, socklen_t data_size);

DESCRIPTION

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

   explain_setsockopt
       const char *explain_setsockopt(int fildes, int level,  int  name,  void  *data,  socklen_t
       data_size);

       The  explain_setsockopt  function is used to obtain an explanation of an error returned by
       the setsockopt(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 (setsockopt(fildes, level, name, data, data_size) < 0)
              {
                  fprintf(stderr, "%s\n", explain_setsockopt(fildes,
                      level, name, data, data_size));
                  exit(EXIT_FAILURE);
              }

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

       fildes  The original fildes, exactly as passed to the setsockopt(2) system call.

       level   The original level, exactly as passed to the setsockopt(2) system call.

       name    The original name, exactly as passed to the setsockopt(2) system call.

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

       data_size
               The original data_size, exactly as passed to the setsockopt(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_setsockopt
       const  char  *explain_errno_setsockopt(int  errnum,  int fildes, int level, int name, void
       *data, socklen_t data_size);

       The explain_errno_setsockopt function is  used  to  obtain  an  explanation  of  an  error
       returned  by  the  setsockopt(2)  system  call.  The least the message will contain is the
       value of strerror(errnum), 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 (setsockopt(fildes, level, name, data, data_size) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_setsockopt(err,
                      fildes, level, name, data, data_size));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre‐packaged as the explain_setsockopt_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.

       fildes  The original fildes, exactly as passed to the setsockopt(2) system call.

       level   The original level, exactly as passed to the setsockopt(2) system call.

       name    The original name, exactly as passed to the setsockopt(2) system call.

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

       data_size
               The original data_size, exactly as passed to the setsockopt(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_setsockopt
       void  explain_message_setsockopt(char  *message,  int message_size, int fildes, int level,
       int name, void *data, socklen_t data_size);

       The explain_message_setsockopt function may be used to  obtain an explanation of an  error
       returned  by  the  setsockopt(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 (setsockopt(fildes, level, name, data, data_size) < 0)
              {
                  char message[3000];
                  explain_message_setsockopt(message, sizeof(message),
                      fildes, level, name, data, data_size);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre‐packaged as the explain_setsockopt_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.

       fildes  The original fildes, exactly as passed to the setsockopt(2) system call.

       level   The original level, exactly as passed to the setsockopt(2) system call.

       name    The original name, exactly as passed to the setsockopt(2) system call.

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

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

   explain_message_errno_setsockopt
       void  explain_message_errno_setsockopt(char  *message,  int  message_size, int errnum, int
       fildes, int level, int name, void *data, socklen_t data_size);

       The explain_message_errno_setsockopt function may be used to obtain an explanation  of  an
       error  returned  by  the setsockopt(2) system call.  The least the message will contain is
       the value of strerror(errnum), 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 (setsockopt(fildes, level, name, data, data_size) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_setsockopt(message, sizeof(message),
                      err, fildes, level, name, data, data_size);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre‐packaged as the explain_setsockopt_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.

       fildes  The original fildes, exactly as passed to the setsockopt(2) system call.

       level   The original level, exactly as passed to the setsockopt(2) system call.

       name    The original name, exactly as passed to the setsockopt(2) system call.

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

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

SEE ALSO

       setsockopt(2)
               get and set options on sockets

       explain_setsockopt_or_die(3)
               get and set options on sockets and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2009 Peter Miller

                                                                            explain_setsockopt(3)