Provided by: libexplain-dev_1.4.D001-7_amd64 bug

NAME

       explain_getsockopt - explain getsockopt(2) errors

SYNOPSIS

       #include <libexplain/getsockopt.h>
       const char *explain_getsockopt(int fildes, int level, int name, void *data, socklen_t *data_size);
       const  char  *explain_errno_getsockopt(int errnum, int fildes, int level, int name, void *data, socklen_t
       *data_size);
       void explain_message_getsockopt(char *message, int message_size, int fildes, int level,  int  name,  void
       *data, socklen_t *data_size);
       void explain_message_errno_getsockopt(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 getsockopt(2) system call.

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

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

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

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

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

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

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

       data_size
               The original data_size, exactly as passed to the getsockopt(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_getsockopt
       const  char  *explain_errno_getsockopt(int errnum, int fildes, int level, int name, void *data, socklen_t
       *data_size);

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

       The above code example is available pre‐packaged as the explain_getsockopt_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 getsockopt(2) system call.

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

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

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

       data_size
               The original data_size, exactly as passed to the getsockopt(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_getsockopt
       void  explain_message_getsockopt(char  *message,  int message_size, int fildes, int level, int name, void
       *data, socklen_t *data_size);

       The explain_message_getsockopt function may be used to  obtain an explanation of an error returned by the
       getsockopt(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 (getsockopt(fildes, level, name, data, data_size) < 0)
              {
                  char message[3000];
                  explain_message_getsockopt(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_getsockopt_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 getsockopt(2) system call.

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

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

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

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

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

       The explain_message_errno_getsockopt function may be used to obtain an explanation of an  error  returned
       by  the  getsockopt(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 (getsockopt(fildes, level, name, data, data_size) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_getsockopt(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_getsockopt_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 getsockopt(2) system call.

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

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

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

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

SEE ALSO

       getsockopt(2)
               get and set options on sockets

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

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2009 Peter Miller

                                                                                           explain_getsockopt(3)