NAME

       explain_dup - explain dup(2) errors

SYNOPSIS

       #include <libexplain/dup.h>
       const char *explain_dup(int fildes);
       const char *explain_errno_dup(int errnum, int fildes);
       void explain_message_dup(char *message, int message_size, int fildes);
       void explain_message_errno_dup(char *message, int message_size, int errnum, int fildes);

DESCRIPTION

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

   explain_dup
       const char *explain_dup(int fildes);

       The explain_dup function is used to obtain an explanation of  an  error  returned  by  the
       dup(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 (dup(fildes) < 0)
              {
                  fprintf(stderr, "%s\n", explain_dup(fildes));
                  exit(EXIT_FAILURE);
              }

       fildes  The original fildes, exactly as passed to the dup(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_dup
       const char *explain_errno_dup(int errnum, int fildes);

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

       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 dup(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_dup
       void explain_message_dup(char *message, int message_size, int fildes);

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

       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 dup(2) system call.

   explain_message_errno_dup
       void explain_message_errno_dup(char *message, int message_size, int errnum, int fildes);

       The explain_message_errno_dup function may be used to obtain an explanation  of  an  error
       returned  by  the  dup(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 (dup(fildes) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_dup(message, sizeof(message), err, fildes);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       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 dup(2) system call.

SEE ALSO

       dup(2)  duplicate a file descriptor

       explain_dup_or_die(3)
               duplicate a file descriptor and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

                                                                                   explain_dup(3)