Provided by: explain_0.52.D002-1_amd64 bug

NAME

       explain_dup2 - explain dup2(2) errors

SYNOPSIS

       #include <libexplain/dup2.h>
       const char *explain_dup2(int oldfd, int newfd);
       const char *explain_errno_dup2(int errnum, int oldfd, int newfd);
       void explain_message_dup2(char *message, int message_size, int oldfd, int newfd);
       void  explain_message_errno_dup2(char  *message,  int message_size, int errnum, int oldfd,
       int newfd);

DESCRIPTION

       These functions may be used to obtain explanations for  errors  returned  by  the  dup2(2)
       system call.

   explain_dup2
       const char *explain_dup2(int oldfd, int newfd);

       The  explain_dup2  function  is  used to obtain an explanation of an error returned by the
       dup2(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 (dup2(oldfd, newfd) < 0)
              {
                  fprintf(stderr, "%s\n", explain_dup2(oldfd, newfd));
                  exit(EXIT_FAILURE);
              }

       oldfd   The original oldfd, exactly as passed to the dup2(2) system call.

       newfd   The original newfd, exactly as passed to the dup2(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_dup2
       const char *explain_errno_dup2(int errnum, int oldfd, int newfd);

       The  explain_errno_dup2  function is used to obtain an explanation of an error returned by
       the  dup2(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 (dup2(oldfd, newfd) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_dup2(err, oldfd, newfd));
                  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.

       oldfd   The original oldfd, exactly as passed to the dup2(2) system call.

       newfd   The original newfd, exactly as passed to the dup2(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_dup2
       void explain_message_dup2(char *message, int message_size, int oldfd, int newfd);

       The  explain_message_dup2  function  may  be  used  to   obtain an explanation of an error
       returned by the dup2(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 (dup2(oldfd, newfd) < 0)
              {
                  char message[3000];
                  explain_message_dup2(message, sizeof(message), oldfd, newfd);
                  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.

       oldfd   The original oldfd, exactly as passed to the dup2(2) system call.

       newfd   The original newfd, exactly as passed to the dup2(2) system call.

   explain_message_errno_dup2
       void  explain_message_errno_dup2(char  *message,  int message_size, int errnum, int oldfd,
       int newfd);

       The explain_message_errno_dup2 function may be used to obtain an explanation of  an  error
       returned  by  the dup2(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 (dup2(oldfd, newfd) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_dup2(message, sizeof(message), err, oldfd, newfd);
                  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.

       oldfd   The original oldfd, exactly as passed to the dup2(2) system call.

       newfd   The original newfd, exactly as passed to the dup2(2) system call.

SEE ALSO

       dup2(2) duplicate a file descriptor

       explain_dup2_or_die(3)
               duplicate a file descriptor and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2008 Peter Miller

                                                                                  explain_dup2(3)