NAME

       explain_realpath - explain realpath(3) errors

SYNOPSIS

       #include <libexplain/realpath.h>
       const char *explain_realpath(const char *pathname, char *resolved_pathname);
       const char *explain_errno_realpath(int errnum, const char *pathname, char
       *resolved_pathname);
       void explain_message_realpath(char *message, int message_size, const char *pathname, char
       *resolved_pathname);
       void explain_message_errno_realpath(char *message, int message_size, int errnum, const
       char *pathname, char *resolved_pathname);

DESCRIPTION

       These functions may be used to obtain explanations for errors returned by the  realpath(3)
       system call.

   explain_realpath
       const char *explain_realpath(const char *pathname, char *resolved_pathname);

       The explain_realpath function is used to obtain an explanation of an error returned by the
       realpath(3)  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.

       pathname
               The original pathname, exactly as passed to the realpath(3) system call.

       resolved_pathname
               The original resolved_pathname, exactly as passed to the realpath(3) 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.

       Example: This function is intended to be used  in  a  fashion  similar  to  the  following
       example:
              char *result = realpath(pathname, resolved_pathname);
              if (!result)
              {
                  fprintf(stderr, "%s\n", explain_realpath(pathname, resolved_pathname));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre-packaged  as  the explain_realpath_or_die(3)
       function.

   explain_errno_realpath
       const char *explain_errno_realpath(int errnum, const char *pathname, char
       *resolved_pathname);

       The  explain_errno_realpath function is used to obtain an explanation of an error returned
       by the realpath(3) 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.

       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.

       pathname
               The original pathname, exactly as passed to the realpath(3) system call.

       resolved_pathname
               The original resolved_pathname, exactly as passed to the realpath(3) 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.

       Example:  This  function  is  intended  to  be  used in a fashion similar to the following
       example:
              char *result = realpath(pathname, resolved_pathname);
              if (!result)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_realpath(err, pathname,
                  resolved_pathname));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre-packaged  as  the explain_realpath_or_die(3)
       function.

   explain_message_realpath
       void explain_message_realpath(char *message, int message_size, const char *pathname, char
       *resolved_pathname);

       The  explain_message_realpath  function  is  used  to  obtain  an  explanation of an error
       returned by the realpath(3) 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.

       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.

       pathname
               The original pathname, exactly as passed to the realpath(3) system call.

       resolved_pathname
               The original resolved_pathname, exactly as passed to the realpath(3) system call.

       Example:  This  function  is  intended  to  be  used in a fashion similar to the following
       example:
              char *result = realpath(pathname, resolved_pathname);
              if (!result)
              {
                  char message[3000];
                  explain_message_realpath(message, sizeof(message), pathname,
                  resolved_pathname);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is  available  pre-packaged  as  the explain_realpath_or_die(3)
       function.

   explain_message_errno_realpath
       void explain_message_errno_realpath(char *message, int message_size, int errnum, const
       char *pathname, char *resolved_pathname);

       The  explain_message_errno_realpath  function is used to obtain an explanation of an error
       returned by the realpath(3) 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.

       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.

       pathname
               The original pathname, exactly as passed to the realpath(3) system call.

       resolved_pathname
               The original resolved_pathname, exactly as passed to the realpath(3) system call.

       Example: This function is intended to be used  in  a  fashion  similar  to  the  following
       example:
              char *result = realpath(pathname, resolved_pathname);
              if (!result)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_realpath(message, sizeof(message), err, pathname,
                  resolved_pathname);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above  code  example  is  available  pre-packaged  as  the  explain_realpath_or_die(3)
       function.

SEE ALSO

       realpath(3)
               return the canonicalized absolute pathname

       explain_realpath_or_die(3)
               return the canonicalized absolute pathname and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2011 Peter Miller

                                                                              explain_realpath(3)