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NAME

       explain_chdir - explain chdir(2) errors

SYNOPSIS

       #include <libexplain/chdir.h>
       const char *explain_chdir(const char *pathname);
       void  explain_message_chdir(char *message, int message_size, const char
       *pathname);
       const char *explain_errno_chdir(int errnum, const char *pathname);
       void explain_message_errno_chdir(char *message, int  message_size,  int
       errnum, const char *pathname);

DESCRIPTION

       These function may be used to obtain explanations of chdir(2) errors.

   explain_chdir
       const char *explain_chdir(const char *pathname);

       The explain_chdir function is used to obtain an explanation of an error
       returned by the chdir(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 (chdir(pathname) < 0)
              {
                  fprintf(stderr, ’%s0, explain_chdir(pathname));
                  exit(EXIT_FAILURE);
              }

       pathname
               The original pathname, exactly as passed to the chdir(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_chdir
       const char *explain_errno_chdir(int errnum, const char *pathname);

       The explain_errno_chdir function is used to obtain an explanation of an
       error returned by the chdir(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 (chdir(pathname) < 0)
              {
                  int err = errno;
                  fprintf(stderr, ’%s0, explain_errno_chdir(err, pathname));
                  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.

       pathname
               The original pathname, exactly as passed to the chdir(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_chdir
       void explain_message_chdir(char *message, int message_size, const  char
       *pathname);

       The  explain_message_chdir function is used to obtain an explanation of
       an error returned by the chdir(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 (chdir(pathname) < 0)
              {
                  char message[3000];
                  explain_message_chdir(message, sizeof(message), pathname);
                  fprintf(stderr, ’%s0, message);
                  exit(EXIT_FAILURE);
              }

       message The location in which to store the returned message.  Because a
               message  return  buffer  has  been  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 chdir(2) system
               call.

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

       The   explain_message_errno_chdir   function   is  used  to  obtain  an
       explanation of an error returned by  the  chdir(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 (chdir(pathname) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_chdir(message, sizeof(message), err,
                      pathname);
                  fprintf(stderr, ’%s0, message);
                  exit(EXIT_FAILURE);
              }

       message The location in which to store the returned message.  Because a
               message  return  buffer  has  been  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 chdir(2) system
               call.

COPYRIGHT

       libexplain version
       Copyright (C) 2008 Peter Miller

AUTHOR

       Written by Peter Miller <pmiller@opensource.org.au>

                                                              explain_chdir(3)