NAME

       explain_chmod - explain chmod(2) errors

SYNOPSIS

       #include <libexplain/chmod.h>
       const char *explain_chmod(const char *pathname, int mode);
       const char *explain_errno_chmod(int errnum, const char *pathname, int mode);
       void  explain_message_chmod(char  *message,  int  message_size,  const char *pathname, int
       mode);
       void explain_message_errno_chmod(char *message, int message_size, int errnum,  const  char
       *pathname, int mode);

DESCRIPTION

       These functions may be used to otain explanations for chmod(2) errors.

   explain_chmod
       const char *explain_chmod(const char *pathname, int mode);

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

       pathname
               The original pathname, exactly as passed to the chmod(2) system call.

       mode    The original mode, exactly as passed to the chmod(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_chmod
       const char *explain_errno_chmod(int errnum, const char *pathname, int mode);

       The  explain_errno_chmod function is used to obtain an explanation of an error returned by
       the  chmod(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 (chmod(pathname) < 0)
              {
                  int err = errno;
                  fprintf(stderr, '%s0, explain_errno_chmod(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 chmod(2) system call.

       mode    The original mode, exactly as passed to the chmod(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_chmod
       void  explain_message_chmod(char  *message,  int  message_size,  const char *pathname, int
       mode);

       The explain_message_chmod function is used to obtain an explanation of an  error  returned
       by  the  chmod(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 (chmod(pathname, mode) < 0)
              {
                  char message[3000];
                  explain_message_chmod(message, sizeof(message), pathname, mode);
                  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 chmod(2) system call.

       mode    The original mode, exactly as passed to the chmod(2) system call.

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

       The  explain_message_errno_chmod  function  is  used  to obtain an explanation of an error
       returned by the chmod(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 (chmod(pathname) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_chmod(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 chmod(2) system call.

       mode    The original mode, exactly as passed to the chmod(2) system call.

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

AUTHOR

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

                                                                                 explain_chmod(3)