NAME

       explain_access - explain access(2) errors

SYNOPSIS

       #include <libexplain/access.h>
       const char *explain_access(const char *pathname, int mode);
       const char *explain_errno_access(int errnum, const char *pathname, int mode);
       void explain_message_access(char *message, int message_size, const char *pathname, int mode);
       void  explain_message_errno_access(char *message, int message_size, int errnum, const char *pathname, int
       mode);

DESCRIPTION

       These functions may be used to obtain explanations for access(2) errors.

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

       The explain_access function is used to obtain an explanation of an error returned by the access(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:
              int fd = access(pathname, mode);
              if (fd < 0)
              {
                  fprintf(stderr, "%s0, explain_access(pathname, mode));
                  exit(EXIT_FAILURE);
              }

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

       mode    The  original  mode,  exactly as passed to the access(2) system call.  TP 8n 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_access
       const char *explain_errno_access(int errnum, const char *pathname, int mode);

       The  explain_errno_access function is used to obtain an explanation of an error returned by the access(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:
              int fd = access(pathname, mode);
              if (fd < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s0, explain_errno_access(err, pathname,
                      mode));
                  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 access(2) system call.

       mode    The original mode, exactly as passed to the access(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_access
       void explain_message_access(char *message, int message_size, const char *pathname, int mode);

       The explain_message_access function is used to  obtain  an  explanation  of  an  error  returned  by  the
       access(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:
              int fd = access(pathname, mode);
              if (fd < 0)
              {
                  char message[3000];
                  explain_message_access(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 access(2) system call.

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

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

       The explain_message_errno_access function is used to obtain an explanation of an error  returned  by  the
       access(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 exameple:
              int fd = access(pathname, mode);
              if (fd < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_access(message, sizeof(message), err,
                      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.

       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 access(2) system call.

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

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

AUTHOR

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

                                                                                               explain_access(3)