explain_readlink(3)					     Library Functions Manual					       explain_readlink(3)

NAME

       explain_readlink - explain readlink(2) errors

SYNOPSIS

       #include <libexplain/readlink.h>
       const char *explain_readlink(const char *pathname, char *data, size_t data_size);
       const char *explain_errno_readlink(int errnum, const char *pathname, char *data, size_t data_size);
       void explain_message_readlink(char *message, int message_size, const char *pathname, char *data, size_t data_size);
       void explain_message_errno_readlink(char *message, int message_size, int errnum, const char *pathname, char *data, size_t data_size);

DESCRIPTION

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

   explain_readlink
       const char *explain_readlink(const char *pathname, char *data, size_t data_size);

       The  explain_readlink function is used to obtain an explanation of an error returned by the readlink(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 (readlink(pathname, data, data_size) < 0)
	      {
		  fprintf(stderr, "%s
", explain_readlink(pathname, data, data_size));
		  exit(EXIT_FAILURE);
	      }

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

       data    The original data, exactly as passed to the readlink(2) system call.

       data_size
	       The original data_size, exactly as passed to the readlink(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_readlink
       const char *explain_errno_readlink(int errnum, const char *pathname, char *data, size_t data_size);

       The explain_errno_readlink function is used to obtain an explanation of an error returned by the readlink(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 (readlink(pathname, data, data_size) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_readlink(err, pathname, data,
		      data_size));
		  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 neces-
	       sary 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 readlink(2) system call.

       data    The original data, exactly as passed to the readlink(2) system call.

       data_size
	       The original data_size, exactly as passed to the readlink(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_readlink
       void explain_message_readlink(char *message, int message_size, const char *pathname, char *data, size_t data_size);

       The explain_message_readlink function may be used to  obtain an explanation of an error returned by the readlink(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 (readlink(pathname, data, data_size) < 0)
	      {
		  char message[3000];
		  explain_message_readlink(message, sizeof(message), pathname, data,
		      data_size);
		  fprintf(stderr, "%s
", 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.

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

       data    The original data, exactly as passed to the readlink(2) system call.

       data_size
	       The original data_size, exactly as passed to the readlink(2) system call.

   explain_message_errno_readlink
       void explain_message_errno_readlink(char *message, int message_size, int errnum, const char *pathname, char *data, size_t data_size);

       The  explain_message_errno_readlink function may be used to obtain an explanation of an error returned by the readlink(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 (readlink(pathname, data, data_size) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_readlink(message, sizeof(message), err, pathname,
		      data, data_size);
		  fprintf(stderr, "%s
", 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 neces-
	       sary 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 readlink(2) system call.

       data    The original data, exactly as passed to the readlink(2) system call.

       data_size
	       The original data_size, exactly as passed to the readlink(2) system call.

SEE ALSO

       readlink(2)
	       blah blah blah

       explain_readlink_or_die(3)
	       blah blah blah  and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2008 Peter Miller

															       explain_readlink(3)