NAME

       readlink - read the contents of a symbolic link

SYNOPSIS

       #include <unistd.h>

       ssize_t readlink(const char *restrict path, char *restrict buf,
              size_t bufsize);

DESCRIPTION

       The  readlink() function shall place the contents of the symbolic link referred to by path
       in the buffer buf which has size bufsize. If the number of bytes in the symbolic  link  is
       less  than  bufsize,  the  contents  of  the  remainder of buf are unspecified. If the buf
       argument is not large enough to contain the link content, the first bufsize bytes shall be
       placed in buf.

       If the value of bufsize is greater than {SSIZE_MAX}, the result is implementation-defined.

RETURN VALUE

       Upon  successful  completion,  readlink()  shall  return  the count of bytes placed in the
       buffer. Otherwise, it shall return a value of -1, leave  the  buffer  unchanged,  and  set
       errno to indicate the error.

ERRORS

       The readlink() function shall fail if:

       EACCES Search permission is denied for a component of the path prefix of path.

       EINVAL The path argument names a file that is not a symbolic link.

       EIO    An I/O error occurred while reading from the file system.

       ELOOP  A loop exists in symbolic links encountered during resolution of the path argument.

       ENAMETOOLONG
              The  length  of  the  path  argument  exceeds {PATH_MAX} or a pathname component is
              longer than {NAME_MAX}.

       ENOENT A component of path does not name an existing file or path is an empty string.

       ENOTDIR
              A component of the path prefix is not a directory.

       The readlink() function may fail if:

       EACCES Read permission is denied for the directory.

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during  resolution  of  the
              path argument.

       ENAMETOOLONG
              As a result of encountering a symbolic link in resolution of the path argument, the
              length of the substituted pathname string exceeded {PATH_MAX}.

       The following sections are informative.

EXAMPLES

   Reading the Name of a Symbolic Link
       The following example shows how to read the name of a symbolic link named /modules/pass1.

              #include <unistd.h>

              char buf[1024];
              ssizet_t len;
              ...
              if ((len = readlink("/modules/pass1", buf, sizeof(buf)-1)) != -1)
                  buf[len] = '\0';

APPLICATION USAGE

       Conforming applications should not assume that the returned contents of the symbolic  link
       are null-terminated.

RATIONALE

       Since  IEEE Std 1003.1-2001  does  not require any association of file times with symbolic
       links, there is no requirement  that  file  times  be  updated  by  readlink().  The  type
       associated  with bufsiz is a size_t in order to be consistent with both the ISO C standard
       and the definition of read().  The behavior specified for readlink() when bufsiz  is  zero
       represents historical practice. For this case, the standard developers considered a change
       whereby readlink() would return the number of non-null bytes  contained  in  the  symbolic
       link  with  the  buffer  buf remaining unchanged; however, since the stat structure member
       st_size value can be used to determine  the  size  of  buffer  necessary  to  contain  the
       contents  of  the symbolic link as returned by readlink(), this proposal was rejected, and
       the historical practice retained.

FUTURE DIRECTIONS

       None.

SEE ALSO

       lstat() , stat() , symlink()  ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <unistd.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .