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Linux 2.6 - man page for readlink (linux section 3posix)

READLINK(P)			    POSIX Programmer's Manual			      READLINK(P)

       readlink - read the contents of a symbolic link

       #include <unistd.h>

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

       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 argu-
       ment 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.

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

       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.

	      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.

	      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.

	      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.

   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';

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

       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  associ-
       ated  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  rep-
       resents	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  con-
       tents  of the symbolic link as returned by readlink(), this proposal was rejected, and the
       historical practice retained.


       lstat() , stat() , symlink()  ,	the  Base  Definitions	volume	of  IEEE Std 1003.1-2001,

       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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				      READLINK(P)

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