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READLINK(3P)               POSIX Programmer's Manual              READLINK(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
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];
              ssize_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  con-
       tents 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 .

IEEE/The Open Group                  2003                         READLINK(3P)