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 .