NAME

       dlerror - get diagnostic information

SYNOPSIS

       #include <dlfcn.h>

       char *dlerror(void);

DESCRIPTION

       The  dlerror()  function shall return a null-terminated character string (with no trailing
       <newline>) that describes the last error that occurred during dynamic linking  processing.
       If  no  dynamic  linking  errors  have  occurred  since  the last invocation of dlerror(),
       dlerror() shall  return  NULL.   Thus,  invoking  dlerror()  a  second  time,  immediately
       following a prior invocation, shall result in NULL being returned.

       The  dlerror()  function  need  not  be  reentrant.  A function that is not required to be
       reentrant is not required to be thread-safe.

RETURN VALUE

       If successful, dlerror() shall return a null-terminated character string; otherwise,  NULL
       shall be returned.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       The following example prints out the last dynamic linking error:

              ...
              #include <dlfcn.h>

              char *errstr;

              errstr = dlerror();
              if (errstr != NULL)
              printf ("A dynamic linking error occurred: (%s)\n", errstr);
              ...

APPLICATION USAGE

       The  messages  returned  by dlerror() may reside in a static buffer that is overwritten on
       each call to dlerror().  Application code  should  not  write  to  this  buffer.  Programs
       wishing  to  preserve  an  error  message  should  make  their own copies of that message.
       Depending on the application environment with respect to  asynchronous  execution  events,
       such  as  signals  or other asynchronous computation sharing the address space, conforming
       applications should use a critical section to retrieve the error pointer and buffer.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       dlclose() , dlopen() , dlsym() , the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <dlfcn.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 .