DLERROR(3)                 POSIX Programmer's Manual                DLERROR(3)



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

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.

       It is implementation-defined whether or not the dlerror() function is
       thread-safe. A thread-safe implementation shall return only errors that
       occur on the current thread.

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

       The application shall not modify the string returned. The returned
       pointer might be invalidated or the string content might be overwritten
       by a subsequent call to dlerror() in the same thread (if dlerror() is
       thread-safe) or in any thread (if dlerror() is not thread-safe). The
       returned pointer might also be invalidated if the calling thread is
       terminated.

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
       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 POSIX.1-2017, <dlfcn.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                           DLERROR(3)
