dlfcn.h(7posix) [posix man page]

<dlfcn.h>(P)						     POSIX Programmer's Manual						      <dlfcn.h>(P)

NAME

       dlfcn.h - dynamic linking

SYNOPSIS

       #include <dlfcn.h>

DESCRIPTION

       The <dlfcn.h> header shall define at least the following macros for use in the construction of a dlopen() mode argument:

       RTLD_LAZY
	      Relocations are performed at an implementation-defined time.

       RTLD_NOW
	      Relocations are performed when the object is loaded.

       RTLD_GLOBAL
	      All symbols are available for relocation processing of other modules.

       RTLD_LOCAL
	      All symbols are not made available for relocation processing by other modules.

       The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

	      int    dlclose(void *);
	      char  *dlerror(void);
	      void  *dlopen(const char *, int);
	      void  *dlsym(void *restrict, const char *restrict);

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The System Interfaces volume of IEEE Std 1003.1-2001, dlopen(), dlclose(), dlsym(), dlerror()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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							      <dlfcn.h>(P)

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

PROLOG

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

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)
", 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 Technol-
       ogy -- 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							       DLERROR(3P)