glibc/include/dlfcn.h

#ifndef _DLFCN_H
#include <dlfcn/dlfcn.h>
#include <link.h>		/* For ElfW.  */
#include <stdbool.h>

/* Internally used flag.  */
#define __RTLD_DLOPEN	0x80000000
#define __RTLD_SPROF	0x40000000
#define __RTLD_OPENEXEC	0x20000000
#define __RTLD_CALLMAP	0x10000000
#define __RTLD_AUDIT	0x08000000

#define __LM_ID_CALLER	-2

#ifdef SHARED
/* Locally stored program arguments.  */
extern int __dlfcn_argc attribute_hidden;
extern char **__dlfcn_argv attribute_hidden;
#else
/* These variables are defined and initialized in the startup code.  */
extern int __libc_argc attribute_hidden;
extern char **__libc_argv attribute_hidden;

# define __dlfcn_argc __libc_argc
# define __dlfcn_argv __libc_argv
#endif


/* Now define the internal interfaces.  */

#define __libc_dlopen(name) \
  __libc_dlopen_mode (name, RTLD_LAZY | __RTLD_DLOPEN)
extern void *__libc_dlopen_mode  (__const char *__name, int __mode);
extern void *__libc_dlsym   (void *__map, __const char *__name);
extern int   __libc_dlclose (void *__map);
libc_hidden_proto (__libc_dlopen_mode)
libc_hidden_proto (__libc_dlsym)
libc_hidden_proto (__libc_dlclose)

/* Locate shared object containing the given address.  */
#ifdef ElfW
extern int _dl_addr (const void *address, Dl_info *info,
		     struct link_map **mapp, const ElfW(Sym) **symbolp)
     internal_function;
libc_hidden_proto (_dl_addr)
#endif

/* Close an object previously opened by _dl_open.  */
extern void _dl_close (void *map) attribute_hidden;
/* Same as above, but without locking and safety checks for user
   provided map arguments.  */
extern void _dl_close_worker (struct link_map *map) attribute_hidden;

/* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
   RTLD_NEXT).  WHO is the calling function, for RTLD_NEXT.  Returns
   the symbol value, which may be NULL.  */
extern void *_dl_sym (void *handle, const char *name, void *who)
    internal_function;

/* Look up version VERSION of symbol NAME in shared object HANDLE
   (which may be RTLD_DEFAULT or RTLD_NEXT).  WHO is the calling
   function, for RTLD_NEXT.  Returns the symbol value, which may be
   NULL.  */
extern void *_dl_vsym (void *handle, const char *name, const char *version,
		       void *who)
    internal_function;

/* Call OPERATE, catching errors from `dl_signal_error'.  If there is no
   error, *ERRSTRING is set to null.  If there is an error, *ERRSTRING is
   set to a string constructed from the strings passed to _dl_signal_error,
   and the error code passed is the return value and *OBJNAME is set to
   the object name which experienced the problems.  ERRSTRING if nonzero
   points to a malloc'ed string which the caller has to free after use.
   ARGS is passed as argument to OPERATE.  MALLOCEDP is set to true only
   if the returned string is allocated using the libc's malloc.  */
extern int _dl_catch_error (const char **objname, const char **errstring,
			    bool *mallocedp, void (*operate) (void *),
			    void *args)
     internal_function;

/* Helper function for <dlfcn.h> functions.  Runs the OPERATE function via
   _dl_catch_error.  Returns zero for success, nonzero for failure; and
   arranges for `dlerror' to return the error details.
   ARGS is passed as argument to OPERATE.  */
extern int _dlerror_run (void (*operate) (void *), void *args)
     internal_function;

#ifdef SHARED
# define DL_CALLER_DECL /* Nothing */
# define DL_CALLER RETURN_ADDRESS (0)
#else
# define DL_CALLER_DECL , void *dl_caller
# define DL_CALLER dl_caller
#endif

struct dlfcn_hook
{
  void *(*dlopen) (const char *file, int mode, void *dl_caller);
  int (*dlclose) (void *handle);
  void *(*dlsym) (void *handle, const char *name, void *dl_caller);
  void *(*dlvsym) (void *handle, const char *name, const char *version,
		   void *dl_caller);
  char *(*dlerror) (void);
  int (*dladdr) (const void *address, Dl_info *info);
  int (*dladdr1) (const void *address, Dl_info *info,
		  void **extra_info, int flags);
  int (*dlinfo) (void *handle, int request, void *arg, void *dl_caller);
  void *(*dlmopen) (Lmid_t nsid, const char *file, int mode, void *dl_caller);
  void *pad[4];
};

extern struct dlfcn_hook *_dlfcn_hook;
libdl_hidden_proto (_dlfcn_hook)

extern void *__dlopen (const char *file, int mode DL_CALLER_DECL)
     attribute_hidden;
extern void *__dlmopen (Lmid_t nsid, const char *file, int mode DL_CALLER_DECL)
     attribute_hidden;
extern int __dlclose (void *handle)
     attribute_hidden;
extern void *__dlsym (void *handle, const char *name DL_CALLER_DECL)
     attribute_hidden;
extern void *__dlvsym (void *handle, const char *name, const char *version
		       DL_CALLER_DECL)
     attribute_hidden;
extern char *__dlerror (void)
     attribute_hidden;
extern int __dladdr (const void *address, Dl_info *info)
     attribute_hidden;
extern int __dladdr1 (const void *address, Dl_info *info,
		      void **extra_info, int flags)
     attribute_hidden;
extern int __dlinfo (void *handle, int request, void *arg DL_CALLER_DECL)
     attribute_hidden;

#ifndef SHARED
struct link_map;
extern void * __libc_dlsym_private (struct link_map *map, const char *name)
     attribute_hidden;
extern void __libc_register_dl_open_hook (struct link_map *map)
     attribute_hidden;
extern void __libc_register_dlfcn_hook (struct link_map *map)
     attribute_hidden;
#endif

#endif