text: /* $OpenBSD: dso.h,v 1.10 2014/08/14 17:55:28 tobias Exp $ */
  /* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
   * project 2000.
   */
  /* ====================================================================
   * Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    licensing@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com).
   *
   */
  
  #ifndef HEADER_DSO_H
  #define HEADER_DSO_H
  
  #include <openssl/crypto.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* These values are used as commands to DSO_ctrl() */
  #define DSO_CTRL_GET_FLAGS	1
  #define DSO_CTRL_SET_FLAGS	2
  #define DSO_CTRL_OR_FLAGS	3
  
  /* By default, DSO_load() will translate the provided filename into a form
   * typical for the platform (more specifically the DSO_METHOD) using the
   * dso_name_converter function of the method. Eg. win32 will transform "blah"
   * into "blah.dll", and dlfcn will transform it into "libblah.so". The
   * behaviour can be overridden by setting the name_converter callback in the DSO
   * object (using DSO_set_name_converter()). This callback could even utilise
   * the DSO_METHOD's converter too if it only wants to override behaviour for
   * one or two possible DSO methods. However, the following flag can be set in a
   * DSO to prevent *any* native name-translation at all - eg. if the caller has
   * prompted the user for a path to a driver library so the filename should be
   * interpreted as-is. */
  #define DSO_FLAG_NO_NAME_TRANSLATION		0x01
  /* An extra flag to give if only the extension should be added as
   * translation.  This is obviously only of importance on Unix and
   * other operating systems where the translation also may prefix
   * the name with something, like 'lib', and ignored everywhere else.
   * This flag is also ignored if DSO_FLAG_NO_NAME_TRANSLATION is used
   * at the same time. */
  #define DSO_FLAG_NAME_TRANSLATION_EXT_ONLY	0x02
  
  /* The following flag controls the translation of symbol names to upper
   * case.  This is currently only being implemented for OpenVMS.
   */
  #define DSO_FLAG_UPCASE_SYMBOL			0x10
  
  /* This flag loads the library with public symbols.
   * Meaning: The exported symbols of this library are public
   * to all libraries loaded after this library.
   * At the moment only implemented in unix.
   */
  #define DSO_FLAG_GLOBAL_SYMBOLS			0x20
  
  
  typedef void (*DSO_FUNC_TYPE)(void);
  
  typedef struct dso_st DSO;
  
  /* The function prototype used for method functions (or caller-provided
   * callbacks) that transform filenames. They are passed a DSO structure pointer
   * (or NULL if they are to be used independantly of a DSO object) and a
   * filename to transform. They should either return NULL (if there is an error
   * condition) or a newly allocated string containing the transformed form that
   * the caller will need to free with free() when done. */
  typedef char* (*DSO_NAME_CONVERTER_FUNC)(DSO *, const char *);
  /* The function prototype used for method functions (or caller-provided
   * callbacks) that merge two file specifications. They are passed a
   * DSO structure pointer (or NULL if they are to be used independantly of
   * a DSO object) and two file specifications to merge. They should
   * either return NULL (if there is an error condition) or a newly allocated
   * string containing the result of merging that the caller will need
   * to free with free() when done.
   * Here, merging means that bits and pieces are taken from each of the
   * file specifications and added together in whatever fashion that is
   * sensible for the DSO method in question.  The only rule that really
   * applies is that if the two specification contain pieces of the same
   * type, the copy from the first string takes priority.  One could see
   * it as the first specification is the one given by the user and the
   * second being a bunch of defaults to add on if they're missing in the
   * first. */
  typedef char* (*DSO_MERGER_FUNC)(DSO *, const char *, const char *);
  
  typedef struct dso_meth_st {
  	const char *name;
  	/* Loads a shared library, NB: new DSO_METHODs must ensure that a
  	 * successful load populates the loaded_filename field, and likewise a
  	 * successful unload frees and NULLs it out. */
  	int (*dso_load)(DSO *dso);
  	/* Unloads a shared library */
  	int (*dso_unload)(DSO *dso);
  	/* Binds a variable */
  	void *(*dso_bind_var)(DSO *dso, const char *symname);
  	/* Binds a function - assumes a return type of DSO_FUNC_TYPE.
  	 * This should be cast to the real function prototype by the
  	 * caller. Platforms that don't have compatible representations
  	 * for different prototypes (this is possible within ANSI C)
  	 * are highly unlikely to have shared libraries at all, let
  	 * alone a DSO_METHOD implemented for them. */
  	DSO_FUNC_TYPE (*dso_bind_func)(DSO *dso, const char *symname);
  
  	/* The generic (yuck) "ctrl()" function. NB: Negative return
  	 * values (rather than zero) indicate errors. */
  	long (*dso_ctrl)(DSO *dso, int cmd, long larg, void *parg);
  	/* The default DSO_METHOD-specific function for converting filenames to
  	 * a canonical native form. */
  	DSO_NAME_CONVERTER_FUNC dso_name_converter;
  	/* The default DSO_METHOD-specific function for converting filenames to
  	 * a canonical native form. */
  	DSO_MERGER_FUNC dso_merger;
  
  	/* [De]Initialisation handlers. */
  	int (*init)(DSO *dso);
  	int (*finish)(DSO *dso);
  
  	/* Return pathname of the module containing location */
  	int (*pathbyaddr)(void *addr, char *path, int sz);
  	/* Perform global symbol lookup, i.e. among *all* modules */
  	void *(*globallookup)(const char *symname);
  } DSO_METHOD;
  
  /**********************************************************************/
  /* The low-level handle type used to refer to a loaded shared library */
  
  struct dso_st {
  	DSO_METHOD *meth;
  	/* Standard dlopen uses a (void *). Win32 uses a HANDLE. VMS
  	 * doesn't use anything but will need to cache the filename
  	 * for use in the dso_bind handler. All in all, let each
  	 * method control its own destiny. "Handles" and such go in
  	 * a STACK. */
  	STACK_OF(void) *meth_data;
  	int references;
  	int flags;
  	/* For use by applications etc ... use this for your bits'n'pieces,
  	 * don't touch meth_data! */
  	CRYPTO_EX_DATA ex_data;
  	/* If this callback function pointer is set to non-NULL, then it will
  	 * be used in DSO_load() in place of meth->dso_name_converter. NB: This
  	 * should normally set using DSO_set_name_converter(). */
  	DSO_NAME_CONVERTER_FUNC name_converter;
  	/* If this callback function pointer is set to non-NULL, then it will
  	 * be used in DSO_load() in place of meth->dso_merger. NB: This
  	 * should normally set using DSO_set_merger(). */
  	DSO_MERGER_FUNC merger;
  	/* This is populated with (a copy of) the platform-independant
  	 * filename used for this DSO. */
  	char *filename;
  	/* This is populated with (a copy of) the translated filename by which
  	 * the DSO was actually loaded. It is NULL iff the DSO is not currently
  	 * loaded. NB: This is here because the filename translation process
  	 * may involve a callback being invoked more than once not only to
  	 * convert to a platform-specific form, but also to try different
  	 * filenames in the process of trying to perform a load. As such, this
  	 * variable can be used to indicate (a) whether this DSO structure
  	 * corresponds to a loaded library or not, and (b) the filename with
  	 * which it was actually loaded. */
  	char *loaded_filename;
  };
  
  
  DSO *	DSO_new(void);
  DSO *	DSO_new_method(DSO_METHOD *method);
  int	DSO_free(DSO *dso);
  int	DSO_flags(DSO *dso);
  int	DSO_up_ref(DSO *dso);
  long	DSO_ctrl(DSO *dso, int cmd, long larg, void *parg);
  
  /* This function sets the DSO's name_converter callback. If it is non-NULL,
   * then it will be used instead of the associated DSO_METHOD's function. If
   * oldcb is non-NULL then it is set to the function pointer value being
   * replaced. Return value is non-zero for success. */
  int	DSO_set_name_converter(DSO *dso, DSO_NAME_CONVERTER_FUNC cb,
  	    DSO_NAME_CONVERTER_FUNC *oldcb);
  /* These functions can be used to get/set the platform-independant filename
   * used for a DSO. NB: set will fail if the DSO is already loaded. */
  const char *DSO_get_filename(DSO *dso);
  int	DSO_set_filename(DSO *dso, const char *filename);
  /* This function will invoke the DSO's name_converter callback to translate a
   * filename, or if the callback isn't set it will instead use the DSO_METHOD's
   * converter. If "filename" is NULL, the "filename" in the DSO itself will be
   * used. If the DSO_FLAG_NO_NAME_TRANSLATION flag is set, then the filename is
   * simply duplicated. NB: This function is usually called from within a
   * DSO_METHOD during the processing of a DSO_load() call, and is exposed so that
   * caller-created DSO_METHODs can do the same thing. A non-NULL return value
   * will need to be free()'d. */
  char	*DSO_convert_filename(DSO *dso, const char *filename);
  /* This function will invoke the DSO's merger callback to merge two file
   * specifications, or if the callback isn't set it will instead use the
   * DSO_METHOD's merger.  A non-NULL return value will need to be
   * free()'d. */
  char	*DSO_merge(DSO *dso, const char *filespec1, const char *filespec2);
  /* If the DSO is currently loaded, this returns the filename that it was loaded
   * under, otherwise it returns NULL. So it is also useful as a test as to
   * whether the DSO is currently loaded. NB: This will not necessarily return
   * the same value as DSO_convert_filename(dso, dso->filename), because the
   * DSO_METHOD's load function may have tried a variety of filenames (with
   * and/or without the aid of the converters) before settling on the one it
   * actually loaded. */
  const char *DSO_get_loaded_filename(DSO *dso);
  
  void	DSO_set_default_method(DSO_METHOD *meth);
  DSO_METHOD *DSO_get_default_method(void);
  DSO_METHOD *DSO_get_method(DSO *dso);
  DSO_METHOD *DSO_set_method(DSO *dso, DSO_METHOD *meth);
  
  /* The all-singing all-dancing load function, you normally pass NULL
   * for the first and third parameters. Use DSO_up and DSO_free for
   * subsequent reference count handling. Any flags passed in will be set
   * in the constructed DSO after its init() function but before the
   * load operation. If 'dso' is non-NULL, 'flags' is ignored. */
  DSO *DSO_load(DSO *dso, const char *filename, DSO_METHOD *meth, int flags);
  
  /* This function binds to a variable inside a shared library. */
  void *DSO_bind_var(DSO *dso, const char *symname);
  
  /* This function binds to a function inside a shared library. */
  DSO_FUNC_TYPE DSO_bind_func(DSO *dso, const char *symname);
  
  /* This method is the default, but will beg, borrow, or steal whatever
   * method should be the default on any particular platform (including
   * DSO_METH_null() if necessary). */
  DSO_METHOD *DSO_METHOD_openssl(void);
  
  /* This method is defined for all platforms - if a platform has no
   * DSO support then this will be the only method! */
  DSO_METHOD *DSO_METHOD_null(void);
  
  /* If DSO_DLFCN is defined, the standard dlfcn.h-style functions
   * (dlopen, dlclose, dlsym, etc) will be used and incorporated into
   * this method. If not, this method will return NULL. */
  DSO_METHOD *DSO_METHOD_dlfcn(void);
  
  /* This function writes null-terminated pathname of DSO module
   * containing 'addr' into 'sz' large caller-provided 'path' and
   * returns the number of characters [including trailing zero]
   * written to it. If 'sz' is 0 or negative, 'path' is ignored and
   * required amount of charachers [including trailing zero] to
   * accomodate pathname is returned. If 'addr' is NULL, then
   * pathname of cryptolib itself is returned. Negative or zero
   * return value denotes error.
   */
  int DSO_pathbyaddr(void *addr, char *path, int sz);
  
  /* This function should be used with caution! It looks up symbols in
   * *all* loaded modules and if module gets unloaded by somebody else
   * attempt to dereference the pointer is doomed to have fatal
   * consequences. Primary usage for this function is to probe *core*
   * system functionality, e.g. check if getnameinfo(3) is available
   * at run-time without bothering about OS-specific details such as
   * libc.so.versioning or where does it actually reside: in libc
   * itself or libsocket. */
  void *DSO_global_lookup(const char *name);
  
  /* BEGIN ERROR CODES */
  /* The following lines are auto generated by the script mkerr.pl. Any changes
   * made after this point may be overwritten when the script is next run.
   */
  void ERR_load_DSO_strings(void);
  
  /* Error codes for the DSO functions. */
  
  /* Function codes. */
  #define DSO_F_BEOS_BIND_FUNC				 144
  #define DSO_F_BEOS_BIND_VAR				 145
  #define DSO_F_BEOS_LOAD					 146
  #define DSO_F_BEOS_NAME_CONVERTER			 147
  #define DSO_F_BEOS_UNLOAD				 148
  #define DSO_F_DLFCN_BIND_FUNC				 100
  #define DSO_F_DLFCN_BIND_VAR				 101
  #define DSO_F_DLFCN_LOAD				 102
  #define DSO_F_DLFCN_MERGER				 130
  #define DSO_F_DLFCN_NAME_CONVERTER			 123
  #define DSO_F_DLFCN_UNLOAD				 103
  #define DSO_F_DL_BIND_FUNC				 104
  #define DSO_F_DL_BIND_VAR				 105
  #define DSO_F_DL_LOAD					 106
  #define DSO_F_DL_MERGER					 131
  #define DSO_F_DL_NAME_CONVERTER				 124
  #define DSO_F_DL_UNLOAD					 107
  #define DSO_F_DSO_BIND_FUNC				 108
  #define DSO_F_DSO_BIND_VAR				 109
  #define DSO_F_DSO_CONVERT_FILENAME			 126
  #define DSO_F_DSO_CTRL					 110
  #define DSO_F_DSO_FREE					 111
  #define DSO_F_DSO_GET_FILENAME				 127
  #define DSO_F_DSO_GET_LOADED_FILENAME			 128
  #define DSO_F_DSO_GLOBAL_LOOKUP				 139
  #define DSO_F_DSO_LOAD					 112
  #define DSO_F_DSO_MERGE					 132
  #define DSO_F_DSO_NEW_METHOD				 113
  #define DSO_F_DSO_PATHBYADDR				 140
  #define DSO_F_DSO_SET_FILENAME				 129
  #define DSO_F_DSO_SET_NAME_CONVERTER			 122
  #define DSO_F_DSO_UP_REF				 114
  #define DSO_F_GLOBAL_LOOKUP_FUNC			 138
  #define DSO_F_PATHBYADDR				 137
  #define DSO_F_VMS_BIND_SYM				 115
  #define DSO_F_VMS_LOAD					 116
  #define DSO_F_VMS_MERGER				 133
  #define DSO_F_VMS_UNLOAD				 117
  #define DSO_F_WIN32_BIND_FUNC				 118
  #define DSO_F_WIN32_BIND_VAR				 119
  #define DSO_F_WIN32_GLOBALLOOKUP			 142
  #define DSO_F_WIN32_GLOBALLOOKUP_FUNC			 143
  #define DSO_F_WIN32_JOINER				 135
  #define DSO_F_WIN32_LOAD				 120
  #define DSO_F_WIN32_MERGER				 134
  #define DSO_F_WIN32_NAME_CONVERTER			 125
  #define DSO_F_WIN32_PATHBYADDR				 141
  #define DSO_F_WIN32_SPLITTER				 136
  #define DSO_F_WIN32_UNLOAD				 121
  
  /* Reason codes. */
  #define DSO_R_CTRL_FAILED				 100
  #define DSO_R_DSO_ALREADY_LOADED			 110
  #define DSO_R_EMPTY_FILE_STRUCTURE			 113
  #define DSO_R_FAILURE					 114
  #define DSO_R_FILENAME_TOO_BIG				 101
  #define DSO_R_FINISH_FAILED				 102
  #define DSO_R_INCORRECT_FILE_SYNTAX			 115
  #define DSO_R_LOAD_FAILED				 103
  #define DSO_R_NAME_TRANSLATION_FAILED			 109
  #define DSO_R_NO_FILENAME				 111
  #define DSO_R_NO_FILE_SPECIFICATION			 116
  #define DSO_R_NULL_HANDLE				 104
  #define DSO_R_SET_FILENAME_FAILED			 112
  #define DSO_R_STACK_ERROR				 105
  #define DSO_R_SYM_FAILURE				 106
  #define DSO_R_UNLOAD_FAILED				 107
  #define DSO_R_UNSUPPORTED				 108
  
  #ifdef  __cplusplus
  }
  #endif
  #endif
  