dso.h

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/* dso.h -*- mode:C; c-file-style: "eay" -*- */
/* 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
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 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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 */

#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 overriden 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 OPENSSL_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 OPENSSL_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 OPENSSL_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);

/* I don't think this would actually be used in any circumstances. */
#if 0
   /* Unbinds a variable */
   int (*dso_unbind_var)(DSO *dso, char *symname, void *symptr);
   /* Unbinds a function */
   int (*dso_unbind_func)(DSO *dso, char *symname, DSO_FUNC_TYPE symptr);
#endif
   /* 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);
   } 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 *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 OPENSSL_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
 * OPENSSL_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);

/* If DSO_DL is defined, the standard dl.h-style functions (shl_load,
 * shl_unload, shl_findsym, etc) will be used and incorporated into
 * this method. If not, this method will return NULL. */
DSO_METHOD *DSO_METHOD_dl(void);

/* If WIN32 is defined, use DLLs. If not, return NULL. */
DSO_METHOD *DSO_METHOD_win32(void);

/* If VMS is defined, use shared images. If not, return NULL. */
DSO_METHOD *DSO_METHOD_vms(void);

/* 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_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_LOAD               112
#define DSO_F_DSO_MERGE              132
#define DSO_F_DSO_NEW_METHOD            113
#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_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_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_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