gecko-dev/nsprpub/pr/include/prlink.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * The contents of this file are subject to the Netscape Public License
 * Version 1.1 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 * 
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 * 
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

#ifndef prlink_h___
#define prlink_h___

/*
** API to static and dynamic linking.
*/
#include "prtypes.h"

PR_BEGIN_EXTERN_C

typedef struct PRLibrary PRLibrary;

typedef struct PRStaticLinkTable {
    const char *name;
    void (*fp)();
} PRStaticLinkTable;

/*
** Change the default library path to the given string. The string is
** copied. This call will fail if it runs out of memory.
**
** The string provided as 'path' is copied. The caller can do whatever is
** convenient with the argument when the function is complete.
*/
NSPR_API(PRStatus) PR_SetLibraryPath(const char *path);

/*
** Return a character string which contains the path used to search for
** dynamically loadable libraries.
**
** The returned value is basically a copy of a PR_SetLibraryPath().
** The storage is allocated by the runtime and becomes the responsibilty
** of the caller.
*/
NSPR_API(char*) PR_GetLibraryPath(void);

/*
** Given a directory name "dir" and a library name "lib" construct a full
** path name that will refer to the actual dynamically loaded
** library. This does not test for existance of said file, it just
** constructs the full filename. The name constructed is system dependent
** and prepared for PR_LoadLibrary. The result must be free'd when the
** caller is done with it.
**
** The storage for the result is allocated by the runtime and becomes the
** responsibility of the caller.
*/
NSPR_API(char*) PR_GetLibraryName(const char *dir, const char *lib);

/*
**
** Free the memory allocated, for the caller, by PR_GetLibraryName
*/
NSPR_API(void) PR_FreeLibraryName(char *mem);

/*
** Given a library "name" try to load the library. The argument "name"
** is a machine-dependent name for the library, such as the full pathname
** returned by PR_GetLibraryName.  If the library is already loaded,
** this function will avoid loading the library twice.
**
** If the library is loaded successfully, then a pointer to the PRLibrary
** structure representing the library is returned.  Otherwise, NULL is
** returned.
**
** This increments the reference count of the library.
*/
NSPR_API(PRLibrary*) PR_LoadLibrary(const char *name);

/*
** Each operating system has its preferred way of specifying
** a file in the file system.  Most operating systems use
** a pathname.  Mac OS, on the other hand, uses the FSSpec
** structure to specify a file. PRLibSpec allows NSPR clients
** to use the type of file specification that is most efficient
** for a particular platform.
**
** On some operating systems such as Mac OS, a shared library may
** contain code fragments that can be individually loaded.
** PRLibSpec also allows NSPR clients to identify a code fragment
** in a library, if code fragments are supported by the OS.
** A code fragment can be specified by name or by an integer index.
**
** Right now PRLibSpec supports three types of library specification:
** a pathname, a Mac code fragment by name, and a Mac code fragment
** by index.
*/

typedef enum PRLibSpecType {
    PR_LibSpec_Pathname,
    PR_LibSpec_MacNamedFragment,
    PR_LibSpec_MacIndexedFragment
} PRLibSpecType;

struct FSSpec; /* Mac OS FSSpec */

typedef struct PRLibSpec {
    PRLibSpecType type;
    union {
        /* if type is PR_LibSpec_Pathname */
        const char *pathname;

        /* if type is PR_LibSpec_MacNamedFragment */
        struct {
            const struct FSSpec *fsspec;
            const char *name;
        } mac_named_fragment;

        /* if type is PR_LibSpec_MacIndexedFragment */
        struct {
            const struct FSSpec *fsspec;
            PRUint32 index;
        } mac_indexed_fragment;
    } value;
} PRLibSpec;

/*
** The following bit flags may be or'd together and passed
** as the 'flags' argument to PR_LoadLibraryWithFlags.
** Flags not supported by the underlying OS are ignored.
*/

#define PR_LD_LAZY   0x1  /* equivalent to RTLD_LAZY on Unix */
#define PR_LD_NOW    0x2  /* equivalent to RTLD_NOW on Unix */
#define PR_LD_GLOBAL 0x4  /* equivalent to RTLD_GLOBAL on Unix */
#define PR_LD_LOCAL  0x8  /* equivalent to RTLD_LOCAL on Unix */

/*
** Load the specified library, in the manner specified by 'flags'.
*/

NSPR_API(PRLibrary *)
PR_LoadLibraryWithFlags(
    PRLibSpec libSpec,    /* the shared library */
    PRIntn flags          /* flags that affect the loading */
);

/*
** Unload a previously loaded library. If the library was a static
** library then the static link table will no longer be referenced. The
** associated PRLibrary object is freed.
**
** PR_FAILURE is returned if the library cannot be unloaded.
**
** This function decrements the reference count of the library.
*/
NSPR_API(PRStatus) PR_UnloadLibrary(PRLibrary *lib);

/*
** Given the name of a procedure, return the address of the function that
** implements the procedure, or NULL if no such function can be
** found. This does not find symbols in the main program (the ".exe");
** use PR_LoadStaticLibrary to register symbols in the main program.
**
** This function does not modify the reference count of the library.
*/
NSPR_API(void*) PR_FindSymbol(PRLibrary *lib, const char *name);

/*
** Similar to PR_FindSymbol, except that the return value is a pointer to
** a function, and not a pointer to void. Casting between a data pointer
** and a function pointer is not portable according to the C standard.
** Any function pointer can be cast to any other function pointer.
**
** This function does not modify the reference count of the library.
*/
typedef void (*PRFuncPtr)();
NSPR_API(PRFuncPtr) PR_FindFunctionSymbol(PRLibrary *lib, const char *name);

/*
** Finds a symbol in one of the currently loaded libraries. Given the
** name of a procedure, return the address of the function that
** implements the procedure, and return the library that contains that
** symbol, or NULL if no such function can be found. This does not find
** symbols in the main program (the ".exe"); use PR_AddStaticLibrary to
** register symbols in the main program.  
**
** This increments the reference count of the library.
*/
NSPR_API(void*) PR_FindSymbolAndLibrary(const char *name,
						      PRLibrary* *lib);

/*
** Similar to PR_FindSymbolAndLibrary, except that the return value is
** a pointer to a function, and not a pointer to void. Casting between a
** data pointer and a function pointer is not portable according to the C
** standard. Any function pointer can be cast to any other function pointer.
**
** This increments the reference count of the library.
*/
NSPR_API(PRFuncPtr) PR_FindFunctionSymbolAndLibrary(const char *name,
						      PRLibrary* *lib);

/*
** Register a static link table with the runtime under the name
** "name". The symbols present in the static link table will be made
** available to PR_FindSymbol. If "name" is null then the symbols will be
** made available to the library which represents the executable. The
** tables are not copied.
**
** Returns the library object if successful, null otherwise.
**
** This increments the reference count of the library.
*/
NSPR_API(PRLibrary*) PR_LoadStaticLibrary(
    const char *name, const PRStaticLinkTable *table);

PR_END_EXTERN_C

#endif /* prlink_h___ */