sdl_dlcompat.c

SDL库 在进行视频显示程序spcaview安装时必须的库文件

	struct dlstatus *dls = stqueue;
	while (dls && status != dls)
		dls = dls->next;
	if (dls == 0)
		error("invalid handle");
	else if ((dls->module == 0) || (dls->refs == 0))
		error("handle to closed library");
	else
		return TRUE;
	return FALSE;
}

static inline int isFlagSet(int mode, int flag)
{
	return (mode & flag) == flag;
}

static struct dlstatus *lookupStatus(const struct stat *sbuf)
{
	struct dlstatus *dls = stqueue;
	debug("looking for status");
	while (dls && ( /* isFlagSet(dls->mode, RTLD_UNSHARED) */ 0
				   || sbuf->st_dev != dls->device || sbuf->st_ino != dls->inode))
		dls = dls->next;
	return dls;
}

static void insertStatus(struct dlstatus *dls, const struct stat *sbuf)
{
	debug("inserting status");
	dls->inode = sbuf->st_ino;
	dls->device = sbuf->st_dev;
	dls->refs = 0;
	dls->mode = 0;
	if ((dls->flags & DL_IN_LIST) == 0)
	{
		dls->next = stqueue;
		stqueue = dls;
		dls->flags |= DL_IN_LIST;
	}
}

static struct dlstatus *allocStatus()
{
	struct dlstatus *dls;
#ifdef REUSE_STATUS
	dls = stqueue;
	while (dls && dls->module)
		dls = dls->next;
	if (!dls)
#endif
		dls = SDL_calloc(sizeof(*dls),1);
	return dls;
}

static int promoteLocalToGlobal(struct dlstatus *dls)
{
	static int (*p) (NSModule module) = 0;
	debug("promoting");
	if (!p)
		_dyld_func_lookup("__dyld_NSMakePrivateModulePublic", (void **)&p);
	return (dls->module == MAGIC_DYLIB_MOD) || (p && p(dls->module));
}

static void *reference(struct dlstatus *dls, int mode)
{
	if (dls)
	{
		if (dls->module == MAGIC_DYLIB_MOD && isFlagSet(mode, RTLD_LOCAL))
		{
			warning("trying to open a .dylib with RTLD_LOCAL");
			error("unable to open a .dylib with RTLD_LOCAL");
			return NULL;
		}
		if (isFlagSet(mode, RTLD_GLOBAL) &&
			!isFlagSet(dls->mode, RTLD_GLOBAL) && !promoteLocalToGlobal(dls))
		{
			error("unable to promote local module to global");
			return NULL;
		}
		dls->mode |= mode;
		dls->refs++;
	}
	else
		debug("reference called with NULL argument");

	return dls;
}

static const struct mach_header *my_find_image(const char *name)
{
	const struct mach_header *mh = 0;
	const char *id = NULL;
	int i = _dyld_image_count();
	int j;
	mh = (struct mach_header *)
		dyld_NSAddImage(name, NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED |
						NSADDIMAGE_OPTION_RETURN_ON_ERROR);
	if (!mh)
	{
		for (j = 0; j < i; j++)
		{
			id = _dyld_get_image_name(j);
			if (!SDL_strcmp(id, name))
			{
				mh = _dyld_get_image_header(j);
				break;
			}
		}
	}
	return mh;
}

/*
 * dyld adds libraries by first adding the directly dependant libraries in link order, and
 * then adding the dependencies for those libraries, so we should do the same... but we don't
 * bother adding the extra dependencies, if the symbols are neither in the loaded image nor
 * any of it's direct dependencies, then it probably isn't there.
 */
static NSSymbol search_linked_libs(const struct mach_header * mh, const char *symbol)
{
	unsigned int n;
	struct load_command *lc = 0;
	struct mach_header *wh;
	NSSymbol nssym = 0;
	if (dyld_NSAddImage && dyld_NSIsSymbolNameDefinedInImage && dyld_NSLookupSymbolInImage)
	{
		lc = (struct load_command *)((char *)mh + sizeof(struct mach_header));
		for (n = 0; n < mh->ncmds; n++, lc = (struct load_command *)((char *)lc + lc->cmdsize))
		{
			if ((LC_LOAD_DYLIB == lc->cmd) || (LC_LOAD_WEAK_DYLIB == lc->cmd))
			{
				if ((wh = (struct mach_header *)
					 my_find_image((char *)(((struct dylib_command *)lc)->dylib.name.offset +
											(char *)lc))))
				{
					if (dyld_NSIsSymbolNameDefinedInImage(wh, symbol))
					{
						nssym = dyld_NSLookupSymbolInImage(wh,
														   symbol,
														   NSLOOKUPSYMBOLINIMAGE_OPTION_BIND |
														   NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR);
						break;
					}
				}
			}
		}
		if ((!nssym) && NSIsSymbolNameDefined(symbol))
		{
			/* I've never seen this debug message...*/
			debug("Symbol \"%s\" is defined but was not found", symbol);
		}
	}
	return nssym;
}

/* Up to the caller to SDL_free() returned string */
static inline char *dyld_error_str()
{
	NSLinkEditErrors dylder;
	int dylderno;
	const char *dylderrstr;
	const char *dyldfile;
	char* retStr = NULL;
	NSLinkEditError(&dylder, &dylderno, &dyldfile, &dylderrstr);
	if (dylderrstr && *dylderrstr)
	{
		retStr = SDL_strdup(dylderrstr);
	}
	return retStr;
}

static void *dlsymIntern(struct dlstatus *dls, const char *symbol, int canSetError)
{
  NSSymbol nssym = 0;
#ifdef __GCC__  
	void *caller = __builtin_return_address(1);	/* Be *very* careful about inlining */
#else
	void *caller = NULL;
#endif
	const struct mach_header *caller_mh = 0;
	char *savedErrorStr = NULL;
	resetdlerror();
#ifndef RTLD_SELF
#define	RTLD_SELF		((void *) -3)
#endif
	if (NULL == dls)
		dls = RTLD_SELF;
	if ((RTLD_NEXT == dls) || (RTLD_SELF == dls))
	{
		if (dyld_NSIsSymbolNameDefinedInImage && dyld_NSLookupSymbolInImage && caller)
		  {
			caller_mh = image_for_address(caller);
			if (RTLD_SELF == dls)
			{
				/* FIXME: We should be using the NSModule api, if SELF is an MH_BUNDLE
				 * But it appears to work anyway, and looking at the code in dyld_libfuncs.c
				 * this is acceptable.
				 */
				if (dyld_NSIsSymbolNameDefinedInImage(caller_mh, symbol))
				{
					nssym = dyld_NSLookupSymbolInImage(caller_mh,
													   symbol,
													   NSLOOKUPSYMBOLINIMAGE_OPTION_BIND |
													   NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR);
				}
			}
			if (!nssym)
			{
				if (RTLD_SELF == dls)
					savedErrorStr = dyld_error_str();
				nssym = search_linked_libs(caller_mh, symbol);
			}
		}
		else
		{
			if (canSetError)
				error("RTLD_SELF and RTLD_NEXT are not supported");
			return NULL;
		}
	}
	if (!nssym)
	{

		if (RTLD_DEFAULT == dls)
		{
			dls = &mainStatus;
		}
		if (!isValidStatus(dls))
			return NULL;

		if (dls->module != MAGIC_DYLIB_MOD)
		{
			nssym = NSLookupSymbolInModule(dls->module, symbol);
			if (!nssym && NSIsSymbolNameDefined(symbol))
			{
				debug("Searching dependencies");
				savedErrorStr = dyld_error_str();
				nssym = search_linked_libs(get_mach_header_from_NSModule(dls->module), symbol);
			}
		}
		else if (dls->lib && dyld_NSIsSymbolNameDefinedInImage && dyld_NSLookupSymbolInImage)
		{
			if (dyld_NSIsSymbolNameDefinedInImage(dls->lib, symbol))
			{
				nssym = dyld_NSLookupSymbolInImage(dls->lib,
												   symbol,
												   NSLOOKUPSYMBOLINIMAGE_OPTION_BIND |
												   NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR);
			}
			else if (NSIsSymbolNameDefined(symbol))
			{
				debug("Searching dependencies");
				savedErrorStr = dyld_error_str();
				nssym = search_linked_libs(dls->lib, symbol);
			}
		}
		else if (dls->module == MAGIC_DYLIB_MOD)
		{
			/* Global context, use NSLookupAndBindSymbol */
			if (NSIsSymbolNameDefined(symbol))
			{
				/* There doesn't seem to be a return on error option for this call???
				   this is potentially broken, if binding fails, it will improperly
				   exit the application. */
				nssym = NSLookupAndBindSymbol(symbol);
			}
			else
			{
				if (savedErrorStr)
					SDL_free(savedErrorStr);			
				savedErrorStr = SDL_malloc(256);
				SDL_snprintf(savedErrorStr, 256, "Symbol \"%s\" not in global context",symbol);	
			}
		}
	}
	/* Error reporting */
	if (!nssym)
	{
		if (!savedErrorStr || !SDL_strlen(savedErrorStr))
		{
			if (savedErrorStr)
				SDL_free(savedErrorStr);
			savedErrorStr = SDL_malloc(256);
			SDL_snprintf(savedErrorStr, 256,"Symbol \"%s\" not found",symbol);
		}
		if (canSetError)
		{
			error(savedErrorStr);
		}
		else
		{
			debug(savedErrorStr);
		}
		if (savedErrorStr)
			SDL_free(savedErrorStr);
		return NULL;
	}
	return NSAddressOfSymbol(nssym);
}

static struct dlstatus *loadModule(const char *path, const struct stat *sbuf, int mode)
{
	NSObjectFileImage ofi = 0;
	NSObjectFileImageReturnCode ofirc;
	struct dlstatus *dls;
	NSLinkEditErrors ler;
	int lerno;
	const char *errstr;
	const char *file;
	void (*init) (void);

	ofirc = NSCreateObjectFileImageFromFile(path, &ofi);
	switch (ofirc)
	{
		case NSObjectFileImageSuccess:
			break;
		case NSObjectFileImageInappropriateFile:
			if (dyld_NSAddImage && dyld_NSIsSymbolNameDefinedInImage && dyld_NSLookupSymbolInImage)
			{	
				if (isFlagSet(mode, RTLD_LOCAL))
				{
					warning("trying to open a .dylib with RTLD_LOCAL");
					error("unable to open this file with RTLD_LOCAL");
					return NULL;
				}
			}
			else
			{
				error("opening this file is unsupported on this system");
				return NULL;
			}
			break;
		case NSObjectFileImageFailure:
			error("object file setup failure");
			return NULL;
		case NSObjectFileImageArch:
			error("no object for this architecture");
			return NULL;
		case NSObjectFileImageFormat:
			error("bad object file format");
			return NULL;
		case NSObjectFileImageAccess:
			error("can't read object file");
			return NULL;
		default:
			error("unknown error from NSCreateObjectFileImageFromFile()");
			return NULL;
	}
	dls = lookupStatus(sbuf);
	if (!dls)
	{
		dls = allocStatus();
	}
	if (!dls)
	{
		error("unable to allocate memory");
		return NULL;
	}
	//	dls->lib = 0;
	if (ofirc == NSObjectFileImageInappropriateFile)
	{
		if ((dls->lib = dyld_NSAddImage(path, NSADDIMAGE_OPTION_RETURN_ON_ERROR)))
		{
			debug("Dynamic lib loaded at %ld", dls->lib);
			ofi = MAGIC_DYLIB_OFI;
			dls->module = MAGIC_DYLIB_MOD;
			ofirc = NSObjectFileImageSuccess;
			/* Although it is possible with a bit of work to modify this so it works and
			   functions with RTLD_NOW, I don't deem it necessary at the moment */
		}
		if (!(dls->module))
		{
			NSLinkEditError(&ler, &lerno, &file, &errstr);
			if (!errstr || (!SDL_strlen(errstr)))
				error("Can't open this file type");
			else
				error(errstr);
			if ((dls->flags & DL_IN_LIST) == 0)
			{
				SDL_free(dls);
			}
			return NULL;
		}
	}
	else
	{
		dls->module = NSLinkModule(ofi, path,
								   NSLINKMODULE_OPTION_RETURN_ON_ERROR |
								   NSLINKMODULE_OPTION_PRIVATE |
								   (isFlagSet(mode, RTLD_NOW) ? NSLINKMODULE_OPTION_BINDNOW : 0));
		NSDestroyObjectFileImage(ofi);
		if (dls->module)
		{
			dls->lib = get_mach_header_from_NSModule(dls->module);
		}
	}
	if (!dls->module)
	{
		NSLinkEditError(&ler, &lerno, &file, &errstr);
		if ((dls->flags & DL_IN_LIST) == 0)
		{
			SDL_free(dls);
		}
		error(errstr);
		return NULL;
	}

	insertStatus(dls, sbuf);
	dls = reference(dls, mode);
	if ((init = dlsymIntern(dls, "__init", 0)))
	{
		debug("calling _init()");
		init();
	}
	return dls;
}

inline static void dlcompat_init_check(void)
{
	static pthread_mutex_t l = PTHREAD_MUTEX_INITIALIZER;
	static int init_done = 0;

	pthread_mutex_lock(&l);
	if (!init_done) {
		dlcompat_init_func();
		init_done = 1;
	}
	pthread_mutex_unlock(&l);
}

static void dlcompat_init_func(void)
{
        _dyld_func_lookup("__dyld_NSAddImage", (void **)&dyld_NSAddImage);
	_dyld_func_lookup("__dyld_NSIsSymbolNameDefinedInImage",
			  (void **)&dyld_NSIsSymbolNameDefinedInImage);
	_dyld_func_lookup("__dyld_NSLookupSymbolInImage", (void **)&dyld_NSLookupSymbolInImage);
	if (pthread_mutex_init(&dlcompat_mutex, NULL))
	    exit(1);
	if (pthread_key_create(&dlerror_key, &dlerrorfree))
	    exit(1);
}

static void resetdlerror()
{
	struct dlthread *tss;
	tss = pthread_getspecific(dlerror_key);
	tss->errset = 0;
}

static void dlerrorfree(void *data)
{
	SDL_free(data);
}

/* We kind of want a recursive lock here, but meet a little trouble
 * because they are not available pre OS X 10.2, so we fake it
 * using thread specific storage to keep a lock count
 */ 
static inline void dolock(void)
{
	int err = 0;
	struct dlthread *tss;
	dlcompat_init_check();
	tss = pthread_getspecific(dlerror_key);
	if (!tss)
	{
		tss = SDL_malloc(sizeof(struct dlthread));
		tss->lockcnt = 0;
		tss->errset = 0;