dlfcn.c

		free(malloc_sym);
	}
	else
	{
		error("Unable to allocate memory");
	}
	return value;
}

void *dlsym_auto_underscore(void *handle, const char *symbol)
{
	void *answer;
	dolock();
	answer = dlsym_auto_underscore_intern(handle, symbol);
	dounlock();
	return answer;

}
static void *dlsym_auto_underscore_intern(void *handle, const char *symbol)
{
	struct dlstatus *dls = handle;
	void *addr = 0;
	addr = dlsymIntern(dls, symbol, 0);
	if (!addr)
		addr = dlsym_prepend_underscore_intern(handle, symbol);
	return addr;
}


void *dlsym(void * dl_restrict handle, const char * dl_restrict symbol)
{
	struct dlstatus *dls = handle;
	void *addr = 0;
	dolock();
	addr = dlsymIntern(dls, symbol, 1);
	dounlock();
	return addr;
}
#endif

int dlclose(void *handle)
{
	struct dlstatus *dls = handle;
	dolock();
	resetdlerror();
	if (!isValidStatus(dls))
	{
		goto dlcloseerror;
	}
	if (dls->module == MAGIC_DYLIB_MOD)
	{
		const char *name;
		if (!dls->lib)
		{
			name = "global context";
		}
		else
		{
			name = get_lib_name(dls->lib);
		}
		warning("trying to close a .dylib!");
		error("Not closing \"%s\" - dynamic libraries cannot be closed", name);
		goto dlcloseerror;
	}
	if (!dls->module)
	{
		error("module already closed");
		goto dlcloseerror;
	}
	
	if (dls->refs == 1)
	{
		unsigned long options = 0;
		void (*fini) (void);
		if ((fini = dlsymIntern(dls, "__fini", 0)))
		{
			debug("calling _fini()");
			fini();
		}
#ifdef __ppc__
		options |= NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES;
#endif
#if 1
/*  Currently, if a module contains c++ static destructors and it is unloaded, we
 *  get a segfault in atexit(), due to compiler and dynamic loader differences of
 *  opinion, this works around that.
 *  I really need a way to figure out from code if this is still necessary.
 */
		if ((const struct section *)NULL !=
			getsectbynamefromheader(get_mach_header_from_NSModule(dls->module),
									"__DATA", "__mod_term_func"))
		{
			options |= NSUNLINKMODULE_OPTION_KEEP_MEMORY_MAPPED;
		}
#endif
#ifdef RTLD_NODELETE
		if (isFlagSet(dls->mode, RTLD_NODELETE))
			options |= NSUNLINKMODULE_OPTION_KEEP_MEMORY_MAPPED;
#endif
		if (!NSUnLinkModule(dls->module, options))
		{
			error("unable to unlink module");
			goto dlcloseerror;
		}
		dls->refs--;
		dls->module = 0;
		/* Note: the dlstatus struct dls is neither removed from the list
		 * nor is the memory it occupies freed. This shouldn't pose a 
		 * problem in mostly all cases, though.
		 */
	}
	dounlock();
	return 0;
  dlcloseerror:
	dounlock();
	return 1;
}

const char *dlerror(void)
{
	struct dlthread  *tss;
	char * err_str;
	tss = pthread_getspecific(dlerror_key);
	err_str = tss->errstr;
	tss = pthread_getspecific(dlerror_key);
	if (tss->errset == 0)
		return 0;
	tss->errset = 0;	
	return (err_str );
}

/* Given an address, return the mach_header for the image containing it
 * or zero if the given address is not contained in any loaded images.
 */
const struct mach_header *image_for_address(const void *address)
{
	unsigned long i;
	unsigned long j;
	unsigned long count = _dyld_image_count();
	struct mach_header *mh = 0;
	struct load_command *lc = 0;
	unsigned long addr = NULL;
	for (i = 0; i < count; i++)
	{
		addr = (unsigned long)address - _dyld_get_image_vmaddr_slide(i);
		mh = _dyld_get_image_header(i);
		if (mh)
		{
			lc = (struct load_command *)((char *)mh + sizeof(struct mach_header));
			for (j = 0; j < mh->ncmds; j++, lc = (struct load_command *)((char *)lc + lc->cmdsize))
			{
				if (LC_SEGMENT == lc->cmd &&
					addr >= ((struct segment_command *)lc)->vmaddr &&
					addr <
					((struct segment_command *)lc)->vmaddr + ((struct segment_command *)lc)->vmsize)
				{
					goto image_found;
				}
			}
		}
		mh = 0;
	}
  image_found:
	return mh;
}

int dladdr(const void * dl_restrict p, Dl_info * dl_restrict info)
{
/*
	FIXME: USe the routine image_for_address.
*/
	unsigned long i;
	unsigned long j;
	unsigned long count = _dyld_image_count();
	struct mach_header *mh = 0;
	struct load_command *lc = 0;
	unsigned long addr = NULL;
	unsigned long table_off = (unsigned long)0;
	int found = 0;
	if (!info)
		return 0;
	dolock();
	resetdlerror();
	info->dli_fname = 0;
	info->dli_fbase = 0;
	info->dli_sname = 0;
	info->dli_saddr = 0;
/* Some of this was swiped from code posted by Douglas Davidson <ddavidso AT apple DOT com>
 * to darwin-development AT lists DOT apple DOT com and slightly modified
 */
	for (i = 0; i < count; i++)
	{
		addr = (unsigned long)p - _dyld_get_image_vmaddr_slide(i);
		mh = _dyld_get_image_header(i);
		if (mh)
		{
			lc = (struct load_command *)((char *)mh + sizeof(struct mach_header));
			for (j = 0; j < mh->ncmds; j++, lc = (struct load_command *)((char *)lc + lc->cmdsize))
			{
				if (LC_SEGMENT == lc->cmd &&
					addr >= ((struct segment_command *)lc)->vmaddr &&
					addr <
					((struct segment_command *)lc)->vmaddr + ((struct segment_command *)lc)->vmsize)
				{
					info->dli_fname = _dyld_get_image_name(i);
					info->dli_fbase = (void *)mh;
					found = 1;
					break;
				}
			}
			if (found)
				break;
		}
	}
	if (!found)
	{
		dounlock();
		return 0;
	}
	lc = (struct load_command *)((char *)mh + sizeof(struct mach_header));
	for (j = 0; j < mh->ncmds; j++, lc = (struct load_command *)((char *)lc + lc->cmdsize))
	{
		if (LC_SEGMENT == lc->cmd)
		{
			if (!strcmp(((struct segment_command *)lc)->segname, "__LINKEDIT"))
				break;
		}
	}
	table_off =
		((unsigned long)((struct segment_command *)lc)->vmaddr) -
		((unsigned long)((struct segment_command *)lc)->fileoff) + _dyld_get_image_vmaddr_slide(i);
	debug("table off %x", table_off);

	lc = (struct load_command *)((char *)mh + sizeof(struct mach_header));
	for (j = 0; j < mh->ncmds; j++, lc = (struct load_command *)((char *)lc + lc->cmdsize))
	{
		if (LC_SYMTAB == lc->cmd)
		{

			struct nlist *symtable = (struct nlist *)(((struct symtab_command *)lc)->symoff + table_off);
			unsigned long numsyms = ((struct symtab_command *)lc)->nsyms;
			struct nlist *nearest = NULL;
			unsigned long diff = 0xffffffff;
			unsigned long strtable = (unsigned long)(((struct symtab_command *)lc)->stroff + table_off);
			debug("symtable %x", symtable);
			for (i = 0; i < numsyms; i++)
			{
				/* Ignore the following kinds of Symbols */
				if ((!symtable->n_value)	/* Undefined */
					|| (symtable->n_type >= N_PEXT)	/* Debug symbol */
					|| (!(symtable->n_type & N_EXT))	/* Local Symbol */
					)
				{
					symtable++;
					continue;
				}
				if ((addr >= symtable->n_value) && (diff >= (symtable->n_value - addr)))
				{
					diff = (unsigned long)symtable->n_value - addr;
					nearest = symtable;
				}
				symtable++;
			}
			if (nearest)
			{
				info->dli_saddr = nearest->n_value + ((void *)p - addr);
				info->dli_sname = (char *)(strtable + nearest->n_un.n_strx);
			}
		}
	}
	dounlock();
	return 1;
}


/*
 * Implement the dlfunc() interface, which behaves exactly the same as
 * dlsym() except that it returns a function pointer instead of a data
 * pointer.  This can be used by applications to avoid compiler warnings
 * about undefined behavior, and is intended as prior art for future
 * POSIX standardization.  This function requires that all pointer types
 * have the same representation, which is true on all platforms FreeBSD
 * runs on, but is not guaranteed by the C standard.
 */
#if 0 
dlfunc_t dlfunc(void * dl_restrict handle, const char * dl_restrict symbol)
{
	union
	{
		void *d;
		dlfunc_t f;
	} rv;
	int sym_len = strlen(symbol);
	char *malloc_sym = NULL;
	dolock();
	malloc_sym = malloc(sym_len + 2);
	if (malloc_sym)
	{
		sprintf(malloc_sym, "_%s", symbol);
		rv.d = dlsymIntern(handle, malloc_sym, 1);
		free(malloc_sym);
	}
	else
	{
		error("Unable to allocate memory");
		goto dlfuncerror;
	}
	dounlock();
	return rv.f;
  dlfuncerror:
	dounlock();
	return NULL;
}
#endif