libtool/libltdl/loader-dyld.c

/* loader-dyld.c -- dynamic linking on darwin and OS X
   Copyright (C) 1998, 1999, 2000, 2004 Free Software Foundation, Inc.
   Originally by Thomas Tanner <tanner@ffii.org>

   NOTE: The canonical source of this file is maintained with the
   GNU Libtool package.  Report bugs to bug-libtool@gnu.org.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

As a special exception to the GNU Lesser General Public License,
if you distribute this file as part of a program or library that
is built using GNU libtool, you may include it under the same
distribution terms that you use for the rest of that program.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307  USA

*/

#include "lt__private.h"
#include "lt_dlloader.h"

#if defined(HAVE_MACH_O_DYLD_H)
#  if !defined(__APPLE_CC__) && !defined(__MWERKS__) && !defined(__private_extern__)
  /* Is this correct? Does it still function properly? */
#    define __private_extern__ extern
#  endif
#  include <mach-o/dyld.h>
#endif

#include <mach-o/getsect.h>

/* We have to put some stuff here that isn't in older dyld.h files */
#if !defined(ENUM_DYLD_BOOL)
# define ENUM_DYLD_BOOL
# undef FALSE
# undef TRUE
 enum DYLD_BOOL {
    FALSE,
    TRUE
 };
#endif
#if !defined(LC_REQ_DYLD)
# define LC_REQ_DYLD 0x80000000
#endif
#if !defined(LC_LOAD_WEAK_DYLIB)
# define LC_LOAD_WEAK_DYLIB (0x18 | LC_REQ_DYLD)
#endif

typedef struct mach_header mach_header;
typedef struct dylib_command dylib_command;

static const mach_header *(*lt__addimage)	(const char *image_name,
						 unsigned long options) = 0;
static NSSymbol	(*lt__image_symbol)		(const mach_header *image,
						 const char *symbolName,
						 unsigned long options) = 0;
static enum DYLD_BOOL (*lt__image_symbol_p)	(const mach_header *image,
						 const char *symbolName) = 0;
static enum DYLD_BOOL (*lt__module_export)	(NSModule module) = 0;

static int dyld_cannot_close				= 0;

#if !defined(NSADDIMAGE_OPTION_NONE)
#  define NSADDIMAGE_OPTION_NONE                          0x0
#endif
#if !defined(NSADDIMAGE_OPTION_RETURN_ON_ERROR)
#  define NSADDIMAGE_OPTION_RETURN_ON_ERROR               0x1
#endif
#if !defined(NSADDIMAGE_OPTION_WITH_SEARCHING)
#  define NSADDIMAGE_OPTION_WITH_SEARCHING                0x2
#endif
#if !defined(NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED)
#  define NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED         0x4
#endif
#if !defined(NSADDIMAGE_OPTION_MATCH_FILENAME_BY_INSTALLNAME)
#  define NSADDIMAGE_OPTION_MATCH_FILENAME_BY_INSTALLNAME 0x8
#endif

#if !defined(NSLOOKUPSYMBOLINIMAGE_OPTION_BIND)
#  define NSLOOKUPSYMBOLINIMAGE_OPTION_BIND               0x0
#endif
#if !defined(NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_NOW)
#  define NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_NOW           0x1
#endif
#if !defined(NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_FULLY)
#  define NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_FULLY         0x2
#endif
#if !defined(NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR)
#  define NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR    0x4
#endif

#define LT__SYMLOOKUP_OPTS	(NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_NOW \
				| NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR)

#if defined(__BIG_ENDIAN__)
#  define LT__MAGIC	MH_MAGIC
#else
#  define LT__MAGIC	MH_CIGAM
#endif

#define DYLD__MUTEX_SETERROR(errorcode) \
	LT__MUTEX_SETERRORSTR (lt__dylderror (errorcode))

/* Return the dyld error string, or the passed in error string if none. */
static const char *
lt__dylderror (int errnum)
{
  NSLinkEditErrors ler;
  int lerno;
  const char *file;
  const char *errstr;

  NSLinkEditError (&ler, &lerno, &file, &errstr);

  if (! (errstr && *errstr))
    {
      errstr = LT__STRERROR (errnum);
    }

  return errstr;
}

/* There should probably be an apple dyld api for this. */
static const mach_header *
lt__nsmodule_get_header (NSModule module)
{
  int i = _dyld_image_count();
  const char *modname = NSNameOfModule (module);
  const mach_header *mh = 0;

  if (!modname)
    return NULL;

  while (i > 0)
    {
      --i;
      if (strcmp (_dyld_get_image_name (i), modname) != 0)
	{
	  mh = _dyld_get_image_header (i);
	  break;
	}
    }

  return mh;
}

/* NSAddImage is also used to get the loaded image, but it only works if
   the lib is installed, for uninstalled libs we need to check the
   install_names against each other.  Note that this is still broken if
   DYLD_IMAGE_SUFFIX is set and a different lib was loaded as a result.  */
static const char *
lt__header_get_instnam (const mach_header *mh)
{
  unsigned long offset = sizeof(mach_header);
  const char* result   = 0;
  int j;

  for (j = 0; j < mh->ncmds; j++)
    {
      struct load_command *lc;

      lc = (struct load_command*) (((unsigned long) mh) + offset);
      if (LC_ID_DYLIB == lc->cmd)
	{
	  result=(char*)(((dylib_command*) lc)->dylib.name.offset +
			 (unsigned long) lc);
	}
      offset += lc->cmdsize;
    }

  return result;
}

static const mach_header *
lt__match_loadedlib (const char *name)
{
  const mach_header *mh	= 0;
  int i = _dyld_image_count();

  while (i > 0)
    {
      const char *id;

      --i;
      id = lt__header_get_instnam (_dyld_get_image_header (i));
      if (id && (strcmp (id, name) != 0))
	{
	  mh = _dyld_get_image_header (i);
	  break;
	}
    }

  return mh;
}

/* Safe to assume our mh is good. */
static NSSymbol
lt__linkedlib_symbol (const char *symname, const mach_header *mh)
{
  NSSymbol symbol = 0;

  if (lt__image_symbol && NSIsSymbolNameDefined (symname))
    {
      unsigned long offset = sizeof(mach_header);
      struct load_command *lc;
      int j;

      for (j = 0; j < mh->ncmds; j++)
	{
	  lc = (struct load_command*) (((unsigned long) mh) + offset);
	  if ((LC_LOAD_DYLIB == lc->cmd) || (LC_LOAD_WEAK_DYLIB == lc->cmd))
	    {
	      unsigned long base = ((dylib_command *) lc)->dylib.name.offset;
	      char *name = (char *) (base + (unsigned long) lc);
	      const mach_header *mh1 = lt__match_loadedlib (name);

	      if (!mh1)
		{
		  /* Maybe NSAddImage can find it */
		  mh1 = lt__addimage (name,
				      NSADDIMAGE_OPTION_RETURN_ONLY_IF_LOADED
				      | NSADDIMAGE_OPTION_WITH_SEARCHING
				      | NSADDIMAGE_OPTION_RETURN_ON_ERROR);
		}

	      if (mh1)
		{
		  symbol = lt__image_symbol (mh1, symname, LT__SYMLOOKUP_OPTS);
		  if (symbol)
		    break;
		}
	    }

	  offset += lc->cmdsize;
	}
    }

  return symbol;
}

int
lt__sys_dyld_init (void)
{
  int errors = 0;

  LT__MUTEX_LOCK ();

  if (! dyld_cannot_close)
    {
      if (!_dyld_present ())
	{
	  ++errors;
	}
      else
	{
	  (void) _dyld_func_lookup ("__dyld_NSAddImage",
				    (unsigned long*) &lt__addimage);
	  (void) _dyld_func_lookup ("__dyld_NSLookupSymbolInImage",
				    (unsigned long*)&lt__image_symbol);
	  (void) _dyld_func_lookup ("__dyld_NSIsSymbolNameDefinedInImage",
				    (unsigned long*) &lt__image_symbol_p);
	  (void) _dyld_func_lookup ("__dyld_NSMakePrivateModulePublic",
				    (unsigned long*) &lt__module_export);
	  dyld_cannot_close = lt_dladderror ("can't close a dylib");
	}
    }

  LT__MUTEX_UNLOCK ();

  return errors;
}

static lt_module
sys_dyld_open (lt_user_data loader_data, const char *filename)
{
  lt_module module = 0;
  NSObjectFileImage ofi = 0;

  if (!filename)
    {
      return (lt_module) -1;
    }

  switch (NSCreateObjectFileImageFromFile (filename, &ofi))
    {
    case NSObjectFileImageSuccess:
      module = NSLinkModule (ofi, filename, NSLINKMODULE_OPTION_RETURN_ON_ERROR
			     		    | NSLINKMODULE_OPTION_PRIVATE
			     		    | NSLINKMODULE_OPTION_BINDNOW);
      NSDestroyObjectFileImage (ofi);

      if (module)
	{
	  lt__module_export (module);
	}
      break;

    case NSObjectFileImageInappropriateFile:
      if (lt__image_symbol_p && lt__image_symbol)
	{
	  module = (lt_module) lt__addimage(filename,
					    NSADDIMAGE_OPTION_RETURN_ON_ERROR);
	}
      break;
    }

  if (!module)
    {
      DYLD__MUTEX_SETERROR (CANNOT_OPEN);
    }

  return module;
}

static int
sys_dyld_close (lt_user_data loader_data, lt_module module)
{
  int errors = 0;

  if (module != (lt_module) -1)
    {
      const mach_header *mh = (const mach_header *) module;
      int flags = 0;
      if (mh->magic == LT__MAGIC)
	{
	  DYLD__MUTEX_SETERROR(dyld_cannot_close);
	  ++errors;
	}
      else
	{
	  /* 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.  */
	  if ((const struct section *) NULL !=
	      getsectbynamefromheader (lt__nsmodule_get_header (module),
				       "__DATA", "__mod_term_func"))
	    {
	      flags |= NSUNLINKMODULE_OPTION_KEEP_MEMORY_MAPPED;
	    }
#if defined(__ppc__)
	  flags |= NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES;
#endif
	  if (!NSUnLinkModule (module, flags))
	    {
	      DYLD__MUTEX_SETERRORSTR (CANNOT_CLOSE);
	      ++errors;
	    }
	}
    }

  return errors;
}

static void *
sys_dyld_sym (lt_user_data loader_data, lt_module module, const char *symbol)
{
  NSSymbol *nssym = 0;
  mach_header *mh = (mach_header *) module;
  char saveError[256] = "Symbol not found";

  if (module == (lt_module)-1)
    {
      void *address, *unused;
      _dyld_lookup_and_bind(symbol, (unsigned long*) &address, &unused);
      return address;
    }

  if (mh->magic == LT__MAGIC)
    {
      if (lt__image_symbol_p && lt__image_symbol)
	{
	  if (lt__image_symbol_p (mh, symbol))
	    {
	      nssym = lt__image_symbol (mh, symbol, LT__SYMLOOKUP_OPTS);
	    }
	}

    }
  else
    {
      nssym = NSLookupSymbolInModule (module, symbol);
    }

  if (!nssym)
    {
      strncpy (saveError, lt__dylderror (SYMBOL_NOT_FOUND), 255);
      saveError[255] = 0;
      if (!mh)
	{
	  mh = lt__nsmodule_get_header (module);
	}
      nssym = lt__linkedlib_symbol (symbol, mh);
    }

  if (!nssym)
    {
      LT__MUTEX_SETERRORSTR (saveError);
    }

  return nssym ? NSAddressOfSymbol (nssym) : 0;
}

struct lt_user_dlloader lt__sys_dyld =
  { "_", sys_dyld_open, sys_dyld_close, sys_dyld_sym, 0, 0 };