crt.c   [plain text]

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.1 (the "License").  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * The common startup code.  This code is ifdef'ed with the 'C' preprocessor
 * macros CRT0, CRT1, GCRT and POSTSCRIPT.  It is used to create
 * the following files when compiled with the following macros defined:
 *
 *  File      Dedined Macros	   Purpose
 * crt1.o	CRT1		 startup for programs compiled -dynamic
 * gcrt1.o	CRT1, GCRT	 profiling startup, programs compiled -dynamic
 *
 * pscrt1.o	CRT1, POSTSCRIPT startup for postscript compiled -dynamic
 * crt0.o	CRT0		 startup for programs compiled -static 
 * gcrt0.o	CRT0, GCRT	 profiling startup for programs compiled -static
 * pscrt0.o	CRT0, POSTSCRIPT startup for postscript compiled -static
 * 
 * Starting in 5.0, Rhapsody, the first two files are to be placed in /lib the
 * others in /usr/local/lib.
 */

/*
 * Global data definitions (initialized data).
 */
int NXArgc = 0;
char **NXArgv = (char **)0;
char **environ = (char **)0;
char *__progname = "";
#if defined(CRT1)
/*
 * The following symbols are reference by System Framework symbolicly (instead
 * of through undefined references (to allow prebinding). To get strip(1) to
 * know these symbols are not to be stripped they need to have the
 * REFERENCED_DYNAMICALLY bit (0x10) set.  This would have been done automaticly
 * by ld(1) if these symbols were referenced through undefined symbols.
 * The catch_exception_raise symbol is special in that the Mach API specifically
 * requires that the library call into the user program for its implementation.
 * Therefore, we need to create a common definition and make sure the symbol
 * doesn't get stripped.
 */
asm(".desc _NXArgc, 0x10");
asm(".desc _NXArgv, 0x10");
asm(".desc _environ, 0x10");
asm(".desc __mh_execute_header, 0x10");
#if !defined(__ppc64__)
asm(".comm _catch_exception_raise, 4");
asm(".desc _catch_exception_raise, 0x10");
asm(".comm _catch_exception_raise_state, 4");
asm(".desc _catch_exception_raise_state, 0x10");
asm(".comm _catch_exception_raise_state_identity, 4");
asm(".desc _catch_exception_raise_state_identity, 0x10");
asm(".comm _do_mach_notify_dead_name, 4");
asm(".desc _do_mach_notify_dead_name, 0x10");
asm(".comm _do_seqnos_mach_notify_dead_name, 4");
asm(".desc _do_seqnos_mach_notify_dead_name, 0x10");
asm(".comm _do_mach_notify_no_senders, 4");
asm(".desc _do_mach_notify_no_senders, 0x10");
asm(".comm _do_seqnos_mach_notify_no_senders, 4");
asm(".desc _do_seqnos_mach_notify_no_senders, 0x10");
asm(".comm _do_mach_notify_port_deleted, 4");
asm(".desc _do_mach_notify_port_deleted, 0x10");
asm(".comm _do_seqnos_mach_notify_port_deleted, 4");
asm(".desc _do_seqnos_mach_notify_port_deleted, 0x10");
asm(".comm _do_mach_notify_send_once, 4");
asm(".desc _do_mach_notify_send_once, 0x10");
asm(".comm _do_seqnos_mach_notify_send_once, 4");
asm(".desc _do_seqnos_mach_notify_send_once, 0x10");
asm(".comm _clock_alarm_reply, 4");
asm(".desc _clock_alarm_reply, 0x10");
asm(".comm _receive_samples, 4");
asm(".desc _receive_samples, 0x10");
#endif /* --ppc64__ */
asm(".desc ___progname, 0x10");
#endif /* CRT1 */

/*
 * Common data definitions.  If the routines in System Framework are not pulled
 * into the executable then the static linker will allocate these as common
 * symbols.  The code in here tests the value of these are non-zero to know if
 * the routines in System Framework got pulled in and should be called.  The
 * first two are pointers to functions.  The second two use just the symbol
 * itself.  In the later case we are using the symbol with two different 'C'
 * types.  To make it as clean as possible the 'C' type declared is that of the
 * external function.  The common symbol is declared with an asm() and the code
 * casts the function name to a pointer to an int and then indirects through
 * the pointer to see if the value is not zero to know the function got linked
 * in.  Then the code uses a pointer in the data area to the function to call
 * the function.  The pointer in the data area is needed on various RISC
 * architectutes like the PowerPC to avoid a relocation overflow error when
 * linking programs with large data area.
 */
extern int (*mach_init_routine)(void);
extern int (*_cthread_init_routine)(void);
#ifdef CRT0
asm(".comm __cplus_init, 4");
extern void _cplus_init(void);
#endif
#if defined(__ppc__) && defined(CRT1)
asm(".comm ___darwin_gcc3_preregister_frame_info, 4");
extern void __darwin_gcc3_preregister_frame_info (void);
static void (*pointer_to__darwin_gcc3_preregister_frame_info)(void) =
	__darwin_gcc3_preregister_frame_info;
#endif

/*
 * Prototypes for routines that are called.
 */
extern int main(
    int argc,
    char **argv,
    char **envp,
    char **apple);
extern void exit(
    int status) __attribute__ ((noreturn));
extern int atexit(
    void (*fcn)(void));

#ifdef GCRT
extern void moninit(
    void);
static void _mcleanup(
    void);
extern void monitor(
    char *lowpc,
    char *highpc,
    char *buf,
    int bufsiz,
    int nfunc);
#endif /* GCRT */

#ifdef  CRT1
extern void _dyld_init_check(
    void);
static void _call_mod_init_funcs(
    void);
__private_extern__
int _dyld_func_lookup(
    const char *dyld_func_name,
    unsigned long *address);

extern void __keymgr_dwarf2_register_sections (void);
#endif /* CRT1 */

#if defined(CRT1)  &&  !defined(POSTSCRIPT) && !defined(__ppc64__)
static void _call_objcInit(void);
#endif

extern int errno;

/*
 * _start() is called from the machine dependent assembly entry point "start:" .
 * It takes care of setting up the stack so 'C' routines can be called and
 * passes argc, argv and envp to here.
 */
__private_extern__
void
_start(
int argc,
char **argv,
char **envp)
{
    int i;
    char *p, **apple;
#if defined(__ppc__) ||defined(__ppc64__) || defined(__i386__)
    char **q;
#endif
#ifdef CRT1
    void (*term)(void);
#endif

#ifdef CRT1
	_dyld_init_check();
#endif

	NXArgc = argc;
	NXArgv = argv;
	environ = envp;

	if(mach_init_routine != 0)
	    (void) mach_init_routine();
	if(_cthread_init_routine != 0)
	    (*_cthread_init_routine)();

#ifdef CRT1
	__keymgr_dwarf2_register_sections ();
#endif

#if defined(__ppc__) && defined(CRT1)
       /* Call a ppc GCC 3.3-specific function (in libgcc.a) to
          "preregister" exception frame info, meaning to set up the
          dyld hooks that do the actual registration.  */
       if(*((int *)pointer_to__darwin_gcc3_preregister_frame_info) != 0)
           pointer_to__darwin_gcc3_preregister_frame_info ();
#endif

#ifdef CRT0
        if(*((int *)_cplus_init) != 0)
            _cplus_init();
#endif

#ifdef CRT1
	_call_mod_init_funcs();
#endif

#if defined(CRT1)  &&  !defined(POSTSCRIPT) && !defined(__ppc64__)
        _call_objcInit();
#endif

#ifdef GCRT
	atexit(_mcleanup);
	moninit();
#endif

#ifdef CRT1
	/*
	 * If the dyld we are running with supports module termination routines
	 * for all types of images then register the function to call them with
     * atexit().
	 */
        _dyld_func_lookup("__dyld_mod_term_funcs", (unsigned long *)&term);
        if(term != 0)
	    atexit(term);
#endif

	errno = 0;

	if(argv[0] != 0){
	    p = 0;
	    for(i = 0; argv[0][i] != 0; i++){
		if(argv[0][i] == '/')
		    p = argv[0] + i; 
	    }
	    if(p != 0)
		__progname = p + 1;
	    else
		__progname = argv[0];
	}

#if defined(__ppc__) ||defined(__ppc64__) || defined(__i386__)
	/*
	 * Pickup the pointer to the array that contains as its first pointer a
     * pointer to the exec path (the actual first argument to exec(2) which
	 * most of the time is the same as argv[0]).  This array is placed by
	 * the kernel just after the trailing 0 of the envp[] array.  See the
	 * comments in start.s .
	 */
	for(q = envp; *q != (char *)0; q++)
	    ;
	apple = q + 1;
#endif

	exit(main(argc, argv, envp, apple));
}

#ifdef GCRT
/*
 * For profiling the routine _mcleanup gets registered with atexit so monitor(0)
 * gets called.
 */
static
void
_mcleanup(
void)
{
	monitor(0,0,0,0,0);
}
#endif /* GCRT */

#ifdef CRT1
/*
 * Cause the module initialization routines to be called for the modules linked
 * into the program that have been delayed waiting for the initialization in the
 * runtime startoff (like mach_init, etc).  This is used for C++ constructors
 * and destructors when -dynamic is used.
 */
static
void
_call_mod_init_funcs(void)
{
    void (*p)(void);

        _dyld_func_lookup("__dyld_make_delayed_module_initializer_calls",
                          (unsigned long *)&p);
        p();
}
#endif /* CRT1 */

#if defined(CRT1)  &&  !defined(POSTSCRIPT) && !defined(__ppc64__)

/*
 * Look for a function called _objcInit() in any library whose name 
 * starts with "libobjc", and call it if one exists. This is used to 
 * initialize the Objective-C runtime on Panther and earlier. This 
 * is completely unnecessary on Tiger and later.
 */
static 
const char *
crt_basename(const char *path)
{
    const char *s;
    const char *last = path;

    for (s = path; *s != '\0'; s++) {
        if (*s == '/') last = s+1;
    }

    return last;
}

static 
int
crt_strbeginswith(const char *s1, const char *s2)
{
    int i;

    for (i = 0; ; i++) {
        if (s2[i] == '\0') return 1;
        else if (s1[i] != s2[i]) return 0;
    }
}

static
void
_call_objcInit(void)
{
    unsigned int i, count;

    unsigned int (*_dyld_image_count_fn)(void);
    const char *(*_dyld_get_image_name_fn)(unsigned int image_index);
    const void *(*_dyld_get_image_header_fn)(unsigned int image_index);
    const void *(*NSLookupSymbolInImage_fn)(const void *image, const char *symbolName, unsigned int options);
    void *(*NSAddressOfSymbol_fn)(const void *symbol);

    // Find some dyld functions.
    _dyld_func_lookup("__dyld_image_count", 
                      (unsigned long *)&_dyld_image_count_fn);
    _dyld_func_lookup("__dyld_get_image_name", 
                      (unsigned long *)&_dyld_get_image_name_fn);
    _dyld_func_lookup("__dyld_get_image_header", 
                      (unsigned long *)&_dyld_get_image_header_fn);
    _dyld_func_lookup("__dyld_NSLookupSymbolInImage", 
                      (unsigned long *)&NSLookupSymbolInImage_fn);
    _dyld_func_lookup("__dyld_NSAddressOfSymbol", 
                      (unsigned long *)&NSAddressOfSymbol_fn);

    // If any of the dyld functions don't exist, assume we're 
    // on a post-Panther dyld and silently do nothing.
    if (!_dyld_image_count_fn) return;
    if (!_dyld_get_image_name_fn) return;
    if (!_dyld_get_image_header_fn) return;
    if (!NSLookupSymbolInImage_fn) return;
    if (!NSAddressOfSymbol_fn) return;

    // Search for an image whose library name starts with "libobjc".
    count = (*_dyld_image_count_fn)();
    for (i = 0; i < count; i++) {
        const void *image;
        const char *path = (*_dyld_get_image_name_fn)(i);
        const char *base = crt_basename(path);
        if (!crt_strbeginswith(base, "libobjc")) continue;

        // Call _objcInit() if library exports it.
        if ((image = (*_dyld_get_image_header_fn)(i))) {
            const void *symbol;
            // 4 == NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR
            if ((symbol = (*NSLookupSymbolInImage_fn)(image,"__objcInit",4))) {
                void (*_objcInit_fn)(void) = 
                    (void(*)(void))(*NSAddressOfSymbol_fn)(symbol);
                if (_objcInit_fn) {
                    (*_objcInit_fn)();
                    break;
                }
            }
        }
    }
}

#endif /* defined(CRT1)  &&  !defined(POSTSCRIPT) && !defined(__ppc64__) */