aboutsummaryrefslogtreecommitdiff
path: root/lib/csu/i386/crt0.c
blob: 5f7e4ab724ce3638a88148769efa2d1d43cf2bf6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
/*
 * Copyright (c) 1993 Paul Kranenburg
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Paul Kranenburg.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *	$Id$
 */

#include <sys/param.h>

#include <stdlib.h>
#include <dlfcn.h>

#ifdef DYNAMIC
#include <sys/types.h>
#include <sys/syscall.h>
#include <a.out.h>
#include <string.h>
#include <sys/mman.h>
#include <link.h>

/* !!!
 * This is gross, ld.so is a ZMAGIC a.out, but has `sizeof(hdr)' for
 * an entry point and not at PAGSIZ as the N_*ADDR macros assume.
 */
#undef N_DATADDR
#define N_DATADDR(x)	((x).a_text)

#undef N_BSSADDR
#define N_BSSADDR(x)	((x).a_text + (x).a_data)

#ifndef N_GETMAGIC
#define N_GETMAGIC(x)	((x).a_magic)
#endif /* N_GETMAGIC */

#ifndef	MAP_PRIVATE
#define MAP_PRIVATE	MAP_COPY
#endif /* MAP_PRIVATE */

#ifndef MAP_FILE
#define MAP_FILE	0
#endif /* MAP_FILE */

#ifndef MAP_ANON
#define MAP_ANON	0
#endif /* MAP_ANON */

#ifdef DEBUG 
/*
 * We need these two because we are going to call them before the ld.so is
 * finished (as a matter of fact before we know if it exists !) so we must
 * provide these versions for them
 */
static char		*_getenv();
static int		_strncmp();
#endif /* DEBUG */

#ifndef LDSO
#define LDSO		"/usr/libexec/ld.so"
#endif /* LDSO */

extern struct _dynamic	_DYNAMIC;
static struct ld_entry	*ld_entry;
static void		__do_dynamic_link ();
#endif /* DYNAMIC */

int			_callmain();
int			errno;
static char		empty[1];
char			*__progname = empty;
char			**environ;

extern	unsigned char	etext;
extern	unsigned char	eprol asm ("eprol");
extern			start() asm("start");
extern			mcount() asm ("mcount");
extern	int		main(int argc, char **argv, char **envp);
int			__syscall(int syscall,...);
#ifdef MCRT0
void			monstartup(void *low, void *high);
#endif /* MCRT0 */


/*
 * We need these system calls, but can't use library stubs because the are
 * not accessible until we have done the ld.so stunt.
 */

#define _exit(v) \
	__syscall(SYS_exit, (int)(v))
#define _open(name, f, m) \
	__syscall(SYS_open, (char *)(name), (int)(f), (int)(m))
#define _read(fd, s, n) \
	__syscall(SYS_read, (int)(fd), (void *)(s), (size_t)(n))
#define _write(fd, s, n) \
	__syscall(SYS_write, (int)(fd), (void *)(s), (size_t)(n))
#define _mmap(addr, len, prot, flags, fd, off)	\
	(caddr_t) __syscall(SYS_mmap, (caddr_t)(addr), (size_t)(len), \
		(int)(prot), (int)(flags), (int)(fd), (long)0L, (off_t)(off))

#define _PUTNMSG(str, len)	_write(2, (str), (len))
#define _PUTMSG(str)		_PUTNMSG((str), sizeof (str) - 1)
#define _FATAL(str)		( _PUTMSG(str), _exit(1) )


int
start()
{
	struct kframe {
		int	kargc;
		char	*kargv[1];	/* size depends on kargc */
		char	kargstr[1];	/* size varies */
		char	kenvstr[1];	/* size varies */
	};
	/*
	 *	ALL REGISTER VARIABLES!!!
	 */
	register struct kframe *kfp;
	register char **targv;
	register char **argv;
	extern void _mcleanup();
#ifdef DYNAMIC
	volatile caddr_t x;
#endif

#ifdef lint
	kfp = 0;
#else /* not lint */
	/* just above the saved frame pointer */
	asm ("lea 4(%%ebp), %0" : "=r" (kfp) );
#endif /* not lint */
	for (argv = targv = &kfp->kargv[0]; *targv++; /* void */)
		/* void */ ;
	if (targv >= (char **)(*argv))
		--targv;
	environ = targv;

	if (argv[0]) {
		register char *s;
		__progname = argv[0];
		for (s=__progname; *s != '\0'; s++)
			if (*s == '/')
				__progname = s+1;
	}

#ifdef DYNAMIC
	/* ld(1) convention: if DYNAMIC = 0 then statically linked */
	/* sometimes GCC is too smart/stupid for its own good */
	x = (caddr_t)&_DYNAMIC;
	if (x)
		__do_dynamic_link();
#endif /* DYNAMIC */

asm("eprol:");

#ifdef MCRT0
	atexit(_mcleanup);
	monstartup(&eprol, &etext);
#endif /* MCRT0 */

asm ("__callmain:");		/* Defined for the benefit of debuggers */
	exit(main(kfp->kargc, argv, environ));
}

#ifdef DYNAMIC
static void
__do_dynamic_link ()
{
	struct crt_ldso	crt;
	struct exec	hdr;
	char		*ldso;
	int		(*entry)();
	int		ret;

#ifdef DEBUG
	/* Provision for alternate ld.so - security risk! */
	if (!(ldso = _getenv("LDSO")))
#endif
		ldso = LDSO;

	crt.crt_ldfd = _open(ldso, 0, 0);
	if (crt.crt_ldfd == -1) {
		_PUTMSG("Couldn't open ");
		_PUTMSG(LDSO);
		_FATAL(".\n");
	}

	/* Read LDSO exec header */
	if (_read(crt.crt_ldfd, &hdr, sizeof hdr) < sizeof hdr) {
		_FATAL("Failure reading ld.so\n");
	}
	if ((N_GETMAGIC_NET(hdr) != ZMAGIC) && (N_GETMAGIC(hdr) != QMAGIC)) {
		_FATAL("Bad magic: ld.so\n");
	}

	/* We use MAP_ANON */
	crt.crt_dzfd = -1;

	/* Map in ld.so */
	crt.crt_ba = (int)_mmap(0, hdr.a_text,
			PROT_READ|PROT_EXEC,
			MAP_FILE|MAP_PRIVATE,
			crt.crt_ldfd, N_TXTOFF(hdr));
	if (crt.crt_ba == -1) {
		_FATAL("Cannot map ld.so (text)\n");
	}

	/* Map in data segment of ld.so writable */
	if ((int)_mmap((caddr_t)(crt.crt_ba+N_DATADDR(hdr)), hdr.a_data,
			PROT_READ|PROT_WRITE,
			MAP_FIXED|MAP_FILE|MAP_PRIVATE,
			crt.crt_ldfd, N_DATOFF(hdr)) == -1) {
		_FATAL("Cannot map ld.so (data)\n");
	}

	/* Map bss segment of ld.so zero */
	if (hdr.a_bss && (int)_mmap((caddr_t)(crt.crt_ba+N_BSSADDR(hdr)),
			hdr.a_bss,
			PROT_READ|PROT_WRITE,
			MAP_FIXED|MAP_ANON|MAP_PRIVATE,
			crt.crt_dzfd, 0) == -1) {
		_FATAL("Cannot map ld.so (bss)\n");
	}

	crt.crt_dp = &_DYNAMIC;
	crt.crt_ep = environ;
	crt.crt_bp = (caddr_t)_callmain;
	crt.crt_prog = __progname;
	crt.crt_ldso = ldso;
	crt.crt_ldentry = NULL;

	entry = (int (*)())(crt.crt_ba + sizeof hdr);
	ret = (*entry)(CRT_VERSION_BSD_4, &crt);
	ld_entry = crt.crt_ldentry;
	if (ret == -1 && ld_entry == NULL) {
		/* if version 4 not recognised, try version 3 */
		ret = (*entry)(CRT_VERSION_BSD_3, &crt);
		ld_entry = _DYNAMIC.d_entry;
	}
	if (ret == -1) {
		_PUTMSG("ld.so failed");
		if (ld_entry != NULL) {
			char *msg = (ld_entry->dlerror)();
			if(msg != NULL) {
				char *endp;
				_PUTMSG(": ");
				for(endp = msg;  *endp != '\0';  ++endp)
					;	/* Find the end */
				_PUTNMSG(msg, endp - msg);
			}
		}
		_FATAL("\n");
	}


	if (ret >= LDSO_VERSION_HAS_DLEXIT)
		atexit(ld_entry->dlexit);

	return;
}

/*
 * DL stubs
 */

void *
dlopen(name, mode)
char	*name;
int	mode;
{
	if (ld_entry == NULL)
		return NULL;

	return (ld_entry->dlopen)(name, mode);
}

int
dlclose(fd)
void	*fd;
{
	if (ld_entry == NULL)
		return -1;

	return (ld_entry->dlclose)(fd);
}

void *
dlsym(fd, name)
void	*fd;
char	*name;
{
	if (ld_entry == NULL)
		return NULL;

	return (ld_entry->dlsym)(fd, name);
}


char *
dlerror()
{
	if (ld_entry == NULL)
		return "Service unavailable";

	return (ld_entry->dlerror)();
}


/*
 * Support routines
 */

#ifdef DEBUG
static int
_strncmp(s1, s2, n)
	register char *s1, *s2;
	register n;
{

	if (n == 0)
		return (0);
	do {
		if (*s1 != *s2++)
			return (*(unsigned char *)s1 - *(unsigned char *)--s2);
		if (*s1++ == 0)
			break;
	} while (--n != 0);
	return (0);
}

static char *
_getenv(name)
	register char *name;
{
	extern char **environ;
	register int len;
	register char **P, *C;

	for (C = name, len = 0; *C && *C != '='; ++C, ++len);
	for (P = environ; *P; ++P)
		if (!_strncmp(*P, name, len))
			if (*(C = *P + len) == '=') {
				return(++C);
			}
	return (char *)0;
}

#endif /* DEBUG */

	asm("	___syscall:");
	asm("		popl %ecx");
	asm("		popl %eax");
	asm("		pushl %ecx");
	asm("		.byte 0x9a");
	asm("		.long 0");
	asm("		.word 7");
	asm("		pushl %ecx");
	asm("		jc 1f");
	asm("		ret");
	asm("	1:");
	asm("		movl	$-1,%eax");
	asm("		ret");

#else /* DYNAMIC */

/*
 * DL stubs for static linking case (just return error)
 */

void *
dlopen(name, mode)
char	*name;
int	mode;
{
	return NULL;
}

int
dlclose(fd)
void	*fd;
{
	return -1;
}

void *
dlsym(fd, name)
void	*fd;
char	*name;
{
	return NULL;
}


char *
dlerror()
{
	return "Service unavailable";
}
#endif /* DYNAMIC */


/*
 * Support routines
 */

#ifdef MCRT0
asm ("	.text");
asm ("_eprol:");
#endif