xref: /xnu-8020.140.41/osfmk/device/subrs.c (revision 27b03b360a988dfd3dfdf34262bb0042026747cc) !
1 /*
2  * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
3  *
4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5  *
6  * This file contains Original Code and/or Modifications of Original Code
7  * as defined in and that are subject to the Apple Public Source License
8  * Version 2.0 (the 'License'). You may not use this file except in
9  * compliance with the License. The rights granted to you under the License
10  * may not be used to create, or enable the creation or redistribution of,
11  * unlawful or unlicensed copies of an Apple operating system, or to
12  * circumvent, violate, or enable the circumvention or violation of, any
13  * terms of an Apple operating system software license agreement.
14  *
15  * Please obtain a copy of the License at
16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
17  *
18  * The Original Code and all software distributed under the License are
19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23  * Please see the License for the specific language governing rights and
24  * limitations under the License.
25  *
26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27  */
28 /*
29  * @OSF_COPYRIGHT@
30  */
31 /*
32  *(C)UNIX System Laboratories, Inc. all or some portions of this file are
33  * derived from material licensed to the University of California by
34  * American Telephone and Telegraph Co. or UNIX System Laboratories,
35  * Inc. and are reproduced herein with the permission of UNIX System
36  * Laboratories, Inc.
37  */
38 
39 /*
40  * Mach Operating System
41  * Copyright (c) 1993,1991,1990,1989,1988 Carnegie Mellon University
42  * All Rights Reserved.
43  *
44  * Permission to use, copy, modify and distribute this software and its
45  * documentation is hereby granted, provided that both the copyright
46  * notice and this permission notice appear in all copies of the
47  * software, derivative works or modified versions, and any portions
48  * thereof, and that both notices appear in supporting documentation.
49  *
50  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
51  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
52  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
53  *
54  * Carnegie Mellon requests users of this software to return to
55  *
56  *  Software Distribution Coordinator  or  [email protected]
57  *  School of Computer Science
58  *  Carnegie Mellon University
59  *  Pittsburgh PA 15213-3890
60  *
61  * any improvements or extensions that they make and grant Carnegie Mellon
62  * the rights to redistribute these changes.
63  */
64 /*
65  */
66 /*
67  * Copyright (c) 1988 Regents of the University of California.
68  * All rights reserved.
69  *
70  * Redistribution and use in source and binary forms, with or without
71  * modification, are permitted provided that the following conditions
72  * are met:
73  * 1. Redistributions of source code must retain the above copyright
74  *    notice, this list of conditions and the following disclaimer.
75  * 2. Redistributions in binary form must reproduce the above copyright
76  *    notice, this list of conditions and the following disclaimer in the
77  *    documentation and/or other materials provided with the distribution.
78  * 3. All advertising materials mentioning features or use of this software
79  *    must display the following acknowledgement:
80  *	This product includes software developed by the University of
81  *	California, Berkeley and its contributors.
82  * 4. Neither the name of the University nor the names of its contributors
83  *    may be used to endorse or promote products derived from this software
84  *    without specific prior written permission.
85  *
86  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
87  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
88  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
89  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
90  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
91  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
92  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
93  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
94  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
95  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
96  * SUCH DAMAGE.
97  */
98 
99 /*
100  * Copyright (c) 1998 Todd C. Miller <[email protected]>
101  * All rights reserved.
102  *
103  * Redistribution and use in source and binary forms, with or without
104  * modification, are permitted provided that the following conditions
105  * are met:
106  * 1. Redistributions of source code must retain the above copyright
107  *    notice, this list of conditions and the following disclaimer.
108  * 2. Redistributions in binary form must reproduce the above copyright
109  *    notice, this list of conditions and the following disclaimer in the
110  *    documentation and/or other materials provided with the distribution.
111  * 3. The name of the author may not be used to endorse or promote products
112  *    derived from this software without specific prior written permission.
113  *
114  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
115  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
116  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
117  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
118  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
119  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
120  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
121  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
122  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
123  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
124  */
125 
126 /*
127  * NOTICE: This file was modified by McAfee Research in 2004 to introduce
128  * support for mandatory and extensible security protections.  This notice
129  * is included in support of clause 2.2 (b) of the Apple Public License,
130  * Version 2.0.
131  */
132 /*
133  * Random device subroutines and stubs.
134  */
135 
136 #include <vm/vm_kern.h>
137 #include <kern/misc_protos.h>
138 #include <libsa/stdlib.h>
139 #include <sys/malloc.h>
140 #include <libkern/section_keywords.h>
141 
142 /* String routines, from CMU */
143 #ifdef  strcpy
144 #undef strcmp
145 #undef strncmp
146 #undef strcpy
147 #undef strlen
148 #endif
149 
150 /* to prevent recursion in the _chk functions */
151 #undef strcat
152 #undef strncpy
153 #undef strncat
154 #undef memcpy
155 #undef memset
156 #undef memmove
157 #undef strlcpy
158 #undef strlcat
159 /*
160  * Abstract:
161  *      strcmp (s1, s2) compares the strings "s1" and "s2".
162  *      It returns 0 if the strings are identical. It returns
163  *      > 0 if the first character that differs in the two strings
164  *      is larger in s1 than in s2 or if s1 is longer than s2 and
165  *      the contents are identical up to the length of s2.
166  *      It returns < 0 if the first differing character is smaller
167  *      in s1 than in s2 or if s1 is shorter than s2 and the
168  *      contents are identical upto the length of s1.
169  * Deprecation Warning:
170  *	strcmp() is being deprecated. Please use strncmp() instead.
171  */
172 
173 int
strcmp(const char * s1,const char * s2)174 strcmp(
175 	const char *s1,
176 	const char *s2)
177 {
178 	unsigned int a, b;
179 
180 	do {
181 		a = *s1++;
182 		b = *s2++;
183 		if (a != b) {
184 			return a - b;     /* includes case when
185 			                   *  'a' is zero and 'b' is not zero
186 			                   *  or vice versa */
187 		}
188 	} while (a != '\0');
189 
190 	return 0;       /* both are zero */
191 }
192 
193 /*
194  * Abstract:
195  *      strncmp (s1, s2, n) compares the strings "s1" and "s2"
196  *      in exactly the same way as strcmp does.  Except the
197  *      comparison runs for at most "n" characters.
198  */
199 
200 #if !defined __arm__ && !defined __arm64__
201 // ARM implementation in ../arm/strncmp.s
202 // ARM64 implementation in ../arm64/strncmp.s
203 int
strncmp(const char * s1,const char * s2,size_t n)204 strncmp(
205 	const char *s1,
206 	const char *s2,
207 	size_t n)
208 {
209 	unsigned int a, b;
210 
211 	while (n != 0) {
212 		a = *s1++;
213 		b = *s2++;
214 		if (a != b) {
215 			return a - b;     /* includes case when
216 			                   *  'a' is zero and 'b' is not zero
217 			                   *  or vice versa */
218 		}
219 		if (a == '\0') {
220 			return 0;       /* both are zero */
221 		}
222 		n--;
223 	}
224 
225 	return 0;
226 }
227 #endif // #ifndef __arm__
228 
229 
230 //
231 // Lame implementation just for use by strcasecmp/strncasecmp
232 //
233 static int
tolower(unsigned char ch)234 tolower(unsigned char ch)
235 {
236 	if (ch >= 'A' && ch <= 'Z') {
237 		ch = 'a' + (ch - 'A');
238 	}
239 
240 	return ch;
241 }
242 
243 int
strcasecmp(const char * s1,const char * s2)244 strcasecmp(const char *s1, const char *s2)
245 {
246 	const unsigned char *us1 = (const u_char *)s1,
247 	    *us2 = (const u_char *)s2;
248 
249 	while (tolower(*us1) == tolower(*us2++)) {
250 		if (*us1++ == '\0') {
251 			return 0;
252 		}
253 	}
254 	return tolower(*us1) - tolower(*--us2);
255 }
256 
257 int
strncasecmp(const char * s1,const char * s2,size_t n)258 strncasecmp(const char *s1, const char *s2, size_t n)
259 {
260 	if (n != 0) {
261 		const unsigned char *us1 = (const u_char *)s1,
262 		    *us2 = (const u_char *)s2;
263 
264 		do {
265 			if (tolower(*us1) != tolower(*us2++)) {
266 				return tolower(*us1) - tolower(*--us2);
267 			}
268 			if (*us1++ == '\0') {
269 				break;
270 			}
271 		} while (--n != 0);
272 	}
273 	return 0;
274 }
275 
276 char *
strchr(const char * s,int c)277 strchr(const char *s, int c)
278 {
279 	if (!s) {
280 		return NULL;
281 	}
282 
283 	do {
284 		if (*s == c) {
285 			return __CAST_AWAY_QUALIFIER(s, const, char *);
286 		}
287 	} while (*s++);
288 
289 	return NULL;
290 }
291 
292 char *
strrchr(const char * s,int c)293 strrchr(const char *s, int c)
294 {
295 	const char *found = NULL;
296 
297 	if (!s) {
298 		return NULL;
299 	}
300 
301 	do {
302 		if (*s == c) {
303 			found = s;
304 		}
305 	} while (*s++);
306 
307 	return __CAST_AWAY_QUALIFIER(found, const, char *);
308 }
309 
310 #if CONFIG_VSPRINTF
311 /*
312  * Abstract:
313  *      strcpy copies the contents of the string "from" including
314  *      the null terminator to the string "to". A pointer to "to"
315  *      is returned.
316  * Deprecation Warning:
317  *	strcpy() is being deprecated. Please use strlcpy() instead.
318  */
319 char *
strcpy(char * to,const char * from)320 strcpy(
321 	char *to,
322 	const char *from)
323 {
324 	char *ret = to;
325 
326 	while ((*to++ = *from++) != '\0') {
327 		continue;
328 	}
329 
330 	return ret;
331 }
332 #endif
333 
334 /*
335  * Abstract:
336  *      strncpy copies "count" characters from the "from" string to
337  *      the "to" string. If "from" contains less than "count" characters
338  *      "to" will be padded with null characters until exactly "count"
339  *      characters have been written. The return value is a pointer
340  *      to the "to" string.
341  */
342 
343 #if !defined __arm__ && !defined __arm64__
344 // ARM and ARM64 implementation in ../arm/strncpy.c
345 #undef strncpy
346 char *
strncpy(char * s1,const char * s2,size_t n)347 strncpy(
348 	char *s1,
349 	const char *s2,
350 	size_t n)
351 {
352 	char *os1 = s1;
353 	unsigned long i;
354 
355 	for (i = 0; i < n;) {
356 		if ((*s1++ = *s2++) == '\0') {
357 			for (i++; i < n; i++) {
358 				*s1++ = '\0';
359 			}
360 		} else {
361 			i++;
362 		}
363 	}
364 	return os1;
365 }
366 #endif // #ifndef __arm__
367 
368 /*
369  * atoi:
370  *
371  *      This function converts an ascii string into an integer.
372  *
373  * input        : string
374  * output       : a number
375  */
376 
377 int
atoi(const char * cp)378 atoi(const char *cp)
379 {
380 	int     number;
381 
382 	for (number = 0; ('0' <= *cp) && (*cp <= '9'); cp++) {
383 		number = (number * 10) + (*cp - '0');
384 	}
385 
386 	return number;
387 }
388 
389 /*
390  * Does the same thing as strlen, except only looks up
391  * to max chars inside the buffer.
392  * Taken from archive/kern-stuff/sbf_machine.c in
393  * seatbelt.
394  * inputs:
395  *      s	string whose length is to be measured
396  *	max	maximum length of string to search for null
397  * outputs:
398  *	length of s or max; whichever is smaller
399  */
400 
401 #if !defined __arm__ && !defined __arm64__
402 // ARM implementation in ../arm/strnlen.s
403 // ARM64 implementation in ../arm64/strnlen.s
404 #undef strnlen
405 size_t
strnlen(const char * s,size_t max)406 strnlen(const char *s, size_t max)
407 {
408 	const char *es = s + max, *p = s;
409 	while (p != es && *p) {
410 		p++;
411 	}
412 
413 	return p - s;
414 }
415 #endif // #ifndef __arm__
416 
417 /*
418  * convert an integer to an ASCII string.
419  * inputs:
420  *	num	integer to be converted
421  *	str	string pointer.
422  *
423  * outputs:
424  *	pointer to string start.
425  */
426 
427 char *
itoa(int num,char * str)428 itoa(
429 	int     num,
430 	char    *str)
431 {
432 	char    digits[11];
433 	char *dp;
434 	char *cp = str;
435 
436 	if (num == 0) {
437 		*cp++ = '0';
438 	} else {
439 		dp = digits;
440 		while (num) {
441 			*dp++ = '0' + num % 10;
442 			num /= 10;
443 		}
444 		while (dp != digits) {
445 			*cp++ = *--dp;
446 		}
447 	}
448 	*cp++ = '\0';
449 
450 	return str;
451 }
452 
453 #if CONFIG_VSPRINTF
454 /*
455  * Deprecation Warning:
456  *	strcat() is being deprecated. Please use strlcat() instead.
457  */
458 char *
strcat(char * dest,const char * src)459 strcat(
460 	char *dest,
461 	const char *src)
462 {
463 	char *old = dest;
464 
465 	while (*dest) {
466 		++dest;
467 	}
468 	while ((*dest++ = *src++)) {
469 		;
470 	}
471 	return old;
472 }
473 #endif
474 
475 /*
476  * Appends src to string dst of size siz (unlike strncat, siz is the
477  * full size of dst, not space left).  At most siz-1 characters
478  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
479  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
480  * If retval >= siz, truncation occurred.
481  */
482 #undef strlcat
483 size_t
strlcat(char * dst,const char * src,size_t siz)484 strlcat(char *dst, const char *src, size_t siz)
485 {
486 	char *d = dst;
487 	const char *s = src;
488 	size_t n = siz;
489 	size_t dlen;
490 
491 	/* Find the end of dst and adjust bytes left but don't go past end */
492 	while (n-- != 0 && *d != '\0') {
493 		d++;
494 	}
495 	dlen = d - dst;
496 	n = siz - dlen;
497 
498 	if (n == 0) {
499 		return dlen + strlen(s);
500 	}
501 	while (*s != '\0') {
502 		if (n != 1) {
503 			*d++ = *s;
504 			n--;
505 		}
506 		s++;
507 	}
508 	*d = '\0';
509 
510 	return dlen + (s - src);       /* count does not include NUL */
511 }
512 
513 /*
514  * Copy src to string dst of size siz.  At most siz-1 characters
515  * will be copied.  Always NUL terminates (unless siz == 0).
516  * Returns strlen(src); if retval >= siz, truncation occurred.
517  */
518 
519 #if !defined __arm__ && !defined __arm64__
520 // ARM and ARM64 implementation in ../arm/strlcpy.c
521 #undef strlcpy
522 size_t
strlcpy(char * dst,const char * src,size_t siz)523 strlcpy(char *dst, const char *src, size_t siz)
524 {
525 	char *d = dst;
526 	const char *s = src;
527 	size_t n = siz;
528 
529 	/* Copy as many bytes as will fit */
530 	if (n != 0 && --n != 0) {
531 		do {
532 			if ((*d++ = *s++) == 0) {
533 				break;
534 			}
535 		} while (--n != 0);
536 	}
537 
538 	/* Not enough room in dst, add NUL and traverse rest of src */
539 	if (n == 0) {
540 		if (siz != 0) {
541 			*d = '\0';              /* NUL-terminate dst */
542 		}
543 		while (*s++) {
544 			;
545 		}
546 	}
547 
548 	return s - src - 1;    /* count does not include NUL */
549 }
550 #endif
551 
552 /*
553  * Return TRUE(1) if string 2 is a prefix of string 1.
554  */
555 int
strprefix(const char * s1,const char * s2)556 strprefix(const char *s1, const char *s2)
557 {
558 	int c;
559 
560 	while ((c = *s2++) != '\0') {
561 		if (c != *s1++) {
562 			return 0;
563 		}
564 	}
565 	return 1;
566 }
567 
568 const char *
strnstr(const char * s,const char * find,size_t slen)569 strnstr(const char *s, const char *find, size_t slen)
570 {
571 	char c, sc;
572 	size_t len;
573 
574 	if ((c = *find++) != '\0') {
575 		len = strlen(find);
576 		do {
577 			do {
578 				if ((sc = *s++) == '\0' || slen-- < 1) {
579 					return NULL;
580 				}
581 			} while (sc != c);
582 			if (len > slen) {
583 				return NULL;
584 			}
585 		} while (strncmp(s, find, len) != 0);
586 		s--;
587 	}
588 	return s;
589 }
590 
591 void * __memcpy_chk(void *dst, void const *src, size_t s, size_t chk_size);
592 void * __memmove_chk(void *dst, void const *src, size_t s, size_t chk_size);
593 void * __memset_chk(void *dst, int c, size_t s, size_t chk_size);
594 size_t __strlcpy_chk(char *dst, char const *src, size_t s, size_t chk_size);
595 size_t __strlcat_chk(char *dst, char const *src, size_t s, size_t chk_size);
596 char * __strncpy_chk(char *restrict dst, char *restrict src, size_t len, size_t chk_size);
597 char * __strncat_chk(char *restrict dst, const char *restrict src, size_t len, size_t chk_size);
598 char * __strcpy_chk(char *restrict dst, const char *restrict src, size_t chk_size);
599 char * __strcat_chk(char *restrict dst, const char *restrict src, size_t chk_size);
600 
601 MARK_AS_HIBERNATE_TEXT
602 void *
__memcpy_chk(void * dst,void const * src,size_t s,size_t chk_size)603 __memcpy_chk(void *dst, void const *src, size_t s, size_t chk_size)
604 {
605 	if (__improbable(chk_size < s)) {
606 		panic("__memcpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
607 	}
608 	return memcpy(dst, src, s);
609 }
610 
611 void *
__memmove_chk(void * dst,void const * src,size_t s,size_t chk_size)612 __memmove_chk(void *dst, void const *src, size_t s, size_t chk_size)
613 {
614 	if (__improbable(chk_size < s)) {
615 		panic("__memmove_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
616 	}
617 	return memmove(dst, src, s);
618 }
619 
620 MARK_AS_HIBERNATE_TEXT
621 void *
__memset_chk(void * dst,int c,size_t s,size_t chk_size)622 __memset_chk(void *dst, int c, size_t s, size_t chk_size)
623 {
624 	if (__improbable(chk_size < s)) {
625 		panic("__memset_chk object size check failed: dst %p, c %c, (%zu < %zu)", dst, c, chk_size, s);
626 	}
627 	return memset(dst, c, s);
628 }
629 
630 size_t
__strlcat_chk(char * dst,char const * src,size_t s,size_t chk_size)631 __strlcat_chk(char *dst, char const *src, size_t s, size_t chk_size)
632 {
633 	if (__improbable(chk_size < s)) {
634 		panic("__strlcat_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
635 	}
636 	return strlcat(dst, src, s);
637 }
638 
639 size_t
__strlcpy_chk(char * dst,char const * src,size_t s,size_t chk_size)640 __strlcpy_chk(char *dst, char const *src, size_t s, size_t chk_size)
641 {
642 	if (__improbable(chk_size < s)) {
643 		panic("__strlcpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
644 	}
645 	return strlcpy(dst, src, s);
646 }
647 
648 char *
__strncpy_chk(char * restrict dst,char * restrict src,size_t len,size_t chk_size)649 __strncpy_chk(char *restrict dst, char *restrict src,
650     size_t len, size_t chk_size)
651 {
652 	if (__improbable(chk_size < len)) {
653 		panic("__strncpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, len);
654 	}
655 	return strncpy(dst, src, len);
656 }
657 
658 char *
__strncat_chk(char * restrict dst,const char * restrict src,size_t len,size_t chk_size)659 __strncat_chk(char *restrict dst, const char *restrict src,
660     size_t len, size_t chk_size)
661 {
662 	size_t len1 = strlen(dst);
663 	size_t len2 = strnlen(src, len);
664 	if (__improbable(chk_size < len1 + len2 + 1)) {
665 		panic("__strncat_chk object size check failed: dst %p, src %p, (%zu < %zu + %zu + 1)", dst, src, chk_size, len1, len2);
666 	}
667 	return strncat(dst, src, len);
668 }
669 
670 char *
__strcpy_chk(char * restrict dst,const char * restrict src,size_t chk_size)671 __strcpy_chk(char *restrict dst, const char *restrict src, size_t chk_size)
672 {
673 	size_t len = strlen(src);
674 	if (__improbable(chk_size < len + 1)) {
675 		panic("__strcpy_chk object size check failed: dst %p, src %p, (%zu < %zu + 1)", dst, src, chk_size, len);
676 	}
677 	memcpy(dst, src, len + 1);
678 	return dst;
679 }
680 
681 char *
__strcat_chk(char * restrict dst,const char * restrict src,size_t chk_size)682 __strcat_chk(char *restrict dst, const char *restrict src, size_t chk_size)
683 {
684 	size_t len1 = strlen(dst);
685 	size_t len2 = strlen(src);
686 	size_t required_len = len1 + len2 + 1;
687 	if (__improbable(chk_size < required_len)) {
688 		panic("__strcat_chk object size check failed: dst %p, src %p, (%zu < %zu + %zu + 1)", dst, src, chk_size, len1, len2);
689 	}
690 	memcpy(dst + len1, src, len2 + 1);
691 	return dst;
692 }
693