xref: /xnu-8792.61.2/osfmk/device/subrs.c (revision 42e220869062b56f8d7d0726fd4c88954f87902c)
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(__arm64__)
201 // ARM64 implementation in ../arm64/strncmp.s
202 int
strncmp(const char * s1,const char * s2,size_t n)203 strncmp(
204 	const char *s1,
205 	const char *s2,
206 	size_t n)
207 {
208 	unsigned int a, b;
209 
210 	while (n != 0) {
211 		a = *s1++;
212 		b = *s2++;
213 		if (a != b) {
214 			return a - b;     /* includes case when
215 			                   *  'a' is zero and 'b' is not zero
216 			                   *  or vice versa */
217 		}
218 		if (a == '\0') {
219 			return 0;       /* both are zero */
220 		}
221 		n--;
222 	}
223 
224 	return 0;
225 }
226 #endif // #ifndef __arm64__
227 
228 
229 //
230 // Lame implementation just for use by strcasecmp/strncasecmp
231 //
232 static int
tolower(unsigned char ch)233 tolower(unsigned char ch)
234 {
235 	if (ch >= 'A' && ch <= 'Z') {
236 		ch = 'a' + (ch - 'A');
237 	}
238 
239 	return ch;
240 }
241 
242 int
strcasecmp(const char * s1,const char * s2)243 strcasecmp(const char *s1, const char *s2)
244 {
245 	const unsigned char *us1 = (const u_char *)s1,
246 	    *us2 = (const u_char *)s2;
247 
248 	while (tolower(*us1) == tolower(*us2++)) {
249 		if (*us1++ == '\0') {
250 			return 0;
251 		}
252 	}
253 	return tolower(*us1) - tolower(*--us2);
254 }
255 
256 int
strncasecmp(const char * s1,const char * s2,size_t n)257 strncasecmp(const char *s1, const char *s2, size_t n)
258 {
259 	if (n != 0) {
260 		const unsigned char *us1 = (const u_char *)s1,
261 		    *us2 = (const u_char *)s2;
262 
263 		do {
264 			if (tolower(*us1) != tolower(*us2++)) {
265 				return tolower(*us1) - tolower(*--us2);
266 			}
267 			if (*us1++ == '\0') {
268 				break;
269 			}
270 		} while (--n != 0);
271 	}
272 	return 0;
273 }
274 
275 char *
strchr(const char * s,int c)276 strchr(const char *s, int c)
277 {
278 	if (!s) {
279 		return NULL;
280 	}
281 
282 	do {
283 		if (*s == c) {
284 			return __CAST_AWAY_QUALIFIER(s, const, char *);
285 		}
286 	} while (*s++);
287 
288 	return NULL;
289 }
290 
291 char *
strrchr(const char * s,int c)292 strrchr(const char *s, int c)
293 {
294 	const char *found = NULL;
295 
296 	if (!s) {
297 		return NULL;
298 	}
299 
300 	do {
301 		if (*s == c) {
302 			found = s;
303 		}
304 	} while (*s++);
305 
306 	return __CAST_AWAY_QUALIFIER(found, const, char *);
307 }
308 
309 #if CONFIG_VSPRINTF
310 /*
311  * Abstract:
312  *      strcpy copies the contents of the string "from" including
313  *      the null terminator to the string "to". A pointer to "to"
314  *      is returned.
315  * Deprecation Warning:
316  *	strcpy() is being deprecated. Please use strlcpy() instead.
317  */
318 char *
strcpy(char * to,const char * from)319 strcpy(
320 	char *to,
321 	const char *from)
322 {
323 	char *ret = to;
324 
325 	while ((*to++ = *from++) != '\0') {
326 		continue;
327 	}
328 
329 	return ret;
330 }
331 #endif
332 
333 /*
334  * Abstract:
335  *      strncpy copies "count" characters from the "from" string to
336  *      the "to" string. If "from" contains less than "count" characters
337  *      "to" will be padded with null characters until exactly "count"
338  *      characters have been written. The return value is a pointer
339  *      to the "to" string.
340  */
341 
342 #if !defined(__arm64__)
343 // ARM64 implementation in ../arm/strncpy.c
344 #undef strncpy
345 char *
strncpy(char * s1,const char * s2,size_t n)346 strncpy(
347 	char *s1,
348 	const char *s2,
349 	size_t n)
350 {
351 	char *os1 = s1;
352 	unsigned long i;
353 
354 	for (i = 0; i < n;) {
355 		if ((*s1++ = *s2++) == '\0') {
356 			for (i++; i < n; i++) {
357 				*s1++ = '\0';
358 			}
359 		} else {
360 			i++;
361 		}
362 	}
363 	return os1;
364 }
365 #endif // #ifndef __arm64__
366 
367 /*
368  * atoi:
369  *
370  *      This function converts an ascii string into an integer.
371  *
372  * input        : string
373  * output       : a number
374  */
375 
376 int
atoi(const char * cp)377 atoi(const char *cp)
378 {
379 	int     number;
380 
381 	for (number = 0; ('0' <= *cp) && (*cp <= '9'); cp++) {
382 		number = (number * 10) + (*cp - '0');
383 	}
384 
385 	return number;
386 }
387 
388 /*
389  * Does the same thing as strlen, except only looks up
390  * to max chars inside the buffer.
391  * Taken from archive/kern-stuff/sbf_machine.c in
392  * seatbelt.
393  * inputs:
394  *      s	string whose length is to be measured
395  *	max	maximum length of string to search for null
396  * outputs:
397  *	length of s or max; whichever is smaller
398  */
399 
400 #if !defined(__arm64__)
401 // ARM64 implementation in ../arm64/strnlen.s
402 #undef strnlen
403 size_t
strnlen(const char * s,size_t max)404 strnlen(const char *s, size_t max)
405 {
406 	const char *es = s + max, *p = s;
407 	while (p != es && *p) {
408 		p++;
409 	}
410 
411 	return p - s;
412 }
413 #endif // #ifndef __arm64__
414 
415 /*
416  * convert an integer to an ASCII string.
417  * inputs:
418  *	num	integer to be converted
419  *	str	string pointer.
420  *
421  * outputs:
422  *	pointer to string start.
423  */
424 
425 char *
itoa(int num,char * str)426 itoa(
427 	int     num,
428 	char    *str)
429 {
430 	char    digits[11];
431 	char *dp;
432 	char *cp = str;
433 
434 	if (num == 0) {
435 		*cp++ = '0';
436 	} else {
437 		dp = digits;
438 		while (num) {
439 			*dp++ = '0' + num % 10;
440 			num /= 10;
441 		}
442 		while (dp != digits) {
443 			*cp++ = *--dp;
444 		}
445 	}
446 	*cp++ = '\0';
447 
448 	return str;
449 }
450 
451 #if CONFIG_VSPRINTF
452 /*
453  * Deprecation Warning:
454  *	strcat() is being deprecated. Please use strlcat() instead.
455  */
456 char *
strcat(char * dest,const char * src)457 strcat(
458 	char *dest,
459 	const char *src)
460 {
461 	char *old = dest;
462 
463 	while (*dest) {
464 		++dest;
465 	}
466 	while ((*dest++ = *src++)) {
467 		;
468 	}
469 	return old;
470 }
471 #endif
472 
473 /*
474  * Appends src to string dst of size siz (unlike strncat, siz is the
475  * full size of dst, not space left).  At most siz-1 characters
476  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
477  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
478  * If retval >= siz, truncation occurred.
479  */
480 #undef strlcat
481 size_t
strlcat(char * dst,const char * src,size_t siz)482 strlcat(char *dst, const char *src, size_t siz)
483 {
484 	char *d = dst;
485 	const char *s = src;
486 	size_t n = siz;
487 	size_t dlen;
488 
489 	/* Find the end of dst and adjust bytes left but don't go past end */
490 	while (n-- != 0 && *d != '\0') {
491 		d++;
492 	}
493 	dlen = d - dst;
494 	n = siz - dlen;
495 
496 	if (n == 0) {
497 		return dlen + strlen(s);
498 	}
499 	while (*s != '\0') {
500 		if (n != 1) {
501 			*d++ = *s;
502 			n--;
503 		}
504 		s++;
505 	}
506 	*d = '\0';
507 
508 	return dlen + (s - src);       /* count does not include NUL */
509 }
510 
511 /*
512  * Copy src to string dst of size siz.  At most siz-1 characters
513  * will be copied.  Always NUL terminates (unless siz == 0).
514  * Returns strlen(src); if retval >= siz, truncation occurred.
515  */
516 
517 #if !defined(__arm64__)
518 // ARM64 implementation in ../arm/strlcpy.c
519 #undef strlcpy
520 size_t
strlcpy(char * dst,const char * src,size_t siz)521 strlcpy(char *dst, const char *src, size_t siz)
522 {
523 	char *d = dst;
524 	const char *s = src;
525 	size_t n = siz;
526 
527 	/* Copy as many bytes as will fit */
528 	if (n != 0 && --n != 0) {
529 		do {
530 			if ((*d++ = *s++) == 0) {
531 				break;
532 			}
533 		} while (--n != 0);
534 	}
535 
536 	/* Not enough room in dst, add NUL and traverse rest of src */
537 	if (n == 0) {
538 		if (siz != 0) {
539 			*d = '\0';              /* NUL-terminate dst */
540 		}
541 		while (*s++) {
542 			;
543 		}
544 	}
545 
546 	return s - src - 1;    /* count does not include NUL */
547 }
548 #endif /* !defined(__arm64) */
549 
550 /*
551  * Return TRUE(1) if string 2 is a prefix of string 1.
552  */
553 int
strprefix(const char * s1,const char * s2)554 strprefix(const char *s1, const char *s2)
555 {
556 	int c;
557 
558 	while ((c = *s2++) != '\0') {
559 		if (c != *s1++) {
560 			return 0;
561 		}
562 	}
563 	return 1;
564 }
565 
566 const char *
strnstr(const char * s,const char * find,size_t slen)567 strnstr(const char *s, const char *find, size_t slen)
568 {
569 	char c, sc;
570 	size_t len;
571 
572 	if ((c = *find++) != '\0') {
573 		len = strlen(find);
574 		do {
575 			do {
576 				if ((sc = *s++) == '\0' || slen-- < 1) {
577 					return NULL;
578 				}
579 			} while (sc != c);
580 			if (len > slen) {
581 				return NULL;
582 			}
583 		} while (strncmp(s, find, len) != 0);
584 		s--;
585 	}
586 	return s;
587 }
588 
589 void * __memcpy_chk(void *dst, void const *src, size_t s, size_t chk_size);
590 void * __memmove_chk(void *dst, void const *src, size_t s, size_t chk_size);
591 void * __memset_chk(void *dst, int c, size_t s, size_t chk_size);
592 size_t __strlcpy_chk(char *dst, char const *src, size_t s, size_t chk_size);
593 size_t __strlcat_chk(char *dst, char const *src, size_t s, size_t chk_size);
594 char * __strncpy_chk(char *restrict dst, char *restrict src, size_t len, size_t chk_size);
595 char * __strncat_chk(char *restrict dst, const char *restrict src, size_t len, size_t chk_size);
596 char * __strcpy_chk(char *restrict dst, const char *restrict src, size_t chk_size);
597 char * __strcat_chk(char *restrict dst, const char *restrict src, size_t chk_size);
598 
599 MARK_AS_HIBERNATE_TEXT
600 void *
__memcpy_chk(void * dst,void const * src,size_t s,size_t chk_size)601 __memcpy_chk(void *dst, void const *src, size_t s, size_t chk_size)
602 {
603 	if (__improbable(chk_size < s)) {
604 		panic("__memcpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
605 	}
606 	return memcpy(dst, src, s);
607 }
608 
609 void *
__memmove_chk(void * dst,void const * src,size_t s,size_t chk_size)610 __memmove_chk(void *dst, void const *src, size_t s, size_t chk_size)
611 {
612 	if (__improbable(chk_size < s)) {
613 		panic("__memmove_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
614 	}
615 	return memmove(dst, src, s);
616 }
617 
618 MARK_AS_HIBERNATE_TEXT
619 void *
__memset_chk(void * dst,int c,size_t s,size_t chk_size)620 __memset_chk(void *dst, int c, size_t s, size_t chk_size)
621 {
622 	if (__improbable(chk_size < s)) {
623 		panic("__memset_chk object size check failed: dst %p, c %c, (%zu < %zu)", dst, c, chk_size, s);
624 	}
625 	return memset(dst, c, s);
626 }
627 
628 size_t
__strlcat_chk(char * dst,char const * src,size_t s,size_t chk_size)629 __strlcat_chk(char *dst, char const *src, size_t s, size_t chk_size)
630 {
631 	if (__improbable(chk_size < s)) {
632 		panic("__strlcat_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
633 	}
634 	return strlcat(dst, src, s);
635 }
636 
637 size_t
__strlcpy_chk(char * dst,char const * src,size_t s,size_t chk_size)638 __strlcpy_chk(char *dst, char const *src, size_t s, size_t chk_size)
639 {
640 	if (__improbable(chk_size < s)) {
641 		panic("__strlcpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, s);
642 	}
643 	return strlcpy(dst, src, s);
644 }
645 
646 char *
__strncpy_chk(char * restrict dst,char * restrict src,size_t len,size_t chk_size)647 __strncpy_chk(char *restrict dst, char *restrict src,
648     size_t len, size_t chk_size)
649 {
650 	if (__improbable(chk_size < len)) {
651 		panic("__strncpy_chk object size check failed: dst %p, src %p, (%zu < %zu)", dst, src, chk_size, len);
652 	}
653 	return strncpy(dst, src, len);
654 }
655 
656 char *
__strncat_chk(char * restrict dst,const char * restrict src,size_t len,size_t chk_size)657 __strncat_chk(char *restrict dst, const char *restrict src,
658     size_t len, size_t chk_size)
659 {
660 	size_t len1 = strlen(dst);
661 	size_t len2 = strnlen(src, len);
662 	if (__improbable(chk_size < len1 + len2 + 1)) {
663 		panic("__strncat_chk object size check failed: dst %p, src %p, (%zu < %zu + %zu + 1)", dst, src, chk_size, len1, len2);
664 	}
665 	return strncat(dst, src, len);
666 }
667 
668 char *
__strcpy_chk(char * restrict dst,const char * restrict src,size_t chk_size)669 __strcpy_chk(char *restrict dst, const char *restrict src, size_t chk_size)
670 {
671 	size_t len = strlen(src);
672 	if (__improbable(chk_size < len + 1)) {
673 		panic("__strcpy_chk object size check failed: dst %p, src %p, (%zu < %zu + 1)", dst, src, chk_size, len);
674 	}
675 	memcpy(dst, src, len + 1);
676 	return dst;
677 }
678 
679 char *
__strcat_chk(char * restrict dst,const char * restrict src,size_t chk_size)680 __strcat_chk(char *restrict dst, const char *restrict src, size_t chk_size)
681 {
682 	size_t len1 = strlen(dst);
683 	size_t len2 = strlen(src);
684 	size_t required_len = len1 + len2 + 1;
685 	if (__improbable(chk_size < required_len)) {
686 		panic("__strcat_chk object size check failed: dst %p, src %p, (%zu < %zu + %zu + 1)", dst, src, chk_size, len1, len2);
687 	}
688 	memcpy(dst + len1, src, len2 + 1);
689 	return dst;
690 }
691