direwolf/misc/strlcpy.c

121 lines
3.7 KiB
C

/*------------------------------------------------------------------
*
* Module: strlcpy.c
*
* Purpose: Safe string functions to guard against buffer overflow.
*
* Description: The size of character strings, especially when coming from the
* outside, can sometimes exceed a fixed size storage area.
*
* There was one case where a MIC-E format packet had an enormous
* comment that exceeded an internal buffer of 256 characters,
* resulting in a crash.
*
* We are not always meticulous about checking sizes to avoid overflow.
* Use of these functions, instead of strcpy and strcat, should
* help avoid issues.
*
* Orgin: From OpenBSD as the copyright notice indicates.
* The GNU folks didn't think it was appropriate for inclusion
* in glibc. https://lwn.net/Articles/507319/
*
* Modifications: Added extra debug output when strings are truncated.
* Not sure if I will leave this in the release version
* or just let it happen silently.
*
*---------------------------------------------------------------*/
/* $NetBSD: strlcpy.c,v 1.5 2014/10/31 18:59:32 spz Exp $ */
/* from NetBSD: strlcpy.c,v 1.14 2003/10/27 00:12:42 lukem Exp */
/* from OpenBSD: strlcpy.c,v 1.7 2003/04/12 21:56:39 millert Exp */
/*
* Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
* FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "direwolf.h"
#include <stdlib.h>
#include <string.h>
#include "textcolor.h"
/*
* Copy src to string dst of size siz. At most siz-1 characters
* will be copied. Always NUL terminates (unless siz == 0).
* Returns strlen(src); if retval >= siz, truncation occurred.
*/
#if DEBUG_STRL
size_t strlcpy_debug(char *__restrict__ dst, const char *__restrict__ src, size_t siz, const char *file, const char *func, int line)
#else
size_t strlcpy_debug(char *__restrict__ dst, const char *__restrict__ src, size_t siz)
#endif
{
char *d = dst;
const char *s = src;
size_t n = siz;
size_t retval;
#if DEBUG_STRL
if (dst == NULL) {
text_color_set (DW_COLOR_ERROR);
dw_printf ("ERROR: strlcpy dst is NULL. (%s %s %d)\n", file, func, line);
return (0);
}
if (src == NULL) {
text_color_set (DW_COLOR_ERROR);
dw_printf ("ERROR: strlcpy src is NULL. (%s %s %d)\n", file, func, line);
return (0);
}
if (siz == 1 || siz == 4) {
text_color_set (DW_COLOR_ERROR);
dw_printf ("Suspicious strlcpy siz. Is it using sizeof a pointer variable? (%s %s %d)\n", file, func, line);
}
#endif
/* Copy as many bytes as will fit */
if (n != 0 && --n != 0) {
do {
if ((*d++ = *s++) == 0)
break;
} while (--n != 0);
}
/* Not enough room in dst, add NUL and traverse rest of src */
if (n == 0) {
if (siz != 0)
*d = '\0'; /* NUL-terminate dst */
while (*s++)
;
}
retval = s - src - 1; /* count does not include NUL */
#if DEBUG_STRL
if (retval >= siz) {
text_color_set (DW_COLOR_ERROR);
dw_printf ("WARNING: strlcpy result length %d exceeds maximum length %d. (%s %s %d)\n",
(int)retval, (int)(siz-1), file, func, line);
}
#endif
return (retval);
}