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1 | /* Copyright (C) 1993,1995,1996,1997,2002,2005 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. | |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Lesser General Public | |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public | |
15 | License along with the GNU C Library; if not, write to the Free | |
16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
17 | 02111-1307 USA. */ | |
18 | ||
19 | /* This is almost copied from strncpy.c, written by Torbjorn Granlund. */ | |
20 | ||
21 | #include <string.h> | |
22 | ||
23 | ||
24 | /* Copy no more than N characters of SRC to DEST, returning the address of | |
25 | the terminating '\0' in DEST, if any, or else DEST + N. */ | |
26 | char * | |
27 | __stpncpy_chk (char *dest, const char *src, size_t n, size_t destlen) | |
28 | { | |
29 | char c; | |
30 | char *s = dest; | |
31 | ||
32 | if (__builtin_expect (destlen < n, 0)) | |
33 | __chk_fail (); | |
34 | ||
35 | if (n >= 4) | |
36 | { | |
37 | size_t n4 = n >> 2; | |
38 | ||
39 | for (;;) | |
40 | { | |
41 | c = *src++; | |
42 | *dest++ = c; | |
43 | if (c == '\0') | |
44 | break; | |
45 | c = *src++; | |
46 | *dest++ = c; | |
47 | if (c == '\0') | |
48 | break; | |
49 | c = *src++; | |
50 | *dest++ = c; | |
51 | if (c == '\0') | |
52 | break; | |
53 | c = *src++; | |
54 | *dest++ = c; | |
55 | if (c == '\0') | |
56 | break; | |
57 | if (--n4 == 0) | |
58 | goto last_chars; | |
59 | } | |
60 | n -= dest - s; | |
61 | goto zero_fill; | |
62 | } | |
63 | ||
64 | last_chars: | |
65 | n &= 3; | |
66 | if (n == 0) | |
67 | return dest; | |
68 | ||
69 | for (;;) | |
70 | { | |
71 | c = *src++; | |
72 | --n; | |
73 | *dest++ = c; | |
74 | if (c == '\0') | |
75 | break; | |
76 | if (n == 0) | |
77 | return dest; | |
78 | } | |
79 | ||
80 | zero_fill: | |
81 | while (n-- > 0) | |
82 | dest[n] = '\0'; | |
83 | ||
84 | return dest - 1; | |
85 | } |