1 /* strncpy( char *, const char *, size_t )
2
3 This file is part of the Public Domain C Library (PDCLib).
4 Permission is granted to use, modify, and / or redistribute at will.
5 */
6
7 #include <string.h>
8
9 #ifndef REGTEST
10
strncpy(char * _PDCLIB_restrict s1,const char * _PDCLIB_restrict s2,size_t n)11 char * strncpy( char * _PDCLIB_restrict s1, const char * _PDCLIB_restrict s2, size_t n )
12 {
13 char * rc = s1;
14
15 while ( n && ( *s1++ = *s2++ ) )
16 {
17 /* Cannot do "n--" in the conditional as size_t is unsigned and we have
18 to check it again for >0 in the next loop below, so we must not risk
19 underflow.
20 */
21 --n;
22 }
23
24 /* Checking against 1 as we missed the last --n in the loop above. */
25 while ( n-- > 1 )
26 {
27 *s1++ = '\0';
28 }
29
30 return rc;
31 }
32
33 #endif
34
35 #ifdef TEST
36
37 #include "_PDCLIB_test.h"
38
main(void)39 int main( void )
40 {
41 char s[] = "xxxxxxx";
42 TESTCASE( strncpy( s, "", 1 ) == s );
43 TESTCASE( s[0] == '\0' );
44 TESTCASE( s[1] == 'x' );
45 TESTCASE( strncpy( s, abcde, 6 ) == s );
46 TESTCASE( s[0] == 'a' );
47 TESTCASE( s[4] == 'e' );
48 TESTCASE( s[5] == '\0' );
49 TESTCASE( s[6] == 'x' );
50 TESTCASE( strncpy( s, abcde, 7 ) == s );
51 TESTCASE( s[6] == '\0' );
52 TESTCASE( strncpy( s, "xxxx", 3 ) == s );
53 TESTCASE( s[0] == 'x' );
54 TESTCASE( s[2] == 'x' );
55 TESTCASE( s[3] == 'd' );
56 return TEST_RESULTS;
57 }
58
59 #endif
60