1#include <string.h>
2#include <stdio.h>
3
4char b[50];
5
6void reset_b(void)
7{
8   int i;
9
10   for (i = 0; i < 50; i++)
11      b[i] = '_';
12   b[49] = '\0';
13}
14
15void reset_b2(void)
16{
17   reset_b();
18   strcpy(b, "ABCDEFG");
19}
20
21int main(void)
22{
23   char x[100];
24   char a[] = "abcdefghijklmnopqrstuvwxyz";
25   int  i;
26
27   /* testing memcpy/strcpy overlap */
28
29   for (i = 0; i < 50; i++) {
30      x[i] = i+1;    // don't put any zeroes in there
31   }
32   for (i = 50; i < 100; i++) {
33      // because of the errors, the strcpy's will overrun, so put some
34      // zeroes in the second half to stop them eventually
35      x[i] = 0;
36
37   }
38
39   memcpy(x+20, x, 20);    // ok
40   memcpy(x+20, x, 21);    // overlap
41   memcpy(x, x+20, 20);    // ok
42   memcpy(x, x+20, 21);    // overlap
43
44   strncpy(x+20, x, 20);    // ok
45   strncpy(x+20, x, 21);    // overlap
46   strncpy(x, x+20, 20);    // ok
47   strncpy(x, x+20, 21);    // overlap
48
49   x[39] = '\0';
50   strcpy(x, x+20);    // ok
51
52   x[39] = 39;
53   x[40] = '\0';
54   strcpy(x, x+20);    // overlap
55
56   x[19] = '\0';
57   strcpy(x+20, x);    // ok
58
59/*
60   x[19] = 19;
61   x[20] = '\0';
62   strcpy(x+20, x);    // overlap, but runs forever (or until it seg faults)
63*/
64
65   /* testing strcpy, strncpy() */
66
67   reset_b();
68   printf("`%s'\n", b);
69
70   strcpy(b, a);
71   printf("`%s'\n", b);
72
73   reset_b();
74   strncpy(b, a, 25);
75   printf("`%s'\n", b);
76
77   reset_b();
78   strncpy(b, a, 26);
79   printf("`%s'\n", b);
80
81   reset_b();
82   strncpy(b, a, 27);
83   printf("`%s'\n", b);
84
85   printf("\n");
86
87   /* testing strncat() */
88
89   reset_b2();
90   printf("`%s'\n", b);
91
92   reset_b2();
93   strcat(b, a);
94   printf("`%s'\n", b);
95
96   reset_b2();
97   strncat(b, a, 25);
98   printf("`%s'\n", b);
99
100   reset_b2();
101   strncat(b, a, 26);
102   printf("`%s'\n", b);
103
104   reset_b2();
105   strncat(b, a, 27);
106   printf("`%s'\n", b);
107
108   /* Nb: can't actually get strcat warning -- if any overlap occurs, it will
109      always run forever, I think... */
110
111   for ( i = 0; i < 2; i++)
112      strncat(a+20, a, 21);    // run twice to check 2nd error isn't shown
113   strncat(a, a+20, 21);
114
115   /* This is ok, but once gave a warning when strncpy() was wrong,
116      and used 'n' for the length, even when the src was shorter than 'n' */
117   {
118      char dest[64];
119      char src [16];
120      strcpy( src, "short" );
121      strncpy( dest, src, 20 );
122   }
123
124   return 0;
125}
126