clang/test/Sema/warn-strncat-size.c

   1 // RUN: %clang_cc1 -Wstrncat-size -verify -fsyntax-only %s
   2 // RUN: %clang_cc1 -DUSE_BUILTINS -Wstrncat-size -verify -fsyntax-only %s
   3 // RUN: %clang_cc1 -Wstrncat-size -fixit -x c %s
   4 // RUN: %clang_cc1 -DUSE_BUILTINS -Wstrncat-size -fixit -x c %s
   5
   6 typedef __SIZE_TYPE__ size_t;
   7 size_t strlen (const char *s);
   8
   9 #ifdef USE_BUILTINS
  10 # define BUILTIN(f) __builtin_ ## f
  11 #else
  12 # define BUILTIN(f) f
  13 #endif
  14
  15 #define strncat BUILTIN(strncat)
  16 char *strncat(char *restrict s1, const char *restrict s2, size_t n);
  17
  18 struct {
  19   char f1[100];
  20   char f2[100][3];
  21 } s4, **s5;
  22
  23 char s1[100];
  24 char s2[200];
  25 int x;
  26
  27 void test(char *src) {
  28   char dest[10];
  29
  30   strncat(dest, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAA", sizeof(dest) - strlen(dest) - 1); // no-warning
  31   strncat(dest, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAA", sizeof(dest) - 1); // no-warning - the code might assume that dest is empty
  32
  33   strncat(dest, src, sizeof(src)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  34
  35   strncat(dest, src, sizeof(src) - 1); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  36
  37   strncat(dest, "AAAAAAAAAAAAAAAAAAAAAAAAAAA", sizeof(dest)); // expected-warning{{the value of the size argument in 'strncat' is too large, might lead to a buffer overflow}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  38
  39   strncat(dest, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", sizeof(dest) - strlen(dest)); // expected-warning{{the value of the size argument in 'strncat' is too large, might lead to a buffer overflow}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  40
  41   strncat((*s5)->f2[x], s2, sizeof(s2)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  42   strncat(s1+3, s2, sizeof(s2)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-warning {{strncat' size argument is too large; destination buffer has size 97, but size argument is 200}}
  43   strncat(s4.f1, s2, sizeof(s2)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  44 }
  45
  46 // Don't issue FIXIT for flexible arrays.
  47 struct S {
  48   int y;
  49   char x[];
  50 };
  51
  52 void flexible_arrays(struct S *s) {
  53   char str[] = "hi";
  54   strncat(s->x, str,  sizeof(str)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}}
  55 }
  56
  57 // Don't issue FIXIT for destinations of size 1.
  58 void size_1(void) {
  59   char z[1];
  60   char str[] = "hi";
  61
  62   strncat(z, str, sizeof(z)); // expected-warning{{the value of the size argument to 'strncat' is wrong}}
  63 }
  64
  65 // Support VLAs.
  66 void vlas(int size) {
  67   char z[size];
  68   char str[] = "hi";
  69
  70   strncat(z, str, sizeof(str)); // expected-warning {{size argument in 'strncat' call appears to be size of the source}} expected-note {{change the argument to be the free space in the destination buffer minus the terminating null byte}}
  71 }
  72
  73 // Non-array type gets a different error message.
  74 void f(char* s, char* d) {
  75   strncat(d, s, sizeof(d)); // expected-warning {{the value of the size argument to 'strncat' is wrong}}
  76 }