gcc/testsuite/gcc.dg/tree-ssa/builtin-snprintf-warn-2.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -Wformat -Wformat-truncation=2 -ftrack-macro-expansion=0" } */
   3
   4 typedef struct
   5 {
   6   char a0[0];
   7   /* Separate a0 from a1 to prevent the former from being substituted
   8      for the latter and causing false positives.  */
   9   int: 8;
  10   char a1[1];
  11   char a2[2];
  12   char a3[3];
  13   char a4[4];
  14   char ax[];
  15 } Arrays;
  16
  17 char buffer[1024];
  18 #define buffer(size) (buffer + sizeof buffer - size)
  19
  20 static int value_range (int min, int max)
  21 {
  22   extern int value (void);
  23   int val = value ();
  24   return val < min || max < val ? min : val;
  25 }
  26
  27 #define R(min, max)  value_range (min, max)
  28
  29 /* Verify that calls to snprintf whose return value is unused are
  30    diagnosed if certain or possible truncation is detected.  */
  31
  32 #define T(size, ...) \
  33   __builtin_snprintf (buffer (size), size, __VA_ARGS__)
  34
  35 void test_int_retval_unused (void)
  36 {
  37   T (2, "%i", 123);          /* { dg-warning "output truncated" } */
  38   T (2, "%i", R (1, 99));    /* { dg-warning "output may be truncated" } */
  39   T (2, "%i", R (10, 99));   /* { dg-warning "output truncated" } */
  40   T (3, "%i%i", R (1, 99), R (1, 99));   /* { dg-warning "output may be truncated" } */
  41 }
  42
  43 void test_string_retval_unused (const Arrays *ar)
  44 {
  45   /* At level 2 strings of unknown length are assumed to be 1 character
  46      long, so the following is diagnosed.  */
  47   T (1, "%-s", ar->a0);   /* { dg-warning "output may be truncated" } */
  48   T (1, "%-s", ar->a1);
  49   T (1, "%-s", ar->a2);   /* { dg-warning "output may be truncated" } */
  50 }
  51
  52
  53 /* Verify that (at -Wformat-trunc=2) calls to snprintf whose return value
  54    is used are diagnosed the same way as those whose value is unused.  */
  55
  56 volatile int retval;
  57
  58 #undef T
  59 #define T(size, ...) \
  60   retval = __builtin_snprintf (buffer (size), size, __VA_ARGS__)
  61
  62 void test_int_retval_used (void)
  63 {
  64   T (2, "%i", 123);          /* { dg-warning "output truncated" } */
  65   T (2, "%i", R (1, 99));    /* { dg-warning "output may be truncated" } */
  66   T (2, "%i", R (10, 99));   /* { dg-warning "output truncated" } */
  67   T (3, "%i%i", R (1, 99), R (1, 99));   /* { dg-warning "output may be truncated" } */
  68 }
  69
  70 void test_string_retval_used (const Arrays *ar)
  71 {
  72   T (1, "%-s", ar->a0);   /* { dg-warning "output may be truncated" } */
  73   T (1, "%-s", ar->a1);
  74   T (1, "%-s", ar->a2);   /* { dg-warning "output may be truncated" } */
  75 }