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111
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1 /* { dg-do compile } */
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2 /* { dg-options "-O2 -Wformat -Wformat-truncation=1 -ftrack-macro-expansion=0" } */
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3
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4 typedef struct
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5 {
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6 char a0[0];
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7 /* Separate a0 from a1 to prevent the former from being substituted
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8 for the latter and causing false positives. */
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9 int: 8;
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10 char a1[1];
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11 char a2[2];
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12 char a3[3];
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13 char a4[4];
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14 char ax[];
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15 } Arrays;
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16
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17 char buffer[1024];
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18 #define buffer(size) (buffer + sizeof buffer - size)
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19
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131
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20 static int value_range (int min, int max)
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111
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21 {
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22 extern int value (void);
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23 int val = value ();
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24 return val < min || max < val ? min : val;
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25 }
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26
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27 #define R(min, max) value_range (min, max)
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28
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29 extern void sink (void*);
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30
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31 /* Verify that calls to snprintf whose return value is unused are
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32 diagnosed if certain or possible truncation is detected. */
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33
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34 #define T(size, ...) \
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35 __builtin_snprintf (buffer (size), size, __VA_ARGS__), sink (buffer)
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36
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37 void test_int_retval_unused (void)
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38 {
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39 T (2, "%i", 123); /* { dg-warning "output truncated" } */
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40 T (2, "%i", R (1, 99)); /* { dg-warning "output may be truncated" } */
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41 T (2, "%i", R (10, 99)); /* { dg-warning "output truncated" } */
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42 T (3, "%i%i", R (1, 99), R (1, 99)); /* { dg-warning "output may be truncated" } */
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43 }
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44
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45 void test_string_retval_unused (const Arrays *ar)
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46 {
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47 /* At level 1 strings of unknown length are assumed to be empty so
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48 the following is not diagnosed. */
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49 T (1, "%-s", ar->a0);
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50 /* A one-byte array can only hold an empty string, so the following
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51 isn't diagnosed. */
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52 T (1, "%-s", ar->a1);
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53 /* Unlike the ar->a0 case above, at level 1, the length of an unknown
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54 string that points to an array of known size is assumed to be the
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55 size of the array minus 1. */
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56 T (1, "%-s", ar->a2); /* { dg-warning "output may be truncated" } */
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57 T (1, "%-s", ar->a3); /* { dg-warning "output may be truncated" } */
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58 T (1, "%-s", ar->a4); /* { dg-warning "output may be truncated" } */
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59 /* Same as the ar->a0 case above. */
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60 T (1, "%-s", ar->ax);
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61 }
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62
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63
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64 /* Verify that calls to snprintf whose return value is used are
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65 diagnosed only if certain truncation is detected but not when
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66 truncation is only possible but not certain. */
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67
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68 volatile int retval;
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69
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70 #undef T
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71 #define T(size, ...) \
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72 retval = __builtin_snprintf (buffer (size), size, __VA_ARGS__)
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73
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74 void test_int_retval_used (void)
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75 {
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76 T (2, "%i", 123); /* { dg-warning "output truncated" } */
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77 T (2, "%i", R (1, 99));
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78 T (2, "%i", R (10, 99)); /* { dg-warning "output truncated" } */
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79 T (3, "%i%i", R (1, 99), R (1, 99));
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80 }
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81
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82 void test_string_retval_used (const Arrays *ar)
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83 {
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84 T (1, "%-s", ar->a0);
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85 T (1, "%-s", ar->a1);
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86 T (1, "%-s", ar->a2);
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87 T (1, "%-s", ar->a3);
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88 T (1, "%-s", ar->a4);
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89 T (1, "%-s", "123"); /* { dg-warning "output truncated" } */
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90 }
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