Viewing file:  builtin-snprintf-warn-1.c (2.7 KB) -rw-r--r--
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/* { dg-do compile } */
/* { dg-options "-O2 -Wformat -Wformat-truncation=1 -ftrack-macro-expansion=0" } */
typedef struct
{
char a0[0];
/* Separate a0 from a1 to prevent the former from being substituted
for the latter and causing false positives. */
int: 8;
char a1[1];
char a2[2];
char a3[3];
char a4[4];
char ax[];
} Arrays;
char buffer[1024];
#define buffer(size) (buffer + sizeof buffer - size)
static int value_range (int min, int max)
{
extern int value (void);
int val = value ();
return val < min || max < val ? min : val;
}
#define R(min, max) value_range (min, max)
extern void sink (void*);
/* Verify that calls to snprintf whose return value is unused are
diagnosed if certain or possible truncation is detected. */
#define T(size, ...) \
__builtin_snprintf (buffer (size), size, __VA_ARGS__), sink (buffer)
void test_int_retval_unused (void)
{
T (2, "%i", 123); /* { dg-warning "output truncated" } */
T (2, "%i", R (1, 99)); /* { dg-warning "output may be truncated" } */
T (2, "%i", R (10, 99)); /* { dg-warning "output truncated" } */
T (3, "%i%i", R (1, 99), R (1, 99)); /* { dg-warning "output may be truncated" } */
}
void test_string_retval_unused (const Arrays *ar)
{
/* At level 1 strings of unknown length are assumed to be empty so
the following is not diagnosed. */
T (1, "%-s", ar->a0);
/* A one-byte array can only hold an empty string, so the following
isn't diagnosed. */
T (1, "%-s", ar->a1);
/* Unlike the ar->a0 case above, at level 1, the length of an unknown
string that points to an array of known size is assumed to be the
size of the array minus 1. */
T (1, "%-s", ar->a2); /* { dg-warning "output may be truncated" } */
T (1, "%-s", ar->a3); /* { dg-warning "output may be truncated" } */
T (1, "%-s", ar->a4); /* { dg-warning "output may be truncated" } */
/* Same as the ar->a0 case above. */
T (1, "%-s", ar->ax);
}
/* Verify that calls to snprintf whose return value is used are
diagnosed only if certain truncation is detected but not when
truncation is only possible but not certain. */
volatile int retval;
#undef T
#define T(size, ...) \
retval = __builtin_snprintf (buffer (size), size, __VA_ARGS__)
void test_int_retval_used (void)
{
T (2, "%i", 123); /* { dg-warning "output truncated" } */
T (2, "%i", R (1, 99));
T (2, "%i", R (10, 99)); /* { dg-warning "output truncated" } */
T (3, "%i%i", R (1, 99), R (1, 99));
}
void test_string_retval_used (const Arrays *ar)
{
T (1, "%-s", ar->a0);
T (1, "%-s", ar->a1);
T (1, "%-s", ar->a2);
T (1, "%-s", ar->a3);
T (1, "%-s", ar->a4);
T (1, "%-s", "123"); /* { dg-warning "output truncated" } */
}
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