Viewing file:  builtin-snprintf-warn-2.c (2.29 KB) -rw-r--r--
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/* { dg-do compile } */
/* { dg-options "-O2 -Wformat -Wformat-truncation=2 -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)
/* 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__)
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 2 strings of unknown length are assumed to be 1 character
long, so the following is diagnosed. */
T (1, "%-s", ar->a0); /* { dg-warning "output may be truncated" } */
T (1, "%-s", ar->a1);
T (1, "%-s", ar->a2); /* { dg-warning "output may be truncated" } */
}
/* Verify that (at -Wformat-trunc=2) calls to snprintf whose return value
is used are diagnosed the same way as those whose value is unused. */
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)); /* { 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_used (const Arrays *ar)
{
T (1, "%-s", ar->a0); /* { dg-warning "output may be truncated" } */
T (1, "%-s", ar->a1);
T (1, "%-s", ar->a2); /* { dg-warning "output may be truncated" } */
}
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