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lib/timeutil: avoid implementation-defined behavior

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The algorithm for converting broken-down civil time to seconds in the
POSIX epoch time scale would produce undefined behavior on a toolchain
that uses a 32-bit time_t in cases where the referenced time could not
be represented exactly.

However, there are use cases in Zephyr for civil time conversions
outside the 32-bit representable range of 1901-12-13T20:45:52Z through
2038-01-19T03:14:07Z inclusive.

Add new API that specifically returns a 64-bit signed seconds count, and
revise the existing API to detect out-of-range values and convert them
to a diagnosible error.

Closes #18465

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
This commit is contained in:
Peter A. Bigot 2019-08-18 03:16:02 -05:00 • committed by Anas Nashif
commit 55ace13c32
3 changed files with 157 additions and 15 deletions
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118
tests/lib/timeutil/src/test_s64.c
View file

@ -6,6 +6,7 @@
/* Tests where time_t requires a 64-bit value */
#include <errno.h>
#include <ztest.h>
#include "timeutil_test.h"
@ -210,10 +211,125 @@ static const struct timeutil_test_data tests[] = {
} },
};
static void test_time32_errno_clear(void)
{
const struct timeutil_test_data *tp = &(const struct timeutil_test_data){
.unix = 0,
.civil = "1970-01-01 00:00:00 Thu 001",
.tm = {
.tm_sec = 0,
.tm_min = 0,
.tm_hour = 0,
.tm_mday = 1,
.tm_mon = 0,
.tm_year = 70,
.tm_wday = 4,
.tm_yday = 0,
},
};
errno = EINVAL;
time_t unix = timeutil_timegm(&tp->tm);
zassert_equal(unix, tp->unix,
"conversion incorrect");
zassert_equal(errno, 0,
"errno was not cleared");
}
static void test_time32_epochm1(void)
{
const struct timeutil_test_data *tp = &(const struct timeutil_test_data){
.unix = -1,
.civil = "1969-12-31 23:59:59 Wed 365",
.tm = {
.tm_sec = 59,
.tm_min = 59,
.tm_hour = 23,
.tm_mday = 31,
.tm_mon = 11,
.tm_year = 69,
.tm_wday = 3,
.tm_yday = 364,
},
};
errno = EINVAL;
time_t unix = timeutil_timegm(&tp->tm);
zassert_equal(unix, tp->unix,
"conversion incorrect");
zassert_equal(errno, 0,
"final errno state bad");
}
static void test_time32_underflow(void)
{
const s64_t unix64 = -2147483649;
const struct timeutil_test_data *tp = &(const struct timeutil_test_data){
.civil = "1901-12-13 20:45:51 Fri 347",
.tm = {
.tm_sec = 51,
.tm_min = 45,
.tm_hour = 20,
.tm_mday = 13,
.tm_mon = 11,
.tm_year = 1,
.tm_wday = 5,
.tm_yday = 346,
},
};
zassert_equal(timeutil_timegm64(&tp->tm), unix64,
"fullscale failed");
errno = 0;
time_t unix = timeutil_timegm(&tp->tm);
zassert_equal(unix, -1,
"underflow undetected");
zassert_equal(errno, ERANGE,
"final errno state bad");
}
static void test_time32_overflow(void)
{
const s64_t unix64 = 2147483648;
const struct timeutil_test_data *tp = &(const struct timeutil_test_data){
.civil = "2038-01-19 03:14:08 Tue 019",
.tm = {
.tm_sec = 8,
.tm_min = 14,
.tm_hour = 3,
.tm_mday = 19,
.tm_mon = 0,
.tm_year = 138,
.tm_wday = 2,
.tm_yday = 18,
},
};
zassert_equal(timeutil_timegm64(&tp->tm), unix64,
"fullscale failed");
errno = 0;
time_t unix = timeutil_timegm(&tp->tm);
zassert_equal(unix, -1,
"overflow undetected");
zassert_equal(errno, ERANGE,
"final errno state bad");
}
void test_s64(void)
{
if (sizeof(time_t) < 8U) {
ztest_test_skip();
test_time32_errno_clear();
test_time32_epochm1();
test_time32_underflow();
test_time32_overflow();
return;
}
timeutil_check(tests, sizeof(tests) / sizeof(*tests));