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Re: [PATCH RESEND v2] util/cutils: Expand do_strtosz parsing precision t
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From: |
Christophe de Dinechin |
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Subject: |
Re: [PATCH RESEND v2] util/cutils: Expand do_strtosz parsing precision to 64 bits |
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Date: |
Tue, 17 Dec 2019 12:44:29 +0100 |
> On 9 Dec 2019, at 09:30, Tao Xu <address@hidden> wrote:
>
> Parse input string both as a double and as a uint64_t, then use the
> method which consumes more characters. Update the related test cases.
>
> Signed-off-by: Tao Xu <address@hidden>
> ---
>
> Changes in v2:
> - Resend to use double small than DBL_MIN
> - Add more test case for double overflow and underflow.
> - Set mul as int64_t (Markus)
> - Restore endptr (Markus)
> ---
> tests/test-cutils.c | 37 +++++++----------------
> tests/test-keyval.c | 47 +++++------------------------
> tests/test-qemu-opts.c | 39 +++++-------------------
> util/cutils.c | 67 +++++++++++++++++++++++++++++++-----------
> 4 files changed, 75 insertions(+), 115 deletions(-)
>
> diff --git a/tests/test-cutils.c b/tests/test-cutils.c
> index 1aa8351520..49e495b8ba 100644
> --- a/tests/test-cutils.c
> +++ b/tests/test-cutils.c
> @@ -1970,40 +1970,25 @@ static void test_qemu_strtosz_simple(void)
> g_assert_cmpint(err, ==, 0);
> g_assert_cmpint(res, ==, 12345);
>
> - /* Note: precision is 53 bits since we're parsing with strtod() */
> -
> - str = "9007199254740991"; /* 2^53-1 */
> - err = qemu_strtosz(str, &endptr, &res);
> - g_assert_cmpint(err, ==, 0);
> - g_assert_cmpint(res, ==, 0x1fffffffffffff);
> - g_assert(endptr == str + 16);
> -
> - str = "9007199254740992"; /* 2^53 */
> - err = qemu_strtosz(str, &endptr, &res);
> - g_assert_cmpint(err, ==, 0);
> - g_assert_cmpint(res, ==, 0x20000000000000);
> - g_assert(endptr == str + 16);
> + /* Note: precision is 64 bits (UINT64_MAX) */
>
> str = "9007199254740993"; /* 2^53+1 */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, 0);
> - g_assert_cmpint(res, ==, 0x20000000000000); /* rounded to 53 bits */
> + g_assert_cmpint(res, ==, 0x20000000000001);
> g_assert(endptr == str + 16);
>
> - str = "18446744073709549568"; /* 0xfffffffffffff800 (53 msbs set) */
> + str = "18446744073709550591"; /* 0xfffffffffffffbff */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, 0);
> - g_assert_cmpint(res, ==, 0xfffffffffffff800);
> + g_assert_cmpint(res, ==, 0xfffffffffffffbff);
> g_assert(endptr == str + 20);
>
> - str = "18446744073709550591"; /* 0xfffffffffffffbff */
> + str = "18446744073709551615"; /* 2^64-1 (UINT64_MAX) */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, 0);
> - g_assert_cmpint(res, ==, 0xfffffffffffff800); /* rounded to 53 bits */
> + g_assert_cmpint(res, ==, 0xffffffffffffffff);
> g_assert(endptr == str + 20);
> -
> - /* 0x7ffffffffffffe00..0x7fffffffffffffff get rounded to
> - * 0x8000000000000000, thus -ERANGE; see test_qemu_strtosz_erange() */
> }
>
> static void test_qemu_strtosz_units(void)
> @@ -2145,20 +2130,20 @@ static void test_qemu_strtosz_erange(void)
> g_assert_cmpint(err, ==, -ERANGE);
> g_assert(endptr == str + 2);
>
> - str = "18446744073709550592"; /* 0xfffffffffffffc00 */
> + str = "18446744073709551616"; /* 2^64 */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, -ERANGE);
> g_assert(endptr == str + 20);
>
> - str = "18446744073709551615"; /* 2^64-1 */
> + str = "1.7976931348623158e+308"; /* DBL_MAX, double overflows */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, -ERANGE);
> - g_assert(endptr == str + 20);
> + g_assert(endptr == str + 23);
>
> - str = "18446744073709551616"; /* 2^64 */
> + str = "2.225e-308"; /* Small than DBL_MIN, double underflows */
> err = qemu_strtosz(str, &endptr, &res);
> g_assert_cmpint(err, ==, -ERANGE);
> - g_assert(endptr == str + 20);
> + g_assert(endptr == str + 10);
>
> str = "20E";
> err = qemu_strtosz(str, &endptr, &res);
> diff --git a/tests/test-keyval.c b/tests/test-keyval.c
> index 09b0ae3c68..fad941fcb8 100644
> --- a/tests/test-keyval.c
> +++ b/tests/test-keyval.c
> @@ -383,59 +383,26 @@ static void test_keyval_visit_size(void)
> visit_end_struct(v, NULL);
> visit_free(v);
>
> - /* Note: precision is 53 bits since we're parsing with strtod() */
> + /* Note: precision is 64 bits (UINT64_MAX) */
>
> - /* Around limit of precision: 2^53-1, 2^53, 2^53+1 */
> - qdict = keyval_parse("sz1=9007199254740991,"
> - "sz2=9007199254740992,"
> - "sz3=9007199254740993",
> + /* Around limit of precision: UINT64_MAX - 1, UINT64_MAX */
> + qdict = keyval_parse("sz1=18446744073709551614,"
> + "sz2=18446744073709551615",
> NULL, &error_abort);
> v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
> qobject_unref(qdict);
> visit_start_struct(v, NULL, NULL, 0, &error_abort);
> visit_type_size(v, "sz1", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0x1fffffffffffff);
> + g_assert_cmphex(sz, ==, 0xfffffffffffffffe);
> visit_type_size(v, "sz2", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0x20000000000000);
> - visit_type_size(v, "sz3", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0x20000000000000);
> - visit_check_struct(v, &error_abort);
> - visit_end_struct(v, NULL);
> - visit_free(v);
> -
> - /* Close to signed upper limit 0x7ffffffffffffc00 (53 msbs set) */
> - qdict = keyval_parse("sz1=9223372036854774784," /* 7ffffffffffffc00 */
> - "sz2=9223372036854775295", /* 7ffffffffffffdff */
> - NULL, &error_abort);
> - v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
> - qobject_unref(qdict);
> - visit_start_struct(v, NULL, NULL, 0, &error_abort);
> - visit_type_size(v, "sz1", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0x7ffffffffffffc00);
> - visit_type_size(v, "sz2", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0x7ffffffffffffc00);
> - visit_check_struct(v, &error_abort);
> - visit_end_struct(v, NULL);
> - visit_free(v);
> -
> - /* Close to actual upper limit 0xfffffffffffff800 (53 msbs set) */
> - qdict = keyval_parse("sz1=18446744073709549568," /* fffffffffffff800 */
> - "sz2=18446744073709550591", /* fffffffffffffbff */
> - NULL, &error_abort);
> - v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
> - qobject_unref(qdict);
> - visit_start_struct(v, NULL, NULL, 0, &error_abort);
> - visit_type_size(v, "sz1", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0xfffffffffffff800);
> - visit_type_size(v, "sz2", &sz, &error_abort);
> - g_assert_cmphex(sz, ==, 0xfffffffffffff800);
> + g_assert_cmphex(sz, ==, 0xffffffffffffffff);
> visit_check_struct(v, &error_abort);
> visit_end_struct(v, NULL);
> visit_free(v);
>
> /* Beyond limits */
> qdict = keyval_parse("sz1=-1,"
> - "sz2=18446744073709550592", /* fffffffffffffc00 */
> + "sz2=18446744073709551616", /* 2^64 */
> NULL, &error_abort);
> v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
> qobject_unref(qdict);
> diff --git a/tests/test-qemu-opts.c b/tests/test-qemu-opts.c
> index ef96e84aed..3a8b8c0168 100644
> --- a/tests/test-qemu-opts.c
> +++ b/tests/test-qemu-opts.c
> @@ -650,50 +650,25 @@ static void test_opts_parse_size(void)
> g_assert_cmpuint(opts_count(opts), ==, 1);
> g_assert_cmpuint(qemu_opt_get_size(opts, "size1", 1), ==, 0);
>
> - /* Note: precision is 53 bits since we're parsing with strtod() */
> + /* Note: precision is 64 bits (UINT64_MAX) */
>
> - /* Around limit of precision: 2^53-1, 2^53, 2^54 */
> + /* Around limit of precision: UINT64_MAX - 1, UINT64_MAX */
> opts = qemu_opts_parse(&opts_list_02,
> - "size1=9007199254740991,"
> - "size2=9007199254740992,"
> - "size3=9007199254740993",
> - false, &error_abort);
> - g_assert_cmpuint(opts_count(opts), ==, 3);
> - g_assert_cmphex(qemu_opt_get_size(opts, "size1", 1),
> - ==, 0x1fffffffffffff);
> - g_assert_cmphex(qemu_opt_get_size(opts, "size2", 1),
> - ==, 0x20000000000000);
> - g_assert_cmphex(qemu_opt_get_size(opts, "size3", 1),
> - ==, 0x20000000000000);
> -
> - /* Close to signed upper limit 0x7ffffffffffffc00 (53 msbs set) */
> - opts = qemu_opts_parse(&opts_list_02,
> - "size1=9223372036854774784," /* 7ffffffffffffc00
> */
> - "size2=9223372036854775295", /* 7ffffffffffffdff
> */
> - false, &error_abort);
> - g_assert_cmpuint(opts_count(opts), ==, 2);
> - g_assert_cmphex(qemu_opt_get_size(opts, "size1", 1),
> - ==, 0x7ffffffffffffc00);
> - g_assert_cmphex(qemu_opt_get_size(opts, "size2", 1),
> - ==, 0x7ffffffffffffc00);
> -
> - /* Close to actual upper limit 0xfffffffffffff800 (53 msbs set) */
> - opts = qemu_opts_parse(&opts_list_02,
> - "size1=18446744073709549568," /* fffffffffffff800
> */
> - "size2=18446744073709550591", /* fffffffffffffbff
> */
> + "size1=18446744073709551614,"
> + "size2=18446744073709551615",
> false, &error_abort);
> g_assert_cmpuint(opts_count(opts), ==, 2);
> g_assert_cmphex(qemu_opt_get_size(opts, "size1", 1),
> - ==, 0xfffffffffffff800);
> + ==, 0xfffffffffffffffe);
> g_assert_cmphex(qemu_opt_get_size(opts, "size2", 1),
> - ==, 0xfffffffffffff800);
> + ==, 0xffffffffffffffff);
>
> /* Beyond limits */
> opts = qemu_opts_parse(&opts_list_02, "size1=-1", false, &err);
> error_free_or_abort(&err);
> g_assert(!opts);
> opts = qemu_opts_parse(&opts_list_02,
> - "size1=18446744073709550592", /* fffffffffffffc00
> */
> + "size1=18446744073709551616", /* 2^64 */
> false, &err);
> error_free_or_abort(&err);
> g_assert(!opts);
> diff --git a/util/cutils.c b/util/cutils.c
> index 77acadc70a..7c94ff2f0b 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -212,19 +212,39 @@ static int do_strtosz(const char *nptr, const char
> **end,
> const char default_suffix, int64_t unit,
> uint64_t *result)
> {
> - int retval;
> - const char *endptr;
> + int retval, retd, retu;
> + const char *endptr, *suffixd, *suffixu;
> unsigned char c;
> int mul_required = 0;
> - double val, mul, integral, fraction;
> + bool use_strtod;
> + uint64_t valu;
> + int64_t mul;
> + double vald, integral, fraction;
> +
> + /*
> + * Parse @nptr both as a double and as a uint64_t, then use the method
> + * which consumes more characters.
> + */
Why do ever need to parse as double if you have uint64?
> + retd = qemu_strtod_finite(nptr, &suffixd, &vald);
> + retu = qemu_strtou64(nptr, &suffixu, 0, &valu);
> + use_strtod = strlen(suffixd) < strlen(suffixu);
You could simply compare suffixd and suffixu:
use_strtod = suffixd > suffixu;
> +
> + if (use_strtod) {
> + endptr = suffixd;
> + retval = retd;
> + } else {
> + endptr = suffixu;
> + retval = retu;
> + }
>
> - retval = qemu_strtod_finite(nptr, &endptr, &val);
> if (retval) {
> goto out;
> }
> - fraction = modf(val, &integral);
> - if (fraction != 0) {
> - mul_required = 1;
> + if (use_strtod) {
> + fraction = modf(vald, &integral);
> + if (fraction != 0) {
> + mul_required = 1;
> + }
> }
> c = *endptr;
> mul = suffix_mul(c, unit);
> @@ -238,17 +258,30 @@ static int do_strtosz(const char *nptr, const char
> **end,
> retval = -EINVAL;
> goto out;
> }
> - /*
> - * Values near UINT64_MAX overflow to 2**64 when converting to double
> - * precision. Compare against the maximum representable double precision
> - * value below 2**64, computed as "the next value after 2**64 (0x1p64) in
> - * the direction of 0".
> - */
> - if ((val * mul > nextafter(0x1p64, 0)) || val < 0) {
> - retval = -ERANGE;
> - goto out;
> +
> + if (use_strtod) {
> + /*
> + * Values near UINT64_MAX overflow to 2**64 when converting to double
> + * precision. Compare against the maximum representable double
> precision
> + * value below 2**64, computed as "the next value after 2**64
> (0x1p64)
> + * in the direction of 0".
> + */
> + if ((vald * mul > nextafter(0x1p64, 0)) || vald < 0) {
> + retval = -ERANGE;
> + goto out;
> + }
> + *result = vald * mul;
> + } else {
> + /* Reject negative input and overflow output */
> + while (qemu_isspace(*nptr)) {
> + nptr++;
> + }
> + if (*nptr == '-' || UINT64_MAX / mul < valu) {
> + retval = -ERANGE;
> + goto out;
> + }
> + *result = valu * mul;
> }
> - *result = val * mul;
> retval = 0;
>
> out:
> --
> 2.20.1
>
>