cutils: Improve qemu_strtosz handling of fractions
We have several limitations and bugs worth fixing; they are inter-related enough that it is not worth splitting this patch into smaller pieces: * ".5k" should work to specify 512, just as "0.5k" does * "1.9999k" and "1." + "9"*50 + "k" should both produce the same result of 2048 after rounding * "1." + "0"*350 + "1B" should not be treated the same as "1.0B"; underflow in the fraction should not be lost * "7.99e99" and "7.99e999" look similar, but our code was doing a read-out-of-bounds on the latter because it was not expecting ERANGE due to overflow. While we document that scientific notation is not supported, and the previous patch actually fixed qemu_strtod_finite() to no longer return ERANGE overflows, it is easier to pre-filter than to try and determine after the fact if strtod() consumed more than we wanted. Note that this is a low-level semantic change (when endptr is not NULL, we can now successfully parse with a scale of 'E' and then report trailing junk, instead of failing outright with EINVAL); but an earlier commit already argued that this is not a high-level semantic change since the only caller passing in a non-NULL endptr also checks that the tail is whitespace-only. Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1629 Fixes:cf923b78("utils: Improve qemu_strtosz() to have 64 bits of precision", 6.0.0) Fixes:7625a1ed("utils: Use fixed-point arithmetic in qemu_strtosz", 6.0.0) Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Hanna Czenczek <hreitz@redhat.com> Message-Id: <20230522190441.64278-20-eblake@redhat.com> [eblake: tweak function comment for accuracy]
This commit is contained in:
Eric Blake
parent
c25b168344
commit
42cc08d13a
@ -3408,19 +3408,18 @@ static void test_qemu_strtosz_float(void)
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/* An empty fraction tail is tolerated */
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do_strtosz("1.k", 0, 1024, 3);
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/* FIXME An empty fraction head should be tolerated */
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do_strtosz(" .5k", -EINVAL /* FIXME 0 */, 0 /* FIXME 512 */,
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0 /* FIXME 4 */);
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/* An empty fraction head is tolerated */
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do_strtosz(" .5k", 0, 512, 4);
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/* For convenience, we permit values that are not byte-exact */
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do_strtosz("12.345M", 0, (uint64_t) (12.345 * MiB + 0.5), 7);
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/* FIXME Fraction tail should round correctly */
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/* Fraction tail can round up */
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do_strtosz("1.9999k", 0, 2048, 7);
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do_strtosz("1.9999999999999999999999999999999999999999999999999999k", 0,
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1024 /* FIXME 2048 */, 55);
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2048, 55);
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/* FIXME ERANGE underflow in the fraction tail should not matter for 'k' */
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/* ERANGE underflow in the fraction tail does not matter for 'k' */
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do_strtosz("1."
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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@ -3429,7 +3428,7 @@ static void test_qemu_strtosz_float(void)
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"1k", 0, 1 /* FIXME 1024 */, 354);
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"1k", 0, 1024, 354);
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}
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static void test_qemu_strtosz_invalid(void)
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@ -3453,10 +3452,9 @@ static void test_qemu_strtosz_invalid(void)
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do_strtosz("1.1B", -EINVAL, 0, 0);
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do_strtosz("1.1", -EINVAL, 0, 0);
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/* FIXME underflow in the fraction tail should matter for 'B' */
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/* 'B' cannot have any nonzero fraction, even with rounding or underflow */
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do_strtosz("1.00001B", -EINVAL, 0, 0);
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do_strtosz("1.00000000000000000001B", 0 /* FIXME -EINVAL */,
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1 /* FIXME 0 */, 23 /* FIXME 0 */);
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do_strtosz("1.00000000000000000001B", -EINVAL, 0, 0);
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do_strtosz("1."
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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@ -3465,8 +3463,7 @@ static void test_qemu_strtosz_invalid(void)
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"1B", 0 /* FIXME -EINVAL */, 1 /* FIXME 0 */,
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354 /* FIXME 0 */);
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"1B", -EINVAL, 0, 0);
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/* No hex fractions */
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do_strtosz("0x1.8k", -EINVAL, 0, 0);
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@ -3512,28 +3509,20 @@ static void test_qemu_strtosz_trailing(void)
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do_strtosz_full("123-45", qemu_strtosz, 0, 123, 3, -EINVAL, 0);
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do_strtosz_full(" 123 - 45", qemu_strtosz, 0, 123, 4, -EINVAL, 0);
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/* FIXME should stop parse after 'e'. No floating point exponents */
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do_strtosz_full("1.5e1k", qemu_strtosz, -EINVAL /* FIXME 0 */,
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0 /* FIXME EiB * 1.5 */, 0 /* FIXME 4 */,
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-EINVAL, 0);
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do_strtosz_full("1.5E+0k", qemu_strtosz, -EINVAL /* FIXME 0 */,
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0 /* FIXME EiB * 1.5 */, 0 /* FIXME 4 */,
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-EINVAL, 0);
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/* FIXME overflow in fraction is still buggy */
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do_strtosz_full("1.5E999", qemu_strtosz, 0, 1 /* FIXME EiB * 1.5 */,
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2 /* FIXME 4 */, -EINVAL, 0);
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/* Parse stops at 'e', which is not a floating point exponent */
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do_strtosz_full("1.5e1k", qemu_strtosz, 0, EiB * 1.5, 4, -EINVAL, 0);
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do_strtosz_full("1.5E+0k", qemu_strtosz, 0, EiB * 1.5, 4, -EINVAL, 0);
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do_strtosz_full("1.5E999", qemu_strtosz, 0, EiB * 1.5, 4, -EINVAL, 0);
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}
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static void test_qemu_strtosz_erange(void)
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{
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/* FIXME negative values fit better as ERANGE */
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/* no negative values */
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do_strtosz(" -0", -ERANGE, 0, 3);
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do_strtosz("-1", -ERANGE, 0, 2);
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do_strtosz_full("-2M", qemu_strtosz, -ERANGE, 0, 2, -EINVAL, 0);
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do_strtosz(" -.0", -EINVAL /* FIXME -ERANGE */, 0, 0 /* FIXME 4 */);
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do_strtosz_full("-.1k", qemu_strtosz, -EINVAL /* FIXME -ERANGE */, 0,
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0 /* FIXME 3 */, -EINVAL, 0);
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do_strtosz(" -.0", -ERANGE, 0, 4);
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do_strtosz_full("-.1k", qemu_strtosz, -ERANGE, 0, 3, -EINVAL, 0);
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do_strtosz_full(" -."
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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@ -3542,17 +3531,16 @@ static void test_qemu_strtosz_erange(void)
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"00000000000000000000000000000000000000000000000000"
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"1M", qemu_strtosz, -EINVAL /* FIXME -ERANGE */, 0,
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0 /* FIXME 354 */, -EINVAL, 0);
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"1M", qemu_strtosz, -ERANGE, 0, 354, -EINVAL, 0);
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/* 2^64; see strtosz_simple for 2^64-1 */
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do_strtosz("18446744073709551616", -ERANGE, 0, 20);
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do_strtosz("20E", -ERANGE, 0, 3);
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/* FIXME Fraction tail can cause ERANGE overflow */
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/* Fraction tail can cause ERANGE overflow */
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do_strtosz("15.9999999999999999999999999999999999999999999999999999E",
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0 /* FIXME -ERANGE */, 15ULL * EiB /* FIXME 0 */, 56);
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-ERANGE, 0, 56);
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/* EINVAL has priority over ERANGE */
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do_strtosz_full("100000Pjunk", qemu_strtosz, -ERANGE, 0, 7, -EINVAL, 0);
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@ -194,15 +194,19 @@ static int64_t suffix_mul(char suffix, int64_t unit)
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* - 12345 - decimal, scale determined by @default_suffix and @unit
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* - 12345{bBkKmMgGtTpPeE} - decimal, scale determined by suffix and @unit
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* - 12345.678{kKmMgGtTpPeE} - decimal, scale determined by suffix, and
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* fractional portion is truncated to byte
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* fractional portion is truncated to byte, either side of . may be empty
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* - 0x7fEE - hexadecimal, unit determined by @default_suffix
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*
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* The following are intentionally not supported
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* - hex with scaling suffix, such as 0x20M
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* - octal, such as 08
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* - fractional hex, such as 0x1.8
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* - negative values, including -0
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* - floating point exponents, such as 1e3
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* - hex with scaling suffix, such as 0x20M or 0x1p3 (both fail with
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* -EINVAL), while 0x1b is 27 (not 1 with byte scale)
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* - octal, such as 08 (parsed as decimal instead)
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* - binary, such as 0b1000 (parsed as 0b with trailing garbage "1000")
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* - fractional hex, such as 0x1.8 (parsed as 0 with trailing garbage "x1.8")
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* - negative values, including -0 (fail with -ERANGE)
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* - floating point exponents, such as 1e3 (parsed as 1e with trailing
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* garbage "3") or 0x1p3 (rejected as hex with scaling suffix)
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* - non-finite values, such as inf or NaN (fail with -EINVAL)
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*
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* The end pointer will be returned in *end, if not NULL. If there is
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* no fraction, the input can be decimal or hexadecimal; if there is a
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@ -221,17 +225,17 @@ static int do_strtosz(const char *nptr, const char **end,
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uint64_t *result)
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{
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int retval;
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const char *endptr, *f;
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const char *endptr;
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unsigned char c;
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uint64_t val, valf = 0;
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uint64_t val = 0, valf = 0;
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int64_t mul;
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/* Parse integral portion as decimal. */
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retval = parse_uint(nptr, &endptr, 10, &val);
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if (retval) {
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if (retval == -ERANGE || !nptr) {
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goto out;
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}
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if (val == 0 && (*endptr == 'x' || *endptr == 'X')) {
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if (retval == 0 && val == 0 && (*endptr == 'x' || *endptr == 'X')) {
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/* Input looks like hex; reparse, and insist on no fraction or suffix. */
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retval = qemu_strtou64(nptr, &endptr, 16, &val);
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if (retval) {
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@ -242,26 +246,68 @@ static int do_strtosz(const char *nptr, const char **end,
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retval = -EINVAL;
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goto out;
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}
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} else if (*endptr == '.') {
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} else if (*endptr == '.' || (endptr == nptr && strchr(nptr, '.'))) {
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/*
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* Input looks like a fraction. Make sure even 1.k works
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* without fractional digits. If we see an exponent, treat
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* the entire input as invalid instead.
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* without fractional digits. strtod tries to treat 'e' as an
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* exponent, but we want to treat it as a scaling suffix;
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* doing this requires modifying a copy of the fraction.
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*/
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double fraction;
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double fraction = 0.0;
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f = endptr;
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retval = qemu_strtod_finite(f, &endptr, &fraction);
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if (retval) {
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if (retval == 0 && *endptr == '.' && !isdigit(endptr[1])) {
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/* If we got here, we parsed at least one digit already. */
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endptr++;
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} else if (memchr(f, 'e', endptr - f) || memchr(f, 'E', endptr - f)) {
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endptr = nptr;
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retval = -EINVAL;
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goto out;
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} else {
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/* Extract into a 64-bit fixed-point fraction. */
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valf = (uint64_t)(fraction * 0x1p64);
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char *e;
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const char *tail;
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g_autofree char *copy = g_strdup(endptr);
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e = strchr(copy, 'e');
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if (e) {
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*e = '\0';
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}
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e = strchr(copy, 'E');
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if (e) {
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*e = '\0';
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}
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/*
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* If this is a floating point, we are guaranteed that '.'
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* appears before any possible digits in copy. If it is
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* not a floating point, strtod will fail. Either way,
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* there is now no exponent in copy, so if it parses, we
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* know 0.0 <= abs(result) <= 1.0 (after rounding), and
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* ERANGE is only possible on underflow which is okay.
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*/
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retval = qemu_strtod_finite(copy, &tail, &fraction);
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endptr += tail - copy;
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if (signbit(fraction)) {
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retval = -ERANGE;
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goto out;
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}
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}
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/* Extract into a 64-bit fixed-point fraction. */
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if (fraction == 1.0) {
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if (val == UINT64_MAX) {
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retval = -ERANGE;
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goto out;
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}
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val++;
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} else if (retval == -ERANGE) {
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/* See comments above about underflow */
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valf = 1;
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retval = 0;
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} else {
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/* We want non-zero valf for any non-zero fraction */
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valf = (uint64_t)(fraction * 0x1p64);
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if (valf == 0 && fraction > 0.0) {
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valf = 1;
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}
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}
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}
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if (retval) {
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goto out;
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}
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c = *endptr;
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mul = suffix_mul(c, unit);
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