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]
42cc08d13a