Re: [PATCH v2 4/4] utils: Deprecate inexact fractional suffix sizes

The value '1.1k' is inexact; 1126.4 bytes is not possible, so we happen to truncate it to 1126. Our use of fractional sizes is intended for convenience, but when a user specifies a fraction that is not a clean translation to binary, truncating/rounding behind their backs can cause confusion. Better is to deprecate inexact values, which still leaves '1.5k' as valid, but alerts the user to spell out their values as a precise byte number in cases where they are currently being rounded. Note that values like '0.1G' in the testsuite need adjustment as a result. Since qemu_strtosz() does not have an Err** parameter, and plumbing that in would be a much larger task, we instead go with just directly emitting the deprecation warning to stderr. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- I'm not a fan of this patch, but am proposing it for discussion purposes.

--- docs/system/deprecated.rst | 9 +++++++++ tests/test-cutils.c | 6 +++--- tests/test-keyval.c | 4 ++-- tests/test-qemu-opts.c | 4 ++-- util/cutils.c | 9 +++++++-- 5 files changed, 23 insertions(+), 9 deletions(-) diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst index 113c2e933f1b..2c9cb849eec5 100644 --- a/docs/system/deprecated.rst +++ b/docs/system/deprecated.rst @@ -154,6 +154,15 @@ Input parameters that take a size value should only use a size suffix the value is hexadecimal. That is, '0x20M' is deprecated, and should be written either as '32M' or as '0x2000000'. +inexact sizes via scaled fractions (since 6.0) +'''''''''''''''''''''''''''''''''''''''''''''' + +Input parameters that take a size value should only use a fractional +size (such as '1.5M') that will result in an exact byte value. The +use of inexact values (such as '1.1M') that require truncation or +rounding is deprecated, and you should instead consider writing your +unusual size in bytes (here, '1153433' or '1153434' as desired).