On CHERI, and thus Arm's Morello prototype, pointers are represented as
hardware capabilities. These capabilities are comprised of not just an
integer address, as is the representation for traditional pointers, but
also bounds, permissions and other metadata, plus a tag bit used as the
validity bit, which provides fine-grained spatial and referential safety
for C and C++ in hardware. This tag bit is not part of the data itself
and is instead kept on the side, flowing with the capability between
registers and the memory subsystem, and any attempt to amplify the
privilege of or corrupt a capability clears this tag (or, in some cases,
traps), rendering them impossible to forge; you can only create
capabilities that are (possibly trivial) subsets of existing ones.
When the capability is stored in memory, this tag bit needs to be
preserved, which is done through the use of tagged memory. Every
capability-sized word gains an additional non-addressable (from the
CPU's perspective; depending on the implementation the tag bits may be
stored in a small block of memory carved out of normal DRAM that the CPU
is blocked from accessing) bit. This means that capabilities can only be
stored to aligned locations; attempting to store them to unaligned
locations will trap with an alignment fault or, if you end up using a
memcpy call, will copy the raw bytes of the capability's representation
but lose the tag, so when it is eventually loaded back as a capability
and dereferenced it will fault.
Since, on 64-bit architectures, our capabilities, used to implement C
language pointers, are 128-bit quantities, this means they need 16-byte
alignment. Currently the various #pragma pack directives, used to work
around (extremely broken and bogus) code that includes jsoncpp in a
context where the maximum alignment has been overridden, hard-code 8 as
the maximum alignment to use, and so do not sufficiently align CHERI /
Morello capabilities on 64-bit architectures. On Windows x64, the
default is also not 8 but 16 (ARM64 is supposedly 8), so this is
slightly dodgy to do there too, but in practice likely not an issue so
long as you don't use any 128-bit types there.
Instead of hard-coding a width, use a directive that resets the packing
back to the default. Unfortunately, whilst GCC and Clang both accept
using #pragma pack(push, 0) as shorthand like for any non-zero value,
MSVC does not, so this needs to be two directives.
Return 1.9.1 functionality where values too large to fit in
double are converted to positive or negative infinity.
Commit 645cd04 changed functionality so that large floats cause
parse error, while version 1.9.1 accepted them as infinite.
This is problematic because writer outputs infinity values
as `1e+9999`, which could no longer be parsed back.
Fixed also legacy Reader even though it did not parse large values
even before breaking change, due to problematic output/parse asymmetry.
`>>` operator sets value to numeric_limits::max/lowest value if
representation is too large to fit to double. [1][2] In macos
value appears to be parsed to infinity.
> | value in *val* | description |
> |--------------------------|-------------|
> | numeric_limits::max() | The sequence represents a value too large for the type of val |
> | numeric_limits::lowest() | The sequence represents a value too large negative for the type of val |
[1] https://www.cplusplus.com/reference/istream/istream/operator%3E%3E/
[2] https://www.cplusplus.com/reference/locale/num_get/get/
Signed-off-by: Tero Kinnunen <tero.kinnunen@vaisala.com>
Co-authored-by: Tero Kinnunen <tero.kinnunen@vaisala.com>
When the static libary is available use it as exported alias, otherwise use shared library. Cmake takes care about import library when Windows platform DLL is used
CMake provides helpers to generate config file. Generated config file has usefull macro check_required_components() to set necessary variables like PackageName_FOUND if requirements has been satisfied. An absence of dedicated config file confuses user project as necessary variables are not set.
* Fix a precision bug of valueToString, prevent to give an error result on input of wanted precision 0 and a double value which end of zero before decimal point ,such as 1230.01,12300.1;
Add test cases for double valueToString with precision 0;
* Delete a test case with platform differences in the previous commit
* Fix clang-format.
* Fix clang-format!
Co-authored-by: lilei <dlilei@126.com>
* ENH: Prevent cmake in source builds
Building directly inside the root of the source tree
can cause problems where the build intermediate files
overwrite or conflict with the intended source code
files.
This modification identifies this problem and
issues failure messages and suggestions to over
come the problem with more robust build suggestion.
Co-authored-by: Jordan Bayles <jophba@chromium.org>
This lets us simplify linux a little.
However, we still want to test cmake, so there is only so much we
can simplify.
For OSX, we still need `clang-format` from homebrew.
* Add PYTHONUSERBASE/bin to PATH for linux
