Picolibc's 'minimal' printf mode reduces functionality and size even more
than the 'integer' mode. Use this where memory is at a premium and where
the application knows that it does not require exact printf semantics.
1.8.5 adds two more printf variants, 'long long' and 'minimal'. The 'long
long' variant is the same as the 'integer' variant but with long long
support enabled. The 'minimal' variant reduces functionality and size even
more than the 'integer' mode. Applications can use this where memory is at
a premium and where the application does not require exact printf
semantics.
With these two added variants, the SDK has enough options so that all of
the cbprintf modes can be supported with the pre-compiled bits:
1. CBPRINTF_NANO - picolibc's 'minimal' variant
2. CBPRINTF_REDUCED_INTEGRAL - picolibc's 'integer' variant
3. CBPRINTF_FULL_INTEGRAL - picolibc's 'long long' variant
4. CBPRINTF_FB_SUPPORT - picolibc's 'double' variant
This patch makes the cbprintf Kconfig values drive the default picolibc
variant, disables picolibc variants not capable of supporting the required
cbprintf level, but allows applications to select more functionality in
picolibc than cbprintf requires.
Note that this depends on the SDK including picolibc 1.8.5. Without that,
selecting the 'minimal' or 'long long' variant in Zephyr will end up with
the default variant from picolibc, which is the full version with floating
point support. When using the module things will work as specified.
Signed-off-by: Keith Packard <keithp@keithp.com>
CBPRINTF_FULL_INTEGRAL doesn't happen to explicitly conflict with
CBPRINTF_NANO, but when CBPRINTF_NANO is enabled, there's no long long I/O
support provided.
Allow picolibc long-long I/O support to also be elided when CBPRINTF_NANO
is enabled to save similar amounts of space.
Signed-off-by: Keith Packard <keithp@keithp.com>
* Picolibc doesn't provide the %a-only mode.
* On advice from security experts, who report numerous vulnerabilities
caused by %n in printf specifiers, picolibc never supports this
feature.
* Picolibc doesn't use cbprintf for C-library compatible functions,
instead it provides aliases for the *printfcb functions using stdio
names.
Signed-off-by: Keith Packard <keithp@keithp.com>
Add CONFIG_CBPRINTF_CONVERT_CHECK_PTR which enables support for
checking if string candidate pointer is not %p. It is by default
disabled when logging strings are removed from the binary. Option
is added to save code.
Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
When aiming for the smallest build result, it is desirable to
use CONFIG_CBPRINTF_NANO together with CONFIG_MINIMAL_LIBC. However
that doesn't mean we need all the functions enabled by having
CONFIG_CBPRINTF_LIBC_SUBSTS=y which increases the binary size even if
those functions are not used and not linked in.
When CONFIG_CBPRINTF_LIBC_SUBSTS=n such functions are not defined
anyway so z_cbvprintf_impl() won't be invoked with missing
functionalities.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
People interested in those options may be truly concerned by binary
sizes. Let's provide complete information.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Static packaging is using only argument types to build a package. There
is one case where analysing argument type only is not enough to
determine package content. That is %p with (unsigned) char pointer vs
%s. In case of %s a string might need to be appended to the package
and in case of %p it must be avoided. Format string analysis is required
to distinguish those two cases.
In order to speed up the runtime inspection, additional information is
added to a static package. That is index of the string argument (where
first argument has index 0). This information allows quick format string
inspection where nth format specifier is found and checked if it is a
pointer format specifier.
Inspection algorithm is added to cbprintf_package_convert() and if %p
is found then data for that argument is discarded. Additionally, log
warning is printed with suggestion to cast pointer argument to void *
to avoid confusion. It is desired to get rid of this ambiguity because
there are going to be logging configurations where strings are stripped
from a binary and runtime inspection cannot be performed.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Picolibc doesn't have the non-standard printf support required for tagged
arguments in cbprintf. Disable this and use the format string parsing code
instead.
Signed-off-by: Keith Packard <keithp@keithp.com>
Picolibc already provides the functionality offered by cbprintf, so
there's no reason to use the larger and less functional version included
in zephyr.
Signed-off-by: Keith Packard <keithp@keithp.com>
This adds some bits to support tagged arguments to be used for
packaging. If enabled, the packaging function no longer looks at
the format strings to determine the types of arguments, but
instead, each argument is tagged with a type by preceding it
with another argument as type (integer). This allows the format
strings to be removed from the final binary to conserve space.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
According to Kconfig guidelines, boolean prompts must not start with
"Enable...". The following command has been used to automate the changes
in this patch:
sed -i "s/bool \"[Ee]nables\? \(\w\)/bool \"\U\1/g" **/Kconfig*
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
Prevent CONFIG_CBPRINTF_STATIC_PACKAGE_CHECK_ALIGNMENT when LOG_PRINTK.
Prevent use of assert in cbprintf header when printk is redirected
to logging. Enabling it would lead to circular header includes and
compilation failure.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
This commit adds a C99 stdio value formatter capability where
generated text is emitted through a callback. This allows generation
of arbitrarily long output without a buffer, functionality that is
core to printk, logging, and other system and application needs.
The formatter supports most C99 specifications, excluding:
* %Lf long double conversion
* wide character output
Kconfig options allow disabling features like floating-point
conversion if they are not necessary. By default most conversions are
enabled.
The original z_vprintk() implementation is adapted to meet the
interface requirements of cbvprintf, and made available as an opt-in
feature for space-constrained applications that do not need full
formatting support.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
