Otherwise, the math will fail badly. Documentation improved to reflect
reality.
Change-Id: I9e3d261ad9bf41cfb2b6fffd159085cd38e3c388
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
It is not available in the GNU C Library.
Change-Id: I36dc92fca283c126669885b75406c8e57f563ce3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
It appears messenne_twisters in the latest libstdc++ has one more
requirement before it is willing to construct with our
SystemGenerator struct as an sseq provider.
Change-Id: If38151d1fa6f40a80274acc26d9ed6b4ac6049fe
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
We need to override this snippet for the documentation
we generate for Qt for Python, and it is easier to have
it on a separate file.
Task-number: PYSIDE-801
Task-number: PYSIDE-691
Change-Id: Ideb5b6af25024279f167137d3b65660bb9c96a7e
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
Add it to configure.json and replace all occurrences of QT_NO_THREAD
with QT_CONFIG(thread). Add conditions for other features that depend
on thread support. Remove conditions where we can use the QMutex and
QThreadStorage stubs.
Change-Id: I284e5d794fda9a4c6f4a1ab29e55aa686272a0eb
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
The function does not exist. QRandomGenerator::generate() is the equivalent
function
Change-Id: I5d65f2913fc5a9e60004d206733993254885a5e6
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Tripped over by Alexei Fedotov and brought to light on the developer
list; Thiago says it's a left-over from before reworking to actually
use getentropy() instead of getrandom(); it should no longer be
needed.
Change-Id: Id09b0628e58fa62170a0f0da35b2b121f3fb0172
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Added missing template clause to \fn commands required by clang-qdoc.
Removed several obsolete \sa targets. Added a few missing return types
to \fn commands.
Also changed a } to ] in a \fn command in qrandom.cpp.
Change-Id: I0f004a1e57507ff5fb035e822ca8b1baa7faad9b
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
Due to the integration of clang in qdoc, several qdoc warnings
appeared for class QRandomGenerator. This update corrects all
the remaining qdoc warnings.
Change-Id: I92fe9f7d9cb193e145ee8ad0e7198625b9a5bf7b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This fixes only those that look fixable. There are a number of errors in
the online documentation that look like qdoc tool bugs, like missing
functions (operator==) and documentation text that does not exist in the
source code. This fixes:
- QRandomGenerator(System) constructor showing up
- Links for C++ reference documentation not showing up as links
Change-Id: I9e2892cb6c374e93bcb7fffd14fe21db5a6969d9
Reviewed-by: Martin Smith <martin.smith@qt.io>
src/corelib/global/qrandom.cpp:915: warning: Cannot find 'bounded(...)' in '\fn' qreal QRandomGenerator::bounded(qreal highest)
src/corelib/tools/qstring.cpp:774: warning: Command '\snippet (//! [qCompareStrings-QSV-QSV])' failed at end of file 'qstring/main.cpp'
src/corelib/tools/qstring.cpp:5281: warning: Cannot find 'qTrimmed(...)' in '\fn' QStringView qTrimmed(QStringView s)
src/corelib/tools/qstring.cpp:5281: warning: Cannot find 'qTrimmed(...)' in '\fn' QLatin1String qTrimmed(QLatin1String s)
src/corelib/global/qrandom.h:171: warning: No documentation for 'QRandomGenerator::System'
src/corelib/global/qrandom.h:105: warning: No documentation for 'QRandomGenerator::bounded(double highest)'
src/corelib/global/qrandom.h:84: warning: No documentation for 'QRandomGenerator::generate64()'
src/corelib/global/qrandom.h:77: warning: No documentation for 'QRandomGenerator::generate()'
src/corelib/global/qrandom.cpp:799: warning: No such parameter 'sseq' in QRandomGenerator::seed()
src/corelib/global/qrandom.cpp:1096: warning: Can't link to 'operator()()'
src/corelib/tools/qstring.cpp:8982: warning: Can't link to 'qStartsWith()'
src/corelib/tools/qstring.cpp:9203: warning: Can't link to 'qTrimmed()'
src/corelib/tools/qstring.cpp:4798: warning: Can't link to 'qConvertToLatin1()'
src/corelib/tools/qstring.cpp:4825: warning: Can't link to 'qConvertToLocal8Bit()'
src/corelib/tools/qstring.cpp:4928: warning: Can't link to 'qConvertToUcs4()'
src/corelib/tools/qstring.cpp:4884: warning: Can't link to 'qConvertToUtf8()'
Change-Id: I5c7c89b230d3d1de8a679c10833319a470a44e80
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Instead of trying to adapt to whatever the C library may have and using
QThreadLocalStorage, let's use a simple linear congruential generator
engine from <random>. We can't use a single instance because qsrand()
is documented to work per thread.
I thought of using QRandomEngine, but had to make the choice between
growing the QtCore code size and growing the per-thread data size. Code
is sharable and is actually smaller than the sizeof(QRandomEngine),
which is over 2500 bytes. sizeof(std::minstd_rand) is just
sizeof(uint_fast32_t).
Change-Id: I0a103569c81b4711a649fffd14ec8e641d02bf20
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
During the container BoF session at the Qt Contributor Summit 2017 the
name of the signed size type became a subject of discussion in the
context of readability of code using this type and the intention of
using it for all length, size and count properties throughout the entire
framework in future versions of Qt.
This change proposes qsizetype as new name for qssize_t to emphasize the
readability of code over POSIX compatibility, the former being
potentially more relevant than the latter to the majority of users of
Qt.
Change-Id: Idb99cb4a8782703c054fa463a9e5af23a918e7f3
Reviewed-by: Samuel Gaist <samuel.gaist@edeltech.ch>
Reviewed-by: David Faure <david.faure@kdab.com>
We store both in a single memory structure, instead of two local
statics. By construction, we also ensure that the global PRNG mutex is
in a different cacheline from the global PRNG state itself.
Finally, we don't store the full system QRandomGenerator, since we only
need the type member from it.
Change-Id: Icaa86fc7b54d4b368c0efffd14eecc48ff05ec27
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
This brings us to almost parity with the C++11 Random Engine API
requirements (see chapter 26.5.1.4 [rand.req.eng]). We don't implement
the templated Sseq requirements because it would require moving the
implementation details to the public API. And we don't implement the
<iostreams> code because we don't want to.
Change-Id: Icaa86fc7b54d4b368c0efffd14f05ff813ebd759
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Since we don't document how many bytes one needs (it's 2496), it's
difficult for the caller to provide just enough data in the seed
sequence. Moreover, since std::mt19937 doesn't make it easy to provide
the ideal size either, we can't actually write code that operates
optimally given a quint32 range either -- we only provide it via
std::seed_seq, which is inefficient.
However, we can do it internally by passing QRandomGenerator to the
std::mersenne_twister_engine constructor, as it's designed to work.
Change-Id: Icaa86fc7b54d4b368c0efffd14f0613c10998321
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Now only QRandomGenerator::system() will access the system-wide RNG,
which we document to be cryptographically-safe and possibly backed by a
true HWRNG. Everything else just wraps a Mersenne Twister.
Change-Id: I0a103569c81b4711a649fffd14ec8cd3469425df
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Since we're adding a deterministic generator that inherently does not
use syscalls, and people should really use that one by default, there is
no point in optimizing the secure generator wrt syscalls. Besides,
keeping the random data in memory for longer than needed is likely
inadviseable.
Change-Id: Ib17dde1a1dbb49a7bba8fffd14ed0871117fe930
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
"global/qrandom.cpp", line 155: error #2000-D: attribute "destructor" is not implemented and will be ignored
Task-number: QTBUG-63948
Change-Id: Icaa86fc7b54d4b368c0efffd14efa35381d4e797
Reviewed-by: Liang Qi <liang.qi@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Let's make it happen even later: at the time of QtCore's unloading from
memory. This prevents issues with something using QRandomGenerator after
the global static destructor would have run.
Change-Id: Icaa86fc7b54d4b368c0efffd14eed56bbbb51cb6
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Error out if it's missing or broken (Mersenne Twister not present).
This ensures that we never have a low-quality random generator in Qt.
Change-Id: I0a103569c81b4711a649fffd14ec80649df7087e
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Commit 282065d443 renamed the generator
functions but we didn't update all the docs.
Change-Id: I0a103569c81b4711a649fffd14ec877ffbfe710d
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
There are a couple of Q_ASSERT wrapped by the new noexcepts, but most of
those aren't validation of external parameters, only of internal
construction. The two exceptions are the checks for pointer alignment.
Change-Id: I0a103569c81b4711a649fffd14ec8523d741dfb6
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Copy into the intended array elements, not into the start of the
array.
Change-Id: I05c4ece2450583c9358aa1eddfd702262e995146
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
"generate" is better than "get", and we already have "generate(it, it)"
which uses std::generate(). This changes:
- get32() → generate()
- get64() → generate64() and QRandomGenerator64::generate()
- getReal() → generateDouble()
Change-Id: I6e1fe42ae4b742a7b811fffd14e5d7bd69abcdb3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Conflicts:
examples/examples.pro
qmake/library/qmakebuiltins.cpp
src/corelib/global/qglobal.cpp
Re-apply b525ec2 to qrandom.cpp(code movement in 030782e)
src/corelib/global/qnamespace.qdoc
src/corelib/global/qrandom.cpp
src/gui/kernel/qwindow.cpp
Re-apply a3d59c7 to QWindowPrivate::setVisible() (code movement in d7a9e08)
src/network/ssl/qsslkey_openssl.cpp
src/plugins/platforms/android/androidjniinput.cpp
src/plugins/platforms/xcb/qxcbconnection.cpp
src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
src/widgets/widgets/qmenu.cpp
tests/auto/widgets/kernel/qwidget_window/tst_qwidget_window.cpp
Change-Id: If7ab427804408877a93cbe02079fca58e568bfd3
The full documentation explains it well but a more prominent warning
will help avoid the wrong use of that class and encourage user to read
further the documentation.
Change-Id: I3178749f2b1b0350040f81eef253fd85c7ba0a5f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Found while working on suppressing the warning about the return value
(which is either 0 or -1) was being ignored.
Task-number: QTBUG-61968
Change-Id: I02d22222fff64d4dbda4fffd14d148b1724547ca
Reviewed-by: Florian Bruhin <qt-project.org@the-compiler.org>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
The getentropy function, first found in OpenBSD, is present in glibc
since version 2.25 and Bionic since Android 6.0 and NDK r11. It uses the
Linux 3.17 getrandom system call. Unlike glibc's getrandom() wrapper,
the glibc implementation of getentropy() function is not a POSIX thread
cancellation point, so we prefer to use that even though we have to
break the reading into 256-byte blocks.
The big advantage is that these functions work even in the absence of a
/dev/urandom device node, in addition to a few cycles shaved off by not
having to open a file descriptor and close it at exit. What's more, the
glibc implementation blocks until entropy is available on early boot, so
we don't have to worry about a failure mode. The Bionic implementation
will fall back by itself to /dev/urandom and, failing that, gathering
entropy from elsewhere in the system in a way it cannot fail either.
uClibc has a wrapper to getrandom(2) but no getentropy(3). MUSL has
neither.
Change-Id: Ia53158e207a94bf49489fffd14c8cee1b968a619
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
qdeadlinetimer.cpp and qelapsedtimer_*.cpp are not part of the bootstrap
library. Instead of adding them there, just remove this entropy source
from bootstrapped builds (instead of just qmake).
To compensate, store all the bits instead of trying to combine them into
just one 32-bit word. We've got a few new sources from the stack and
libc, plus two more ELF auxvec values that the Linux kernel supplies
(inspired by OpenBSD's getentropy_linux.c, which is used in Bionic).
Task-number: QTBUG-61492
Change-Id: I1d5a585d4af842f9a66ffffd14c999ae8c44f46c
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Found this in a few uses of qrand() that assumed the result would be
non-negative.
Change-Id: Ia53158e207a94bf49489fffd14c7c029515cf42c
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
GCC didn't support it until version 5 or 6, so add configure tests for
both <random> and <sys/auxv.h>. Normally I'd say "upgrade", but this is
too low-level and important a feature.
There's a good chance that all our supported compilers have <random>
anyway. As for <sys/auxv.h>, it's present on Glibc, Bionic and MUSL, but
I don't see it in uClibc (AT_RANDOM is a Linux-specific feature).
Change-Id: Ia3e896da908f42939148fffd14c5b2af491f7a77
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
The Linux kernel gives us 16 bytes of random data and sets a pointer to
it in the ELF AuxV (the same one that allows us to get HWCAP on ARM
systems). So if we end up in the fallback generator, at leat we'll get a
good amount of entropy to seed the Mersenne Twister.
This could happen if the application is run in a chroot(2) or container
without /dev/random or /dev/urandom. That is probably an installation
mistake, so we don't optimize this case for performance.
With this commit, we have now good, high-quality fallbacks for Windows
(rand_s), for BSDs (arc4random) and for Linux. The only missing,
supported OS without a good entropy source is QNX.
Change-Id: Ia3e896da908f42939148fffd14c5b1084051f1a8
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
If we've never read any samples from hardware RNG or from /dev/urandom,
then there are no stored samples for us to seed the Mersenne Twister. In
that case, attempt to obtain an emergency sample that consists of some
random bits from the variable addresses (ASLR should help) and from the
clock (using nanosecond quality, instead of seconds).
There's still the possibility that we'll get poor entropy: very close to
boot, if the kernel entropy pool is empty, ASLR could be poor and the
monotonic clock value could be consistent from boot to boot. There's
nothing we can do about that.
Change-Id: Ia3e896da908f42939148fffd14c5b0c7b608371b
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This function works even in chroots where /dev is not available. Since
it's part of the OS, it may have better ways of gathering entropy even
when we don't.
Change-Id: Ia3e896da908f42939148fffd14c5afedc8569dbc
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit adds support for the x86 RDRAND instruction for
QRandomGenerator. This is the same that libstdc++-v3 uses for
std::random_device() by default. If it fails because the hardware does
not have enough entropy collected, we fall back to the operating system
generator, which often has more entropy collected from other sources.
Change-Id: Icd0e0d4b27cb4e5eb892fffd14b5167214e1ea3f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This class provides a reasonably-secure random number generator that
does not need seeding. That is quite unlike qrand(), which requires a
seed and is low-quality (definitely not secure).
This class is also like std::random_device, but better. It provides an
operator() like std::random_device, but unlike that, it also provides a
way to fill a buffer with random data, not just one 32-bit quantity.
It's also stateless.
Finally, it also implements std::seed_seq-like generate(). It obeys the
standard requirement of the range (32-bit) but not that of the algorithm
(if you wanted that, you'd use std::seed_seq itself). Instead,
generate() fills with pure random data.
Change-Id: Icd0e0d4b27cb4e5eb892fffd14b4e3ba9ea04da8
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Thiago Macieira
Edward Welbourne
Dmitry Shachnev
Allan Sandfeld Jensen
Cristian Maureira-Fredes
Ulf Hermann
Alex Blasche
Liang Qi
Martin Smith
Lars Knoll
Friedemann Kleint
Simon Hausmann
Eirik Aavitsland
Samuel Gaist