AuroraMiddleware/qt5base-lts - qt5base-lts - Gitea: Git with a cup of tea

AuroraMiddleware/qt5base-lts

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QRandomGenerator: use getentropy on Linux & OpenBSD 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>

2017-06-17 04:39:04 +00:00

SOURCES = getentropy.cpp