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| author | Wladimir J. van der Laan <laanwj@gmail.com> | 2014-06-24 15:27:37 +0200 |
|---|---|---|
| committer | Wladimir J. van der Laan <laanwj@gmail.com> | 2014-06-26 15:15:17 +0200 |
| commit | 8ae973c00cfb02161bb2c2a6c839e510cd409278 (patch) | |
| tree | 26796124f38b81c31dcfd1908268a06bb246757c /src/util.cpp | |
| parent | be873f64540d3c0b1227920eb466097ed738f452 (diff) | |
| download | bitcoin-8ae973c00cfb02161bb2c2a6c839e510cd409278.tar.xz | |
Allocate more space if necessary in RandSeedAddPerfMon
Currently we use a fixed buffer of 250000 bytes to request
HKEY_PERFORMANCE_DATA. In many cases this is not enough, causing the
entropy collection to be skipped.
Use a loop that grows the buffer as specified in the RegQueryValueEx
documentation:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms724911%28v=vs.85%29.aspx
(as the size of the performance data can differ for every call, the
normal solution of requesting the size then allocating that can't work)
Diffstat (limited to 'src/util.cpp')
| -rw-r--r-- | src/util.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/util.cpp b/src/util.cpp index 7946089571..a96963689a 100644 --- a/src/util.cpp +++ b/src/util.cpp @@ -169,8 +169,17 @@ void RandAddSeedPerfmon() // Don't need this on Linux, OpenSSL automatically uses /dev/urandom // Seed with the entire set of perfmon data std::vector <unsigned char> vData(250000,0); - unsigned long nSize = vData.size(); - long ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", NULL, NULL, begin_ptr(vData), &nSize); + long ret = 0; + unsigned long nSize = 0; + const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data + while (true) + { + nSize = vData.size(); + ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", NULL, NULL, begin_ptr(vData), &nSize); + if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize) + break; + vData.resize(std::max((vData.size()*3)/2, nMaxSize)); // Grow size of buffer exponentially + } RegCloseKey(HKEY_PERFORMANCE_DATA); if (ret == ERROR_SUCCESS) { |