diff options
| author | Anders Kaseorg <andersk@mit.edu> | 2026-03-26 23:45:07 -0700 |
|---|---|---|
| committer | Julian Andres Klode <jak@debian.org> | 2026-04-07 09:34:15 +0000 |
| commit | df55da00262a7a6b7f885e3fc66559767761cae5 (patch) | |
| tree | 4065ff1f0a7a4848822803e903565dec111bf732 | |
| parent | 6cc5779d18baf520278952aed504b9d9b168a4bd (diff) | |
Fix Phased-Update-Percentage probability mistake
Previously a package with Phased-Update-Percentage: n would be updated
with probability (n + 1)/101 instead of n/100. For example, a package
with Phased-Update-Percentage: 0 could still be updated even though it
shouldn’t, and a package with Phased-Update-Percentage: 1 would be
installed almost twice as much as it should be. Correct the erroneous
math.
Note that libstdc++ implements std::uniform_int_distribution in such a
way that for a given seed, changing dist(0, 100) to dist(0, 99) has
the effect of decreasing each sample by 0 or 1; therefore, this patch
will not randomly trigger extra phased updates that had previously
been excluded.
Fixes: c5bc86d45e003905ef411146e66b414d26fb1ff8
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
| -rw-r--r-- | apt-pkg/depcache.cc | 4 | ||||
| -rw-r--r-- | apt-pkg/policy.cc | 4 |
2 files changed, 4 insertions, 4 deletions
diff --git a/apt-pkg/depcache.cc b/apt-pkg/depcache.cc index 2a9ef50d2..777fa0c80 100644 --- a/apt-pkg/depcache.cc +++ b/apt-pkg/depcache.cc @@ -2591,9 +2591,9 @@ static bool IsIgnoredPhasedUpdate(std::string machineID, pkgCache::VerIterator c std::string seedStr = std::string(Ver.SourcePkgName()) + "-" + Ver.SourceVerStr() + "-" + machineID; std::seed_seq seed(seedStr.begin(), seedStr.end()); std::minstd_rand rand(seed); - std::uniform_int_distribution<unsigned int> dist(0, 100); + std::uniform_int_distribution<unsigned int> dist(0, 99); - return dist(rand) > Ver.PhasedUpdatePercentage(); + return dist(rand) >= Ver.PhasedUpdatePercentage(); } bool pkgDepCache::PhasingApplied(pkgCache::PkgIterator Pkg) const diff --git a/apt-pkg/policy.cc b/apt-pkg/policy.cc index ab21cd039..7d11ba898 100644 --- a/apt-pkg/policy.cc +++ b/apt-pkg/policy.cc @@ -314,9 +314,9 @@ static inline bool ExcludePhased(std::string machineID, pkgCache::VerIterator co std::string seedStr = std::string(Ver.SourcePkgName()) + "-" + Ver.SourceVerStr() + "-" + machineID; std::seed_seq seed(seedStr.begin(), seedStr.end()); std::minstd_rand rand(seed); - std::uniform_int_distribution<unsigned int> dist(0, 100); + std::uniform_int_distribution<unsigned int> dist(0, 99); - return dist(rand) > Ver.PhasedUpdatePercentage(); + return dist(rand) >= Ver.PhasedUpdatePercentage(); } APT_PURE signed short pkgPolicy::GetPriority(pkgCache::VerIterator const &Ver, bool ConsiderFiles) { |