From 976edb7597692ac04111b3c51b13e18105c14f42 Mon Sep 17 00:00:00 2001 From: Alberto Gonzalez Date: Fri, 24 Apr 2020 08:37:16 +0000 Subject: [PATCH] kernel: Ensure `dict` always hashes to the same value given the same contents. --- kernel/hashlib.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/hashlib.h b/kernel/hashlib.h index 18114b6ad..1284f3f8d 100644 --- a/kernel/hashlib.h +++ b/kernel/hashlib.h @@ -207,6 +207,7 @@ class dict entry_t() { } entry_t(const std::pair &udata, int next) : udata(udata), next(next) { } entry_t(std::pair &&udata, int next) : udata(std::move(udata)), next(next) { } + bool operator<(const entry_t &other) const { return udata.first < other.udata.first; } }; std::vector hashtable; @@ -616,10 +617,12 @@ public: } unsigned int hash() const { + std::vector entries_(entries); //make a copy to preserve const-ness + std::sort(entries_.begin(), entries_.end()); unsigned int h = mkhash_init; - for (auto &it : entries) { - h = mkhash(h, hash_ops::hash(it.udata.first)); - h = mkhash(h, hash_ops::hash(it.udata.second)); + for (unsigned int i = 0; i < entries_.size(); ++i) { + h = mkhash(h, hash_ops::hash(entries_[i].udata.first)); + h = mkhash(h, hash_ops::hash(entries_[i].udata.second)); } return h; } -- 2.30.2