forked from lix-project/lix
libexpr: Fix prim_replaceStrings() to work on an empty source string
Otherwise, running e.g.
nix-instantiate --eval -E --strict 'builtins.replaceStrings [""] ["X"] "abc"'
would just hang in an infinite loop.
Found by afl-fuzz.
First attempt of this was reverted in e2d71bd186
because it caused
another infinite loop, which is fixed now and a test added.
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24ec750003
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@ -1913,21 +1913,32 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
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auto s = state.forceString(*args[2], context, pos);
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string res;
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for (size_t p = 0; p < s.size(); ) {
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// Loops one past last character to handle the case where 'from' contains an empty string.
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for (size_t p = 0; p <= s.size(); ) {
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bool found = false;
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auto i = from.begin();
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auto j = to.begin();
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for (; i != from.end(); ++i, ++j)
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if (s.compare(p, i->size(), *i) == 0) {
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found = true;
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p += i->size();
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res += j->first;
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if (i->empty()) {
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if (p < s.size())
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res += s[p];
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p++;
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} else {
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p += i->size();
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}
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for (auto& path : j->second)
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context.insert(path);
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j->second.clear();
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break;
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}
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if (!found) res += s[p++];
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if (!found) {
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if (p < s.size())
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res += s[p];
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p++;
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}
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}
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mkString(v, res, context);
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@ -1 +1 @@
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[ "faabar" "fbar" "fubar" "faboor" "fubar" ]
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[ "faabar" "fbar" "fubar" "faboor" "fubar" "XaXbXcX" "X" "a_b" ]
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@ -5,4 +5,7 @@ with builtins;
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(replaceStrings ["oo"] ["u"] "foobar")
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(replaceStrings ["oo" "a"] ["a" "oo"] "foobar")
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(replaceStrings ["oo" "oo"] ["u" "i"] "foobar")
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(replaceStrings [""] ["X"] "abc")
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(replaceStrings [""] ["X"] "")
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(replaceStrings ["-"] ["_"] "a-b")
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]
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