From 9b88bf8adf721d6b2d1a5666a97a0c6e9046a2d7 Mon Sep 17 00:00:00 2001 From: Robert Hensing Date: Sat, 29 Jun 2024 13:48:17 +0200 Subject: [PATCH 1/4] Fix underflow in Printer::printAttrs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The code that counts the number of elided attrs incorrectly used the per-printer "global" attribute counter instead of a counter that was relevant only to the current attribute set. This bug flew under the radar because often the attribute sets aren't nested, not big enough, or we wouldn't pay attention to the numbers. I've noticed the issue because the difference underflowed. Although this behavior is tested by the functional test lang/eval-fail-bad-string-interpolation-4.nix, the underflow slipped through review. A simpler reproducer would be as follows, but I haven't added it to the test suite to keep it simple and marginally faster. ``` $ nix run nix/2.23.1 -- eval --expr '"" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v)' error: … while evaluating a path segment at «string»:1:6: 1| "" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v) | ^ error: cannot coerce a set to a string: { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; «4294967289 attributes elided» }; } ``` --- src/libexpr/print.cc | 5 ++++- .../lang/eval-fail-bad-string-interpolation-4.err.exp | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc index 10fe7923f..4e44fa721 100644 --- a/src/libexpr/print.cc +++ b/src/libexpr/print.cc @@ -345,11 +345,13 @@ private: auto prettyPrint = shouldPrettyPrintAttrs(sorted); + size_t currentAttrsPrinted = 0; + for (auto & i : sorted) { printSpace(prettyPrint); if (attrsPrinted >= options.maxAttrs) { - printElided(sorted.size() - attrsPrinted, "attribute", "attributes"); + printElided(sorted.size() - currentAttrsPrinted, "attribute", "attributes"); break; } @@ -358,6 +360,7 @@ private: print(*i.second, depth + 1); output << ";"; attrsPrinted++; + currentAttrsPrinted++; } decreaseIndent(); diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp index 6f907106b..b262e814d 100644 --- a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp +++ b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp @@ -6,4 +6,4 @@ error: | ^ 10| - error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «4294967295 attributes elided» }; «4294967294 attributes elided» }; «4294967293 attributes elided» } + error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «8 attributes elided» }; «8 attributes elided» }; «8 attributes elided» } From ce1dc87711e06d1b04e444e3215ad8d35f191abd Mon Sep 17 00:00:00 2001 From: Robert Hensing Date: Sat, 29 Jun 2024 14:01:10 +0200 Subject: [PATCH 2/4] Refactor: rename ValuePrinter::totalAttrsPrinted Make it more distinct from the attrs printed of any specific attrset. --- src/libexpr/print.cc | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc index 4e44fa721..5f6a08cfe 100644 --- a/src/libexpr/print.cc +++ b/src/libexpr/print.cc @@ -163,7 +163,7 @@ private: EvalState & state; PrintOptions options; std::optional seen; - size_t attrsPrinted = 0; + size_t totalAttrsPrinted = 0; size_t listItemsPrinted = 0; std::string indent; @@ -350,7 +350,7 @@ private: for (auto & i : sorted) { printSpace(prettyPrint); - if (attrsPrinted >= options.maxAttrs) { + if (totalAttrsPrinted >= options.maxAttrs) { printElided(sorted.size() - currentAttrsPrinted, "attribute", "attributes"); break; } @@ -359,7 +359,7 @@ private: output << " = "; print(*i.second, depth + 1); output << ";"; - attrsPrinted++; + totalAttrsPrinted++; currentAttrsPrinted++; } @@ -591,7 +591,7 @@ public: void print(Value & v) { - attrsPrinted = 0; + totalAttrsPrinted = 0; listItemsPrinted = 0; indent.clear(); From bfc54162405213b65f045a422fcb90ae62a18df1 Mon Sep 17 00:00:00 2001 From: Robert Hensing Date: Sat, 29 Jun 2024 14:02:28 +0200 Subject: [PATCH 3/4] Refactor: rename ValuePrinter::totalListItemsPrinted --- src/libexpr/print.cc | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc index 5f6a08cfe..74aa52d48 100644 --- a/src/libexpr/print.cc +++ b/src/libexpr/print.cc @@ -164,7 +164,7 @@ private: PrintOptions options; std::optional seen; size_t totalAttrsPrinted = 0; - size_t listItemsPrinted = 0; + size_t totalListItemsPrinted = 0; std::string indent; void increaseIndent() @@ -408,8 +408,8 @@ private: for (auto elem : listItems) { printSpace(prettyPrint); - if (listItemsPrinted >= options.maxListItems) { - printElided(listItems.size() - listItemsPrinted, "item", "items"); + if (totalListItemsPrinted >= options.maxListItems) { + printElided(listItems.size() - totalListItemsPrinted, "item", "items"); break; } @@ -418,7 +418,7 @@ private: } else { printNullptr(); } - listItemsPrinted++; + totalListItemsPrinted++; } decreaseIndent(); @@ -592,7 +592,7 @@ public: void print(Value & v) { totalAttrsPrinted = 0; - listItemsPrinted = 0; + totalListItemsPrinted = 0; indent.clear(); if (options.trackRepeated) { From b2c7f09b0a095ba0c0f3141a5734bf958d23b86a Mon Sep 17 00:00:00 2001 From: Robert Hensing Date: Sat, 29 Jun 2024 14:08:43 +0200 Subject: [PATCH 4/4] Fix underflow in Printer::printList Analogous to 9b88bf8adf7 / three commits back --- src/libexpr/print.cc | 6 +++++- .../lang/eval-fail-nested-list-items.err.exp | 9 +++++++++ tests/functional/lang/eval-fail-nested-list-items.nix | 11 +++++++++++ 3 files changed, 25 insertions(+), 1 deletion(-) create mode 100644 tests/functional/lang/eval-fail-nested-list-items.err.exp create mode 100644 tests/functional/lang/eval-fail-nested-list-items.nix diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc index 74aa52d48..2f377e588 100644 --- a/src/libexpr/print.cc +++ b/src/libexpr/print.cc @@ -405,11 +405,14 @@ private: output << "["; auto listItems = v.listItems(); auto prettyPrint = shouldPrettyPrintList(listItems); + + size_t currentListItemsPrinted = 0; + for (auto elem : listItems) { printSpace(prettyPrint); if (totalListItemsPrinted >= options.maxListItems) { - printElided(listItems.size() - totalListItemsPrinted, "item", "items"); + printElided(listItems.size() - currentListItemsPrinted, "item", "items"); break; } @@ -419,6 +422,7 @@ private: printNullptr(); } totalListItemsPrinted++; + currentListItemsPrinted++; } decreaseIndent(); diff --git a/tests/functional/lang/eval-fail-nested-list-items.err.exp b/tests/functional/lang/eval-fail-nested-list-items.err.exp new file mode 100644 index 000000000..90d439061 --- /dev/null +++ b/tests/functional/lang/eval-fail-nested-list-items.err.exp @@ -0,0 +1,9 @@ +error: + … while evaluating a path segment + at /pwd/lang/eval-fail-nested-list-items.nix:11:6: + 10| + 11| "" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v) + | ^ + 12| + + error: cannot coerce a list to a string: [ [ 1 2 3 4 5 6 7 8 ] [ 1 «3 items elided» ] ] diff --git a/tests/functional/lang/eval-fail-nested-list-items.nix b/tests/functional/lang/eval-fail-nested-list-items.nix new file mode 100644 index 000000000..af45b1dd4 --- /dev/null +++ b/tests/functional/lang/eval-fail-nested-list-items.nix @@ -0,0 +1,11 @@ +# This reproduces https://github.com/NixOS/nix/issues/10993, for lists +# $ nix run nix/2.23.1 -- eval --expr '"" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)' +# error: +# … while evaluating a path segment +# at «string»:1:6: +# 1| "" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v) +# | ^ +# +# error: cannot coerce a list to a string: [ [ 1 2 3 4 5 6 7 8 ] [ 1 «4294967290 items elided» ] ] + +"" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)