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2024-08-26treewide: fix a bunch of lintsJade Lovelace
Fixes: - Identifiers starting with _ are prohibited - Some driveby header dependency cleaning which wound up with doing some extra fixups. - Fucking C style casts, man. C++ made these 1000% worse by letting you also do memory corruption with them with references. - Remove casts to Expr * where ExprBlackHole is an incomplete type by introducing an explicitly-cast eBlackHoleAddr as Expr *. - An incredibly illegal cast of the text bytes of the StorePath hash into a size_t directly. You can't DO THAT. Replaced with actually parsing the hash so we get 100% of the bits being entropy, then memcpying the start of the hash. If this shows up in a profile we should just make the hash parser faster with a lookup table or something sensible like that. - This horrendous bit of UB which I thankfully slapped a deprecation warning on, built, and it didn't trigger anywhere so it was dead code and I just deleted it. But holy crap you *cannot* do that. inline void mkString(const Symbol & s) { mkString(((const std::string &) s).c_str()); } - Some wrong lints. Lots of wrong macro lints, one wrong suspicious-sizeof lint triggered by the template being instantiated with only pointers, but the calculation being correct for both pointers and not-pointers. - Exceptions in destructors strike again. I tried to catch the exceptions that might actually happen rather than all the exceptions imaginable. We can let the runtime hard-kill it on other exceptions imo. Change-Id: I71761620846cba64d66ee7ca231b20c061e69710
2024-07-31libexpr: implement actual constructors for nix::ValueQyriad
Change-Id: Iebc2bb4e4ea5e93045afe47677df756de4ec4d05
2024-07-20libexpr: refactor gc-agnostic helpers into one placeQyriad
Change-Id: Icc4b367e4f670d47256f62a3a002cd248a5c2d3b
2024-07-13language: cleanly ban integer overflowsJade Lovelace
This also bans various sneaking of negative numbers from the language into unsuspecting builtins as was exposed while auditing the consequences of changing the Nix language integer type to a newtype. It's unlikely that this change comprehensively ensures correctness when passing integers out of the Nix language and we should probably add a checked-narrowing function or something similar, but that's out of scope for the immediate change. During the development of this I found a few fun facts about the language: - You could overflow integers by converting from unsigned JSON values. - You could overflow unsigned integers by converting negative numbers into them when going into Nix config, into fetchTree, and into flake inputs. The flake inputs and Nix config cannot actually be tested properly since they both ban thunks, however, we put in checks anyway because it's possible these could somehow be used to do such shenanigans some other way. Note that Lix has banned Nix language integer overflows since the very first public beta, but threw a SIGILL about them because we run with -fsanitize=signed-overflow -fsanitize-undefined-trap-on-error in production builds. Since the Nix language uses signed integers, overflow was simply undefined behaviour, and since we defined that to trap, it did. Trapping on it was a bad UX, but we didn't even entirely notice that we had done this at all until it was reported as a bug a couple of months later (which is, to be fair, that flag working as intended), and it's got enough production time that, aside from code that is IMHO buggy (and which is, in any case, not in nixpkgs) such as https://git.lix.systems/lix-project/lix/issues/445, we don't think anyone doing anything reasonable actually depends on wrapping overflow. Even for weird use cases such as doing funny bit crimes, it doesn't make sense IMO to have wrapping behaviour, since two's complement arithmetic overflow behaviour is so *aggressively* not what you want for *any* kind of mathematics/algorithms. The Nix language exists for package management, a domain where bit crimes are already only dubiously in scope to begin with, and it makes a lot more sense for that domain for the integers to never lose precision, either by throwing errors if they would, or by being arbitrary-precision. This change will be ported to CppNix as well, to maintain language consistency. Fixes: https://git.lix.systems/lix-project/lix/issues/423 Change-Id: I51f253840c4af2ea5422b8a420aa5fafbf8fae75
2024-06-17libexpr: pass Exprs as references, not pointerseldritch horrors
almost all places where Exprs are passed as pointers expect the pointers to be non-null. pass them as references to encode this constraint in the type system as well (and also communicate that Exprs must not be freed). Change-Id: Ia98f166fec3c23151f906e13acb4a0954a5980a2
2024-05-16Loosen constness on listElems() resultPuck Meerburg
Change-Id: I1caff000362c83e5172413a036c22a2e9ed3ede8
2024-03-09libexpr: Support structured error classeseldritch horrors
While preparing PRs like #9753, I've had to change error messages in dozens of code paths. It would be nice if instead of EvalError("expected 'boolean' but found '%1%'", showType(v)) we could write TypeError(v, "boolean") or similar. Then, changing the error message could be a mechanical refactor with the compiler pointing out places the constructor needs to be changed, rather than the error-prone process of grepping through the codebase. Structured errors would also help prevent the "same" error from having multiple slightly different messages, and could be a first step towards error codes / an error index. This PR reworks the exception infrastructure in `libexpr` to support exception types with different constructor signatures than `BaseError`. Actually refactoring the exceptions to use structured data will come in a future PR (this one is big enough already, as it has to touch every exception in `libexpr`). The core design is in `eval-error.hh`. Generally, errors like this: state.error("'%s' is not a string", getAttrPathStr()) .debugThrow<TypeError>() are transformed like this: state.error<TypeError>("'%s' is not a string", getAttrPathStr()) .debugThrow() The type annotation has moved from `ErrorBuilder::debugThrow` to `EvalState::error`. (cherry picked from commit c6a89c1a1659b31694c0fbcd21d78a6dd521c732) Change-Id: Iced91ba4e00ca9e801518071fb43798936cbd05a
2024-03-09Unify and refactor value printingeldritch horrors
Previously, there were two mostly-identical value printers -- one in `libexpr/eval.cc` (which didn't force values) and one in `libcmd/repl.cc` (which did force values and also printed ANSI color codes). This PR unifies both of these printers into `print.cc` and provides a `PrintOptions` struct for controlling the output, which allows for toggling whether values are forced, whether repeated values are tracked, and whether ANSI color codes are displayed. Additionally, `PrintOptions` allows tuning the maximum number of attributes, list items, and bytes in a string that will be displayed; this makes it ideal for contexts where printing too much output (e.g. all of Nixpkgs) is distracting. (As requested by @roberth in https://github.com/NixOS/nix/pull/9554#issuecomment-1845095735) Please read the tests for example output. Future work: - It would be nice to provide this function as a builtin, perhaps `builtins.toStringDebug` -- a printing function that never fails would be useful when debugging Nix code. - It would be nice to support customizing `PrintOptions` members on the command line, e.g. `--option to-string-max-attrs 1000`. (cherry picked from commit 0fa08b451682fb3311fe58112ff05c4fe5bee3a4, ) === Restore ambiguous value printer for `nix-instantiate` The Nix team has requested that this output format remain unchanged. I've added a warning to the man page explaining that `nix-instantiate --eval` output will not parse correctly in many situations. (cherry picked from commit df84dd4d8dd3fd6381ac2ca3064432ab31a16b79) Change-Id: I7cca6b4b53cd0642f2d49af657d5676a8554c9f8
2024-03-05Merge pull request #9634 from 9999years/combine-abstract-pos-and-poseldritch horrors
Combine `AbstractPos`, `PosAdapter`, and `Pos` (cherry picked from commit 113499d16fc87d53b73fb62fe6242154909756ed) === this is a bit cursed because originally it was based on InputAccessor code that we don't have and moved/patched features we likewise don't have (fetchToStore caching, all the individual accessors, ContentAddressMethod). the commit is adjusted accordingly to match (remove caching, ignore accessors, use FileIngestionMethod). note that `state.rootPath . CanonPath == abs` and computeStorePathForPath works relative to cwd, so the slight rewrite in the moved fetchToStore is legal. Change-Id: I05fd340c273f0bcc8ffabfebdc4a88b98083bce5
2024-03-04Merge pull request #9582 from pennae/misc-optseldritch horrors
a packet of small optimizations (cherry picked from commit ee439734e924eb337a869ff2e48aff8b989198bc) Change-Id: I125d870710750a32a0dece48f39a3e9132b0d023
2024-03-04Merge pull request #7348 from thufschmitt/dont-use-vlaseldritch horrors
Remove the usage of VLAs in the code (cherry picked from commit ac4431e9d016e62fb5dc9ae36833bd0c6cdadeec) Change-Id: Ifbf5fbfc2e27122362a2aaea4b62c7cf3ca46b1a
2023-07-01Merge pull request #8566 from inclyc/nixd/value-print-depthRobert Hensing
libexpr: extend `Value::print` to allow limited depth
2023-06-27Automatically document builtin constantsJohn Ericson
This is done in roughly the same way builtin functions are documented. Also auto-link experimental features for primops, subsuming PR #8371. Co-authored-by: Eelco Dolstra <edolstra@gmail.com> Co-authored-by: Robert Hensing <roberth@users.noreply.github.com> Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
2023-06-22libexpr: extend `Value::print` to allow limited depthYingchi Long
2023-04-24Merge remote-tracking branch 'origin/master' into source-pathEelco Dolstra
2023-04-21Use `std::set<StringContextElem>` not `PathSet` for string contextsJohn Ericson
Motivation `PathSet` is not correct because string contexts have other forms (`Built` and `DrvDeep`) that are not rendered as plain store paths. Instead of wrongly using `PathSet`, or "stringly typed" using `StringSet`, use `std::std<StringContextElem>`. ----- In support of this change, `NixStringContext` is now defined as `std::std<StringContextElem>` not `std:vector<StringContextElem>`. The old definition was just used by a `getContext` method which was only used by the eval cache. It can be deleted altogether since the types are now unified and the preexisting `copyContext` function already suffices. Summarizing the previous paragraph: Old: - `value/context.hh`: `NixStringContext = std::vector<StringContextElem>` - `value.hh`: `NixStringContext Value::getContext(...)` - `value.hh`: `copyContext(...)` New: - `value/context.hh`: `NixStringContext = std::set<StringContextElem>` - `value.hh`: `copyContext(...)` ---- The string representation of string context elements no longer contains the store dir. The diff of `src/libexpr/tests/value/context.cc` should make clear what the new representation is, so we recommend reviewing that file first. This was done for two reasons: Less API churn: `Value::mkString` and friends did not take a `Store` before. But if `NixStringContextElem::{parse, to_string}` *do* take a store (as they did before), then we cannot have the `Value` functions use them (in order to work with the fully-structured `NixStringContext`) without adding that argument. That would have been a lot of churn of threading the store, and this diff is already large enough, so the easier and less invasive thing to do was simply make the element `parse` and `to_string` functions not take the `Store` reference, and the easiest way to do that was to simply drop the store dir. Space usage: Dropping the `/nix/store/` (or similar) from the internal representation will safe space in the heap of the Nix programming being interpreted. If the heap contains many strings with non-trivial contexts, the saving could add up to something significant. ---- The eval cache version is bumped. The eval cache serialization uses `NixStringContextElem::{parse, to_string}`, and since those functions are changed per the above, that means the on-disk representation is also changed. This is simply done by changing the name of the used for the eval cache from `eval-cache-v4` to eval-cache-v5`. ---- To avoid some duplication `EvalCache::mkPathString` is added to abstract over the simple case of turning a store path to a string with just that string in the context. Context This PR picks up where #7543 left off. That one introduced the fully structured `NixStringContextElem` data type, but kept `PathSet context` as an awkward middle ground between internal `char[][]` interpreter heap string contexts and `NixStringContext` fully parsed string contexts. The infelicity of `PathSet context` was specifically called out during Nix team group review, but it was agreeing that fixing it could be left as future work. This is that future work. A possible follow-up step would be to get rid of the `char[][]` evaluator heap representation, too, but it is not yet clear how to do that. To use `NixStringContextElem` there we would need to get the STL containers to GC pointers in the GC build, and I am not sure how to do that. ---- PR #7543 effectively is writing the inverse of a `mkPathString`, `mkOutputString`, and one more such function for the `DrvDeep` case. I would like that PR to have property tests ensuring it is actually the inverse as expected. This PR sets things up nicely so that reworking that PR to be in that more elegant and better tested way is possible. Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
2023-04-17Merge remote-tracking branch 'upstream/master' into source-pathRobert Hensing
2023-04-07Finish converting existing comments for internal API docs (#8146)John Ericson
* Finish converting existing comments for internal API docs 99% of this was just reformatting existing comments. Only two exceptions: - Expanded upon `BuildResult::status` compat note - Split up file-level `symbol-table.hh` doc comments to get per-definition docs Also fixed a few whitespace goofs, turning leading tabs to spaces and removing trailing spaces. Picking up from #8133 * Fix two things from comments * Use triple-backtick not indent for `dumpPath` * Convert GNU-style `\`..'` quotes to markdown style in API docs This will render correctly.
2023-04-06Backport SourcePath from the lazy-trees branchEelco Dolstra
This introduces the SourcePath type from lazy-trees as an abstraction for accessing files from inputs that may not be materialized in the real filesystem (e.g. Git repositories). Currently, however, it's just a wrapper around CanonPath, so it shouldn't change any behaviour. (On lazy-trees, SourcePath is a <InputAccessor, CanonPath> tuple.)
2023-03-31Ensure all headers have `#pragma once` and are in API docsJohn Ericson
`///@file` makes them show up in the internal API dos. A tiny few were missing `#pragma once`.
2023-01-18Revert "Merge pull request #6204 from layus/coerce-string"Robert Hensing
This reverts commit a75b7ba30f1e4f8b15e810fd18e63ee9552e0815, reversing changes made to 9af16c5f742300e831a2cc400e43df1e22f87f31.
2023-01-10Parse string context elements properlyJohn Ericson
Prior to this change, we had a bunch of ad-hoc string manipulation code scattered around. This made it hard to figure out what data model for string contexts is. Now, we still store string contexts most of the time as encoded strings --- I was wary of the performance implications of changing that --- but whenever we parse them we do so only through the `NixStringContextElem::parse` method, which handles all cases. This creates a data type that is very similar to `DerivedPath` but: - Represents the funky `=<drvpath>` case as properly distinct from the others. - Only encodes a single output, no wildcards and no set, for the "built" case. (I would like to deprecate `=<path>`, after which we are in spitting distance of `DerivedPath` and could maybe get away with fewer types, but that is another topic for another day.)
2023-01-02Merge remote-tracking branch 'origin/master' into coerce-stringEelco Dolstra
2022-11-16Replace src/libutil/json.cc with nlohmann json generationYorick van Pelt
2022-09-07WIP: broken merge but need a git checkpointGuillaume Maudoux
2022-08-22JSON: print paths as strings without copying them to the storeNaïm Favier
Makes `printValueAsJSON` not copy paths to the store for `nix eval --json`, `nix-instantiate --eval --json` and `nix-env --json`. Fixes https://github.com/NixOS/nix/issues/5612
2022-05-26Remove pre-C++11 hackinessEelco Dolstra
2022-04-29Merge remote-tracking branch 'origin/master' into coerce-stringGuillaume Maudoux
2022-04-28No point in passing string_views by referenceGuillaume Maudoux
2022-04-25rename SymbolIdx -> Symbol, Symbol -> SymbolStrpennae
after #6218 `Symbol` no longer confers a uniqueness invariant on the string it wraps, it is now possible to create multiple symbols that compare equal but whose string contents have different addresses. this guarantee is now only provided by `SymbolIdx`, leaving `Symbol` only as a string wrapper that knows about the intricacies of how symbols need to be formatted for output. this change renames `SymbolIdx` to `Symbol` to restore the previous semantics of `Symbol` to that name. we also keep the wrapper type and rename it to `SymbolStr` instead of returning plain strings from lookups into the symbol table because symbols are formatted for output in many places. theoretically we do not need `SymbolStr`, only a function that formats a string for output as a symbol, but having to wrap every symbol that appears in a message into eg `formatSymbol()` is error-prone and inconvient.
2022-04-21store Symbols in a table as well, like positionspennae
this slightly increases the amount of memory used for any given symbol, but this increase is more than made up for if the symbol is referenced more than once in the EvalState that holds it. on average every symbol should be referenced at least twice (once to introduce a binding, once to use it), so we expect no increase in memory on average. symbol tables are limited to 2³² entries like position tables, and similar arguments apply to why overflow is not likely: 2³² symbols would require as many string instances (at 24 bytes each) and map entries (at 24 bytes or more each, assuming that the map holds on average at most one item per bucket as the docs say). a full symbol table would require at least 192GB of memory just for symbols, which is well out of reach. (an ofborg eval of nixpks today creates less than a million symbols!)
2022-04-21replace most Pos objects/ptrs with indexes into a position tablepennae
Pos objects are somewhat wasteful as they duplicate the origin file name and input type for each object. on files that produce more than one Pos when parsed this a sizeable waste of memory (one pointer per Pos). the same goes for ptr<Pos> on 64 bit machines: parsing enough source to require 8 bytes to locate a position would need at least 8GB of input and 64GB of expression memory. it's not likely that we'll hit that any time soon, so we can use a uint32_t index to locate positions instead.
2022-03-22Don't hide repeated values while generating manifest.nixEelco Dolstra
Fixes #6243.
2022-03-18Decode string context straight to using `StorePath`sJohn Ericson
I gather decoding happens on demand, so I hope don't think this should have any perf implications one way or the other.
2022-03-18Refactor to use more traces and less string manipulationsGuillaume Maudoux
2022-03-11Create some type aliases for string ContextsJohn Ericson
2022-03-04Add detailed error mesage for coerceTo{String,Path}Guillaume Maudoux
2022-03-03Be more aggressive in hiding repeated valuesEelco Dolstra
We now memoize on Bindings / list element vectors rather than Values, so that e.g. two Values that point to the same Bindings will be printed only once.
2022-03-03printValue(): Don't show repeated valuesEelco Dolstra
Fixes #6157.
2022-02-21Remove std::string aliasEelco Dolstra
2022-02-04Make most calls to determinePos() lazyEelco Dolstra
2022-01-12optimize ExprConcatStrings::evalpennae
constructing an ostringstream for non-string concats (like integer addition) is a small constant cost that we can avoid. for string concats we can keep all the string temporaries we get from coerceToString and concatenate them in one go, which saves a lot of intermediate temporaries and copies in ostringstream. we can also avoid copying the concatenated string again by directly allocating it in GC memory and moving ownership of the concatenated string into the target value. saves about 2% on system eval. before: Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' Time (mean ± σ): 2.837 s ± 0.031 s [User: 2.562 s, System: 0.191 s] Range (min … max): 2.796 s … 2.892 s 20 runs after: Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system' Time (mean ± σ): 2.790 s ± 0.035 s [User: 2.532 s, System: 0.187 s] Range (min … max): 2.722 s … 2.836 s 20 runs
2022-01-04Turn mkString(Symbol) into a methodEelco Dolstra
2022-01-04Remove non-method mkPath()Eelco Dolstra
2022-01-04Remove non-method mk<X> functionsEelco Dolstra
2022-01-04Remove non-method mkString()Eelco Dolstra
2022-01-04Ensure that attrsets are sortedEelco Dolstra
Previously you had to remember to call value->attrs->sort() after populating value->attrs. Now there is a BindingsBuilder helper that wraps Bindings and ensures that sort() is called before you can use it.
2021-12-02Introduce builtins.groupBy primopSilvan Mosberger
This function is very useful in nixpkgs, but its implementation in Nix itself is rather slow due to it requiring a lot of attribute set and list appends.
2021-11-25Support range-based for loop over list valuesEelco Dolstra
2021-11-13toXML: display errors positionKevin Amado
- This change applies to builtins.toXML and inner workings - Proof of concept: ```nix let e = builtins.toXML e; in e ``` - Before: ``` $ nix-instantiate --eval poc.nix error: infinite recursion encountered ``` - After: ``` $ nix-instantiate --eval poc.nix error: infinite recursion encountered at /data/github/kamadorueda/nix/poc.nix:1:9: 1| let e = builtins.toXML e; in e | ```