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Diffstat (limited to 'third_party/nix/src/libexpr/eval.hh')
| -rw-r--r-- | third_party/nix/src/libexpr/eval.hh | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/third_party/nix/src/libexpr/eval.hh b/third_party/nix/src/libexpr/eval.hh new file mode 100644 index 000000000000..0352a89a2ab8 --- /dev/null +++ b/third_party/nix/src/libexpr/eval.hh @@ -0,0 +1,365 @@ +#pragma once + +#include <map> +#include <optional> +#include <unordered_map> +#include <vector> + +#include "libexpr/attr-set.hh" +#include "libexpr/nixexpr.hh" +#include "libexpr/symbol-table.hh" +#include "libexpr/value.hh" +#include "libutil/config.hh" +#include "libutil/hash.hh" + +namespace nix { +namespace expr { + +// Initialise the Boehm GC once per program instance. This should be +// called in places that require the garbage collector. +void InitGC(); + +} // namespace expr + +class Store; +class EvalState; +enum RepairFlag : bool; + +typedef void (*PrimOpFun)(EvalState& state, const Pos& pos, Value** args, + Value& v); + +struct PrimOp { + PrimOpFun fun; + size_t arity; + Symbol name; + PrimOp(PrimOpFun fun, size_t arity, Symbol name) + : fun(fun), arity(arity), name(name) {} +}; + +struct Env { + Env(unsigned short size) : size(size) { values = std::vector<Value*>(size); } + + Env* up; + unsigned short size; // used by ‘valueSize’ + unsigned short prevWith : 14; // nr of levels up to next `with' environment + enum { Plain = 0, HasWithExpr, HasWithAttrs } type : 2; + std::vector<Value*> values; + Expr* withAttrsExpr = nullptr; +}; + +Value& mkString(Value& v, const std::string& s, + const PathSet& context = PathSet()); + +void copyContext(const Value& v, PathSet& context); + +/* Cache for calls to addToStore(); maps source paths to the store + paths. */ +using SrcToStore = std::map<Path, Path>; + +std::ostream& operator<<(std::ostream& str, const Value& v); + +using SearchPathElem = std::pair<std::string, std::string>; +using SearchPath = std::list<SearchPathElem>; + +using FileParseCache = std::map<Path, Expr*>; + +class EvalState { + public: + SymbolTable symbols; + + const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName, sValue, sSystem, + sOutputs, sOutputName, sIgnoreNulls, sFile, sLine, sColumn, sFunctor, + sToString, sRight, sWrong, sStructuredAttrs, sBuilder, sArgs, sOutputHash, + sOutputHashAlgo, sOutputHashMode; + + // Symbol representing the path to the built-in 'derivation.nix' + // file, set during primops initialisation. + std::optional<Symbol> sDerivationNix; + + /* If set, force copying files to the Nix store even if they + already exist there. */ + RepairFlag repair; + + /* The allowed filesystem paths in restricted or pure evaluation + mode. */ + std::optional<PathSet> allowedPaths; + + const ref<Store> store; + + private: + SrcToStore srcToStore; + + /* A cache from path names to parse trees. */ + FileParseCache fileParseCache; + + /* A cache from path names to values. */ + using FileEvalCache = std::map<Path, Value>; + FileEvalCache fileEvalCache; + + SearchPath searchPath; + + std::map<std::string, std::pair<bool, std::string>> searchPathResolved; + + /* Cache used by checkSourcePath(). */ + std::unordered_map<Path, Path> resolvedPaths; + + public: + EvalState(const Strings& _searchPath, const ref<Store>& store); + ~EvalState(); + + void addToSearchPath(const std::string& s); + + SearchPath getSearchPath() { return searchPath; } + + Path checkSourcePath(const Path& path); + + void checkURI(const std::string& uri); + + /* When using a diverted store and 'path' is in the Nix store, map + 'path' to the diverted location (e.g. /nix/store/foo is mapped + to /home/alice/my-nix/nix/store/foo). However, this is only + done if the context is not empty, since otherwise we're + probably trying to read from the actual /nix/store. This is + intended to distinguish between import-from-derivation and + sources stored in the actual /nix/store. */ + Path toRealPath(const Path& path, const PathSet& context); + + /* Parse a Nix expression from the specified file. */ + Expr* parseExprFromFile(const Path& path); + Expr* parseExprFromFile(const Path& path, StaticEnv& staticEnv); + + /* Parse a Nix expression from the specified string. */ + Expr* parseExprFromString(const std::string& s, const Path& basePath, + StaticEnv& staticEnv); + Expr* parseExprFromString(const std::string& s, const Path& basePath); + + Expr* parseStdin(); + + /* Evaluate an expression read from the given file to normal + form. */ + void evalFile(const Path& path, Value& v); + + void resetFileCache(); + + /* Look up a file in the search path. */ + Path findFile(const std::string& path); + Path findFile(SearchPath& searchPath, const std::string& path, + const Pos& pos = noPos); + + /* If the specified search path element is a URI, download it. */ + std::pair<bool, std::string> resolveSearchPathElem( + const SearchPathElem& elem); + + /* Evaluate an expression to normal form, storing the result in + value `v'. */ + void eval(Expr* e, Value& v); + + /* Evaluation the expression, then verify that it has the expected + type. */ + inline bool evalBool(Env& env, Expr* e); + inline bool evalBool(Env& env, Expr* e, const Pos& pos); + inline void evalAttrs(Env& env, Expr* e, Value& v); + + /* If `v' is a thunk, enter it and overwrite `v' with the result + of the evaluation of the thunk. If `v' is a delayed function + application, call the function and overwrite `v' with the + result. Otherwise, this is a no-op. */ + inline void forceValue(Value& v, const Pos& pos = noPos); + + /* Force a value, then recursively force list elements and + attributes. */ + void forceValueDeep(Value& v); + + /* Force `v', and then verify that it has the expected type. */ + NixInt forceInt(Value& v, const Pos& pos); + NixFloat forceFloat(Value& v, const Pos& pos); + bool forceBool(Value& v, const Pos& pos); + inline void forceAttrs(Value& v); + inline void forceAttrs(Value& v, const Pos& pos); + inline void forceList(Value& v); + inline void forceList(Value& v, const Pos& pos); + void forceFunction(Value& v, const Pos& pos); // either lambda or primop + std::string forceString(Value& v, const Pos& pos = noPos); + std::string forceString(Value& v, PathSet& context, const Pos& pos = noPos); + std::string forceStringNoCtx(Value& v, const Pos& pos = noPos); + + /* Return true iff the value `v' denotes a derivation (i.e. a + set with attribute `type = "derivation"'). */ + bool isDerivation(Value& v); + + std::optional<std::string> tryAttrsToString(const Pos& pos, Value& v, + PathSet& context, + bool coerceMore = false, + bool copyToStore = true); + + /* String coercion. Converts strings, paths and derivations to a + string. If `coerceMore' is set, also converts nulls, integers, + booleans and lists to a string. If `copyToStore' is set, + referenced paths are copied to the Nix store as a side effect. */ + std::string coerceToString(const Pos& pos, Value& v, PathSet& context, + bool coerceMore = false, bool copyToStore = true); + + std::string copyPathToStore(PathSet& context, const Path& path); + + /* Path coercion. Converts strings, paths and derivations to a + path. The result is guaranteed to be a canonicalised, absolute + path. Nothing is copied to the store. */ + Path coerceToPath(const Pos& pos, Value& v, PathSet& context); + + public: + /* The base environment, containing the builtin functions and + values. */ + Env& baseEnv; + + /* The same, but used during parsing to resolve variables. */ + StaticEnv staticBaseEnv; // !!! should be private + + private: + unsigned int baseEnvDispl = 0; + + void createBaseEnv(); + + Value* addConstant(const std::string& name, Value& v); + + Value* addPrimOp(const std::string& name, size_t arity, PrimOpFun primOp); + + public: + Value& getBuiltin(const std::string& name); + + private: + inline Value* lookupVar(Env* env, const ExprVar& var, bool noEval); + + friend struct ExprVar; + friend struct ExprAttrs; + friend struct ExprLet; + + Expr* parse(const char* text, const Path& path, const Path& basePath, + StaticEnv& staticEnv); + + public: + /* Do a deep equality test between two values. That is, list + elements and attributes are compared recursively. */ + bool eqValues(Value& v1, Value& v2); + + bool isFunctor(Value& fun); + + void callFunction(Value& fun, Value& arg, Value& v, const Pos& pos); + void callPrimOp(Value& fun, Value& arg, Value& v, const Pos& pos); + + /* Automatically call a function for which each argument has a + default value or has a binding in the `args' map. 'args' need + not live past the end of the call. */ + void autoCallFunction(Bindings* args, Value& fun, Value& res); + + /* Allocation primitives. */ + Value* allocValue(); + Env& allocEnv(size_t size); + + Value* allocAttr(Value& vAttrs, const Symbol& name); + + // Create a list value from the specified vector. + void mkList(Value& v, std::shared_ptr<NixList> list); + + // Create a list value, allocating as many elements as specified in + // size. This is used for the many cases in this codebase where + // assignment happens into the preallocated list. + void mkList(Value& v, size_t size = 0); + + void mkAttrs(Value& v, size_t capacity); + void mkThunk_(Value& v, Expr* expr); + void mkPos(Value& v, Pos* pos); + + void concatLists(Value& v, const NixList& lists, const Pos& pos); + + /* Print statistics. */ + void printStats(); + + void realiseContext(const PathSet& context); + + /* File access tracing. */ + void TraceFileAccess(const Path& path); + void EnableFileAccessTracing(std::function<void(const Path&)> fn); + + private: + unsigned long nrEnvs = 0; + unsigned long nrValuesInEnvs = 0; + unsigned long nrValues = 0; + unsigned long nrListElems = 0; + unsigned long nrAttrsets = 0; + unsigned long nrAttrsInAttrsets = 0; + unsigned long nrOpUpdates = 0; + unsigned long nrOpUpdateValuesCopied = 0; + unsigned long nrListConcats = 0; + unsigned long nrPrimOpCalls = 0; + unsigned long nrFunctionCalls = 0; + + bool countCalls; + + std::function<void(const Path&)> file_access_trace_fn = nullptr; + Path last_traced_file = ""; + + using PrimOpCalls = std::map<Symbol, size_t>; + PrimOpCalls primOpCalls; + + using FunctionCalls = std::map<ExprLambda*, size_t>; + FunctionCalls functionCalls; + + void incrFunctionCall(ExprLambda* fun); + + using AttrSelects = std::map<Pos, size_t>; + AttrSelects attrSelects; + + friend struct ExprOpUpdate; + friend struct ExprOpConcatLists; + friend struct ExprSelect; + friend void prim_getAttr(EvalState& state, const Pos& pos, Value** args, + Value& v); +}; + +/* Return a string representing the type of the value `v'. */ +std::string showType(const Value& v); + +/* Decode a context string ‘!<name>!<path>’ into a pair <path, + name>. */ +std::pair<std::string, std::string> decodeContext(const std::string& s); + +/* If `path' refers to a directory, then append "/default.nix". */ +Path resolveExprPath(Path path); + +struct InvalidPathError : EvalError { + Path path; + InvalidPathError(const Path& path); +#ifdef EXCEPTION_NEEDS_THROW_SPEC + ~InvalidPathError() noexcept {}; +#endif +}; + +struct EvalSettings : Config { + Setting<bool> restrictEval{ + this, false, "restrict-eval", + "Whether to restrict file system access to paths in $NIX_PATH, " + "and network access to the URI prefixes listed in 'allowed-uris'."}; + + Setting<bool> pureEval{this, false, "pure-eval", + "Whether to restrict file system and network access " + "to files specified by cryptographic hash."}; + + Setting<bool> enableImportFromDerivation{ + this, true, "allow-import-from-derivation", + "Whether the evaluator allows importing the result of a derivation."}; + + Setting<Strings> allowedUris{ + this, + {}, + "allowed-uris", + "Prefixes of URIs that builtin functions such as fetchurl and fetchGit " + "are allowed to fetch."}; + + Setting<bool> traceFunctionCalls{this, false, "trace-function-calls", + "Emit log messages for each function entry " + "and exit at the 'vomit' log level (-vvvv)"}; +}; + +extern EvalSettings evalSettings; + +} // namespace nix |