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Diffstat (limited to 'third_party/nix/src/libexpr/eval.hh')
| -rw-r--r-- | third_party/nix/src/libexpr/eval.hh | 363 |
1 files changed, 363 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 0000000000..8126e4ea50 --- /dev/null +++ b/third_party/nix/src/libexpr/eval.hh @@ -0,0 +1,363 @@ +#pragma once + +#include "attr-set.hh" +#include "value.hh" +#include "nixexpr.hh" +#include "symbol-table.hh" +#include "hash.hh" +#include "config.hh" + +#include <map> +#include <optional> +#include <unordered_map> + + +namespace nix { + + +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 * 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; + Value * values[0]; +}; + + +Value & mkString(Value & v, const 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. */ +typedef std::map<Path, Path> SrcToStore; + + +std::ostream & operator << (std::ostream & str, const Value & v); + + +typedef std::pair<std::string, std::string> SearchPathElem; +typedef std::list<SearchPathElem> SearchPath; + + +/* Initialise the Boehm GC, if applicable. */ +void initGC(); + + +class EvalState +{ +public: + SymbolTable symbols; + + const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName, sValue, + sSystem, sOverrides, sOutputs, sOutputName, sIgnoreNulls, + sFile, sLine, sColumn, sFunctor, sToString, + sRight, sWrong, sStructuredAttrs, sBuilder, sArgs, + sOutputHash, sOutputHashAlgo, sOutputHashMode; + 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; + + Value vEmptySet; + + const ref<Store> store; + +private: + SrcToStore srcToStore; + + /* A cache from path names to parse trees. */ +#if HAVE_BOEHMGC + typedef std::map<Path, Expr *, std::less<Path>, traceable_allocator<std::pair<const Path, Expr *> > > FileParseCache; +#else + typedef std::map<Path, Expr *> FileParseCache; +#endif + FileParseCache fileParseCache; + + /* A cache from path names to values. */ +#if HAVE_BOEHMGC + typedef std::map<Path, Value, std::less<Path>, traceable_allocator<std::pair<const Path, Value> > > FileEvalCache; +#else + typedef std::map<Path, Value> FileEvalCache; +#endif + 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, ref<Store> store); + ~EvalState(); + + void addToSearchPath(const 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 string & s, const Path & basePath, StaticEnv & staticEnv); + Expr * parseExprFromString(const 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 string & path); + Path findFile(SearchPath & searchPath, const 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 + string forceString(Value & v, const Pos & pos = noPos); + string forceString(Value & v, PathSet & context, const Pos & pos = noPos); + 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<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. */ + string coerceToString(const Pos & pos, Value & v, PathSet & context, + bool coerceMore = false, bool copyToStore = true); + + 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 string & name, Value & v); + + Value * addPrimOp(const string & name, + size_t arity, PrimOpFun primOp); + +public: + + Value & getBuiltin(const 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. */ + void autoCallFunction(Bindings & args, Value & fun, Value & res); + + /* Allocation primitives. */ + Value * allocValue(); + Env & allocEnv(size_t size); + + Value * allocAttr(Value & vAttrs, const Symbol & name); + + Bindings * allocBindings(size_t capacity); + + void mkList(Value & v, size_t length); + void mkAttrs(Value & v, size_t capacity); + void mkThunk_(Value & v, Expr * expr); + void mkPos(Value & v, Pos * pos); + + void concatLists(Value & v, size_t nrLists, Value * * lists, const Pos & pos); + + /* Print statistics. */ + void printStats(); + + void realiseContext(const PathSet & context); + +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; + + typedef std::map<Symbol, size_t> PrimOpCalls; + PrimOpCalls primOpCalls; + + typedef std::map<ExprLambda *, size_t> FunctionCalls; + FunctionCalls functionCalls; + + void incrFunctionCall(ExprLambda * fun); + + typedef std::map<Pos, size_t> AttrSelects; + 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'. */ +string showType(const Value & v); + +/* Decode a context string ‘!<name>!<path>’ into a pair <path, + name>. */ +std::pair<string, string> decodeContext(const 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() throw () { }; +#endif +}; + +struct EvalSettings : Config +{ + Setting<bool> enableNativeCode{this, false, "allow-unsafe-native-code-during-evaluation", + "Whether builtin functions that allow executing native code should be enabled."}; + + 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; + +} |