lix/src/libexpr/eval.cc
Andreas Rammhold 059ae7f6c4
Add unit tests for libexpr (#5377)
* libexpr: fix builtins.split example

The example was previously indicating that multiple whitespaces would be
collapsed into a single captured whitespace. That isn't true and was
likely a mistake when being documented initially.

* Fix segfault on unitilized list when printing value

Since lists are just chunks of memory the individual elements in the
list might be unitilized when a programming error happens within Nix.

In this case the values are null-initialized (at least with Boehm GC)
and we can avoid a nullptr deref when printing them.

I ran into this issue while ensuring that new expression tests would
show the actual value on an assertion failure.

This is unlikely to cause any runtime performance regressions as
printing values is not really in the hot path (unless the repl is the
primary use case).

* Add operator<< for ValueTypes

* Add libexpr tests

This introduces tests for libexpr that evalulate various trivial Nix
language expressions and primop invocations that should be good smoke
tests wheter or not the implementation is behaving as expected.
2022-05-06 18:05:27 +02:00

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#include "eval.hh"
#include "hash.hh"
#include "types.hh"
#include "util.hh"
#include "store-api.hh"
#include "derivations.hh"
#include "globals.hh"
#include "eval-inline.hh"
#include "filetransfer.hh"
#include "json.hh"
#include "function-trace.hh"
#include <algorithm>
#include <chrono>
#include <cstring>
#include <unistd.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <iostream>
#include <fstream>
#include <sys/resource.h>
#if HAVE_BOEHMGC
#define GC_INCLUDE_NEW
#include <gc/gc.h>
#include <gc/gc_cpp.h>
#include <boost/coroutine2/coroutine.hpp>
#include <boost/coroutine2/protected_fixedsize_stack.hpp>
#include <boost/context/stack_context.hpp>
#endif
namespace nix {
static char * allocString(size_t size)
{
char * t;
#if HAVE_BOEHMGC
t = (char *) GC_MALLOC_ATOMIC(size);
#else
t = malloc(size);
#endif
if (!t) throw std::bad_alloc();
return t;
}
static char * dupString(const char * s)
{
char * t;
#if HAVE_BOEHMGC
t = GC_STRDUP(s);
#else
t = strdup(s);
#endif
if (!t) throw std::bad_alloc();
return t;
}
// When there's no need to write to the string, we can optimize away empty
// string allocations.
// This function handles makeImmutableStringWithLen(null, 0) by returning the
// empty string.
static const char * makeImmutableStringWithLen(const char * s, size_t size)
{
char * t;
if (size == 0)
return "";
#if HAVE_BOEHMGC
t = GC_STRNDUP(s, size);
#else
t = strndup(s, size);
#endif
if (!t) throw std::bad_alloc();
return t;
}
static inline const char * makeImmutableString(std::string_view s) {
return makeImmutableStringWithLen(s.data(), s.size());
}
RootValue allocRootValue(Value * v)
{
#if HAVE_BOEHMGC
return std::allocate_shared<Value *>(traceable_allocator<Value *>(), v);
#else
return std::make_shared<Value *>(v);
#endif
}
void Value::print(const SymbolTable & symbols, std::ostream & str,
std::set<const void *> * seen) const
{
checkInterrupt();
switch (internalType) {
case tInt:
str << integer;
break;
case tBool:
str << (boolean ? "true" : "false");
break;
case tString:
str << "\"";
for (const char * i = string.s; *i; i++)
if (*i == '\"' || *i == '\\') str << "\\" << *i;
else if (*i == '\n') str << "\\n";
else if (*i == '\r') str << "\\r";
else if (*i == '\t') str << "\\t";
else if (*i == '$' && *(i+1) == '{') str << "\\" << *i;
else str << *i;
str << "\"";
break;
case tPath:
str << path; // !!! escaping?
break;
case tNull:
str << "null";
break;
case tAttrs: {
if (seen && !attrs->empty() && !seen->insert(attrs).second)
str << "«repeated»";
else {
str << "{ ";
for (auto & i : attrs->lexicographicOrder(symbols)) {
str << symbols[i->name] << " = ";
i->value->print(symbols, str, seen);
str << "; ";
}
str << "}";
}
break;
}
case tList1:
case tList2:
case tListN:
if (seen && listSize() && !seen->insert(listElems()).second)
str << "«repeated»";
else {
str << "[ ";
for (auto v2 : listItems()) {
if (v2)
v2->print(symbols, str, seen);
else
str << "(nullptr)";
str << " ";
}
str << "]";
}
break;
case tThunk:
case tApp:
str << "<CODE>";
break;
case tLambda:
str << "<LAMBDA>";
break;
case tPrimOp:
str << "<PRIMOP>";
break;
case tPrimOpApp:
str << "<PRIMOP-APP>";
break;
case tExternal:
str << *external;
break;
case tFloat:
str << fpoint;
break;
default:
abort();
}
}
void Value::print(const SymbolTable & symbols, std::ostream & str, bool showRepeated) const
{
std::set<const void *> seen;
print(symbols, str, showRepeated ? nullptr : &seen);
}
// Pretty print types for assertion errors
std::ostream & operator << (std::ostream & os, const ValueType t) {
os << showType(t);
return os;
}
std::string printValue(const EvalState & state, const Value & v)
{
std::ostringstream out;
v.print(state.symbols, out);
return out.str();
}
const Value * getPrimOp(const Value &v) {
const Value * primOp = &v;
while (primOp->isPrimOpApp()) {
primOp = primOp->primOpApp.left;
}
assert(primOp->isPrimOp());
return primOp;
}
std::string_view showType(ValueType type)
{
switch (type) {
case nInt: return "an integer";
case nBool: return "a Boolean";
case nString: return "a string";
case nPath: return "a path";
case nNull: return "null";
case nAttrs: return "a set";
case nList: return "a list";
case nFunction: return "a function";
case nExternal: return "an external value";
case nFloat: return "a float";
case nThunk: return "a thunk";
}
abort();
}
std::string showType(const Value & v)
{
switch (v.internalType) {
case tString: return v.string.context ? "a string with context" : "a string";
case tPrimOp:
return fmt("the built-in function '%s'", std::string(v.primOp->name));
case tPrimOpApp:
return fmt("the partially applied built-in function '%s'", std::string(getPrimOp(v)->primOp->name));
case tExternal: return v.external->showType();
case tThunk: return "a thunk";
case tApp: return "a function application";
case tBlackhole: return "a black hole";
default:
return std::string(showType(v.type()));
}
}
PosIdx Value::determinePos(const PosIdx pos) const
{
switch (internalType) {
case tAttrs: return attrs->pos;
case tLambda: return lambda.fun->pos;
case tApp: return app.left->determinePos(pos);
default: return pos;
}
}
bool Value::isTrivial() const
{
return
internalType != tApp
&& internalType != tPrimOpApp
&& (internalType != tThunk
|| (dynamic_cast<ExprAttrs *>(thunk.expr)
&& ((ExprAttrs *) thunk.expr)->dynamicAttrs.empty())
|| dynamic_cast<ExprLambda *>(thunk.expr)
|| dynamic_cast<ExprList *>(thunk.expr));
}
#if HAVE_BOEHMGC
/* Called when the Boehm GC runs out of memory. */
static void * oomHandler(size_t requested)
{
/* Convert this to a proper C++ exception. */
throw std::bad_alloc();
}
class BoehmGCStackAllocator : public StackAllocator {
boost::coroutines2::protected_fixedsize_stack stack {
// We allocate 8 MB, the default max stack size on NixOS.
// A smaller stack might be quicker to allocate but reduces the stack
// depth available for source filter expressions etc.
std::max(boost::context::stack_traits::default_size(), static_cast<std::size_t>(8 * 1024 * 1024))
};
// This is specific to boost::coroutines2::protected_fixedsize_stack.
// The stack protection page is included in sctx.size, so we have to
// subtract one page size from the stack size.
std::size_t pfss_usable_stack_size(boost::context::stack_context &sctx) {
return sctx.size - boost::context::stack_traits::page_size();
}
public:
boost::context::stack_context allocate() override {
auto sctx = stack.allocate();
// Stacks generally start at a high address and grow to lower addresses.
// Architectures that do the opposite are rare; in fact so rare that
// boost_routine does not implement it.
// So we subtract the stack size.
GC_add_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
return sctx;
}
void deallocate(boost::context::stack_context sctx) override {
GC_remove_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
stack.deallocate(sctx);
}
};
static BoehmGCStackAllocator boehmGCStackAllocator;
#endif
static Symbol getName(const AttrName & name, EvalState & state, Env & env)
{
if (name.symbol) {
return name.symbol;
} else {
Value nameValue;
name.expr->eval(state, env, nameValue);
state.forceStringNoCtx(nameValue);
return state.symbols.create(nameValue.string.s);
}
}
static bool gcInitialised = false;
void initGC()
{
if (gcInitialised) return;
#if HAVE_BOEHMGC
/* Initialise the Boehm garbage collector. */
/* Don't look for interior pointers. This reduces the odds of
misdetection a bit. */
GC_set_all_interior_pointers(0);
/* We don't have any roots in data segments, so don't scan from
there. */
GC_set_no_dls(1);
GC_INIT();
GC_set_oom_fn(oomHandler);
StackAllocator::defaultAllocator = &boehmGCStackAllocator;
/* Set the initial heap size to something fairly big (25% of
physical RAM, up to a maximum of 384 MiB) so that in most cases
we don't need to garbage collect at all. (Collection has a
fairly significant overhead.) The heap size can be overridden
through libgc's GC_INITIAL_HEAP_SIZE environment variable. We
should probably also provide a nix.conf setting for this. Note
that GC_expand_hp() causes a lot of virtual, but not physical
(resident) memory to be allocated. This might be a problem on
systems that don't overcommit. */
if (!getEnv("GC_INITIAL_HEAP_SIZE")) {
size_t size = 32 * 1024 * 1024;
#if HAVE_SYSCONF && defined(_SC_PAGESIZE) && defined(_SC_PHYS_PAGES)
size_t maxSize = 384 * 1024 * 1024;
long pageSize = sysconf(_SC_PAGESIZE);
long pages = sysconf(_SC_PHYS_PAGES);
if (pageSize != -1)
size = (pageSize * pages) / 4; // 25% of RAM
if (size > maxSize) size = maxSize;
#endif
debug(format("setting initial heap size to %1% bytes") % size);
GC_expand_hp(size);
}
#endif
gcInitialised = true;
}
/* Very hacky way to parse $NIX_PATH, which is colon-separated, but
can contain URLs (e.g. "nixpkgs=https://bla...:foo=https://"). */
static Strings parseNixPath(const std::string & s)
{
Strings res;
auto p = s.begin();
while (p != s.end()) {
auto start = p;
auto start2 = p;
while (p != s.end() && *p != ':') {
if (*p == '=') start2 = p + 1;
++p;
}
if (p == s.end()) {
if (p != start) res.push_back(std::string(start, p));
break;
}
if (*p == ':') {
if (isUri(std::string(start2, s.end()))) {
++p;
while (p != s.end() && *p != ':') ++p;
}
res.push_back(std::string(start, p));
if (p == s.end()) break;
}
++p;
}
return res;
}
EvalState::EvalState(
const Strings & _searchPath,
ref<Store> store,
std::shared_ptr<Store> buildStore)
: sWith(symbols.create("<with>"))
, sOutPath(symbols.create("outPath"))
, sDrvPath(symbols.create("drvPath"))
, sType(symbols.create("type"))
, sMeta(symbols.create("meta"))
, sName(symbols.create("name"))
, sValue(symbols.create("value"))
, sSystem(symbols.create("system"))
, sOverrides(symbols.create("__overrides"))
, sOutputs(symbols.create("outputs"))
, sOutputName(symbols.create("outputName"))
, sIgnoreNulls(symbols.create("__ignoreNulls"))
, sFile(symbols.create("file"))
, sLine(symbols.create("line"))
, sColumn(symbols.create("column"))
, sFunctor(symbols.create("__functor"))
, sToString(symbols.create("__toString"))
, sRight(symbols.create("right"))
, sWrong(symbols.create("wrong"))
, sStructuredAttrs(symbols.create("__structuredAttrs"))
, sBuilder(symbols.create("builder"))
, sArgs(symbols.create("args"))
, sContentAddressed(symbols.create("__contentAddressed"))
, sImpure(symbols.create("__impure"))
, sOutputHash(symbols.create("outputHash"))
, sOutputHashAlgo(symbols.create("outputHashAlgo"))
, sOutputHashMode(symbols.create("outputHashMode"))
, sRecurseForDerivations(symbols.create("recurseForDerivations"))
, sDescription(symbols.create("description"))
, sSelf(symbols.create("self"))
, sEpsilon(symbols.create(""))
, sStartSet(symbols.create("startSet"))
, sOperator(symbols.create("operator"))
, sKey(symbols.create("key"))
, sPath(symbols.create("path"))
, sPrefix(symbols.create("prefix"))
, repair(NoRepair)
, emptyBindings(0)
, store(store)
, buildStore(buildStore ? buildStore : store)
, regexCache(makeRegexCache())
#if HAVE_BOEHMGC
, valueAllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
, env1AllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
#else
, valueAllocCache(std::make_shared<void *>(nullptr))
, env1AllocCache(std::make_shared<void *>(nullptr))
#endif
, baseEnv(allocEnv(128))
, staticBaseEnv(false, 0)
{
countCalls = getEnv("NIX_COUNT_CALLS").value_or("0") != "0";
assert(gcInitialised);
static_assert(sizeof(Env) <= 16, "environment must be <= 16 bytes");
/* Initialise the Nix expression search path. */
if (!evalSettings.pureEval) {
for (auto & i : _searchPath) addToSearchPath(i);
for (auto & i : evalSettings.nixPath.get()) addToSearchPath(i);
}
if (evalSettings.restrictEval || evalSettings.pureEval) {
allowedPaths = PathSet();
for (auto & i : searchPath) {
auto r = resolveSearchPathElem(i);
if (!r.first) continue;
auto path = r.second;
if (store->isInStore(r.second)) {
try {
StorePathSet closure;
store->computeFSClosure(store->toStorePath(r.second).first, closure);
for (auto & path : closure)
allowPath(path);
} catch (InvalidPath &) {
allowPath(r.second);
}
} else
allowPath(r.second);
}
}
createBaseEnv();
}
EvalState::~EvalState()
{
}
void EvalState::allowPath(const Path & path)
{
if (allowedPaths)
allowedPaths->insert(path);
}
void EvalState::allowPath(const StorePath & storePath)
{
if (allowedPaths)
allowedPaths->insert(store->toRealPath(storePath));
}
void EvalState::allowAndSetStorePathString(const StorePath &storePath, Value & v)
{
allowPath(storePath);
auto path = store->printStorePath(storePath);
v.mkString(path, PathSet({path}));
}
Path EvalState::checkSourcePath(const Path & path_)
{
if (!allowedPaths) return path_;
auto i = resolvedPaths.find(path_);
if (i != resolvedPaths.end())
return i->second;
bool found = false;
/* First canonicalize the path without symlinks, so we make sure an
* attacker can't append ../../... to a path that would be in allowedPaths
* and thus leak symlink targets.
*/
Path abspath = canonPath(path_);
if (hasPrefix(abspath, corepkgsPrefix)) return abspath;
for (auto & i : *allowedPaths) {
if (isDirOrInDir(abspath, i)) {
found = true;
break;
}
}
if (!found) {
auto modeInformation = evalSettings.pureEval
? "in pure eval mode (use '--impure' to override)"
: "in restricted mode";
throw RestrictedPathError("access to absolute path '%1%' is forbidden %2%", abspath, modeInformation);
}
/* Resolve symlinks. */
debug(format("checking access to '%s'") % abspath);
Path path = canonPath(abspath, true);
for (auto & i : *allowedPaths) {
if (isDirOrInDir(path, i)) {
resolvedPaths[path_] = path;
return path;
}
}
throw RestrictedPathError("access to canonical path '%1%' is forbidden in restricted mode", path);
}
void EvalState::checkURI(const std::string & uri)
{
if (!evalSettings.restrictEval) return;
/* 'uri' should be equal to a prefix, or in a subdirectory of a
prefix. Thus, the prefix https://github.co does not permit
access to https://github.com. Note: this allows 'http://' and
'https://' as prefixes for any http/https URI. */
for (auto & prefix : evalSettings.allowedUris.get())
if (uri == prefix ||
(uri.size() > prefix.size()
&& prefix.size() > 0
&& hasPrefix(uri, prefix)
&& (prefix[prefix.size() - 1] == '/' || uri[prefix.size()] == '/')))
return;
/* If the URI is a path, then check it against allowedPaths as
well. */
if (hasPrefix(uri, "/")) {
checkSourcePath(uri);
return;
}
if (hasPrefix(uri, "file://")) {
checkSourcePath(std::string(uri, 7));
return;
}
throw RestrictedPathError("access to URI '%s' is forbidden in restricted mode", uri);
}
Path EvalState::toRealPath(const Path & path, const PathSet & context)
{
// FIXME: check whether 'path' is in 'context'.
return
!context.empty() && store->isInStore(path)
? store->toRealPath(path)
: path;
}
Value * EvalState::addConstant(const std::string & name, Value & v)
{
Value * v2 = allocValue();
*v2 = v;
addConstant(name, v2);
return v2;
}
void EvalState::addConstant(const std::string & name, Value * v)
{
staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
baseEnv.values[baseEnvDispl++] = v;
auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v));
}
Value * EvalState::addPrimOp(const std::string & name,
size_t arity, PrimOpFun primOp)
{
auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
auto sym = symbols.create(name2);
/* Hack to make constants lazy: turn them into a application of
the primop to a dummy value. */
if (arity == 0) {
auto vPrimOp = allocValue();
vPrimOp->mkPrimOp(new PrimOp { .fun = primOp, .arity = 1, .name = name2 });
Value v;
v.mkApp(vPrimOp, vPrimOp);
return addConstant(name, v);
}
Value * v = allocValue();
v->mkPrimOp(new PrimOp { .fun = primOp, .arity = arity, .name = name2 });
staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
baseEnv.values[baseEnvDispl++] = v;
baseEnv.values[0]->attrs->push_back(Attr(sym, v));
return v;
}
Value * EvalState::addPrimOp(PrimOp && primOp)
{
/* Hack to make constants lazy: turn them into a application of
the primop to a dummy value. */
if (primOp.arity == 0) {
primOp.arity = 1;
auto vPrimOp = allocValue();
vPrimOp->mkPrimOp(new PrimOp(primOp));
Value v;
v.mkApp(vPrimOp, vPrimOp);
return addConstant(primOp.name, v);
}
auto envName = symbols.create(primOp.name);
if (hasPrefix(primOp.name, "__"))
primOp.name = primOp.name.substr(2);
Value * v = allocValue();
v->mkPrimOp(new PrimOp(primOp));
staticBaseEnv.vars.emplace_back(envName, baseEnvDispl);
baseEnv.values[baseEnvDispl++] = v;
baseEnv.values[0]->attrs->push_back(Attr(symbols.create(primOp.name), v));
return v;
}
Value & EvalState::getBuiltin(const std::string & name)
{
return *baseEnv.values[0]->attrs->find(symbols.create(name))->value;
}
std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
{
if (v.isPrimOp()) {
auto v2 = &v;
if (v2->primOp->doc)
return Doc {
.pos = {},
.name = v2->primOp->name,
.arity = v2->primOp->arity,
.args = v2->primOp->args,
.doc = v2->primOp->doc,
};
}
return {};
}
/* Every "format" object (even temporary) takes up a few hundred bytes
of stack space, which is a real killer in the recursive
evaluator. So here are some helper functions for throwing
exceptions. */
void EvalState::throwEvalError(const PosIdx pos, const char * s) const
{
throw EvalError({
.msg = hintfmt(s),
.errPos = positions[pos]
});
}
void EvalState::throwTypeError(const PosIdx pos, const char * s, const Value & v) const
{
throw TypeError({
.msg = hintfmt(s, showType(v)),
.errPos = positions[pos]
});
}
void EvalState::throwEvalError(const char * s, const std::string & s2) const
{
throw EvalError(s, s2);
}
void EvalState::throwEvalError(const PosIdx pos, const Suggestions & suggestions, const char * s,
const std::string & s2) const
{
throw EvalError(ErrorInfo {
.msg = hintfmt(s, s2),
.errPos = positions[pos],
.suggestions = suggestions,
});
}
void EvalState::throwEvalError(const PosIdx pos, const char * s, const std::string & s2) const
{
throw EvalError(ErrorInfo {
.msg = hintfmt(s, s2),
.errPos = positions[pos]
});
}
void EvalState::throwEvalError(const char * s, const std::string & s2, const std::string & s3) const
{
throw EvalError(s, s2, s3);
}
void EvalState::throwEvalError(const PosIdx pos, const char * s, const std::string & s2,
const std::string & s3) const
{
throw EvalError({
.msg = hintfmt(s, s2, s3),
.errPos = positions[pos]
});
}
void EvalState::throwEvalError(const PosIdx p1, const char * s, const Symbol sym, const PosIdx p2) const
{
// p1 is where the error occurred; p2 is a position mentioned in the message.
throw EvalError({
.msg = hintfmt(s, symbols[sym], positions[p2]),
.errPos = positions[p1]
});
}
void EvalState::throwTypeError(const PosIdx pos, const char * s) const
{
throw TypeError({
.msg = hintfmt(s),
.errPos = positions[pos]
});
}
void EvalState::throwTypeError(const PosIdx pos, const char * s, const ExprLambda & fun,
const Symbol s2) const
{
throw TypeError({
.msg = hintfmt(s, fun.showNamePos(*this), symbols[s2]),
.errPos = positions[pos]
});
}
void EvalState::throwTypeError(const PosIdx pos, const Suggestions & suggestions, const char * s,
const ExprLambda & fun, const Symbol s2) const
{
throw TypeError(ErrorInfo {
.msg = hintfmt(s, fun.showNamePos(*this), symbols[s2]),
.errPos = positions[pos],
.suggestions = suggestions,
});
}
void EvalState::throwTypeError(const char * s, const Value & v) const
{
throw TypeError(s, showType(v));
}
void EvalState::throwAssertionError(const PosIdx pos, const char * s, const std::string & s1) const
{
throw AssertionError({
.msg = hintfmt(s, s1),
.errPos = positions[pos]
});
}
void EvalState::throwUndefinedVarError(const PosIdx pos, const char * s, const std::string & s1) const
{
throw UndefinedVarError({
.msg = hintfmt(s, s1),
.errPos = positions[pos]
});
}
void EvalState::throwMissingArgumentError(const PosIdx pos, const char * s, const std::string & s1) const
{
throw MissingArgumentError({
.msg = hintfmt(s, s1),
.errPos = positions[pos]
});
}
void EvalState::addErrorTrace(Error & e, const char * s, const std::string & s2) const
{
e.addTrace(std::nullopt, s, s2);
}
void EvalState::addErrorTrace(Error & e, const PosIdx pos, const char * s, const std::string & s2) const
{
e.addTrace(positions[pos], s, s2);
}
void Value::mkString(std::string_view s)
{
mkString(makeImmutableString(s));
}
static void copyContextToValue(Value & v, const PathSet & context)
{
if (!context.empty()) {
size_t n = 0;
v.string.context = (const char * *)
allocBytes((context.size() + 1) * sizeof(char *));
for (auto & i : context)
v.string.context[n++] = dupString(i.c_str());
v.string.context[n] = 0;
}
}
void Value::mkString(std::string_view s, const PathSet & context)
{
mkString(s);
copyContextToValue(*this, context);
}
void Value::mkStringMove(const char * s, const PathSet & context)
{
mkString(s);
copyContextToValue(*this, context);
}
void Value::mkPath(std::string_view s)
{
mkPath(makeImmutableString(s));
}
inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
{
for (auto l = var.level; l; --l, env = env->up) ;
if (!var.fromWith) return env->values[var.displ];
while (1) {
if (env->type == Env::HasWithExpr) {
if (noEval) return 0;
Value * v = allocValue();
evalAttrs(*env->up, (Expr *) env->values[0], *v);
env->values[0] = v;
env->type = Env::HasWithAttrs;
}
Bindings::iterator j = env->values[0]->attrs->find(var.name);
if (j != env->values[0]->attrs->end()) {
if (countCalls) attrSelects[j->pos]++;
return j->value;
}
if (!env->prevWith)
throwUndefinedVarError(var.pos, "undefined variable '%1%'", symbols[var.name]);
for (size_t l = env->prevWith; l; --l, env = env->up) ;
}
}
void EvalState::mkList(Value & v, size_t size)
{
v.mkList(size);
if (size > 2)
v.bigList.elems = (Value * *) allocBytes(size * sizeof(Value *));
nrListElems += size;
}
unsigned long nrThunks = 0;
static inline void mkThunk(Value & v, Env & env, Expr * expr)
{
v.mkThunk(&env, expr);
nrThunks++;
}
void EvalState::mkThunk_(Value & v, Expr * expr)
{
mkThunk(v, baseEnv, expr);
}
void EvalState::mkPos(Value & v, PosIdx p)
{
auto pos = positions[p];
if (!pos.file.empty()) {
auto attrs = buildBindings(3);
attrs.alloc(sFile).mkString(pos.file);
attrs.alloc(sLine).mkInt(pos.line);
attrs.alloc(sColumn).mkInt(pos.column);
v.mkAttrs(attrs);
} else
v.mkNull();
}
/* Create a thunk for the delayed computation of the given expression
in the given environment. But if the expression is a variable,
then look it up right away. This significantly reduces the number
of thunks allocated. */
Value * Expr::maybeThunk(EvalState & state, Env & env)
{
Value * v = state.allocValue();
mkThunk(*v, env, this);
return v;
}
Value * ExprVar::maybeThunk(EvalState & state, Env & env)
{
Value * v = state.lookupVar(&env, *this, true);
/* The value might not be initialised in the environment yet.
In that case, ignore it. */
if (v) { state.nrAvoided++; return v; }
return Expr::maybeThunk(state, env);
}
Value * ExprString::maybeThunk(EvalState & state, Env & env)
{
state.nrAvoided++;
return &v;
}
Value * ExprInt::maybeThunk(EvalState & state, Env & env)
{
state.nrAvoided++;
return &v;
}
Value * ExprFloat::maybeThunk(EvalState & state, Env & env)
{
state.nrAvoided++;
return &v;
}
Value * ExprPath::maybeThunk(EvalState & state, Env & env)
{
state.nrAvoided++;
return &v;
}
void EvalState::evalFile(const Path & path_, Value & v, bool mustBeTrivial)
{
auto path = checkSourcePath(path_);
FileEvalCache::iterator i;
if ((i = fileEvalCache.find(path)) != fileEvalCache.end()) {
v = i->second;
return;
}
Path resolvedPath = resolveExprPath(path);
if ((i = fileEvalCache.find(resolvedPath)) != fileEvalCache.end()) {
v = i->second;
return;
}
printTalkative("evaluating file '%1%'", resolvedPath);
Expr * e = nullptr;
auto j = fileParseCache.find(resolvedPath);
if (j != fileParseCache.end())
e = j->second;
if (!e)
e = parseExprFromFile(checkSourcePath(resolvedPath));
cacheFile(path, resolvedPath, e, v, mustBeTrivial);
}
void EvalState::resetFileCache()
{
fileEvalCache.clear();
fileParseCache.clear();
}
void EvalState::cacheFile(
const Path & path,
const Path & resolvedPath,
Expr * e,
Value & v,
bool mustBeTrivial)
{
fileParseCache[resolvedPath] = e;
try {
// Enforce that 'flake.nix' is a direct attrset, not a
// computation.
if (mustBeTrivial &&
!(dynamic_cast<ExprAttrs *>(e)))
throw EvalError("file '%s' must be an attribute set", path);
eval(e, v);
} catch (Error & e) {
addErrorTrace(e, "while evaluating the file '%1%':", resolvedPath);
throw;
}
fileEvalCache[resolvedPath] = v;
if (path != resolvedPath) fileEvalCache[path] = v;
}
void EvalState::eval(Expr * e, Value & v)
{
e->eval(*this, baseEnv, v);
}
inline bool EvalState::evalBool(Env & env, Expr * e)
{
Value v;
e->eval(*this, env, v);
if (v.type() != nBool)
throwTypeError("value is %1% while a Boolean was expected", v);
return v.boolean;
}
inline bool EvalState::evalBool(Env & env, Expr * e, const PosIdx pos)
{
Value v;
e->eval(*this, env, v);
if (v.type() != nBool)
throwTypeError(pos, "value is %1% while a Boolean was expected", v);
return v.boolean;
}
inline void EvalState::evalAttrs(Env & env, Expr * e, Value & v)
{
e->eval(*this, env, v);
if (v.type() != nAttrs)
throwTypeError("value is %1% while a set was expected", v);
}
void Expr::eval(EvalState & state, Env & env, Value & v)
{
abort();
}
void ExprInt::eval(EvalState & state, Env & env, Value & v)
{
v = this->v;
}
void ExprFloat::eval(EvalState & state, Env & env, Value & v)
{
v = this->v;
}
void ExprString::eval(EvalState & state, Env & env, Value & v)
{
v = this->v;
}
void ExprPath::eval(EvalState & state, Env & env, Value & v)
{
v = this->v;
}
void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
{
v.mkAttrs(state.buildBindings(attrs.size() + dynamicAttrs.size()).finish());
auto dynamicEnv = &env;
if (recursive) {
/* Create a new environment that contains the attributes in
this `rec'. */
Env & env2(state.allocEnv(attrs.size()));
env2.up = &env;
dynamicEnv = &env2;
AttrDefs::iterator overrides = attrs.find(state.sOverrides);
bool hasOverrides = overrides != attrs.end();
/* The recursive attributes are evaluated in the new
environment, while the inherited attributes are evaluated
in the original environment. */
Displacement displ = 0;
for (auto & i : attrs) {
Value * vAttr;
if (hasOverrides && !i.second.inherited) {
vAttr = state.allocValue();
mkThunk(*vAttr, env2, i.second.e);
} else
vAttr = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
env2.values[displ++] = vAttr;
v.attrs->push_back(Attr(i.first, vAttr, i.second.pos));
}
/* If the rec contains an attribute called `__overrides', then
evaluate it, and add the attributes in that set to the rec.
This allows overriding of recursive attributes, which is
otherwise not possible. (You can use the // operator to
replace an attribute, but other attributes in the rec will
still reference the original value, because that value has
been substituted into the bodies of the other attributes.
Hence we need __overrides.) */
if (hasOverrides) {
Value * vOverrides = (*v.attrs)[overrides->second.displ].value;
state.forceAttrs(*vOverrides, [&]() { return vOverrides->determinePos(noPos); });
Bindings * newBnds = state.allocBindings(v.attrs->capacity() + vOverrides->attrs->size());
for (auto & i : *v.attrs)
newBnds->push_back(i);
for (auto & i : *vOverrides->attrs) {
AttrDefs::iterator j = attrs.find(i.name);
if (j != attrs.end()) {
(*newBnds)[j->second.displ] = i;
env2.values[j->second.displ] = i.value;
} else
newBnds->push_back(i);
}
newBnds->sort();
v.attrs = newBnds;
}
}
else
for (auto & i : attrs)
v.attrs->push_back(Attr(i.first, i.second.e->maybeThunk(state, env), i.second.pos));
/* Dynamic attrs apply *after* rec and __overrides. */
for (auto & i : dynamicAttrs) {
Value nameVal;
i.nameExpr->eval(state, *dynamicEnv, nameVal);
state.forceValue(nameVal, i.pos);
if (nameVal.type() == nNull)
continue;
state.forceStringNoCtx(nameVal);
auto nameSym = state.symbols.create(nameVal.string.s);
Bindings::iterator j = v.attrs->find(nameSym);
if (j != v.attrs->end())
state.throwEvalError(i.pos, "dynamic attribute '%1%' already defined at %2%", nameSym, j->pos);
i.valueExpr->setName(nameSym);
/* Keep sorted order so find can catch duplicates */
v.attrs->push_back(Attr(nameSym, i.valueExpr->maybeThunk(state, *dynamicEnv), i.pos));
v.attrs->sort(); // FIXME: inefficient
}
v.attrs->pos = pos;
}
void ExprLet::eval(EvalState & state, Env & env, Value & v)
{
/* Create a new environment that contains the attributes in this
`let'. */
Env & env2(state.allocEnv(attrs->attrs.size()));
env2.up = &env;
/* The recursive attributes are evaluated in the new environment,
while the inherited attributes are evaluated in the original
environment. */
Displacement displ = 0;
for (auto & i : attrs->attrs)
env2.values[displ++] = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
body->eval(state, env2, v);
}
void ExprList::eval(EvalState & state, Env & env, Value & v)
{
state.mkList(v, elems.size());
for (auto [n, v2] : enumerate(v.listItems()))
const_cast<Value * &>(v2) = elems[n]->maybeThunk(state, env);
}
void ExprVar::eval(EvalState & state, Env & env, Value & v)
{
Value * v2 = state.lookupVar(&env, *this, false);
state.forceValue(*v2, pos);
v = *v2;
}
static std::string showAttrPath(EvalState & state, Env & env, const AttrPath & attrPath)
{
std::ostringstream out;
bool first = true;
for (auto & i : attrPath) {
if (!first) out << '.'; else first = false;
try {
out << state.symbols[getName(i, state, env)];
} catch (Error & e) {
assert(!i.symbol);
out << "\"${";
i.expr->show(state.symbols, out);
out << "}\"";
}
}
return out.str();
}
void ExprSelect::eval(EvalState & state, Env & env, Value & v)
{
Value vTmp;
PosIdx pos2;
Value * vAttrs = &vTmp;
e->eval(state, env, vTmp);
try {
for (auto & i : attrPath) {
state.nrLookups++;
Bindings::iterator j;
auto name = getName(i, state, env);
if (def) {
state.forceValue(*vAttrs, pos);
if (vAttrs->type() != nAttrs ||
(j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
{
def->eval(state, env, v);
return;
}
} else {
state.forceAttrs(*vAttrs, pos);
if ((j = vAttrs->attrs->find(name)) == vAttrs->attrs->end()) {
std::set<std::string> allAttrNames;
for (auto & attr : *vAttrs->attrs)
allAttrNames.insert(state.symbols[attr.name]);
state.throwEvalError(
pos,
Suggestions::bestMatches(allAttrNames, state.symbols[name]),
"attribute '%1%' missing", state.symbols[name]);
}
}
vAttrs = j->value;
pos2 = j->pos;
if (state.countCalls) state.attrSelects[pos2]++;
}
state.forceValue(*vAttrs, (pos2 ? pos2 : this->pos ) );
} catch (Error & e) {
auto pos2r = state.positions[pos2];
if (pos2 && pos2r.file != state.derivationNixPath)
state.addErrorTrace(e, pos2, "while evaluating the attribute '%1%'",
showAttrPath(state, env, attrPath));
throw;
}
v = *vAttrs;
}
void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
{
Value vTmp;
Value * vAttrs = &vTmp;
e->eval(state, env, vTmp);
for (auto & i : attrPath) {
state.forceValue(*vAttrs, noPos);
Bindings::iterator j;
auto name = getName(i, state, env);
if (vAttrs->type() != nAttrs ||
(j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
{
v.mkBool(false);
return;
} else {
vAttrs = j->value;
}
}
v.mkBool(true);
}
void ExprLambda::eval(EvalState & state, Env & env, Value & v)
{
v.mkLambda(&env, this);
}
void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value & vRes, const PosIdx pos)
{
auto trace = evalSettings.traceFunctionCalls
? std::make_unique<FunctionCallTrace>(positions[pos])
: nullptr;
forceValue(fun, pos);
Value vCur(fun);
auto makeAppChain = [&]()
{
vRes = vCur;
for (size_t i = 0; i < nrArgs; ++i) {
auto fun2 = allocValue();
*fun2 = vRes;
vRes.mkPrimOpApp(fun2, args[i]);
}
};
Attr * functor;
while (nrArgs > 0) {
if (vCur.isLambda()) {
ExprLambda & lambda(*vCur.lambda.fun);
auto size =
(!lambda.arg ? 0 : 1) +
(lambda.hasFormals() ? lambda.formals->formals.size() : 0);
Env & env2(allocEnv(size));
env2.up = vCur.lambda.env;
Displacement displ = 0;
if (!lambda.hasFormals())
env2.values[displ++] = args[0];
else {
forceAttrs(*args[0], pos);
if (lambda.arg)
env2.values[displ++] = args[0];
/* For each formal argument, get the actual argument. If
there is no matching actual argument but the formal
argument has a default, use the default. */
size_t attrsUsed = 0;
for (auto & i : lambda.formals->formals) {
auto j = args[0]->attrs->get(i.name);
if (!j) {
if (!i.def) throwTypeError(pos, "%1% called without required argument '%2%'",
lambda, i.name);
env2.values[displ++] = i.def->maybeThunk(*this, env2);
} else {
attrsUsed++;
env2.values[displ++] = j->value;
}
}
/* Check that each actual argument is listed as a formal
argument (unless the attribute match specifies a `...'). */
if (!lambda.formals->ellipsis && attrsUsed != args[0]->attrs->size()) {
/* Nope, so show the first unexpected argument to the
user. */
for (auto & i : *args[0]->attrs)
if (!lambda.formals->has(i.name)) {
std::set<std::string> formalNames;
for (auto & formal : lambda.formals->formals)
formalNames.insert(symbols[formal.name]);
throwTypeError(
pos,
Suggestions::bestMatches(formalNames, symbols[i.name]),
"%1% called with unexpected argument '%2%'",
lambda,
i.name);
}
abort(); // can't happen
}
}
nrFunctionCalls++;
if (countCalls) incrFunctionCall(&lambda);
/* Evaluate the body. */
try {
lambda.body->eval(*this, env2, vCur);
} catch (Error & e) {
if (loggerSettings.showTrace.get()) {
addErrorTrace(e, lambda.pos, "while evaluating %s",
(lambda.name
? concatStrings("'", symbols[lambda.name], "'")
: "anonymous lambda"));
addErrorTrace(e, pos, "from call site%s", "");
}
throw;
}
nrArgs--;
args += 1;
}
else if (vCur.isPrimOp()) {
size_t argsLeft = vCur.primOp->arity;
if (nrArgs < argsLeft) {
/* We don't have enough arguments, so create a tPrimOpApp chain. */
makeAppChain();
return;
} else {
/* We have all the arguments, so call the primop. */
nrPrimOpCalls++;
if (countCalls) primOpCalls[vCur.primOp->name]++;
vCur.primOp->fun(*this, pos, args, vCur);
nrArgs -= argsLeft;
args += argsLeft;
}
}
else if (vCur.isPrimOpApp()) {
/* Figure out the number of arguments still needed. */
size_t argsDone = 0;
Value * primOp = &vCur;
while (primOp->isPrimOpApp()) {
argsDone++;
primOp = primOp->primOpApp.left;
}
assert(primOp->isPrimOp());
auto arity = primOp->primOp->arity;
auto argsLeft = arity - argsDone;
if (nrArgs < argsLeft) {
/* We still don't have enough arguments, so extend the tPrimOpApp chain. */
makeAppChain();
return;
} else {
/* We have all the arguments, so call the primop with
the previous and new arguments. */
Value * vArgs[arity];
auto n = argsDone;
for (Value * arg = &vCur; arg->isPrimOpApp(); arg = arg->primOpApp.left)
vArgs[--n] = arg->primOpApp.right;
for (size_t i = 0; i < argsLeft; ++i)
vArgs[argsDone + i] = args[i];
nrPrimOpCalls++;
if (countCalls) primOpCalls[primOp->primOp->name]++;
primOp->primOp->fun(*this, pos, vArgs, vCur);
nrArgs -= argsLeft;
args += argsLeft;
}
}
else if (vCur.type() == nAttrs && (functor = vCur.attrs->get(sFunctor))) {
/* 'vCur' may be allocated on the stack of the calling
function, but for functors we may keep a reference, so
heap-allocate a copy and use that instead. */
Value * args2[] = {allocValue(), args[0]};
*args2[0] = vCur;
/* !!! Should we use the attr pos here? */
callFunction(*functor->value, 2, args2, vCur, pos);
nrArgs--;
args++;
}
else
throwTypeError(pos, "attempt to call something which is not a function but %1%", vCur);
}
vRes = vCur;
}
void ExprCall::eval(EvalState & state, Env & env, Value & v)
{
Value vFun;
fun->eval(state, env, vFun);
Value * vArgs[args.size()];
for (size_t i = 0; i < args.size(); ++i)
vArgs[i] = args[i]->maybeThunk(state, env);
state.callFunction(vFun, args.size(), vArgs, v, pos);
}
// Lifted out of callFunction() because it creates a temporary that
// prevents tail-call optimisation.
void EvalState::incrFunctionCall(ExprLambda * fun)
{
functionCalls[fun]++;
}
void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
{
auto pos = fun.determinePos(noPos);
forceValue(fun, pos);
if (fun.type() == nAttrs) {
auto found = fun.attrs->find(sFunctor);
if (found != fun.attrs->end()) {
Value * v = allocValue();
callFunction(*found->value, fun, *v, pos);
forceValue(*v, pos);
return autoCallFunction(args, *v, res);
}
}
if (!fun.isLambda() || !fun.lambda.fun->hasFormals()) {
res = fun;
return;
}
auto attrs = buildBindings(std::max(static_cast<uint32_t>(fun.lambda.fun->formals->formals.size()), args.size()));
if (fun.lambda.fun->formals->ellipsis) {
// If the formals have an ellipsis (eg the function accepts extra args) pass
// all available automatic arguments (which includes arguments specified on
// the command line via --arg/--argstr)
for (auto & v : args)
attrs.insert(v);
} else {
// Otherwise, only pass the arguments that the function accepts
for (auto & i : fun.lambda.fun->formals->formals) {
Bindings::iterator j = args.find(i.name);
if (j != args.end()) {
attrs.insert(*j);
} else if (!i.def) {
throwMissingArgumentError(i.pos, R"(cannot evaluate a function that has an argument without a value ('%1%')
Nix attempted to evaluate a function as a top level expression; in
this case it must have its arguments supplied either by default
values, or passed explicitly with '--arg' or '--argstr'. See
https://nixos.org/manual/nix/stable/#ss-functions.)", symbols[i.name]);
}
}
}
callFunction(fun, allocValue()->mkAttrs(attrs), res, noPos);
}
void ExprWith::eval(EvalState & state, Env & env, Value & v)
{
Env & env2(state.allocEnv(1));
env2.up = &env;
env2.prevWith = prevWith;
env2.type = Env::HasWithExpr;
env2.values[0] = (Value *) attrs;
body->eval(state, env2, v);
}
void ExprIf::eval(EvalState & state, Env & env, Value & v)
{
(state.evalBool(env, cond, pos) ? then : else_)->eval(state, env, v);
}
void ExprAssert::eval(EvalState & state, Env & env, Value & v)
{
if (!state.evalBool(env, cond, pos)) {
std::ostringstream out;
cond->show(state.symbols, out);
state.throwAssertionError(pos, "assertion '%1%' failed", out.str());
}
body->eval(state, env, v);
}
void ExprOpNot::eval(EvalState & state, Env & env, Value & v)
{
v.mkBool(!state.evalBool(env, e));
}
void ExprOpEq::eval(EvalState & state, Env & env, Value & v)
{
Value v1; e1->eval(state, env, v1);
Value v2; e2->eval(state, env, v2);
v.mkBool(state.eqValues(v1, v2));
}
void ExprOpNEq::eval(EvalState & state, Env & env, Value & v)
{
Value v1; e1->eval(state, env, v1);
Value v2; e2->eval(state, env, v2);
v.mkBool(!state.eqValues(v1, v2));
}
void ExprOpAnd::eval(EvalState & state, Env & env, Value & v)
{
v.mkBool(state.evalBool(env, e1, pos) && state.evalBool(env, e2, pos));
}
void ExprOpOr::eval(EvalState & state, Env & env, Value & v)
{
v.mkBool(state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
}
void ExprOpImpl::eval(EvalState & state, Env & env, Value & v)
{
v.mkBool(!state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
}
void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
{
Value v1, v2;
state.evalAttrs(env, e1, v1);
state.evalAttrs(env, e2, v2);
state.nrOpUpdates++;
if (v1.attrs->size() == 0) { v = v2; return; }
if (v2.attrs->size() == 0) { v = v1; return; }
auto attrs = state.buildBindings(v1.attrs->size() + v2.attrs->size());
/* Merge the sets, preferring values from the second set. Make
sure to keep the resulting vector in sorted order. */
Bindings::iterator i = v1.attrs->begin();
Bindings::iterator j = v2.attrs->begin();
while (i != v1.attrs->end() && j != v2.attrs->end()) {
if (i->name == j->name) {
attrs.insert(*j);
++i; ++j;
}
else if (i->name < j->name)
attrs.insert(*i++);
else
attrs.insert(*j++);
}
while (i != v1.attrs->end()) attrs.insert(*i++);
while (j != v2.attrs->end()) attrs.insert(*j++);
v.mkAttrs(attrs.alreadySorted());
state.nrOpUpdateValuesCopied += v.attrs->size();
}
void ExprOpConcatLists::eval(EvalState & state, Env & env, Value & v)
{
Value v1; e1->eval(state, env, v1);
Value v2; e2->eval(state, env, v2);
Value * lists[2] = { &v1, &v2 };
state.concatLists(v, 2, lists, pos);
}
void EvalState::concatLists(Value & v, size_t nrLists, Value * * lists, const PosIdx pos)
{
nrListConcats++;
Value * nonEmpty = 0;
size_t len = 0;
for (size_t n = 0; n < nrLists; ++n) {
forceList(*lists[n], pos);
auto l = lists[n]->listSize();
len += l;
if (l) nonEmpty = lists[n];
}
if (nonEmpty && len == nonEmpty->listSize()) {
v = *nonEmpty;
return;
}
mkList(v, len);
auto out = v.listElems();
for (size_t n = 0, pos = 0; n < nrLists; ++n) {
auto l = lists[n]->listSize();
if (l)
memcpy(out + pos, lists[n]->listElems(), l * sizeof(Value *));
pos += l;
}
}
void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
{
PathSet context;
std::vector<BackedStringView> s;
size_t sSize = 0;
NixInt n = 0;
NixFloat nf = 0;
bool first = !forceString;
ValueType firstType = nString;
const auto str = [&] {
std::string result;
result.reserve(sSize);
for (const auto & part : s) result += *part;
return result;
};
/* c_str() is not str().c_str() because we want to create a string
Value. allocating a GC'd string directly and moving it into a
Value lets us avoid an allocation and copy. */
const auto c_str = [&] {
char * result = allocString(sSize + 1);
char * tmp = result;
for (const auto & part : s) {
memcpy(tmp, part->data(), part->size());
tmp += part->size();
}
*tmp = 0;
return result;
};
Value values[es->size()];
Value * vTmpP = values;
for (auto & [i_pos, i] : *es) {
Value & vTmp = *vTmpP++;
i->eval(state, env, vTmp);
/* If the first element is a path, then the result will also
be a path, we don't copy anything (yet - that's done later,
since paths are copied when they are used in a derivation),
and none of the strings are allowed to have contexts. */
if (first) {
firstType = vTmp.type();
}
if (firstType == nInt) {
if (vTmp.type() == nInt) {
n += vTmp.integer;
} else if (vTmp.type() == nFloat) {
// Upgrade the type from int to float;
firstType = nFloat;
nf = n;
nf += vTmp.fpoint;
} else
state.throwEvalError(i_pos, "cannot add %1% to an integer", showType(vTmp));
} else if (firstType == nFloat) {
if (vTmp.type() == nInt) {
nf += vTmp.integer;
} else if (vTmp.type() == nFloat) {
nf += vTmp.fpoint;
} else
state.throwEvalError(i_pos, "cannot add %1% to a float", showType(vTmp));
} else {
if (s.empty()) s.reserve(es->size());
/* skip canonization of first path, which would only be not
canonized in the first place if it's coming from a ./${foo} type
path */
auto part = state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first);
sSize += part->size();
s.emplace_back(std::move(part));
}
first = false;
}
if (firstType == nInt)
v.mkInt(n);
else if (firstType == nFloat)
v.mkFloat(nf);
else if (firstType == nPath) {
if (!context.empty())
state.throwEvalError(pos, "a string that refers to a store path cannot be appended to a path");
v.mkPath(canonPath(str()));
} else
v.mkStringMove(c_str(), context);
}
void ExprPos::eval(EvalState & state, Env & env, Value & v)
{
state.mkPos(v, pos);
}
void EvalState::forceValueDeep(Value & v)
{
std::set<const Value *> seen;
std::function<void(Value & v)> recurse;
recurse = [&](Value & v) {
if (!seen.insert(&v).second) return;
forceValue(v, [&]() { return v.determinePos(noPos); });
if (v.type() == nAttrs) {
for (auto & i : *v.attrs)
try {
recurse(*i.value);
} catch (Error & e) {
addErrorTrace(e, i.pos, "while evaluating the attribute '%1%'", symbols[i.name]);
throw;
}
}
else if (v.isList()) {
for (auto v2 : v.listItems())
recurse(*v2);
}
};
recurse(v);
}
NixInt EvalState::forceInt(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (v.type() != nInt)
throwTypeError(pos, "value is %1% while an integer was expected", v);
return v.integer;
}
NixFloat EvalState::forceFloat(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (v.type() == nInt)
return v.integer;
else if (v.type() != nFloat)
throwTypeError(pos, "value is %1% while a float was expected", v);
return v.fpoint;
}
bool EvalState::forceBool(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (v.type() != nBool)
throwTypeError(pos, "value is %1% while a Boolean was expected", v);
return v.boolean;
}
bool EvalState::isFunctor(Value & fun)
{
return fun.type() == nAttrs && fun.attrs->find(sFunctor) != fun.attrs->end();
}
void EvalState::forceFunction(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (v.type() != nFunction && !isFunctor(v))
throwTypeError(pos, "value is %1% while a function was expected", v);
}
std::string_view EvalState::forceString(Value & v, const PosIdx pos)
{
forceValue(v, pos);
if (v.type() != nString) {
if (pos)
throwTypeError(pos, "value is %1% while a string was expected", v);
else
throwTypeError("value is %1% while a string was expected", v);
}
return v.string.s;
}
/* Decode a context string !<name>!<path> into a pair <path,
name>. */
NixStringContextElem decodeContext(const Store & store, std::string_view s)
{
if (s.at(0) == '!') {
size_t index = s.find("!", 1);
return {
store.parseStorePath(s.substr(index + 1)),
std::string(s.substr(1, index - 1)),
};
} else
return {
store.parseStorePath(
s.at(0) == '/'
? s
: s.substr(1)),
"",
};
}
void copyContext(const Value & v, PathSet & context)
{
if (v.string.context)
for (const char * * p = v.string.context; *p; ++p)
context.insert(*p);
}
NixStringContext Value::getContext(const Store & store)
{
NixStringContext res;
assert(internalType == tString);
if (string.context)
for (const char * * p = string.context; *p; ++p)
res.push_back(decodeContext(store, *p));
return res;
}
std::string_view EvalState::forceString(Value & v, PathSet & context, const PosIdx pos)
{
auto s = forceString(v, pos);
copyContext(v, context);
return s;
}
std::string_view EvalState::forceStringNoCtx(Value & v, const PosIdx pos)
{
auto s = forceString(v, pos);
if (v.string.context) {
if (pos)
throwEvalError(pos, "the string '%1%' is not allowed to refer to a store path (such as '%2%')",
v.string.s, v.string.context[0]);
else
throwEvalError("the string '%1%' is not allowed to refer to a store path (such as '%2%')",
v.string.s, v.string.context[0]);
}
return s;
}
bool EvalState::isDerivation(Value & v)
{
if (v.type() != nAttrs) return false;
Bindings::iterator i = v.attrs->find(sType);
if (i == v.attrs->end()) return false;
forceValue(*i->value, i->pos);
if (i->value->type() != nString) return false;
return strcmp(i->value->string.s, "derivation") == 0;
}
std::optional<std::string> EvalState::tryAttrsToString(const PosIdx pos, Value & v,
PathSet & context, bool coerceMore, bool copyToStore)
{
auto i = v.attrs->find(sToString);
if (i != v.attrs->end()) {
Value v1;
callFunction(*i->value, v, v1, pos);
return coerceToString(pos, v1, context, coerceMore, copyToStore).toOwned();
}
return {};
}
BackedStringView EvalState::coerceToString(const PosIdx pos, Value & v, PathSet & context,
bool coerceMore, bool copyToStore, bool canonicalizePath)
{
forceValue(v, pos);
if (v.type() == nString) {
copyContext(v, context);
return std::string_view(v.string.s);
}
if (v.type() == nPath) {
BackedStringView path(PathView(v.path));
if (canonicalizePath)
path = canonPath(*path);
if (copyToStore)
path = copyPathToStore(context, std::move(path).toOwned());
return path;
}
if (v.type() == nAttrs) {
auto maybeString = tryAttrsToString(pos, v, context, coerceMore, copyToStore);
if (maybeString)
return std::move(*maybeString);
auto i = v.attrs->find(sOutPath);
if (i == v.attrs->end()) throwTypeError(pos, "cannot coerce a set to a string");
return coerceToString(pos, *i->value, context, coerceMore, copyToStore);
}
if (v.type() == nExternal)
return v.external->coerceToString(positions[pos], context, coerceMore, copyToStore);
if (coerceMore) {
/* Note that `false' is represented as an empty string for
shell scripting convenience, just like `null'. */
if (v.type() == nBool && v.boolean) return "1";
if (v.type() == nBool && !v.boolean) return "";
if (v.type() == nInt) return std::to_string(v.integer);
if (v.type() == nFloat) return std::to_string(v.fpoint);
if (v.type() == nNull) return "";
if (v.isList()) {
std::string result;
for (auto [n, v2] : enumerate(v.listItems())) {
result += *coerceToString(pos, *v2, context, coerceMore, copyToStore);
if (n < v.listSize() - 1
/* !!! not quite correct */
&& (!v2->isList() || v2->listSize() != 0))
result += " ";
}
return std::move(result);
}
}
throwTypeError(pos, "cannot coerce %1% to a string", v);
}
std::string EvalState::copyPathToStore(PathSet & context, const Path & path)
{
if (nix::isDerivation(path))
throwEvalError("file names are not allowed to end in '%1%'", drvExtension);
Path dstPath;
auto i = srcToStore.find(path);
if (i != srcToStore.end())
dstPath = store->printStorePath(i->second);
else {
auto p = settings.readOnlyMode
? store->computeStorePathForPath(std::string(baseNameOf(path)), checkSourcePath(path)).first
: store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, repair);
dstPath = store->printStorePath(p);
allowPath(p);
srcToStore.insert_or_assign(path, std::move(p));
printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
}
context.insert(dstPath);
return dstPath;
}
Path EvalState::coerceToPath(const PosIdx pos, Value & v, PathSet & context)
{
auto path = coerceToString(pos, v, context, false, false).toOwned();
if (path == "" || path[0] != '/')
throwEvalError(pos, "string '%1%' doesn't represent an absolute path", path);
return path;
}
StorePath EvalState::coerceToStorePath(const PosIdx pos, Value & v, PathSet & context)
{
auto path = coerceToString(pos, v, context, false, false).toOwned();
if (auto storePath = store->maybeParseStorePath(path))
return *storePath;
throw EvalError({
.msg = hintfmt("path '%1%' is not in the Nix store", path),
.errPos = positions[pos]
});
}
bool EvalState::eqValues(Value & v1, Value & v2)
{
forceValue(v1, noPos);
forceValue(v2, noPos);
/* !!! Hack to support some old broken code that relies on pointer
equality tests between sets. (Specifically, builderDefs calls
uniqList on a list of sets.) Will remove this eventually. */
if (&v1 == &v2) return true;
// Special case type-compatibility between float and int
if (v1.type() == nInt && v2.type() == nFloat)
return v1.integer == v2.fpoint;
if (v1.type() == nFloat && v2.type() == nInt)
return v1.fpoint == v2.integer;
// All other types are not compatible with each other.
if (v1.type() != v2.type()) return false;
switch (v1.type()) {
case nInt:
return v1.integer == v2.integer;
case nBool:
return v1.boolean == v2.boolean;
case nString:
return strcmp(v1.string.s, v2.string.s) == 0;
case nPath:
return strcmp(v1.path, v2.path) == 0;
case nNull:
return true;
case nList:
if (v1.listSize() != v2.listSize()) return false;
for (size_t n = 0; n < v1.listSize(); ++n)
if (!eqValues(*v1.listElems()[n], *v2.listElems()[n])) return false;
return true;
case nAttrs: {
/* If both sets denote a derivation (type = "derivation"),
then compare their outPaths. */
if (isDerivation(v1) && isDerivation(v2)) {
Bindings::iterator i = v1.attrs->find(sOutPath);
Bindings::iterator j = v2.attrs->find(sOutPath);
if (i != v1.attrs->end() && j != v2.attrs->end())
return eqValues(*i->value, *j->value);
}
if (v1.attrs->size() != v2.attrs->size()) return false;
/* Otherwise, compare the attributes one by one. */
Bindings::iterator i, j;
for (i = v1.attrs->begin(), j = v2.attrs->begin(); i != v1.attrs->end(); ++i, ++j)
if (i->name != j->name || !eqValues(*i->value, *j->value))
return false;
return true;
}
/* Functions are incomparable. */
case nFunction:
return false;
case nExternal:
return *v1.external == *v2.external;
case nFloat:
return v1.fpoint == v2.fpoint;
default:
throwEvalError("cannot compare %1% with %2%", showType(v1), showType(v2));
}
}
void EvalState::printStats()
{
bool showStats = getEnv("NIX_SHOW_STATS").value_or("0") != "0";
struct rusage buf;
getrusage(RUSAGE_SELF, &buf);
float cpuTime = buf.ru_utime.tv_sec + ((float) buf.ru_utime.tv_usec / 1000000);
uint64_t bEnvs = nrEnvs * sizeof(Env) + nrValuesInEnvs * sizeof(Value *);
uint64_t bLists = nrListElems * sizeof(Value *);
uint64_t bValues = nrValues * sizeof(Value);
uint64_t bAttrsets = nrAttrsets * sizeof(Bindings) + nrAttrsInAttrsets * sizeof(Attr);
#if HAVE_BOEHMGC
GC_word heapSize, totalBytes;
GC_get_heap_usage_safe(&heapSize, 0, 0, 0, &totalBytes);
#endif
if (showStats) {
auto outPath = getEnv("NIX_SHOW_STATS_PATH").value_or("-");
std::fstream fs;
if (outPath != "-")
fs.open(outPath, std::fstream::out);
JSONObject topObj(outPath == "-" ? std::cerr : fs, true);
topObj.attr("cpuTime",cpuTime);
{
auto envs = topObj.object("envs");
envs.attr("number", nrEnvs);
envs.attr("elements", nrValuesInEnvs);
envs.attr("bytes", bEnvs);
}
{
auto lists = topObj.object("list");
lists.attr("elements", nrListElems);
lists.attr("bytes", bLists);
lists.attr("concats", nrListConcats);
}
{
auto values = topObj.object("values");
values.attr("number", nrValues);
values.attr("bytes", bValues);
}
{
auto syms = topObj.object("symbols");
syms.attr("number", symbols.size());
syms.attr("bytes", symbols.totalSize());
}
{
auto sets = topObj.object("sets");
sets.attr("number", nrAttrsets);
sets.attr("bytes", bAttrsets);
sets.attr("elements", nrAttrsInAttrsets);
}
{
auto sizes = topObj.object("sizes");
sizes.attr("Env", sizeof(Env));
sizes.attr("Value", sizeof(Value));
sizes.attr("Bindings", sizeof(Bindings));
sizes.attr("Attr", sizeof(Attr));
}
topObj.attr("nrOpUpdates", nrOpUpdates);
topObj.attr("nrOpUpdateValuesCopied", nrOpUpdateValuesCopied);
topObj.attr("nrThunks", nrThunks);
topObj.attr("nrAvoided", nrAvoided);
topObj.attr("nrLookups", nrLookups);
topObj.attr("nrPrimOpCalls", nrPrimOpCalls);
topObj.attr("nrFunctionCalls", nrFunctionCalls);
#if HAVE_BOEHMGC
{
auto gc = topObj.object("gc");
gc.attr("heapSize", heapSize);
gc.attr("totalBytes", totalBytes);
}
#endif
if (countCalls) {
{
auto obj = topObj.object("primops");
for (auto & i : primOpCalls)
obj.attr(i.first, i.second);
}
{
auto list = topObj.list("functions");
for (auto & i : functionCalls) {
auto obj = list.object();
if (i.first->name)
obj.attr("name", (const std::string &) i.first->name);
else
obj.attr("name", nullptr);
if (auto pos = positions[i.first->pos]) {
obj.attr("file", (const std::string &) pos.file);
obj.attr("line", pos.line);
obj.attr("column", pos.column);
}
obj.attr("count", i.second);
}
}
{
auto list = topObj.list("attributes");
for (auto & i : attrSelects) {
auto obj = list.object();
if (auto pos = positions[i.first]) {
obj.attr("file", (const std::string &) pos.file);
obj.attr("line", pos.line);
obj.attr("column", pos.column);
}
obj.attr("count", i.second);
}
}
}
if (getEnv("NIX_SHOW_SYMBOLS").value_or("0") != "0") {
auto list = topObj.list("symbols");
symbols.dump([&](const std::string & s) { list.elem(s); });
}
}
}
std::string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
{
throw TypeError({
.msg = hintfmt("cannot coerce %1% to a string", showType()),
.errPos = pos
});
}
bool ExternalValueBase::operator==(const ExternalValueBase & b) const
{
return false;
}
std::ostream & operator << (std::ostream & str, const ExternalValueBase & v) {
return v.print(str);
}
EvalSettings::EvalSettings()
{
auto var = getEnv("NIX_PATH");
if (var) nixPath = parseNixPath(*var);
}
Strings EvalSettings::getDefaultNixPath()
{
Strings res;
auto add = [&](const Path & p, const std::string & s = std::string()) {
if (pathExists(p)) {
if (s.empty()) {
res.push_back(p);
} else {
res.push_back(s + "=" + p);
}
}
};
if (!evalSettings.restrictEval && !evalSettings.pureEval) {
add(getHome() + "/.nix-defexpr/channels");
add(settings.nixStateDir + "/profiles/per-user/root/channels/nixpkgs", "nixpkgs");
add(settings.nixStateDir + "/profiles/per-user/root/channels");
}
return res;
}
EvalSettings evalSettings;
static GlobalConfig::Register rEvalSettings(&evalSettings);
}