863dcff6c5
representation of closures as ATerms in the Nix store. Instead, the
file system pointer graph is now stored in the Nix database. This
has many advantages:
- It greatly simplifies the implementation (we can drop the notion
of `successors', and so on).
- It makes registering roots for the garbage collector much easier.
Instead of specifying the closure expression as a root, you can
simply specify the store path that must be retained as a root.
This could not be done previously, since there was no way to find
the closure store expression containing a given store path.
- Better traceability: it is now possible to query what paths are
referenced by a path, and what paths refer to a path.
389 lines
12 KiB
C++
389 lines
12 KiB
C++
#include "normalise.hh"
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#include "eval.hh"
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#include "globals.hh"
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#include "nixexpr-ast.hh"
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/* Load and evaluate an expression from path specified by the
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argument. */
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static Expr primImport(EvalState & state, const ATermVector & args)
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{
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ATerm path;
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Expr fn = evalExpr(state, args[0]);
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if (!matchPath(fn, path))
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throw Error("path expected");
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return evalFile(state, aterm2String(path));
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}
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#if 0
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static PathSet storeExprRootsCached(EvalState & state, const Path & nePath)
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{
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DrvRoots::iterator i = state.drvRoots.find(nePath);
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if (i != state.drvRoots.end())
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return i->second;
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else {
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PathSet paths = storeExprRoots(nePath);
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state.drvRoots[nePath] = paths;
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return paths;
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}
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}
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#endif
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/* Returns the hash of a derivation modulo fixed-output
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subderivations. A fixed-output derivation is a derivation with one
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output (`out') for which an expected hash and hash algorithm are
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specified (using the `outputHash' and `outputHashAlgo'
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attributes). We don't want changes to such derivations to
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propagate upwards through the dependency graph, changing output
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paths everywhere.
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For instance, if we change the url in a call to the `fetchurl'
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function, we do not want to rebuild everything depending on it
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(after all, (the hash of) the file being downloaded is unchanged).
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So the *output paths* should not change. On the other hand, the
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*derivation store expression paths* should change to reflect the
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new dependency graph.
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That's what this function does: it returns a hash which is just the
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of the derivation ATerm, except that any input store expression
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paths have been replaced by the result of a recursive call to this
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function, and that for fixed-output derivations we return
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(basically) its outputHash. */
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static Hash hashDerivationModulo(EvalState & state, Derivation drv)
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{
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/* Return a fixed hash for fixed-output derivations. */
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if (drv.outputs.size() == 1) {
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DerivationOutputs::const_iterator i = drv.outputs.begin();
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if (i->first == "out" &&
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i->second.hash != "")
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{
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return hashString(htSHA256, "fixed:out:"
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+ i->second.hashAlgo + ":"
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+ i->second.hash + ":"
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+ i->second.path);
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}
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}
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/* For other derivations, replace the inputs paths with recursive
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calls to this function.*/
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PathSet inputs2;
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for (PathSet::iterator i = drv.inputDrvs.begin();
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i != drv.inputDrvs.end(); ++i)
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{
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Hash h = state.drvHashes[*i];
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if (h.type == htUnknown) {
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Derivation drv2 = derivationFromPath(*i);
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h = hashDerivationModulo(state, drv2);
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state.drvHashes[*i] = h;
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}
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inputs2.insert(printHash(h));
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}
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drv.inputDrvs = inputs2;
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return hashTerm(unparseDerivation(drv));
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}
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static void processBinding(EvalState & state, Expr e, Derivation & drv,
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Strings & ss)
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{
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e = evalExpr(state, e);
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ATerm s;
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ATermList es;
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int n;
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Expr e1, e2;
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if (matchStr(e, s)) ss.push_back(aterm2String(s));
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else if (matchUri(e, s)) ss.push_back(aterm2String(s));
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else if (e == eTrue) ss.push_back("1");
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else if (e == eFalse) ss.push_back("");
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else if (matchInt(e, n)) {
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ostringstream st;
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st << n;
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ss.push_back(st.str());
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}
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else if (matchAttrs(e, es)) {
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Expr a = queryAttr(e, "type");
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if (a && evalString(state, a) == "derivation") {
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a = queryAttr(e, "drvPath");
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if (!a) throw Error("derivation name missing");
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Path drvPath = evalPath(state, a);
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a = queryAttr(e, "outPath");
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if (!a) throw Error("output path missing");
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/* !!! supports only single output path */
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Path outPath = evalPath(state, a);
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drv.inputDrvs.insert(drvPath);
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ss.push_back(outPath);
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} else
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throw Error("invalid derivation attribute");
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}
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else if (matchPath(e, s)) {
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Path srcPath(aterm2String(s));
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Path dstPath(addToStore(srcPath));
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printMsg(lvlChatty, format("copied source `%1%' -> `%2%'")
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% srcPath % dstPath);
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drv.inputSrcs.insert(dstPath);
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ss.push_back(dstPath);
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}
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else if (matchList(e, es)) {
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for (ATermIterator i(es); i; ++i) {
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startNest(nest, lvlVomit, format("processing list element"));
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processBinding(state, evalExpr(state, *i), drv, ss);
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}
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}
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else if (matchNull(e)) ss.push_back("");
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else if (matchSubPath(e, e1, e2)) {
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Strings ss2;
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processBinding(state, evalExpr(state, e1), drv, ss2);
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if (ss2.size() != 1)
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throw Error("left-hand side of `~' operator cannot be a list");
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e2 = evalExpr(state, e2);
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if (!(matchStr(e2, s) || matchPath(e2, s)))
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throw Error("right-hand side of `~' operator must be a path or string");
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ss.push_back(canonPath(ss2.front() + "/" + aterm2String(s)));
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}
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else throw Error("invalid derivation attribute");
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}
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static string concatStrings(const Strings & ss)
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{
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string s;
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bool first = true;
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for (Strings::const_iterator i = ss.begin(); i != ss.end(); ++i) {
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if (!first) s += " "; else first = false;
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s += *i;
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}
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return s;
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}
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/* Construct (as a unobservable side effect) a Nix derivation
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expression that performs the derivation described by the argument
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set. Returns the original set extended with the following
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attributes: `outPath' containing the primary output path of the
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derivation; `drvPath' containing the path of the Nix expression;
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and `type' set to `derivation' to indicate that this is a
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derivation. */
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static Expr primDerivation(EvalState & state, const ATermVector & _args)
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{
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startNest(nest, lvlVomit, "evaluating derivation");
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ATermMap attrs;
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Expr args = _args[0];
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args = evalExpr(state, args);
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queryAllAttrs(args, attrs, true);
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/* Build the derivation expression by processing the attributes. */
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Derivation drv;
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string drvName;
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string outputHash;
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string outputHashAlgo;
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for (ATermIterator i(attrs.keys()); i; ++i) {
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string key = aterm2String(*i);
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ATerm value;
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Expr pos;
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ATerm rhs = attrs.get(key);
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if (!matchAttrRHS(rhs, value, pos)) abort();
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startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);
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Strings ss;
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try {
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processBinding(state, value, drv, ss);
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} catch (Error & e) {
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throw Error(format("while processing the derivation attribute `%1%' at %2%:\n%3%")
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% key % showPos(pos) % e.msg());
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}
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/* The `args' attribute is special: it supplies the
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command-line arguments to the builder. */
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if (key == "args") {
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for (Strings::iterator i = ss.begin(); i != ss.end(); ++i)
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drv.args.push_back(*i);
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}
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/* All other attributes are passed to the builder through the
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environment. */
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else {
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string s = concatStrings(ss);
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drv.env[key] = s;
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if (key == "builder") drv.builder = s;
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else if (key == "system") drv.platform = s;
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else if (key == "name") drvName = s;
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else if (key == "outputHash") outputHash = s;
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else if (key == "outputHashAlgo") outputHashAlgo = s;
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}
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}
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/* Do we have all required attributes? */
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if (drv.builder == "")
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throw Error("required attribute `builder' missing");
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if (drv.platform == "")
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throw Error("required attribute `system' missing");
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if (drvName == "")
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throw Error("required attribute `name' missing");
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/* If an output hash was given, check it. */
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if (outputHash == "")
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outputHashAlgo = "";
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else {
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HashType ht = parseHashType(outputHashAlgo);
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if (ht == htUnknown)
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throw Error(format("unknown hash algorithm `%1%'") % outputHashAlgo);
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Hash h;
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if (outputHash.size() == Hash(ht).hashSize * 2)
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/* hexadecimal representation */
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h = parseHash(ht, outputHash);
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else
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/* base-32 representation */
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h = parseHash32(ht, outputHash);
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string s = outputHash;
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outputHash = printHash(h);
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}
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/* Check the derivation name. It shouldn't contain whitespace,
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but we are conservative here: we check whether only
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alphanumerics and some other characters appear. */
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string validChars = "+-._?=";
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for (string::iterator i = drvName.begin(); i != drvName.end(); ++i)
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if (!((*i >= 'A' && *i <= 'Z') ||
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(*i >= 'a' && *i <= 'z') ||
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(*i >= '0' && *i <= '9') ||
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validChars.find(*i) != string::npos))
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{
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throw Error(format("invalid character `%1%' in derivation name `%2%'")
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% *i % drvName);
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}
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/* Construct the "masked" derivation store expression, which is
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the final one except that in the list of outputs, the output
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paths are empty, and the corresponding environment variables
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have an empty value. This ensures that changes in the set of
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output names do get reflected in the hash. */
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drv.env["out"] = "";
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drv.outputs["out"] =
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DerivationOutput("", outputHashAlgo, outputHash);
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/* Use the masked derivation expression to compute the output
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path. */
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Path outPath = makeStorePath("output:out",
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hashDerivationModulo(state, drv), drvName);
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/* Construct the final derivation store expression. */
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drv.env["out"] = outPath;
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drv.outputs["out"] =
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DerivationOutput(outPath, outputHashAlgo, outputHash);
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/* Write the resulting term into the Nix store directory. */
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Path drvPath = writeTerm(unparseDerivation(drv), "d-" + drvName);
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printMsg(lvlChatty, format("instantiated `%1%' -> `%2%'")
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% drvName % drvPath);
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/* Optimisation, but required in read-only mode! because in that
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case we don't actually write store expressions, so we can't
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read them later. */
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state.drvHashes[drvPath] = hashDerivationModulo(state, drv);
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/* !!! assumes a single output */
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attrs.set("outPath", makeAttrRHS(makePath(toATerm(outPath)), makeNoPos()));
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attrs.set("drvPath", makeAttrRHS(makePath(toATerm(drvPath)), makeNoPos()));
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attrs.set("type", makeAttrRHS(makeStr(toATerm("derivation")), makeNoPos()));
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return makeAttrs(attrs);
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}
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/* Return the base name of the given string, i.e., everything
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following the last slash. */
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static Expr primBaseNameOf(EvalState & state, const ATermVector & args)
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{
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return makeStr(toATerm(baseNameOf(evalString(state, args[0]))));
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}
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/* Convert the argument (which can be a path or a uri) to a string. */
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static Expr primToString(EvalState & state, const ATermVector & args)
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{
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Expr arg = evalExpr(state, args[0]);
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ATerm s;
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if (matchStr(arg, s) || matchPath(arg, s) || matchUri(arg, s))
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return makeStr(s);
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else throw Error("cannot coerce value to string");
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}
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/* Boolean constructors. */
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static Expr primTrue(EvalState & state, const ATermVector & args)
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{
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return eTrue;
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}
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static Expr primFalse(EvalState & state, const ATermVector & args)
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{
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return eFalse;
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}
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/* Return the null value. */
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Expr primNull(EvalState & state, const ATermVector & args)
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{
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return makeNull();
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}
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/* Determine whether the argument is the null value. */
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Expr primIsNull(EvalState & state, const ATermVector & args)
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{
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return makeBool(matchNull(evalExpr(state, args[0])));
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}
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/* Apply a function to every element of a list. */
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Expr primMap(EvalState & state, const ATermVector & args)
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{
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Expr fun = evalExpr(state, args[0]);
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Expr list = evalExpr(state, args[1]);
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ATermList list2;
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if (!matchList(list, list2))
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throw Error("`map' expects a list as its second argument");
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ATermList list3 = ATempty;
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for (ATermIterator i(list2); i; ++i)
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list3 = ATinsert(list3, makeCall(fun, *i));
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return makeList(ATreverse(list3));
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}
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void EvalState::addPrimOps()
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{
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addPrimOp("true", 0, primTrue);
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addPrimOp("false", 0, primFalse);
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addPrimOp("null", 0, primNull);
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addPrimOp("import", 1, primImport);
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addPrimOp("derivation", 1, primDerivation);
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addPrimOp("baseNameOf", 1, primBaseNameOf);
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addPrimOp("toString", 1, primToString);
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addPrimOp("isNull", 1, primIsNull);
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addPrimOp("map", 2, primMap);
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}
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