* libnix -> libstore.

1 files changed, 369 insertions, 0 deletions

diff --git a/src/libstore/normalise.cc b/src/libstore/normalise.cc
new file mode 100644
index 000000000000..cb2bf4f5b183
--- /dev/null
+++ b/src/libstore/normalise.cc
@@ -0,0 +1,369 @@
+#include <map>
+
+#include "normalise.hh"
+#include "references.hh"
+#include "exec.hh"
+#include "pathlocks.hh"
+#include "globals.hh"
+
+
+static Path useSuccessor(const Path & path)
+{
+    string pathSucc;
+    if (querySuccessor(path, pathSucc)) {
+        debug(format("successor %1% -> %2%") % (string) path % pathSucc);
+        return pathSucc;
+    } else
+        return path;
+}
+
+
+Path normaliseNixExpr(const Path & _nePath, PathSet pending)
+{
+    startNest(nest, lvlTalkative,
+        format("normalising expression in `%1%'") % (string) _nePath);
+
+    /* Try to substitute the expression by any known successors in
+       order to speed up the rewrite process. */
+    Path nePath = useSuccessor(_nePath);
+
+    /* Get the Nix expression. */
+    NixExpr ne = exprFromPath(nePath, pending);
+
+    /* If this is a normal form (i.e., a closure) we are done. */
+    if (ne.type == NixExpr::neClosure) return nePath;
+    if (ne.type != NixExpr::neDerivation) abort();
+    
+
+    /* Otherwise, it's a derivation expression, and we have to build it to
+       determine its normal form. */
+
+
+    /* Some variables. */
+
+    /* Input paths, with their closure elements. */
+    ClosureElems inClosures; 
+
+    /* Referenceable paths (i.e., input and output paths). */
+    PathSet allPaths;
+
+    /* The environment to be passed to the builder. */
+    Environment env; 
+
+    /* The result. */
+    NixExpr nf;
+    nf.type = NixExpr::neClosure;
+
+
+    /* The outputs are referenceable paths. */
+    for (PathSet::iterator i = ne.derivation.outputs.begin();
+         i != ne.derivation.outputs.end(); i++)
+    {
+        debug(format("building path `%1%'") % *i);
+        allPaths.insert(*i);
+    }
+
+    /* Obtain locks on all output paths.  The locks are automatically
+       released when we exit this function or Nix crashes. */
+    PathLocks outputLocks(ne.derivation.outputs);
+
+    /* Now check again whether there is a successor.  This is because
+       another process may have started building in parallel.  After
+       it has finished and released the locks, we can (and should)
+       reuse its results.  (Strictly speaking the first successor
+       check above can be omitted, but that would be less efficient.)
+       Note that since we now hold the locks on the output paths, no
+       other process can build this expression, so no further checks
+       are necessary. */
+    {
+        Path nePath2 = useSuccessor(nePath);
+        if (nePath != nePath2) {
+            NixExpr ne = exprFromPath(nePath2, pending);
+            debug(format("skipping build of expression `%1%', someone beat us to it")
+		  % (string) nePath);
+            if (ne.type != NixExpr::neClosure) abort();
+            return nePath2;
+        }
+    }
+
+    /* Right platform? */
+    if (ne.derivation.platform != thisSystem)
+        throw Error(format("a `%1%' is required, but I am a `%2%'")
+		    % ne.derivation.platform % thisSystem);
+        
+    /* Realise inputs (and remember all input paths). */
+    for (PathSet::iterator i = ne.derivation.inputs.begin();
+         i != ne.derivation.inputs.end(); i++)
+    {
+        Path nfPath = normaliseNixExpr(*i, pending);
+        realiseClosure(nfPath, pending);
+        /* !!! nfPath should be a root of the garbage collector while
+           we are building */
+        NixExpr ne = exprFromPath(nfPath, pending);
+        if (ne.type != NixExpr::neClosure) abort();
+        for (ClosureElems::iterator j = ne.closure.elems.begin();
+             j != ne.closure.elems.end(); j++)
+	{
+            inClosures[j->first] = j->second;
+	    allPaths.insert(j->first);
+	}
+    }
+
+    /* Most shells initialise PATH to some default (/bin:/usr/bin:...) when
+       PATH is not set.  We don't want this, so we fill it in with some dummy
+       value. */
+    env["PATH"] = "/path-not-set";
+
+    /* Set HOME to a non-existing path to prevent certain programs from using
+       /etc/passwd (or NIS, or whatever) to locate the home directory (for
+       example, wget looks for ~/.wgetrc).  I.e., these tools use /etc/passwd
+       if HOME is not set, but they will just assume that the settings file
+       they are looking for does not exist if HOME is set but points to some
+       non-existing path. */
+    env["HOME"] = "/homeless-shelter";
+
+    /* Build the environment. */
+    for (StringPairs::iterator i = ne.derivation.env.begin();
+         i != ne.derivation.env.end(); i++)
+        env[i->first] = i->second;
+
+    /* We can skip running the builder if all output paths are already
+       valid. */
+    bool fastBuild = true;
+    for (PathSet::iterator i = ne.derivation.outputs.begin();
+         i != ne.derivation.outputs.end(); i++)
+    {
+        if (!isValidPath(*i)) { 
+            fastBuild = false;
+            break;
+        }
+    }
+
+    if (!fastBuild) {
+
+        /* If any of the outputs already exist but are not registered,
+           delete them. */
+        for (PathSet::iterator i = ne.derivation.outputs.begin(); 
+             i != ne.derivation.outputs.end(); i++)
+        {
+            Path path = *i;
+            if (isValidPath(path))
+                throw Error(format("obstructed build: path `%1%' exists") % path);
+            if (pathExists(path)) {
+                debug(format("removing unregistered path `%1%'") % path);
+                deletePath(path);
+            }
+        }
+
+        /* Run the builder. */
+        printMsg(lvlChatty, format("building..."));
+        runProgram(ne.derivation.builder, ne.derivation.args, env,
+            nixLogDir + "/" + baseNameOf(nePath));
+        printMsg(lvlChatty, format("build completed"));
+        
+    } else
+        printMsg(lvlChatty, format("fast build succesful"));
+
+    /* Check whether the output paths were created, and grep each
+       output path to determine what other paths it references.  Also make all
+       output paths read-only. */
+    PathSet usedPaths;
+    for (PathSet::iterator i = ne.derivation.outputs.begin(); 
+         i != ne.derivation.outputs.end(); i++)
+    {
+        Path path = *i;
+        if (!pathExists(path))
+            throw Error(format("path `%1%' does not exist") % path);
+        nf.closure.roots.insert(path);
+
+	makePathReadOnly(path);
+
+	/* For this output path, find the references to other paths contained
+	   in it. */
+        Strings refPaths = filterReferences(path, 
+            Strings(allPaths.begin(), allPaths.end()));
+
+	/* Construct a closure element for this output path. */
+        ClosureElem elem;
+
+	/* For each path referenced by this output path, add its id to the
+	   closure element and add the id to the `usedPaths' set (so that the
+	   elements referenced by *its* closure are added below). */
+        for (Paths::iterator j = refPaths.begin();
+	     j != refPaths.end(); j++)
+	{
+	    Path path = *j;
+	    elem.refs.insert(path);
+            if (inClosures.find(path) != inClosures.end())
+                usedPaths.insert(path);
+	    else if (ne.derivation.outputs.find(path) == ne.derivation.outputs.end())
+		abort();
+        }
+
+        nf.closure.elems[path] = elem;
+    }
+
+    /* Close the closure.  That is, for any referenced path, add the paths
+       referenced by it. */
+    PathSet donePaths;
+
+    while (!usedPaths.empty()) {
+	PathSet::iterator i = usedPaths.begin();
+	Path path = *i;
+	usedPaths.erase(i);
+
+	if (donePaths.find(path) != donePaths.end()) continue;
+	donePaths.insert(path);
+
+	ClosureElems::iterator j = inClosures.find(path);
+	if (j == inClosures.end()) abort();
+
+	nf.closure.elems[path] = j->second;
+
+	for (PathSet::iterator k = j->second.refs.begin();
+	     k != j->second.refs.end(); k++)
+	    usedPaths.insert(*k);
+    }
+
+    /* For debugging, print out the referenced and unreferenced paths. */
+    for (ClosureElems::iterator i = inClosures.begin();
+         i != inClosures.end(); i++)
+    {
+        PathSet::iterator j = donePaths.find(i->first);
+        if (j == donePaths.end())
+            debug(format("NOT referenced: `%1%'") % i->first);
+        else
+            debug(format("referenced: `%1%'") % i->first);
+    }
+
+    /* Write the normal form.  This does not have to occur in the
+       transaction below because writing terms is idem-potent. */
+    ATerm nfTerm = unparseNixExpr(nf);
+    printMsg(lvlVomit, format("normal form: %1%") % atPrint(nfTerm));
+    Path nfPath = writeTerm(nfTerm, "-s");
+
+    /* Register each outpat path, and register the normal form.  This
+       is wrapped in one database transaction to ensure that if we
+       crash, either everything is registered or nothing is.  This is
+       for recoverability: unregistered paths in the store can be
+       deleted arbitrarily, while registered paths can only be deleted
+       by running the garbage collector. */
+    Transaction txn;
+    createStoreTransaction(txn);
+    for (PathSet::iterator i = ne.derivation.outputs.begin(); 
+         i != ne.derivation.outputs.end(); i++)
+        registerValidPath(txn, *i);
+    registerSuccessor(txn, nePath, nfPath);
+    txn.commit();
+
+    return nfPath;
+}
+
+
+void realiseClosure(const Path & nePath, PathSet pending)
+{
+    startNest(nest, lvlDebug, format("realising closure `%1%'") % nePath);
+
+    NixExpr ne = exprFromPath(nePath, pending);
+    if (ne.type != NixExpr::neClosure)
+        throw Error(format("expected closure in `%1%'") % nePath);
+    
+    for (ClosureElems::const_iterator i = ne.closure.elems.begin();
+         i != ne.closure.elems.end(); i++)
+        ensurePath(i->first, pending);
+}
+
+
+void ensurePath(const Path & path, PathSet pending)
+{
+    /* If the path is already valid, we're done. */
+    if (isValidPath(path)) return;
+    
+    /* Otherwise, try the substitutes. */
+    Paths subPaths = querySubstitutes(path);
+
+    for (Paths::iterator i = subPaths.begin(); 
+         i != subPaths.end(); i++)
+    {
+        try {
+            normaliseNixExpr(*i, pending);
+            if (isValidPath(path)) return;
+            throw Error(format("substitute failed to produce expected output path"));
+        } catch (Error & e) {
+            printMsg(lvlTalkative, 
+                format("building of substitute `%1%' for `%2%' failed: %3%")
+                % *i % path % e.what());
+        }
+    }
+
+    throw Error(format("path `%1%' is required, "
+        "but there are no (successful) substitutes") % path);
+}
+
+
+NixExpr exprFromPath(const Path & path, PathSet pending)
+{
+    ensurePath(path, pending);
+    ATerm t = ATreadFromNamedFile(path.c_str());
+    if (!t) throw Error(format("cannot read aterm from `%1%'") % path);
+    return parseNixExpr(t);
+}
+
+
+PathSet nixExprRoots(const Path & nePath)
+{
+    PathSet paths;
+
+    NixExpr ne = exprFromPath(nePath);
+
+    if (ne.type == NixExpr::neClosure)
+        paths.insert(ne.closure.roots.begin(), ne.closure.roots.end());
+    else if (ne.type == NixExpr::neDerivation)
+        paths.insert(ne.derivation.outputs.begin(),
+            ne.derivation.outputs.end());
+    else abort();
+
+    return paths;
+}
+
+
+static void requisitesWorker(const Path & nePath,
+    bool includeExprs, bool includeSuccessors,
+    PathSet & paths, PathSet & doneSet)
+{
+    if (doneSet.find(nePath) != doneSet.end()) return;
+    doneSet.insert(nePath);
+
+    NixExpr ne = exprFromPath(nePath);
+
+    if (ne.type == NixExpr::neClosure)
+        for (ClosureElems::iterator i = ne.closure.elems.begin();
+             i != ne.closure.elems.end(); i++)
+            paths.insert(i->first);
+    
+    else if (ne.type == NixExpr::neDerivation)
+        for (PathSet::iterator i = ne.derivation.inputs.begin();
+             i != ne.derivation.inputs.end(); i++)
+            requisitesWorker(*i,
+                includeExprs, includeSuccessors, paths, doneSet);
+
+    else abort();
+
+    if (includeExprs) paths.insert(nePath);
+
+    string nfPath;
+    if (includeSuccessors && (nfPath = useSuccessor(nePath)) != nePath)
+        requisitesWorker(nfPath, includeExprs, includeSuccessors,
+            paths, doneSet);
+}
+
+
+PathSet nixExprRequisites(const Path & nePath,
+    bool includeExprs, bool includeSuccessors)
+{
+    PathSet paths;
+    PathSet doneSet;
+    requisitesWorker(nePath, includeExprs, includeSuccessors,
+        paths, doneSet);
+    return paths;
+}