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Add a mechanism for derivation attributes to reference the derivation's outputs

Browse source 
For example, you can now say:

  configureFlags = "--prefix=${placeholder "out"} --includedir=${placeholder "dev"}";

The strings returned by the ‘placeholder’ builtin are replaced at
build time by the actual store paths corresponding to the specified
outputs.

Previously, you had to work around the inability to self-reference by doing stuff like:

  preConfigure = ''
    configureFlags+=" --prefix $out --includedir=$dev"
  '';

or rely on ad-hoc variable interpolation semantics in Autoconf or Make
(e.g. --prefix=\$(out)), which doesn't always work.
This commit is contained in:
Eelco Dolstra 2016-08-17 15:12:54 +02:00
parent ac841a4679
commit 22d6e31fc6
7 changed files with 63 additions and 16 deletions
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29
src/libstore/build.cc
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@ -652,18 +652,15 @@ HookInstance::~HookInstance()
//////////////////////////////////////////////////////////////////////
typedef map<string, string> HashRewrites;
typedef map<std::string, std::string> StringRewrites;
string rewriteHashes(string s, const HashRewrites & rewrites)
std::string rewriteStrings(std::string s, const StringRewrites & rewrites)
{
for (auto & i : rewrites) {
assert(i.first.size() == i.second.size());
size_t j = 0;
while ((j = s.find(i.first, j)) != string::npos) {
debug(format("rewriting @ %1%") % j);
s.replace(j, i.second.size(), i.second);
}
while ((j = s.find(i.first, j)) != string::npos)
s.replace(j, i.first.size(), i.second);
}
return s;
}
@ -782,7 +779,7 @@ private:
#endif
/* Hash rewriting. */
HashRewrites rewritesToTmp, rewritesFromTmp;
StringRewrites inputRewrites, outputRewrites;
typedef map<Path, Path> RedirectedOutputs;
RedirectedOutputs redirectedOutputs;
@ -1774,6 +1771,10 @@ void DerivationGoal::startBuilder()
for (auto & i : varNames) env[i] = getEnv(i);
}
/* Substitute output placeholders with the actual output paths. */
for (auto & output : drv->outputs)
inputRewrites[hashPlaceholder(output.first)] = output.second.path;
/* The `exportReferencesGraph' feature allows the references graph
to be passed to a builder. This attribute should be a list of
pairs [name1 path1 name2 path2 ...]. The references graph of
@ -2418,7 +2419,7 @@ void DerivationGoal::runChild()
/* Fill in the environment. */
Strings envStrs;
for (auto & i : env)
envStrs.push_back(rewriteHashes(i.first + "=" + i.second, rewritesToTmp));
envStrs.push_back(rewriteStrings(i.first + "=" + i.second, inputRewrites));
/* If we are running in `build-users' mode, then switch to the
user we allocated above. Make sure that we drop all root
@ -2560,7 +2561,7 @@ void DerivationGoal::runChild()
}
for (auto & i : drv->args)
args.push_back(rewriteHashes(i, rewritesToTmp));
args.push_back(rewriteStrings(i, inputRewrites));
restoreSIGPIPE();
@ -2682,7 +2683,7 @@ void DerivationGoal::registerOutputs()
/* Apply hash rewriting if necessary. */
bool rewritten = false;
if (!rewritesFromTmp.empty()) {
if (!outputRewrites.empty()) {
printMsg(lvlError, format("warning: rewriting hashes in ‘%1%’; cross fingers") % path);
/* Canonicalise first. This ensures that the path we're
@ -2694,7 +2695,7 @@ void DerivationGoal::registerOutputs()
StringSink sink;
dumpPath(actualPath, sink);
deletePath(actualPath);
sink.s = make_ref<std::string>(rewriteHashes(*sink.s, rewritesFromTmp));
sink.s = make_ref<std::string>(rewriteStrings(*sink.s, outputRewrites));
StringSource source(*sink.s);
restorePath(actualPath, source);
@ -3033,8 +3034,8 @@ Path DerivationGoal::addHashRewrite(const Path & path)
Path p = worker.store.storeDir + "/" + h2 + string(path, worker.store.storeDir.size() + 33);
deletePath(p);
assert(path.size() == p.size());
rewritesToTmp[h1] = h2;
rewritesFromTmp[h2] = h1;
inputRewrites[h1] = h2;
outputRewrites[h2] = h1;
redirectedOutputs[path] = p;
return p;
}