lix/src/libstore/derivations.cc
2011-09-12 09:07:43 +00:00

256 lines
7.3 KiB
C++

#include "derivations.hh"
#include "store-api.hh"
#include "globals.hh"
#include "util.hh"
#include "misc.hh"
namespace nix {
void DerivationOutput::parseHashInfo(bool & recursive, HashType & hashType, Hash & hash) const
{
recursive = false;
string algo = hashAlgo;
if (string(algo, 0, 2) == "r:") {
recursive = true;
algo = string(algo, 2);
}
hashType = parseHashType(algo);
if (hashType == htUnknown)
throw Error(format("unknown hash algorithm `%1%'") % algo);
hash = parseHash(hashType, this->hash);
}
Path writeDerivation(StoreAPI & store,
const Derivation & drv, const string & name)
{
PathSet references;
references.insert(drv.inputSrcs.begin(), drv.inputSrcs.end());
foreach (DerivationInputs::const_iterator, i, drv.inputDrvs)
references.insert(i->first);
/* Note that the outputs of a derivation are *not* references
(that can be missing (of course) and should not necessarily be
held during a garbage collection). */
string suffix = name + drvExtension;
string contents = unparseDerivation(drv);
return readOnlyMode
? computeStorePathForText(suffix, contents, references)
: store.addTextToStore(suffix, contents, references);
}
static Path parsePath(std::istream & str)
{
string s = parseString(str);
if (s.size() == 0 || s[0] != '/')
throw Error(format("bad path `%1%' in derivation") % s);
return s;
}
static StringSet parseStrings(std::istream & str, bool arePaths)
{
StringSet res;
while (!endOfList(str))
res.insert(arePaths ? parsePath(str) : parseString(str));
return res;
}
Derivation parseDerivation(const string & s)
{
Derivation drv;
std::istringstream str(s);
expect(str, "Derive([");
/* Parse the list of outputs. */
while (!endOfList(str)) {
DerivationOutput out;
expect(str, "("); string id = parseString(str);
expect(str, ","); out.path = parsePath(str);
expect(str, ","); out.hashAlgo = parseString(str);
expect(str, ","); out.hash = parseString(str);
expect(str, ")");
drv.outputs[id] = out;
}
/* Parse the list of input derivations. */
expect(str, ",[");
while (!endOfList(str)) {
expect(str, "(");
Path drvPath = parsePath(str);
expect(str, ",[");
drv.inputDrvs[drvPath] = parseStrings(str, false);
expect(str, ")");
}
expect(str, ",["); drv.inputSrcs = parseStrings(str, true);
expect(str, ","); drv.platform = parseString(str);
expect(str, ","); drv.builder = parseString(str);
/* Parse the builder arguments. */
expect(str, ",[");
while (!endOfList(str))
drv.args.push_back(parseString(str));
/* Parse the environment variables. */
expect(str, ",[");
while (!endOfList(str)) {
expect(str, "("); string name = parseString(str);
expect(str, ","); string value = parseString(str);
expect(str, ")");
drv.env[name] = value;
}
expect(str, ")");
return drv;
}
static void printString(string & res, const string & s)
{
res += '"';
for (const char * i = s.c_str(); *i; i++)
if (*i == '\"' || *i == '\\') { res += "\\"; res += *i; }
else if (*i == '\n') res += "\\n";
else if (*i == '\r') res += "\\r";
else if (*i == '\t') res += "\\t";
else res += *i;
res += '"';
}
template<class ForwardIterator>
static void printStrings(string & res, ForwardIterator i, ForwardIterator j)
{
res += '[';
bool first = true;
for ( ; i != j; ++i) {
if (first) first = false; else res += ',';
printString(res, *i);
}
res += ']';
}
string unparseDerivation(const Derivation & drv)
{
string s;
s.reserve(65536);
s += "Derive([";
bool first = true;
foreach (DerivationOutputs::const_iterator, i, drv.outputs) {
if (first) first = false; else s += ',';
s += '('; printString(s, i->first);
s += ','; printString(s, i->second.path);
s += ','; printString(s, i->second.hashAlgo);
s += ','; printString(s, i->second.hash);
s += ')';
}
s += "],[";
first = true;
foreach (DerivationInputs::const_iterator, i, drv.inputDrvs) {
if (first) first = false; else s += ',';
s += '('; printString(s, i->first);
s += ','; printStrings(s, i->second.begin(), i->second.end());
s += ')';
}
s += "],";
printStrings(s, drv.inputSrcs.begin(), drv.inputSrcs.end());
s += ','; printString(s, drv.platform);
s += ','; printString(s, drv.builder);
s += ','; printStrings(s, drv.args.begin(), drv.args.end());
s += ",[";
first = true;
foreach (StringPairs::const_iterator, i, drv.env) {
if (first) first = false; else s += ',';
s += '('; printString(s, i->first);
s += ','; printString(s, i->second);
s += ')';
}
s += "])";
return s;
}
bool isDerivation(const string & fileName)
{
return hasSuffix(fileName, drvExtension);
}
bool isFixedOutputDrv(const Derivation & drv)
{
return drv.outputs.size() == 1 &&
drv.outputs.begin()->first == "out" &&
drv.outputs.begin()->second.hash != "";
}
DrvHashes drvHashes;
/* Returns the hash of a derivation modulo fixed-output
subderivations. A fixed-output derivation is a derivation with one
output (`out') for which an expected hash and hash algorithm are
specified (using the `outputHash' and `outputHashAlgo'
attributes). We don't want changes to such derivations to
propagate upwards through the dependency graph, changing output
paths everywhere.
For instance, if we change the url in a call to the `fetchurl'
function, we do not want to rebuild everything depending on it
(after all, (the hash of) the file being downloaded is unchanged).
So the *output paths* should not change. On the other hand, the
*derivation paths* should change to reflect the new dependency
graph.
That's what this function does: it returns a hash which is just the
hash of the derivation ATerm, except that any input derivation
paths have been replaced by the result of a recursive call to this
function, and that for fixed-output derivations we return a hash of
its output path. */
Hash hashDerivationModulo(StoreAPI & store, Derivation drv)
{
/* Return a fixed hash for fixed-output derivations. */
if (isFixedOutputDrv(drv)) {
DerivationOutputs::const_iterator i = drv.outputs.begin();
return hashString(htSHA256, "fixed:out:"
+ i->second.hashAlgo + ":"
+ i->second.hash + ":"
+ i->second.path);
}
/* For other derivations, replace the inputs paths with recursive
calls to this function.*/
DerivationInputs inputs2;
foreach (DerivationInputs::const_iterator, i, drv.inputDrvs) {
Hash h = drvHashes[i->first];
if (h.type == htUnknown) {
assert(store.isValidPath(i->first));
Derivation drv2 = parseDerivation(readFile(i->first));
h = hashDerivationModulo(store, drv2);
drvHashes[i->first] = h;
}
inputs2[printHash(h)] = i->second;
}
drv.inputDrvs = inputs2;
return hashString(htSHA256, unparseDerivation(drv));
}
}