lix/src/libexpr/primops.cc
Eelco Dolstra d58a11e019 * Shorten SHA-256 hashes used in store path name generation to 160
bits, then encode them in a radix-32 representation (using digits
  and letters except e, o, u, and t).  This produces store paths like
  /nix/store/4i0zb0z7f88mwghjirkz702a71dcfivn-aterm-2.3.1.  The nice
  thing about this is that the hash part of the file name is still 32
  characters, as before with MD5.

  (Of course, shortening SHA-256 to 160 bits makes it no better than
  SHA-160 in theory, but hopefully it's a bit more resistant to
  attacks; it's certainly a lot slower.)
2005-01-14 16:04:03 +00:00

371 lines
11 KiB
C++

#include "normalise.hh"
#include "eval.hh"
#include "globals.hh"
#include "nixexpr-ast.hh"
/* Load and evaluate an expression from path specified by the
argument. */
static Expr primImport(EvalState & state, const ATermVector & args)
{
ATerm path;
Expr fn = evalExpr(state, args[0]);
if (!matchPath(fn, path))
throw Error("path expected");
return evalFile(state, aterm2String(path));
}
static PathSet storeExprRootsCached(EvalState & state, const Path & nePath)
{
DrvRoots::iterator i = state.drvRoots.find(nePath);
if (i != state.drvRoots.end())
return i->second;
else {
PathSet paths = storeExprRoots(nePath);
state.drvRoots[nePath] = paths;
return paths;
}
}
static Hash hashDerivation(EvalState & state, StoreExpr ne)
{
if (ne.type == StoreExpr::neDerivation) {
PathSet inputs2;
for (PathSet::iterator i = ne.derivation.inputs.begin();
i != ne.derivation.inputs.end(); i++)
{
DrvHashes::iterator j = state.drvHashes.find(*i);
if (j == state.drvHashes.end())
throw Error(format("don't know expression `%1%'") % (string) *i);
inputs2.insert(printHash(j->second));
}
ne.derivation.inputs = inputs2;
}
return hashTerm(unparseStoreExpr(ne));
}
static Path copyAtom(EvalState & state, const Path & srcPath)
{
/* !!! should be cached */
Path dstPath(addToStore(srcPath));
ClosureElem elem;
StoreExpr ne;
ne.type = StoreExpr::neClosure;
ne.closure.roots.insert(dstPath);
ne.closure.elems[dstPath] = elem;
Hash drvHash = hashDerivation(state, ne);
Path drvPath = writeTerm(unparseStoreExpr(ne), "c");
state.drvHashes[drvPath] = drvHash;
state.drvRoots[drvPath] = ne.closure.roots;
printMsg(lvlChatty, format("copied `%1%' -> closure `%2%'")
% srcPath % drvPath);
return drvPath;
}
static string addInput(EvalState & state,
Path & nePath, StoreExpr & ne)
{
PathSet paths = storeExprRootsCached(state, nePath);
if (paths.size() != 1) abort();
Path path = *(paths.begin());
ne.derivation.inputs.insert(nePath);
return path;
}
static void processBinding(EvalState & state, Expr e, StoreExpr & ne,
Strings & ss)
{
e = evalExpr(state, e);
ATerm s;
ATermList es;
int n;
Expr e1, e2;
if (matchStr(e, s)) ss.push_back(aterm2String(s));
else if (matchUri(e, s)) ss.push_back(aterm2String(s));
else if (e == eTrue) ss.push_back("1");
else if (e == eFalse) ss.push_back("");
else if (matchInt(e, n)) {
ostringstream st;
st << n;
ss.push_back(st.str());
}
else if (matchAttrs(e, es)) {
Expr a = queryAttr(e, "type");
if (a && evalString(state, a) == "derivation") {
a = queryAttr(e, "drvPath");
if (!a) throw Error("derivation name missing");
Path drvPath = evalPath(state, a);
a = queryAttr(e, "drvHash");
if (!a) throw Error("derivation hash missing");
Hash drvHash = parseHash(htMD5, evalString(state, a));
a = queryAttr(e, "outPath");
if (!a) throw Error("output path missing");
PathSet drvRoots;
drvRoots.insert(evalPath(state, a));
state.drvHashes[drvPath] = drvHash;
state.drvRoots[drvPath] = drvRoots;
ss.push_back(addInput(state, drvPath, ne));
} else
throw Error("invalid derivation attribute");
}
else if (matchPath(e, s)) {
Path drvPath = copyAtom(state, aterm2String(s));
ss.push_back(addInput(state, drvPath, ne));
}
else if (matchList(e, es)) {
for (ATermIterator i(es); i; ++i) {
startNest(nest, lvlVomit, format("processing list element"));
processBinding(state, evalExpr(state, *i), ne, ss);
}
}
else if (matchNull(e)) ss.push_back("");
else if (matchSubPath(e, e1, e2)) {
Strings ss2;
processBinding(state, evalExpr(state, e1), ne, ss2);
if (ss2.size() != 1)
throw Error("left-hand side of `~' operator cannot be a list");
e2 = evalExpr(state, e2);
if (!(matchStr(e2, s) || matchPath(e2, s)))
throw Error("right-hand side of `~' operator must be a path or string");
ss.push_back(canonPath(ss2.front() + "/" + aterm2String(s)));
}
else throw Error("invalid derivation attribute");
}
static string concatStrings(const Strings & ss)
{
string s;
bool first = true;
for (Strings::const_iterator i = ss.begin(); i != ss.end(); ++i) {
if (!first) s += " "; else first = false;
s += *i;
}
return s;
}
/* Construct (as a unobservable side effect) a Nix derivation
expression that performs the derivation described by the argument
set. Returns the original set extended with the following
attributes: `outPath' containing the primary output path of the
derivation; `drvPath' containing the path of the Nix expression;
and `type' set to `derivation' to indicate that this is a
derivation. */
static Expr primDerivation(EvalState & state, const ATermVector & _args)
{
startNest(nest, lvlVomit, "evaluating derivation");
ATermMap attrs;
Expr args = _args[0];
args = evalExpr(state, args);
queryAllAttrs(args, attrs, true);
/* Build the derivation expression by processing the attributes. */
StoreExpr ne;
ne.type = StoreExpr::neDerivation;
string drvName;
Hash outHash;
bool outHashGiven = false;
for (ATermIterator i(attrs.keys()); i; ++i) {
string key = aterm2String(*i);
ATerm value;
Expr pos;
ATerm rhs = attrs.get(key);
if (!matchAttrRHS(rhs, value, pos)) abort();
startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);
Strings ss;
try {
processBinding(state, value, ne, ss);
} catch (Error & e) {
throw Error(format("while processing the derivation attribute `%1%' at %2%:\n%3%")
% key % showPos(pos) % e.msg());
}
/* The `args' attribute is special: it supplies the
command-line arguments to the builder. */
if (key == "args") {
for (Strings::iterator i = ss.begin(); i != ss.end(); ++i)
ne.derivation.args.push_back(*i);
}
/* All other attributes are passed to the builder through the
environment. */
else {
string s = concatStrings(ss);
ne.derivation.env[key] = s;
if (key == "builder") ne.derivation.builder = s;
else if (key == "system") ne.derivation.platform = s;
else if (key == "name") drvName = s;
else if (key == "id") {
outHash = parseHash(htMD5, s);
outHashGiven = true;
}
}
}
/* Do we have all required attributes? */
if (ne.derivation.builder == "")
throw Error("required attribute `builder' missing");
if (ne.derivation.platform == "")
throw Error("required attribute `system' missing");
if (drvName == "")
throw Error("required attribute `name' missing");
/* Check the derivation name. It shouldn't contain whitespace,
but we are conservative here: we check whether only
alphanumerics and some other characters appear. */
string validChars = "+-._?=";
for (string::iterator i = drvName.begin(); i != drvName.end(); ++i)
if (!((*i >= 'A' && *i <= 'Z') ||
(*i >= 'a' && *i <= 'z') ||
(*i >= '0' && *i <= '9') ||
validChars.find(*i) != string::npos))
{
throw Error(format("invalid character `%1%' in derivation name `%2%'")
% *i % drvName);
}
/* Construct the "masked" derivation store expression, which is
the final one except that the list of output paths is set to
the set of output names, and the corresponding environment
variables have an empty value. This ensures that changes in
the set of output names do get reflected in the hash. */
ne.derivation.env["out"] = "";
ne.derivation.outputs.insert("out");
/* Determine the output path by hashing the Nix expression with no
outputs to produce a unique but deterministic path name for
this derivation. */
if (!outHashGiven) outHash = hashDerivation(state, ne);
Path outPath = makeStorePath("output:out",
outHash, drvName);
/* Construct the final derivation store expression. */
ne.derivation.env["out"] = outPath;
ne.derivation.outputs.clear();
ne.derivation.outputs.insert(outPath);
/* Write the resulting term into the Nix store directory. */
Hash drvHash = outHashGiven
? hashString(printHash(outHash) + outPath, htMD5)
: hashDerivation(state, ne);
Path drvPath = writeTerm(unparseStoreExpr(ne), "d-" + drvName);
printMsg(lvlChatty, format("instantiated `%1%' -> `%2%'")
% drvName % drvPath);
attrs.set("outPath", makeAttrRHS(makePath(toATerm(outPath)), makeNoPos()));
attrs.set("drvPath", makeAttrRHS(makePath(toATerm(drvPath)), makeNoPos()));
attrs.set("drvHash",
makeAttrRHS(makeStr(toATerm(printHash(drvHash))), makeNoPos()));
attrs.set("type", makeAttrRHS(makeStr(toATerm("derivation")), makeNoPos()));
return makeAttrs(attrs);
}
/* Return the base name of the given string, i.e., everything
following the last slash. */
static Expr primBaseNameOf(EvalState & state, const ATermVector & args)
{
return makeStr(toATerm(baseNameOf(evalString(state, args[0]))));
}
/* Convert the argument (which can be a path or a uri) to a string. */
static Expr primToString(EvalState & state, const ATermVector & args)
{
Expr arg = evalExpr(state, args[0]);
ATerm s;
if (matchStr(arg, s) || matchPath(arg, s) || matchUri(arg, s))
return makeStr(s);
else throw Error("cannot coerce value to string");
}
/* Boolean constructors. */
static Expr primTrue(EvalState & state, const ATermVector & args)
{
return eTrue;
}
static Expr primFalse(EvalState & state, const ATermVector & args)
{
return eFalse;
}
/* Return the null value. */
Expr primNull(EvalState & state, const ATermVector & args)
{
return makeNull();
}
/* Determine whether the argument is the null value. */
Expr primIsNull(EvalState & state, const ATermVector & args)
{
return makeBool(matchNull(evalExpr(state, args[0])));
}
/* Apply a function to every element of a list. */
Expr primMap(EvalState & state, const ATermVector & args)
{
Expr fun = evalExpr(state, args[0]);
Expr list = evalExpr(state, args[1]);
ATermList list2;
if (!matchList(list, list2))
throw Error("`map' expects a list as its second argument");
ATermList list3 = ATempty;
for (ATermIterator i(list2); i; ++i)
list3 = ATinsert(list3, makeCall(fun, *i));
return makeList(ATreverse(list3));
}
void EvalState::addPrimOps()
{
addPrimOp("true", 0, primTrue);
addPrimOp("false", 0, primFalse);
addPrimOp("null", 0, primNull);
addPrimOp("import", 1, primImport);
addPrimOp("derivation", 1, primDerivation);
addPrimOp("baseNameOf", 1, primBaseNameOf);
addPrimOp("toString", 1, primToString);
addPrimOp("isNull", 1, primIsNull);
addPrimOp("map", 2, primMap);
}