nix-gh/src/libexpr/primops.cc
Eelco Dolstra 4a053bfdfd * A new primop `builtins', which returns an attribute set containing
all the primops.  This allows Nix expressions to test for new
  primops and take appropriate action if they're not available.  For
  instance, rather than calling a primop `foo' directly, they could
  say `if builtins ? foo then builtins.foo ... else ...'.
2006-08-23 14:39:11 +00:00

708 lines
22 KiB
C++

#include <algorithm>
#include "build.hh"
#include "misc.hh"
#include "eval.hh"
#include "globals.hh"
#include "nixexpr-ast.hh"
static Expr primBuiltins(EvalState & state, const ATermVector & args)
{
/* Return an attribute set containing all primops. This allows
Nix expressions to test for new primops and take appropriate
action if they're not available. For instance, rather than
calling a primop `foo' directly, they could say `if builtins ?
foo then builtins.foo ... else ...'. */
ATermMap builtins(128);
for (ATermMap::const_iterator i = state.primOps.begin();
i != state.primOps.end(); ++i)
{
string name = aterm2String(i->key);
if (string(name, 0, 2) == "__")
name = string(name, 2);
/* !!! should use makePrimOp here, I guess. */
builtins.set(toATerm(name), makeAttrRHS(makeVar(i->key), makeNoPos()));
}
return makeAttrs(builtins);
}
/* Load and evaluate an expression from path specified by the
argument. */
static Expr primImport(EvalState & state, const ATermVector & args)
{
ATermList es;
Path path;
Expr arg = evalExpr(state, args[0]), arg2;
if (matchPath(arg, arg2))
path = aterm2String(arg2);
else if (matchAttrs(arg, es)) {
Expr a = queryAttr(arg, "type");
/* If it is a derivation, we have to realise it and load the
Nix expression created at the derivation's output path. */
if (a && evalString(state, a) == "derivation") {
a = queryAttr(arg, "drvPath");
if (!a) throw EvalError("bad derivation in import");
Path drvPath = evalPath(state, a);
buildDerivations(singleton<PathSet>(drvPath));
a = queryAttr(arg, "outPath");
if (!a) throw EvalError("bad derivation in import");
path = evalPath(state, a);
}
}
if (path == "")
throw TypeError("`import' requires a path or derivation as its argument");
return evalFile(state, path);
}
/* 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 store expression paths* should change to reflect the
new dependency graph.
That's what this function does: it returns a hash which is just the
of the derivation ATerm, except that any input store expression
paths have been replaced by the result of a recursive call to this
function, and that for fixed-output derivations we return
(basically) its outputHash. */
static Hash hashDerivationModulo(EvalState & state, Derivation drv)
{
/* Return a fixed hash for fixed-output derivations. */
if (drv.outputs.size() == 1) {
DerivationOutputs::const_iterator i = drv.outputs.begin();
if (i->first == "out" &&
i->second.hash != "")
{
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;
for (DerivationInputs::iterator i = drv.inputDrvs.begin();
i != drv.inputDrvs.end(); ++i)
{
Hash h = state.drvHashes[i->first];
if (h.type == htUnknown) {
Derivation drv2 = derivationFromPath(i->first);
h = hashDerivationModulo(state, drv2);
state.drvHashes[i->first] = h;
}
inputs2[printHash(h)] = i->second;
}
drv.inputDrvs = inputs2;
return hashTerm(unparseDerivation(drv));
}
static void processBinding(EvalState & state, Expr e, Derivation & drv,
Strings & ss)
{
e = evalExpr(state, e);
ATerm s;
ATermList es;
int n;
Expr e1, e2;
if (matchContext(e, es, e2)) {
e = e2;
for (ATermIterator i(es); i; ++i) {
Strings dummy;
processBinding(state, *i, drv, dummy);
}
}
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 EvalError("derivation name missing");
Path drvPath = evalPath(state, a);
a = queryAttr(e, "outPath");
if (!a) throw EvalError("output path missing");
/* !!! supports only single output path */
Path outPath = evalPath(state, a);
drv.inputDrvs[drvPath] = singleton<StringSet>("out");
ss.push_back(outPath);
}
else if (a && evalString(state, a) == "storePath") {
a = queryAttr(e, "outPath");
if (!a) throw EvalError("output path missing");
/* !!! supports only single output path */
Path outPath = evalPath(state, a);
drv.inputSrcs.insert(outPath);
ss.push_back(outPath);
}
else throw TypeError("attribute sets in derivations must either be derivations or store paths");
}
else if (matchPath(e, s)) {
Path srcPath(canonPath(aterm2String(s)));
if (isStorePath(srcPath)) {
printMsg(lvlChatty, format("using store path `%1%' as source")
% srcPath);
drv.inputSrcs.insert(srcPath);
ss.push_back(srcPath);
}
else {
if (isDerivation(srcPath))
throw EvalError(format("file names are not allowed to end in `%1%'")
% drvExtension);
Path dstPath;
if (state.srcToStore[srcPath] != "")
dstPath = state.srcToStore[srcPath];
else {
dstPath = addToStore(srcPath);
state.srcToStore[srcPath] = dstPath;
printMsg(lvlChatty, format("copied source `%1%' -> `%2%'")
% srcPath % dstPath);
}
drv.inputSrcs.insert(dstPath);
ss.push_back(dstPath);
}
}
else if (matchList(e, es)) {
for (ATermIterator i(es); i; ++i) {
startNest(nest, lvlVomit, format("processing list element"));
processBinding(state, evalExpr(state, *i), drv, ss);
}
}
else if (matchNull(e)) ss.push_back("");
else if (matchSubPath(e, e1, e2)) {
static bool warn = false;
if (!warn) {
printMsg(lvlError, "warning: the subpath operator (~) is deprecated, use string concatenation (+) instead");
warn = true;
}
Strings ss2;
processBinding(state, evalExpr(state, e1), drv, ss2);
if (ss2.size() != 1)
throw TypeError("left-hand side of `~' operator cannot be a list");
e2 = evalExpr(state, e2);
if (!(matchStr(e2, s) || matchPath(e2, s)))
throw TypeError("right-hand side of `~' operator must be a path or string");
ss.push_back(canonPath(ss2.front() + "/" + aterm2String(s)));
}
else throw TypeError(format("%1% is not allowed as a derivation argument") % showType(e));
}
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 primDerivationStrict(EvalState & state, const ATermVector & args)
{
startNest(nest, lvlVomit, "evaluating derivation");
ATermMap attrs(128); /* !!! */
queryAllAttrs(evalExpr(state, args[0]), attrs, true);
/* Figure out the name already (for stack backtraces). */
Expr eDrvName = attrs.get(toATerm("name"));
if (!eDrvName)
throw EvalError("required attribute `name' missing");
ATerm posDrvName;
if (!matchAttrRHS(eDrvName, eDrvName, posDrvName)) abort();
string drvName = evalString(state, eDrvName);
/* Build the derivation expression by processing the attributes. */
Derivation drv;
string outputHash;
string outputHashAlgo;
bool outputHashRecursive = false;
for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i) {
string key = aterm2String(i->key);
ATerm value;
Expr pos;
ATerm rhs = i->value;
if (!matchAttrRHS(rhs, value, pos)) abort();
startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);
Strings ss;
try {
processBinding(state, value, drv, ss);
} catch (Error & e) {
e.addPrefix(format("while processing the derivation attribute `%1%' at %2%:\n")
% key % showPos(pos));
e.addPrefix(format("while instantiating the derivation named `%1%' at %2%:\n")
% drvName % showPos(posDrvName));
throw;
}
/* 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)
drv.args.push_back(*i);
}
/* All other attributes are passed to the builder through the
environment. */
else {
string s = concatStrings(ss);
drv.env[key] = s;
if (key == "builder") drv.builder = s;
else if (key == "system") drv.platform = s;
else if (key == "name") drvName = s;
else if (key == "outputHash") outputHash = s;
else if (key == "outputHashAlgo") outputHashAlgo = s;
else if (key == "outputHashMode") {
if (s == "recursive") outputHashRecursive = true;
else if (s == "flat") outputHashRecursive = false;
else throw EvalError(format("invalid value `%1%' for `outputHashMode' attribute") % s);
}
}
}
/* Do we have all required attributes? */
if (drv.builder == "")
throw EvalError("required attribute `builder' missing");
if (drv.platform == "")
throw EvalError("required attribute `system' missing");
/* If an output hash was given, check it. */
if (outputHash == "")
outputHashAlgo = "";
else {
HashType ht = parseHashType(outputHashAlgo);
if (ht == htUnknown)
throw EvalError(format("unknown hash algorithm `%1%'") % outputHashAlgo);
Hash h;
if (outputHash.size() == Hash(ht).hashSize * 2)
/* hexadecimal representation */
h = parseHash(ht, outputHash);
else
/* base-32 representation */
h = parseHash32(ht, outputHash);
string s = outputHash;
outputHash = printHash(h);
if (outputHashRecursive) outputHashAlgo = "r:" + outputHashAlgo;
}
/* Check the derivation name. It shouldn't contain whitespace,
but we are conservative here: we check whether only
alphanumerics and some other characters appear. */
checkStoreName(drvName);
if (isDerivation(drvName))
throw EvalError(format("derivation names are not allowed to end in `%1%'")
% drvExtension);
/* !!! the name should not end in the derivation extension (.drv).
Likewise for sources. */
/* Construct the "masked" derivation store expression, which is
the final one except that in the list of outputs, the output
paths are empty, 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. */
drv.env["out"] = "";
drv.outputs["out"] =
DerivationOutput("", outputHashAlgo, outputHash);
/* Use the masked derivation expression to compute the output
path. */
Path outPath = makeStorePath("output:out",
hashDerivationModulo(state, drv), drvName);
/* Construct the final derivation store expression. */
drv.env["out"] = outPath;
drv.outputs["out"] =
DerivationOutput(outPath, outputHashAlgo, outputHash);
/* Write the resulting term into the Nix store directory. */
Path drvPath = writeDerivation(drv, drvName);
printMsg(lvlChatty, format("instantiated `%1%' -> `%2%'")
% drvName % drvPath);
/* Optimisation, but required in read-only mode! because in that
case we don't actually write store expressions, so we can't
read them later. */
state.drvHashes[drvPath] = hashDerivationModulo(state, drv);
/* !!! assumes a single output */
ATermMap outAttrs(2);
outAttrs.set(toATerm("outPath"),
makeAttrRHS(makePath(toATerm(outPath)), makeNoPos()));
outAttrs.set(toATerm("drvPath"),
makeAttrRHS(makePath(toATerm(drvPath)), makeNoPos()));
return makeAttrs(outAttrs);
}
static Expr primDerivationLazy(EvalState & state, const ATermVector & args)
{
Expr eAttrs = evalExpr(state, args[0]);
ATermMap attrs(128); /* !!! */
queryAllAttrs(eAttrs, attrs, true);
attrs.set(toATerm("type"),
makeAttrRHS(makeStr(toATerm("derivation")), makeNoPos()));
Expr drvStrict = makeCall(makeVar(toATerm("derivation!")), eAttrs);
attrs.set(toATerm("outPath"),
makeAttrRHS(makeSelect(drvStrict, toATerm("outPath")), makeNoPos()));
attrs.set(toATerm("drvPath"),
makeAttrRHS(makeSelect(drvStrict, toATerm("drvPath")), 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]))));
}
/* Return the directory of the given path, i.e., everything before the
last slash. */
static Expr primDirOf(EvalState & state, const ATermVector & args)
{
return makePath(toATerm(dirOf(evalPath(state, args[0]))));
}
ATerm coerceToString(Expr e)
{
ATerm s;
if (matchStr(e, s) || matchPath(e, s) || matchUri(e, s))
return s;
return 0;
}
/* Convert the argument (which can be a path or a uri) to a string. */
static Expr primToString(EvalState & state, const ATermVector & args)
{
ATermList context = ATempty;
bool dummy;
string s = coerceToStringWithContext(state, context, args[0], dummy);
return wrapInContext(context, makeStr(toATerm(s)));
}
/* 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. */
static Expr primNull(EvalState & state, const ATermVector & args)
{
return makeNull();
}
/* Determine whether the argument is the null value. */
static Expr primIsNull(EvalState & state, const ATermVector & args)
{
return makeBool(matchNull(evalExpr(state, args[0])));
}
static Path findDependency(Path dir, string dep)
{
if (dep[0] == '/') throw EvalError(
format("illegal absolute dependency `%1%'") % dep);
Path p = canonPath(dir + "/" + dep);
if (pathExists(p))
return p;
else
return "";
}
/* Make path `p' relative to directory `pivot'. E.g.,
relativise("/a/b/c", "a/b/x/y") => "../x/y". Both input paths
should be in absolute canonical form. */
static string relativise(Path pivot, Path p)
{
assert(pivot.size() > 0 && pivot[0] == '/');
assert(p.size() > 0 && p[0] == '/');
if (pivot == p) return ".";
/* `p' is in `pivot'? */
Path pivot2 = pivot + "/";
if (p.substr(0, pivot2.size()) == pivot2) {
return p.substr(pivot2.size());
}
/* Otherwise, `p' is in a parent of `pivot'. Find up till which
path component `p' and `pivot' match, and add an appropriate
number of `..' components. */
string::size_type i = 1;
while (1) {
string::size_type j = pivot.find('/', i);
if (j == string::npos) break;
j++;
if (pivot.substr(0, j) != p.substr(0, j)) break;
i = j;
}
string prefix;
unsigned int slashes = count(pivot.begin() + i, pivot.end(), '/') + 1;
while (slashes--) {
prefix += "../";
}
return prefix + p.substr(i);
}
static Expr primDependencyClosure(EvalState & state, const ATermVector & args)
{
startNest(nest, lvlDebug, "finding dependencies");
Expr attrs = evalExpr(state, args[0]);
/* Get the start set. */
Expr startSet = queryAttr(attrs, "startSet");
if (!startSet) throw EvalError("attribute `startSet' required");
ATermList startSet2 = evalList(state, startSet);
Path pivot;
PathSet workSet;
for (ATermIterator i(startSet2); i; ++i) {
Path p = evalPath(state, *i);
workSet.insert(p);
pivot = dirOf(p);
}
/* Get the search path. */
PathSet searchPath;
Expr e = queryAttr(attrs, "searchPath");
if (e) {
ATermList list = evalList(state, e);
for (ATermIterator i(list); i; ++i) {
Path p = evalPath(state, *i);
searchPath.insert(p);
}
}
Expr scanner = queryAttr(attrs, "scanner");
if (!scanner) throw EvalError("attribute `scanner' required");
/* Construct the dependency closure by querying the dependency of
each path in `workSet', adding the dependencies to
`workSet'. */
PathSet doneSet;
while (!workSet.empty()) {
Path path = *(workSet.begin());
workSet.erase(path);
if (doneSet.find(path) != doneSet.end()) continue;
doneSet.insert(path);
try {
/* Call the `scanner' function with `path' as argument. */
debug(format("finding dependencies in `%1%'") % path);
ATermList deps = evalList(state, makeCall(scanner, makePath(toATerm(path))));
/* Try to find the dependencies relative to the `path'. */
for (ATermIterator i(deps); i; ++i) {
string s = evalString(state, *i);
Path dep = findDependency(dirOf(path), s);
if (dep == "") {
for (PathSet::iterator j = searchPath.begin();
j != searchPath.end(); ++j)
{
dep = findDependency(*j, s);
if (dep != "") break;
}
}
if (dep == "")
debug(format("did NOT find dependency `%1%'") % s);
else {
debug(format("found dependency `%1%'") % dep);
workSet.insert(dep);
}
}
} catch (Error & e) {
e.addPrefix(format("while finding dependencies in `%1%':\n")
% path);
throw;
}
}
/* Return a list of the dependencies we've just found. */
ATermList deps = ATempty;
for (PathSet::iterator i = doneSet.begin(); i != doneSet.end(); ++i) {
deps = ATinsert(deps, makeStr(toATerm(relativise(pivot, *i))));
deps = ATinsert(deps, makePath(toATerm(*i)));
}
debug(format("dependency list is `%1%'") % makeList(deps));
return makeList(deps);
}
/* Apply a function to every element of a list. */
static Expr primMap(EvalState & state, const ATermVector & args)
{
Expr fun = evalExpr(state, args[0]);
ATermList list = evalList(state, args[1]);
ATermList res = ATempty;
for (ATermIterator i(list); i; ++i)
res = ATinsert(res, makeCall(fun, *i));
return makeList(ATreverse(res));
}
/* Return a string constant representing the current platform. Note!
that differs between platforms, so Nix expressions using
`__currentSystem' can evaluate to different values on different
platforms. */
static Expr primCurrentSystem(EvalState & state, const ATermVector & args)
{
return makeStr(toATerm(thisSystem));
}
static Expr primCurrentTime(EvalState & state, const ATermVector & args)
{
return ATmake("Int(<int>)", time(0));
}
static Expr primRemoveAttrs(EvalState & state, const ATermVector & args)
{
ATermMap attrs(128); /* !!! */
queryAllAttrs(evalExpr(state, args[0]), attrs, true);
ATermList list = evalList(state, args[1]);
for (ATermIterator i(list); i; ++i)
/* It's not an error for *i not to exist. */
attrs.remove(toATerm(evalString(state, *i)));
return makeAttrs(attrs);
}
static Expr primRelativise(EvalState & state, const ATermVector & args)
{
Path pivot = evalPath(state, args[0]);
Path path = evalPath(state, args[1]);
return makeStr(toATerm(relativise(pivot, path)));
}
void EvalState::addPrimOps()
{
addPrimOp("builtins", 0, primBuiltins);
addPrimOp("true", 0, primTrue);
addPrimOp("false", 0, primFalse);
addPrimOp("null", 0, primNull);
addPrimOp("__currentSystem", 0, primCurrentSystem);
addPrimOp("__currentTime", 0, primCurrentTime);
addPrimOp("import", 1, primImport);
addPrimOp("derivation!", 1, primDerivationStrict);
addPrimOp("derivation", 1, primDerivationLazy);
addPrimOp("baseNameOf", 1, primBaseNameOf);
addPrimOp("dirOf", 1, primDirOf);
addPrimOp("toString", 1, primToString);
addPrimOp("isNull", 1, primIsNull);
addPrimOp("dependencyClosure", 1, primDependencyClosure);
addPrimOp("map", 2, primMap);
addPrimOp("removeAttrs", 2, primRemoveAttrs);
addPrimOp("relativise", 2, primRelativise);
}