path: root/third_party/nix/src/libexpr/get-drvs.cc

#include "get-drvs.hh"
#include <cstring>
#include <regex>
#include "derivations.hh"
#include "eval-inline.hh"
#include "util.hh"

namespace nix {

DrvInfo::DrvInfo(EvalState& state, const string& attrPath, Bindings* attrs)
    : state(&state), attrs(attrs), attrPath(attrPath) {}

DrvInfo::DrvInfo(EvalState& state, ref<Store> store,
                 const std::string& drvPathWithOutputs)
    : state(&state), attrs(nullptr), attrPath("") {
  auto spec = parseDrvPathWithOutputs(drvPathWithOutputs);

  drvPath = spec.first;

  auto drv = store->derivationFromPath(drvPath);

  name = storePathToName(drvPath);

  if (spec.second.size() > 1)
    throw Error(
        "building more than one derivation output is not supported, in '%s'",
        drvPathWithOutputs);

  outputName = spec.second.empty() ? get(drv.env, "outputName", "out")
                                   : *spec.second.begin();

  auto i = drv.outputs.find(outputName);
  if (i == drv.outputs.end())
    throw Error("derivation '%s' does not have output '%s'", drvPath,
                outputName);

  outPath = i->second.path;
}

string DrvInfo::queryName() const {
  if (name == "" && attrs) {
    auto i = attrs->find(state->sName);
    if (i == attrs->end()) throw TypeError("derivation name missing");
    name = state->forceStringNoCtx(*i->value);
  }
  return name;
}

string DrvInfo::querySystem() const {
  if (system == "" && attrs) {
    auto i = attrs->find(state->sSystem);
    system = i == attrs->end() ? "unknown"
                               : state->forceStringNoCtx(*i->value, *i->pos);
  }
  return system;
}

string DrvInfo::queryDrvPath() const {
  if (drvPath == "" && attrs) {
    Bindings::iterator i = attrs->find(state->sDrvPath);
    PathSet context;
    drvPath = i != attrs->end()
                  ? state->coerceToPath(*i->pos, *i->value, context)
                  : "";
  }
  return drvPath;
}

string DrvInfo::queryOutPath() const {
  if (outPath == "" && attrs) {
    Bindings::iterator i = attrs->find(state->sOutPath);
    PathSet context;
    outPath = i != attrs->end()
                  ? state->coerceToPath(*i->pos, *i->value, context)
                  : "";
  }
  return outPath;
}

DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall) {
  if (outputs.empty()) {
    /* Get the ‘outputs’ list. */
    Bindings::iterator i;
    if (attrs && (i = attrs->find(state->sOutputs)) != attrs->end()) {
      state->forceList(*i->value, *i->pos);

      /* For each output... */
      for (unsigned int j = 0; j < i->value->listSize(); ++j) {
        /* Evaluate the corresponding set. */
        string name =
            state->forceStringNoCtx(*i->value->listElems()[j], *i->pos);
        Bindings::iterator out = attrs->find(state->symbols.create(name));
        if (out == attrs->end()) continue;  // FIXME: throw error?
        state->forceAttrs(*out->value);

        /* And evaluate its ‘outPath’ attribute. */
        Bindings::iterator outPath = out->value->attrs->find(state->sOutPath);
        if (outPath == out->value->attrs->end())
          continue;  // FIXME: throw error?
        PathSet context;
        outputs[name] =
            state->coerceToPath(*outPath->pos, *outPath->value, context);
      }
    } else
      outputs["out"] = queryOutPath();
  }
  if (!onlyOutputsToInstall || !attrs) return outputs;

  /* Check for `meta.outputsToInstall` and return `outputs` reduced to that. */
  const Value* outTI = queryMeta("outputsToInstall");
  if (!outTI) return outputs;
  const auto errMsg = Error("this derivation has bad 'meta.outputsToInstall'");
  /* ^ this shows during `nix-env -i` right under the bad derivation */
  if (!outTI->isList()) throw errMsg;
  Outputs result;
  for (auto i = outTI->listElems(); i != outTI->listElems() + outTI->listSize();
       ++i) {
    if ((*i)->type != tString) throw errMsg;
    auto out = outputs.find((*i)->string.s);
    if (out == outputs.end()) throw errMsg;
    result.insert(*out);
  }
  return result;
}

string DrvInfo::queryOutputName() const {
  if (outputName == "" && attrs) {
    Bindings::iterator i = attrs->find(state->sOutputName);
    outputName = i != attrs->end() ? state->forceStringNoCtx(*i->value) : "";
  }
  return outputName;
}

Bindings* DrvInfo::getMeta() {
  if (meta) return meta;
  if (!attrs) return 0;
  Bindings::iterator a = attrs->find(state->sMeta);
  if (a == attrs->end()) return 0;
  state->forceAttrs(*a->value, *a->pos);
  meta = a->value->attrs;
  return meta;
}

StringSet DrvInfo::queryMetaNames() {
  StringSet res;
  if (!getMeta()) return res;
  for (auto& i : *meta) res.insert(i.name);
  return res;
}

bool DrvInfo::checkMeta(Value& v) {
  state->forceValue(v);
  if (v.isList()) {
    for (unsigned int n = 0; n < v.listSize(); ++n)
      if (!checkMeta(*v.listElems()[n])) return false;
    return true;
  } else if (v.type == tAttrs) {
    Bindings::iterator i = v.attrs->find(state->sOutPath);
    if (i != v.attrs->end()) return false;
    for (auto& i : *v.attrs)
      if (!checkMeta(*i.value)) return false;
    return true;
  } else
    return v.type == tInt || v.type == tBool || v.type == tString ||
           v.type == tFloat;
}

Value* DrvInfo::queryMeta(const string& name) {
  if (!getMeta()) return 0;
  Bindings::iterator a = meta->find(state->symbols.create(name));
  if (a == meta->end() || !checkMeta(*a->value)) return 0;
  return a->value;
}

string DrvInfo::queryMetaString(const string& name) {
  Value* v = queryMeta(name);
  if (!v || v->type != tString) return "";
  return v->string.s;
}

NixInt DrvInfo::queryMetaInt(const string& name, NixInt def) {
  Value* v = queryMeta(name);
  if (!v) return def;
  if (v->type == tInt) return v->integer;
  if (v->type == tString) {
    /* Backwards compatibility with before we had support for
       integer meta fields. */
    NixInt n;
    if (string2Int(v->string.s, n)) return n;
  }
  return def;
}

NixFloat DrvInfo::queryMetaFloat(const string& name, NixFloat def) {
  Value* v = queryMeta(name);
  if (!v) return def;
  if (v->type == tFloat) return v->fpoint;
  if (v->type == tString) {
    /* Backwards compatibility with before we had support for
       float meta fields. */
    NixFloat n;
    if (string2Float(v->string.s, n)) return n;
  }
  return def;
}

bool DrvInfo::queryMetaBool(const string& name, bool def) {
  Value* v = queryMeta(name);
  if (!v) return def;
  if (v->type == tBool) return v->boolean;
  if (v->type == tString) {
    /* Backwards compatibility with before we had support for
       Boolean meta fields. */
    if (strcmp(v->string.s, "true") == 0) return true;
    if (strcmp(v->string.s, "false") == 0) return false;
  }
  return def;
}

void DrvInfo::setMeta(const string& name, Value* v) {
  getMeta();
  Bindings* old = meta;
  meta = state->allocBindings(1 + (old ? old->size() : 0));
  Symbol sym = state->symbols.create(name);
  if (old)
    for (auto i : *old)
      if (i.name != sym) meta->push_back(i);
  if (v) meta->push_back(Attr(sym, v));
  meta->sort();
}

/* Cache for already considered attrsets. */
typedef set<Bindings*> Done;

/* Evaluate value `v'.  If it evaluates to a set of type `derivation',
   then put information about it in `drvs' (unless it's already in `done').
   The result boolean indicates whether it makes sense
   for the caller to recursively search for derivations in `v'. */
static bool getDerivation(EvalState& state, Value& v, const string& attrPath,
                          DrvInfos& drvs, Done& done,
                          bool ignoreAssertionFailures) {
  try {
    state.forceValue(v);
    if (!state.isDerivation(v)) return true;

    /* Remove spurious duplicates (e.g., a set like `rec { x =
       derivation {...}; y = x;}'. */
    if (done.find(v.attrs) != done.end()) return false;
    done.insert(v.attrs);

    DrvInfo drv(state, attrPath, v.attrs);

    drv.queryName();

    drvs.push_back(drv);

    return false;

  } catch (AssertionError& e) {
    if (ignoreAssertionFailures) return false;
    throw;
  }
}

std::optional<DrvInfo> getDerivation(EvalState& state, Value& v,
                                     bool ignoreAssertionFailures) {
  Done done;
  DrvInfos drvs;
  getDerivation(state, v, "", drvs, done, ignoreAssertionFailures);
  if (drvs.size() != 1) return {};
  return std::move(drvs.front());
}

static string addToPath(const string& s1, const string& s2) {
  return s1.empty() ? s2 : s1 + "." + s2;
}

static std::regex attrRegex("[A-Za-z_][A-Za-z0-9-_+]*");

static void getDerivations(EvalState& state, Value& vIn,
                           const string& pathPrefix, Bindings& autoArgs,
                           DrvInfos& drvs, Done& done,
                           bool ignoreAssertionFailures) {
  Value v;
  state.autoCallFunction(autoArgs, vIn, v);

  /* Process the expression. */
  if (!getDerivation(state, v, pathPrefix, drvs, done, ignoreAssertionFailures))
    ;

  else if (v.type == tAttrs) {
    /* !!! undocumented hackery to support combining channels in
       nix-env.cc. */
    bool combineChannels =
        v.attrs->find(state.symbols.create("_combineChannels")) !=
        v.attrs->end();

    /* Consider the attributes in sorted order to get more
       deterministic behaviour in nix-env operations (e.g. when
       there are names clashes between derivations, the derivation
       bound to the attribute with the "lower" name should take
       precedence). */
    for (auto& i : v.attrs->lexicographicOrder()) {
      debug("evaluating attribute '%1%'", i->name);
      if (!std::regex_match(std::string(i->name), attrRegex)) continue;
      string pathPrefix2 = addToPath(pathPrefix, i->name);
      if (combineChannels)
        getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done,
                       ignoreAssertionFailures);
      else if (getDerivation(state, *i->value, pathPrefix2, drvs, done,
                             ignoreAssertionFailures)) {
        /* If the value of this attribute is itself a set,
           should we recurse into it?  => Only if it has a
           `recurseForDerivations = true' attribute. */
        if (i->value->type == tAttrs) {
          Bindings::iterator j = i->value->attrs->find(
              state.symbols.create("recurseForDerivations"));
          if (j != i->value->attrs->end() &&
              state.forceBool(*j->value, *j->pos))
            getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done,
                           ignoreAssertionFailures);
        }
      }
    }
  }

  else if (v.isList()) {
    for (unsigned int n = 0; n < v.listSize(); ++n) {
      string pathPrefix2 = addToPath(pathPrefix, (format("%1%") % n).str());
      if (getDerivation(state, *v.listElems()[n], pathPrefix2, drvs, done,
                        ignoreAssertionFailures))
        getDerivations(state, *v.listElems()[n], pathPrefix2, autoArgs, drvs,
                       done, ignoreAssertionFailures);
    }
  }

  else
    throw TypeError(
        "expression does not evaluate to a derivation (or a set or list of "
        "those)");
}

void getDerivations(EvalState& state, Value& v, const string& pathPrefix,
                    Bindings& autoArgs, DrvInfos& drvs,
                    bool ignoreAssertionFailures) {
  Done done;
  getDerivations(state, v, pathPrefix, autoArgs, drvs, done,
                 ignoreAssertionFailures);
}

}  // namespace nix