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

#include "libexpr/get-drvs.hh"

#include <cstring>
#include <regex>
#include <utility>

#include <absl/strings/numbers.h>
#include <glog/logging.h>

#include "libexpr/eval-inline.hh"
#include "libstore/derivations.hh"
#include "libutil/util.hh"

namespace nix {

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

DrvInfo::DrvInfo(EvalState& state, const ref<Store>& store,
                 const std::string& drvPathWithOutputs)
    : state(&state), 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;
}

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

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

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

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

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

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

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

  /* Check for `meta.outputsToInstall` and return `outputs` reduced to that. */
  const Value* outTI = queryMeta("outputsToInstall");
  if (outTI == nullptr) {
    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 (Value* i : *outTI->list) {
    if (i->type != tString) {
      throw errMsg;
    }
    auto out = outputs.find(i->string.s);
    if (out == outputs.end()) {
      throw errMsg;
    }
    result.insert(*out);
  }
  return result;
}

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

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

StringSet DrvInfo::queryMetaNames() {
  StringSet res;
  if (getMeta() == nullptr) {
    return res;
  }
  for (auto& i : *meta) {
    res.insert(i.second.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.list)[n])) {
        return false;
      }
    }
    return true;
  }
  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.second.value)) {
        return false;
      }
    }
    return true;
  } else {
    return v.type == tInt || v.type == tBool || v.type == tString ||
           v.type == tFloat;
  }
}

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

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

NixInt DrvInfo::queryMetaInt(const std::string& name, NixInt def) {
  Value* v = queryMeta(name);
  if (v == nullptr) {
    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 (absl::SimpleAtoi(v->string.s, &n)) {
      return n;
    }
  }
  return def;
}

NixFloat DrvInfo::queryMetaFloat(const std::string& name, NixFloat def) {
  Value* v = queryMeta(name);
  if (v == nullptr) {
    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 std::string& name, bool def) {
  Value* v = queryMeta(name);
  if (v == nullptr) {
    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 std::string& name, Value* v) {
  Bindings* old = getMeta();
  meta = Bindings::NewGC(old->size() + 1);
  Symbol sym = state->symbols.Create(name);
  if (old != nullptr) {
    for (auto i : *old) {
      if (i.second.name != sym) {
        meta->push_back(i.second);
      }
    }
  }
  if (v != nullptr) {
    meta->push_back(Attr(sym, v));
  }
}

/* Cache for already considered attrsets. */
using Done = std::set<Bindings*>;

/* 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 std::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 std::string addToPath(const std::string& s1, const std::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 std::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->SortedByKeys()) {
      DLOG(INFO) << "evaluating attribute '" << i->name << "'";
      if (!std::regex_match(std::string(i->name), attrRegex)) {
        continue;
      }
      std::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->second.value, *j->second.pos)) {
            getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done,
                           ignoreAssertionFailures);
          }
        }
      }
    }
  }

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

}  // namespace nix