forked from lix-project/lix
44bea52ae3
Per the old FIXME, this flag was on too many commands, and mostly ignored. Now it is just on the commands where it actually has an effect. Per https://github.com/NixOS/nix/issues/7261, I would still like to get rid of it entirely, but that is a separate project. This change should be good with or without doing that.
308 lines
10 KiB
C++
308 lines
10 KiB
C++
#include "command.hh"
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#include "store-api.hh"
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#include "progress-bar.hh"
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#include "fs-accessor.hh"
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#include "shared.hh"
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#include <queue>
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using namespace nix;
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static std::string hilite(const std::string & s, size_t pos, size_t len,
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const std::string & colour = ANSI_RED)
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{
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return
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std::string(s, 0, pos)
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+ colour
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+ std::string(s, pos, len)
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+ ANSI_NORMAL
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+ std::string(s, pos + len);
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}
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static std::string filterPrintable(const std::string & s)
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{
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std::string res;
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for (char c : s)
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res += isprint(c) ? c : '.';
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return res;
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}
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struct CmdWhyDepends : SourceExprCommand, MixOperateOnOptions
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{
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std::string _package, _dependency;
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bool all = false;
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bool precise = false;
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CmdWhyDepends()
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{
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expectArgs({
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.label = "package",
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.handler = {&_package},
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.completer = {[&](size_t, std::string_view prefix) {
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completeInstallable(prefix);
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}}
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});
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expectArgs({
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.label = "dependency",
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.handler = {&_dependency},
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.completer = {[&](size_t, std::string_view prefix) {
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completeInstallable(prefix);
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}}
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});
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addFlag({
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.longName = "all",
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.shortName = 'a',
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.description = "Show all edges in the dependency graph leading from *package* to *dependency*, rather than just a shortest path.",
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.handler = {&all, true},
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});
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addFlag({
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.longName = "precise",
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.description = "For each edge in the dependency graph, show the files in the parent that cause the dependency.",
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.handler = {&precise, true},
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});
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}
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std::string description() override
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{
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return "show why a package has another package in its closure";
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}
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std::string doc() override
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{
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return
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#include "why-depends.md"
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;
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}
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Category category() override { return catSecondary; }
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void run(ref<Store> store) override
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{
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auto package = parseInstallable(store, _package);
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auto packagePath = Installable::toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, package);
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/* We don't need to build `dependency`. We try to get the store
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* path if it's already known, and if not, then it's not a dependency.
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*
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* Why? If `package` does depends on `dependency`, then getting the
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* store path of `package` above necessitated having the store path
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* of `dependency`. The contrapositive is, if the store path of
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* `dependency` is not already known at this point (i.e. it's a CA
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* derivation which hasn't been built), then `package` did not need it
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* to build.
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*/
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auto dependency = parseInstallable(store, _dependency);
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auto optDependencyPath = [&]() -> std::optional<StorePath> {
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try {
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return {Installable::toStorePath(getEvalStore(), store, Realise::Derivation, operateOn, dependency)};
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} catch (MissingRealisation &) {
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return std::nullopt;
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}
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}();
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StorePathSet closure;
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store->computeFSClosure({packagePath}, closure, false, false);
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if (!optDependencyPath.has_value() || !closure.count(*optDependencyPath)) {
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printError("'%s' does not depend on '%s'", package->what(), dependency->what());
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return;
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}
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auto dependencyPath = *optDependencyPath;
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auto dependencyPathHash = dependencyPath.hashPart();
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stopProgressBar(); // FIXME
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auto accessor = store->getFSAccessor();
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auto const inf = std::numeric_limits<size_t>::max();
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struct Node
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{
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StorePath path;
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StorePathSet refs;
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StorePathSet rrefs;
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size_t dist = inf;
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Node * prev = nullptr;
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bool queued = false;
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bool visited = false;
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};
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std::map<StorePath, Node> graph;
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for (auto & path : closure)
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graph.emplace(path, Node {
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.path = path,
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.refs = store->queryPathInfo(path)->references,
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.dist = path == dependencyPath ? 0 : inf
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});
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// Transpose the graph.
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for (auto & node : graph)
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for (auto & ref : node.second.refs)
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graph.find(ref)->second.rrefs.insert(node.first);
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/* Run Dijkstra's shortest path algorithm to get the distance
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of every path in the closure to 'dependency'. */
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std::priority_queue<Node *> queue;
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queue.push(&graph.at(dependencyPath));
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while (!queue.empty()) {
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auto & node = *queue.top();
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queue.pop();
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for (auto & rref : node.rrefs) {
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auto & node2 = graph.at(rref);
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auto dist = node.dist + 1;
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if (dist < node2.dist) {
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node2.dist = dist;
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node2.prev = &node;
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if (!node2.queued) {
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node2.queued = true;
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queue.push(&node2);
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}
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}
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}
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}
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/* Print the subgraph of nodes that have 'dependency' in their
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closure (i.e., that have a non-infinite distance to
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'dependency'). Print every edge on a path between `package`
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and `dependency`. */
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std::function<void(Node &, const std::string &, const std::string &)> printNode;
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struct BailOut { };
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printNode = [&](Node & node, const std::string & firstPad, const std::string & tailPad) {
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auto pathS = store->printStorePath(node.path);
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assert(node.dist != inf);
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if (precise) {
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logger->cout("%s%s%s%s" ANSI_NORMAL,
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firstPad,
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node.visited ? "\e[38;5;244m" : "",
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firstPad != "" ? "→ " : "",
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pathS);
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}
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if (node.path == dependencyPath && !all
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&& packagePath != dependencyPath)
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throw BailOut();
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if (node.visited) return;
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if (precise) node.visited = true;
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/* Sort the references by distance to `dependency` to
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ensure that the shortest path is printed first. */
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std::multimap<size_t, Node *> refs;
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std::set<std::string> hashes;
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for (auto & ref : node.refs) {
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if (ref == node.path && packagePath != dependencyPath) continue;
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auto & node2 = graph.at(ref);
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if (node2.dist == inf) continue;
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refs.emplace(node2.dist, &node2);
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hashes.insert(std::string(node2.path.hashPart()));
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}
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/* For each reference, find the files and symlinks that
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contain the reference. */
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std::map<std::string, Strings> hits;
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std::function<void(const Path &)> visitPath;
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visitPath = [&](const Path & p) {
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auto st = accessor->stat(p);
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auto p2 = p == pathS ? "/" : std::string(p, pathS.size() + 1);
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auto getColour = [&](const std::string & hash) {
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return hash == dependencyPathHash ? ANSI_GREEN : ANSI_BLUE;
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};
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if (st.type == FSAccessor::Type::tDirectory) {
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auto names = accessor->readDirectory(p);
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for (auto & name : names)
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visitPath(p + "/" + name);
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}
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else if (st.type == FSAccessor::Type::tRegular) {
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auto contents = accessor->readFile(p);
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for (auto & hash : hashes) {
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auto pos = contents.find(hash);
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if (pos != std::string::npos) {
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size_t margin = 32;
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auto pos2 = pos >= margin ? pos - margin : 0;
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hits[hash].emplace_back(fmt("%s: …%s…\n",
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p2,
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hilite(filterPrintable(
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std::string(contents, pos2, pos - pos2 + hash.size() + margin)),
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pos - pos2, StorePath::HashLen,
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getColour(hash))));
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}
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}
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}
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else if (st.type == FSAccessor::Type::tSymlink) {
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auto target = accessor->readLink(p);
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for (auto & hash : hashes) {
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auto pos = target.find(hash);
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if (pos != std::string::npos)
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hits[hash].emplace_back(fmt("%s -> %s\n", p2,
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hilite(target, pos, StorePath::HashLen, getColour(hash))));
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}
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}
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};
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// FIXME: should use scanForReferences().
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if (precise) visitPath(pathS);
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for (auto & ref : refs) {
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std::string hash(ref.second->path.hashPart());
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bool last = all ? ref == *refs.rbegin() : true;
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for (auto & hit : hits[hash]) {
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bool first = hit == *hits[hash].begin();
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std::cout << tailPad
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<< (first ? (last ? treeLast : treeConn) : (last ? treeNull : treeLine))
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<< hit;
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if (!all) break;
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}
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if (!precise) {
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auto pathS = store->printStorePath(ref.second->path);
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logger->cout("%s%s%s%s" ANSI_NORMAL,
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firstPad,
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ref.second->visited ? "\e[38;5;244m" : "",
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last ? treeLast : treeConn,
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pathS);
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node.visited = true;
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}
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printNode(*ref.second,
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tailPad + (last ? treeNull : treeLine),
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tailPad + (last ? treeNull : treeLine));
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}
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};
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RunPager pager;
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try {
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if (!precise) {
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logger->cout("%s", store->printStorePath(graph.at(packagePath).path));
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}
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printNode(graph.at(packagePath), "", "");
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} catch (BailOut & ) { }
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}
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};
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static auto rCmdWhyDepends = registerCommand<CmdWhyDepends>("why-depends");
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