#include "command.hh"
#include "store-api.hh"
#include "progress-bar.hh"
#include "fs-accessor.hh"
#include "shared.hh"
#include <queue>
using namespace nix;
static std::string hilite(const std::string & s, size_t pos, size_t len,
const std::string & colour = ANSI_RED)
{
return
std::string(s, 0, pos)
+ colour
+ std::string(s, pos, len)
+ ANSI_NORMAL
+ std::string(s, pos + len);
}
static std::string filterPrintable(const std::string & s)
{
std::string res;
for (char c : s)
res += isprint(c) ? c : '.';
return res;
}
struct CmdWhyDepends : SourceExprCommand
{
std::string _package, _dependency;
bool all = false;
CmdWhyDepends()
{
expectArg("package", &_package);
expectArg("dependency", &_dependency);
mkFlag()
.longName("all")
.shortName('a')
.description("show all edges in the dependency graph leading from 'package' to 'dependency', rather than just a shortest path")
.set(&all, true);
}
std::string name() override
{
return "why-depends";
}
std::string description() override
{
return "show why a package has another package in its closure";
}
Examples examples() override
{
return {
Example{
"To show one path through the dependency graph leading from Hello to Glibc:",
"nix why-depends nixpkgs.hello nixpkgs.glibc"
},
Example{
"To show all files and paths in the dependency graph leading from Thunderbird to libX11:",
"nix why-depends --all nixpkgs.thunderbird nixpkgs.xorg.libX11"
},
Example{
"To show why Glibc depends on itself:",
"nix why-depends nixpkgs.glibc nixpkgs.glibc"
},
};
}
void run(ref<Store> store) override
{
auto package = parseInstallable(*this, store, _package, false);
auto packagePath = toStorePath(store, Build, package);
auto dependency = parseInstallable(*this, store, _dependency, false);
auto dependencyPath = toStorePath(store, NoBuild, dependency);
auto dependencyPathHash = storePathToHash(dependencyPath);
PathSet closure;
store->computeFSClosure({packagePath}, closure, false, false);
if (!closure.count(dependencyPath)) {
printError("'%s' does not depend on '%s'", package->what(), dependency->what());
return;
}
stopProgressBar(); // FIXME
auto accessor = store->getFSAccessor();
auto const inf = std::numeric_limits<size_t>::max();
struct Node
{
Path path;
PathSet refs;
PathSet rrefs;
size_t dist = inf;
Node * prev = nullptr;
bool queued = false;
bool visited = false;
};
std::map<Path, Node> graph;
for (auto & path : closure)
graph.emplace(path, Node{path, store->queryPathInfo(path)->references});
// Transpose the graph.
for (auto & node : graph)
for (auto & ref : node.second.refs)
graph[ref].rrefs.insert(node.first);
/* Run Dijkstra's shortest path algorithm to get the distance
of every path in the closure to 'dependency'. */
graph[dependencyPath].dist = 0;
std::priority_queue<Node *> queue;
queue.push(&graph.at(dependencyPath));
while (!queue.empty()) {
auto & node = *queue.top();
queue.pop();
for (auto & rref : node.rrefs) {
auto & node2 = graph.at(rref);
auto dist = node.dist + 1;
if (dist < node2.dist) {
node2.dist = dist;
node2.prev = &node;
if (!node2.queued) {
node2.queued = true;
queue.push(&node2);
}
}
}
}
/* Print the subgraph of nodes that have 'dependency' in their
closure (i.e., that have a non-infinite distance to
'dependency'). Print every edge on a path between `package`
and `dependency`. */
std::function<void(Node &, const string &, const string &)> printNode;
const string treeConn = "╠═══";
const string treeLast = "╚═══";
const string treeLine = "║ ";
const string treeNull = " ";
struct BailOut { };
printNode = [&](Node & node, const string & firstPad, const string & tailPad) {
assert(node.dist != inf);
std::cout << fmt("%s%s%s%s" ANSI_NORMAL "\n",
firstPad,
node.visited ? "\e[38;5;244m" : "",
firstPad != "" ? "=> " : "",
node.path);
if (node.path == dependencyPath && !all
&& packagePath != dependencyPath)
throw BailOut();
if (node.visited) return;
node.visited = true;
/* Sort the references by distance to `dependency` to
ensure that the shortest path is printed first. */
std::multimap<size_t, Node *> refs;
std::set<std::string> hashes;
for (auto & ref : node.refs) {
if (ref == node.path && packagePath != dependencyPath) continue;
auto & node2 = graph.at(ref);
if (node2.dist == inf) continue;
refs.emplace(node2.dist, &node2);
hashes.insert(storePathToHash(node2.path));
}
/* For each reference, find the files and symlinks that
contain the reference. */
std::map<std::string, Strings> hits;
std::function<void(const Path &)> visitPath;
visitPath = [&](const Path & p) {
auto st = accessor->stat(p);
auto p2 = p == node.path ? "/" : std::string(p, node.path.size() + 1);
auto getColour = [&](const std::string & hash) {
return hash == dependencyPathHash ? ANSI_GREEN : ANSI_BLUE;
};
if (st.type == FSAccessor::Type::tDirectory) {
auto names = accessor->readDirectory(p);
for (auto & name : names)
visitPath(p + "/" + name);
}
else if (st.type == FSAccessor::Type::tRegular) {
auto contents = accessor->readFile(p);
for (auto & hash : hashes) {
auto pos = contents.find(hash);
if (pos != std::string::npos) {
size_t margin = 32;
auto pos2 = pos >= margin ? pos - margin : 0;
hits[hash].emplace_back(fmt("%s: …%s…\n",
p2,
hilite(filterPrintable(
std::string(contents, pos2, pos - pos2 + hash.size() + margin)),
pos - pos2, storePathHashLen,
getColour(hash))));
}
}
}
else if (st.type == FSAccessor::Type::tSymlink) {
auto target = accessor->readLink(p);
for (auto & hash : hashes) {
auto pos = target.find(hash);
if (pos != std::string::npos)
hits[hash].emplace_back(fmt("%s -> %s\n", p2,
hilite(target, pos, storePathHashLen, getColour(hash))));
}
}
};
// FIXME: should use scanForReferences().
visitPath(node.path);
RunPager pager;
for (auto & ref : refs) {
auto hash = storePathToHash(ref.second->path);
bool last = all ? ref == *refs.rbegin() : true;
for (auto & hit : hits[hash]) {
bool first = hit == *hits[hash].begin();
std::cout << tailPad
<< (first ? (last ? treeLast : treeConn) : (last ? treeNull : treeLine))
<< hit;
if (!all) break;
}
printNode(*ref.second,
tailPad + (last ? treeNull : treeLine),
tailPad + (last ? treeNull : treeLine));
}
};
try {
printNode(graph.at(packagePath), "", "");
} catch (BailOut & ) { }
}
};
static RegisterCommand r1(make_ref<CmdWhyDepends>());
