forked from lix-project/lix
Add CanonPath wrapper to represent canonicalized paths
This commit is contained in:
Eelco Dolstra
parent
e408af82ab
commit
900b854084
103
src/libutil/canon-path.cc
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103
src/libutil/canon-path.cc
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#include "canon-path.hh"
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#include "util.hh"
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namespace nix {
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CanonPath CanonPath::root = CanonPath("/");
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CanonPath::CanonPath(std::string_view raw)
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: path(absPath((Path) raw, "/"))
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{ }
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CanonPath::CanonPath(std::string_view raw, const CanonPath & root)
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: path(absPath((Path) raw, root.abs()))
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{ }
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std::optional<CanonPath> CanonPath::parent() const
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{
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if (isRoot()) return std::nullopt;
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return CanonPath(unchecked_t(), path.substr(0, std::max((size_t) 1, path.rfind('/'))));
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}
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void CanonPath::pop()
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{
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assert(!isRoot());
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path.resize(std::max((size_t) 1, path.rfind('/')));
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}
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bool CanonPath::isWithin(const CanonPath & parent) const
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{
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return !(
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path.size() < parent.path.size()
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|| path.substr(0, parent.path.size()) != parent.path
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|| (parent.path.size() > 1 && path.size() > parent.path.size()
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&& path[parent.path.size()] != '/'));
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}
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CanonPath CanonPath::removePrefix(const CanonPath & prefix) const
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{
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assert(isWithin(prefix));
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if (prefix.isRoot()) return *this;
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if (path.size() == prefix.path.size()) return root;
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return CanonPath(unchecked_t(), path.substr(prefix.path.size()));
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}
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void CanonPath::extend(const CanonPath & x)
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{
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if (x.isRoot()) return;
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if (isRoot())
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path += x.rel();
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else
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path += x.abs();
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}
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CanonPath CanonPath::operator + (const CanonPath & x) const
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{
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auto res = *this;
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res.extend(x);
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return res;
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}
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void CanonPath::push(std::string_view c)
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{
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assert(c.find('/') == c.npos);
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assert(c != "." && c != "..");
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if (!isRoot()) path += '/';
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path += c;
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}
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CanonPath CanonPath::operator + (std::string_view c) const
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{
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auto res = *this;
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res.push(c);
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return res;
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}
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bool CanonPath::isAllowed(const std::set<CanonPath> & allowed) const
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{
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/* Check if `this` is an exact match or the parent of an
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allowed path. */
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auto lb = allowed.lower_bound(*this);
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if (lb != allowed.end()) {
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if (lb->isWithin(*this))
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return true;
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}
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/* Check if a parent of `this` is allowed. */
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auto path = *this;
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while (!path.isRoot()) {
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path.pop();
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if (allowed.count(path))
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return true;
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}
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return false;
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}
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std::ostream & operator << (std::ostream & stream, const CanonPath & path)
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{
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stream << path.abs();
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return stream;
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}
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}
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173
src/libutil/canon-path.hh
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173
src/libutil/canon-path.hh
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#pragma once
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#include <string>
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#include <optional>
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#include <cassert>
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#include <iostream>
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#include <set>
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namespace nix {
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/* A canonical representation of a path. It ensures the following:
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- It always starts with a slash.
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- It never ends with a slash, except if the path is "/".
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- A slash is never followed by a slash (i.e. no empty components).
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- There are no components equal to '.' or '..'.
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Note that the path does not need to correspond to an actually
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existing path, and there is no guarantee that symlinks are
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resolved.
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*/
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class CanonPath
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{
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std::string path;
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public:
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/* Construct a canon path from a non-canonical path. Any '.', '..'
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or empty components are removed. */
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CanonPath(std::string_view raw);
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explicit CanonPath(const char * raw)
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: CanonPath(std::string_view(raw))
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{ }
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struct unchecked_t { };
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CanonPath(unchecked_t _, std::string path)
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: path(std::move(path))
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{ }
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static CanonPath root;
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/* If `raw` starts with a slash, return
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`CanonPath(raw)`. Otherwise return a `CanonPath` representing
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`root + "/" + raw`. */
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CanonPath(std::string_view raw, const CanonPath & root);
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bool isRoot() const
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{ return path.size() <= 1; }
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explicit operator std::string_view() const
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{ return path; }
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const std::string & abs() const
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{ return path; }
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/* Like abs(), but return an empty string if this path is
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'/'. Thus the returned string never ends in a slash. */
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const std::string & absOrEmpty() const
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{
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const static std::string epsilon;
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return isRoot() ? epsilon : path;
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}
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const char * c_str() const
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{ return path.c_str(); }
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std::string_view rel() const
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{ return ((std::string_view) path).substr(1); }
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struct Iterator
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{
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std::string_view remaining;
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size_t slash;
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Iterator(std::string_view remaining)
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: remaining(remaining)
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, slash(remaining.find('/'))
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{ }
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bool operator != (const Iterator & x) const
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{ return remaining.data() != x.remaining.data(); }
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const std::string_view operator * () const
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{ return remaining.substr(0, slash); }
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void operator ++ ()
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{
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if (slash == remaining.npos)
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remaining = remaining.substr(remaining.size());
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else {
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remaining = remaining.substr(slash + 1);
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slash = remaining.find('/');
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}
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}
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};
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Iterator begin() const { return Iterator(rel()); }
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Iterator end() const { return Iterator(rel().substr(path.size() - 1)); }
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std::optional<CanonPath> parent() const;
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/* Remove the last component. Panics if this path is the root. */
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void pop();
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std::optional<std::string_view> dirOf() const
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{
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if (isRoot()) return std::nullopt;
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return path.substr(0, path.rfind('/'));
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}
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std::optional<std::string_view> baseName() const
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{
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if (isRoot()) return std::nullopt;
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return ((std::string_view) path).substr(path.rfind('/') + 1);
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}
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bool operator == (const CanonPath & x) const
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{ return path == x.path; }
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bool operator != (const CanonPath & x) const
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{ return path != x.path; }
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/* Compare paths lexicographically except that path separators
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are sorted before any other character. That is, in the sorted order
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a directory is always followed directly by its children. For
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instance, 'foo' < 'foo/bar' < 'foo!'. */
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bool operator < (const CanonPath & x) const
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{
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auto i = path.begin();
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auto j = x.path.begin();
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for ( ; i != path.end() && j != x.path.end(); ++i, ++j) {
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auto c_i = *i;
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if (c_i == '/') c_i = 0;
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auto c_j = *j;
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if (c_j == '/') c_j = 0;
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if (c_i < c_j) return true;
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if (c_i > c_j) return false;
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}
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return i == path.end() && j != x.path.end();
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}
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/* Return true if `this` is equal to `parent` or a child of
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`parent`. */
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bool isWithin(const CanonPath & parent) const;
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CanonPath removePrefix(const CanonPath & prefix) const;
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/* Append another path to this one. */
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void extend(const CanonPath & x);
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/* Concatenate two paths. */
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CanonPath operator + (const CanonPath & x) const;
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/* Add a path component to this one. It must not contain any slashes. */
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void push(std::string_view c);
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CanonPath operator + (std::string_view c) const;
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/* Check whether access to this path is allowed, which is the case
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if 1) `this` is within any of the `allowed` paths; or 2) any of
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the `allowed` paths are within `this`. (The latter condition
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ensures access to the parents of allowed paths.) */
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bool isAllowed(const std::set<CanonPath> & allowed) const;
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};
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std::ostream & operator << (std::ostream & stream, const CanonPath & path);
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}
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155
src/libutil/tests/canon-path.cc
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155
src/libutil/tests/canon-path.cc
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@ -0,0 +1,155 @@
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#include "canon-path.hh"
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#include <gtest/gtest.h>
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namespace nix {
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TEST(CanonPath, basic) {
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{
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CanonPath p("/");
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ASSERT_EQ(p.abs(), "/");
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ASSERT_EQ(p.rel(), "");
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ASSERT_EQ(p.baseName(), std::nullopt);
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ASSERT_EQ(p.dirOf(), std::nullopt);
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ASSERT_FALSE(p.parent());
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}
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{
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CanonPath p("/foo//");
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ASSERT_EQ(p.abs(), "/foo");
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ASSERT_EQ(p.rel(), "foo");
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ASSERT_EQ(*p.baseName(), "foo");
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ASSERT_EQ(*p.dirOf(), ""); // FIXME: do we want this?
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ASSERT_EQ(p.parent()->abs(), "/");
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}
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{
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CanonPath p("foo/bar");
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ASSERT_EQ(p.abs(), "/foo/bar");
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ASSERT_EQ(p.rel(), "foo/bar");
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ASSERT_EQ(*p.baseName(), "bar");
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ASSERT_EQ(*p.dirOf(), "/foo");
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ASSERT_EQ(p.parent()->abs(), "/foo");
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}
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{
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CanonPath p("foo//bar/");
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ASSERT_EQ(p.abs(), "/foo/bar");
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ASSERT_EQ(p.rel(), "foo/bar");
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ASSERT_EQ(*p.baseName(), "bar");
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ASSERT_EQ(*p.dirOf(), "/foo");
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}
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}
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TEST(CanonPath, pop) {
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CanonPath p("foo/bar/x");
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ASSERT_EQ(p.abs(), "/foo/bar/x");
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p.pop();
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ASSERT_EQ(p.abs(), "/foo/bar");
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p.pop();
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ASSERT_EQ(p.abs(), "/foo");
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p.pop();
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ASSERT_EQ(p.abs(), "/");
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}
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TEST(CanonPath, removePrefix) {
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CanonPath p1("foo/bar");
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CanonPath p2("foo/bar/a/b/c");
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ASSERT_EQ(p2.removePrefix(p1).abs(), "/a/b/c");
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ASSERT_EQ(p1.removePrefix(p1).abs(), "/");
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ASSERT_EQ(p1.removePrefix(CanonPath("/")).abs(), "/foo/bar");
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}
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TEST(CanonPath, iter) {
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{
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CanonPath p("a//foo/bar//");
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std::vector<std::string_view> ss;
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for (auto & c : p) ss.push_back(c);
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ASSERT_EQ(ss, std::vector<std::string_view>({"a", "foo", "bar"}));
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}
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{
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CanonPath p("/");
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std::vector<std::string_view> ss;
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for (auto & c : p) ss.push_back(c);
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ASSERT_EQ(ss, std::vector<std::string_view>());
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}
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}
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TEST(CanonPath, concat) {
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{
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CanonPath p1("a//foo/bar//");
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CanonPath p2("xyzzy/bla");
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ASSERT_EQ((p1 + p2).abs(), "/a/foo/bar/xyzzy/bla");
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}
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{
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CanonPath p1("/");
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CanonPath p2("/a/b");
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ASSERT_EQ((p1 + p2).abs(), "/a/b");
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}
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{
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CanonPath p1("/a/b");
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CanonPath p2("/");
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ASSERT_EQ((p1 + p2).abs(), "/a/b");
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}
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{
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CanonPath p("/foo/bar");
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ASSERT_EQ((p + "x").abs(), "/foo/bar/x");
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}
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{
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CanonPath p("/");
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ASSERT_EQ((p + "foo" + "bar").abs(), "/foo/bar");
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}
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}
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TEST(CanonPath, within) {
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{
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ASSERT_TRUE(CanonPath("foo").isWithin(CanonPath("foo")));
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ASSERT_FALSE(CanonPath("foo").isWithin(CanonPath("bar")));
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ASSERT_FALSE(CanonPath("foo").isWithin(CanonPath("fo")));
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ASSERT_TRUE(CanonPath("foo/bar").isWithin(CanonPath("foo")));
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ASSERT_FALSE(CanonPath("foo").isWithin(CanonPath("foo/bar")));
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ASSERT_TRUE(CanonPath("/foo/bar/default.nix").isWithin(CanonPath("/")));
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ASSERT_TRUE(CanonPath("/").isWithin(CanonPath("/")));
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}
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}
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TEST(CanonPath, sort) {
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ASSERT_FALSE(CanonPath("foo") < CanonPath("foo"));
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ASSERT_TRUE (CanonPath("foo") < CanonPath("foo/bar"));
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ASSERT_TRUE (CanonPath("foo/bar") < CanonPath("foo!"));
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ASSERT_FALSE(CanonPath("foo!") < CanonPath("foo"));
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ASSERT_TRUE (CanonPath("foo") < CanonPath("foo!"));
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}
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TEST(CanonPath, allowed) {
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{
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std::set<CanonPath> allowed {
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CanonPath("foo/bar"),
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CanonPath("foo!"),
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CanonPath("xyzzy"),
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CanonPath("a/b/c"),
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};
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ASSERT_TRUE (CanonPath("foo/bar").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("foo/bar/bla").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("foo").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("bar").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("bar/a").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("a").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("a/b").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("a/b/c").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("a/b/c/d").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("a/b/c/d/e").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("a/b/a").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("a/b/d").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("aaa").isAllowed(allowed));
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ASSERT_FALSE(CanonPath("zzz").isAllowed(allowed));
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ASSERT_TRUE (CanonPath("/").isAllowed(allowed));
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}
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}
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}
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