forked from lix-project/lix
Merge pull request #9985 from alois31/symlink-resolution
Restore `builtins.pathExists` behavior on broken symlinks
(cherry picked from commit d53c8901ef7f2033855dd99063522e3d56a19dab)
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note that this variant differs markedly from the source commit because
we haven't endured quite as much lazy trees.
Change-Id: I0facf282f21fe0db4134be5c65a8368c1b3a06fc
This commit is contained in:
parent
1342c8f18e
commit
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@ -1540,11 +1540,12 @@ static void prim_pathExists(EvalState & state, const PosIdx pos, Value * * args,
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|| arg.str().ends_with("/."));
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try {
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auto checked = state.checkSourcePath(path);
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auto exists = checked.pathExists();
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if (exists && mustBeDir) {
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exists = checked.lstat().type == InputAccessor::tDirectory;
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}
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auto checked = state
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.checkSourcePath(path)
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.resolveSymlinks(mustBeDir ? SymlinkResolution::Full : SymlinkResolution::Ancestors);
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auto st = checked.maybeLstat();
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auto exists = st && (!mustBeDir || st->type == InputAccessor::tDirectory);
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v.mkBool(exists);
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} catch (SysError & e) {
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/* Don't give away info from errors while canonicalising
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@ -56,7 +56,7 @@ InputAccessor::DirEntries SourcePath::readDirectory() const
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return res;
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}
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SourcePath SourcePath::resolveSymlinks() const
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SourcePath SourcePath::resolveSymlinks(SymlinkResolution mode) const
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{
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SourcePath res(CanonPath::root);
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@ -66,6 +66,8 @@ SourcePath SourcePath::resolveSymlinks() const
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for (auto & c : path)
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todo.push_back(std::string(c));
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bool resolve_last = mode == SymlinkResolution::Full;
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while (!todo.empty()) {
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auto c = *todo.begin();
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todo.pop_front();
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@ -75,14 +77,16 @@ SourcePath SourcePath::resolveSymlinks() const
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res.path.pop();
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else {
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res.path.push(c);
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if (auto st = res.maybeLstat(); st && st->type == InputAccessor::tSymlink) {
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if (!linksAllowed--)
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throw Error("infinite symlink recursion in path '%s'", path);
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auto target = res.readLink();
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res.path.pop();
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if (hasPrefix(target, "/"))
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res.path = CanonPath::root;
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todo.splice(todo.begin(), tokenizeString<std::list<std::string>>(target, "/"));
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if (resolve_last || !todo.empty()) {
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if (auto st = res.maybeLstat(); st && st->type == InputAccessor::tSymlink) {
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if (!linksAllowed--)
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throw Error("infinite symlink recursion in path '%s'", path);
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auto target = res.readLink();
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res.path.pop();
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if (hasPrefix(target, "/"))
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res.path = CanonPath::root;
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todo.splice(todo.begin(), tokenizeString<std::list<std::string>>(target, "/"));
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}
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}
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}
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}
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@ -12,6 +12,26 @@
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namespace nix {
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/**
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* Note there is a decent chance this type soon goes away because the problem is solved another way.
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* See the discussion in https://github.com/NixOS/nix/pull/9985.
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*/
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enum class SymlinkResolution {
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/**
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* Resolve symlinks in the ancestors only.
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*
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* Only the last component of the result is possibly a symlink.
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*/
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Ancestors,
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/**
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* Resolve symlinks fully, realpath(3)-style.
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*
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* No component of the result will be a symlink.
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*/
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Full,
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};
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/**
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* An abstraction for accessing source files during
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* evaluation. Currently, it's just a wrapper around `CanonPath` that
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@ -121,11 +141,14 @@ struct SourcePath
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}
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/**
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* Resolve any symlinks in this `SourcePath` (including its
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* parents). The result is a `SourcePath` in which no element is a
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* symlink.
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* Resolve any symlinks in this `SourcePath` according to the
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* given resolution mode.
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*
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* @param mode might only be a temporary solution for this.
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* See the discussion in https://github.com/NixOS/nix/pull/9985.
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*/
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SourcePath resolveSymlinks() const;
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SourcePath resolveSymlinks(
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SymlinkResolution mode = SymlinkResolution::Full) const;
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};
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std::ostream & operator << (std::ostream & str, const SourcePath & path);
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@ -27,3 +27,6 @@ builtins.pathExists (./lib.nix)
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&& !builtins.pathExists (builtins.toPath (builtins.toString ./bla.nix))
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&& builtins.pathExists ./lib.nix
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&& !builtins.pathExists ./bla.nix
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&& builtins.pathExists ./symlink-resolution/foo/overlays/overlay.nix
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&& builtins.pathExists ./symlink-resolution/broken
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&& builtins.pathExists (builtins.toString ./symlink-resolution/foo/overlays + "/.")
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1
tests/functional/lang/symlink-resolution/broken
Symbolic link
1
tests/functional/lang/symlink-resolution/broken
Symbolic link
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@ -0,0 +1 @@
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nonexistent
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