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Merge pull request #9985 from alois31/symlink-resolution

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Restore `builtins.pathExists` behavior on broken symlinks
This commit is contained in:
John Ericson 2024-02-16 09:24:03 -05:00 • committed by GitHub
commit d53c8901ef
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5 changed files with 53 additions and 19 deletions
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22
src/libutil/source-path.cc
View file

@ -62,7 +62,7 @@ bool SourcePath::operator<(const SourcePath & x) const
return std::tie(*accessor, path) < std::tie(*x.accessor, x.path);
}
SourcePath SourcePath::resolveSymlinks() const
SourcePath SourcePath::resolveSymlinks(SymlinkResolution mode) const
{
auto res = SourcePath(accessor);
@ -72,6 +72,8 @@ SourcePath SourcePath::resolveSymlinks() const
for (auto & c : path)
todo.push_back(std::string(c));
bool resolve_last = mode == SymlinkResolution::Full;
while (!todo.empty()) {
auto c = *todo.begin();
todo.pop_front();
@ -81,14 +83,16 @@ SourcePath SourcePath::resolveSymlinks() const
res.path.pop();
else {
res.path.push(c);
if (auto st = res.maybeLstat(); st && st->type == InputAccessor::tSymlink) {
if (!linksAllowed--)
throw Error("infinite symlink recursion in path '%s'", path);
auto target = res.readLink();
res.path.pop();
if (hasPrefix(target, "/"))
res.path = CanonPath::root;
todo.splice(todo.begin(), tokenizeString<std::list<std::string>>(target, "/"));
if (resolve_last || !todo.empty()) {
if (auto st = res.maybeLstat(); st && st->type == InputAccessor::tSymlink) {
if (!linksAllowed--)
throw Error("infinite symlink recursion in path '%s'", path);
auto target = res.readLink();
res.path.pop();
if (hasPrefix(target, "/"))
res.path = CanonPath::root;
todo.splice(todo.begin(), tokenizeString<std::list<std::string>>(target, "/"));
}
}
}
}

31
src/libutil/source-path.hh
View file

@ -11,6 +11,26 @@
namespace nix {
/**
* Note there is a decent chance this type soon goes away because the problem is solved another way.
* See the discussion in https://github.com/NixOS/nix/pull/9985.
*/
enum class SymlinkResolution {
/**
* Resolve symlinks in the ancestors only.
*
* Only the last component of the result is possibly a symlink.
*/
Ancestors,
/**
* Resolve symlinks fully, realpath(3)-style.
*
* No component of the result will be a symlink.
*/
Full,
};
/**
* An abstraction for accessing source files during
* evaluation. Currently, it's just a wrapper around `CanonPath` that
@ -103,11 +123,14 @@ struct SourcePath
bool operator<(const SourcePath & x) const;
/**
* Resolve any symlinks in this `SourcePath` (including its
* parents). The result is a `SourcePath` in which no element is a
* symlink.
* Resolve any symlinks in this `SourcePath` according to the
* given resolution mode.
*
* @param mode might only be a temporary solution for this.
* See the discussion in https://github.com/NixOS/nix/pull/9985.
*/
SourcePath resolveSymlinks() const;
SourcePath resolveSymlinks(
SymlinkResolution mode = SymlinkResolution::Full) const;
};
std::ostream & operator << (std::ostream & str, const SourcePath & path);