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PosixSourceAccessor: Don't follow any symlinks

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All path components must not be symlinks now (so the user needs to
call `resolveSymlinks()` when needed).
This commit is contained in:
Eelco Dolstra 2023-12-05 23:02:59 +01:00
parent 345f79d016
commit 83c067c0fa
7 changed files with 58 additions and 30 deletions
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11
src/libexpr/parser.y
View file

@ -692,16 +692,17 @@ SourcePath resolveExprPath(SourcePath path)
/* If `path' is a symlink, follow it. This is so that relative
path references work. */
while (true) {
while (!path.path.isRoot()) {
// Basic cycle/depth limit to avoid infinite loops.
if (++followCount >= maxFollow)
throw Error("too many symbolic links encountered while traversing the path '%s'", path);
if (path.lstat().type != InputAccessor::tSymlink) break;
path = {path.accessor, CanonPath(path.readLink(), path.path.parent().value_or(CanonPath::root))};
auto p = path.parent().resolveSymlinks() + path.baseName();
if (p.lstat().type != InputAccessor::tSymlink) break;
path = {path.accessor, CanonPath(p.readLink(), path.path.parent().value_or(CanonPath::root))};
}
/* If `path' refers to a directory, append `/default.nix'. */
if (path.lstat().type == InputAccessor::tDirectory)
if (path.resolveSymlinks().lstat().type == InputAccessor::tDirectory)
return path + "default.nix";
return path;
@ -716,7 +717,7 @@ Expr * EvalState::parseExprFromFile(const SourcePath & path)
Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
{
auto buffer = path.readFile();
auto buffer = path.resolveSymlinks().readFile();
// readFile hopefully have left some extra space for terminators
buffer.append("\0\0", 2);
return parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);

30
src/libexpr/primops.cc
View file

@ -110,7 +110,7 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
return res;
}
static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v)
static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v, bool resolveSymlinks = true)
{
NixStringContext context;
@ -120,9 +120,9 @@ static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v)
if (!context.empty() && path.accessor == state.rootFS) {
auto rewrites = state.realiseContext(context);
auto realPath = state.toRealPath(rewriteStrings(path.path.abs(), rewrites), context);
return {path.accessor, CanonPath(realPath)};
} else
return path;
path = {path.accessor, CanonPath(realPath)};
}
return resolveSymlinks ? path.resolveSymlinks() : path;
} catch (Error & e) {
e.addTrace(state.positions[pos], "while realising the context of path '%s'", path);
throw;
@ -162,7 +162,7 @@ static void mkOutputString(
argument. */
static void import(EvalState & state, const PosIdx pos, Value & vPath, Value * vScope, Value & v)
{
auto path = realisePath(state, pos, vPath);
auto path = realisePath(state, pos, vPath, false);
auto path2 = path.path.abs();
// FIXME
@ -1525,16 +1525,16 @@ static RegisterPrimOp primop_storePath({
static void prim_pathExists(EvalState & state, const PosIdx pos, Value * * args, Value & v)
{
auto & arg = *args[0];
auto path = realisePath(state, pos, arg);
/* SourcePath doesn't know about trailing slash. */
auto mustBeDir = arg.type() == nString
&& (arg.string_view().ends_with("/")
|| arg.string_view().ends_with("/."));
try {
auto & arg = *args[0];
auto path = realisePath(state, pos, arg);
/* SourcePath doesn't know about trailing slash. */
auto mustBeDir = arg.type() == nString
&& (arg.string_view().ends_with("/")
|| arg.string_view().ends_with("/."));
auto st = path.maybeLstat();
auto exists = st && (!mustBeDir || st->type == SourceAccessor::tDirectory);
v.mkBool(exists);
@ -1771,7 +1771,7 @@ static std::string_view fileTypeToString(InputAccessor::Type type)
static void prim_readFileType(EvalState & state, const PosIdx pos, Value * * args, Value & v)
{
auto path = realisePath(state, pos, *args[0]);
auto path = realisePath(state, pos, *args[0], false);
/* Retrieve the directory entry type and stringize it. */
v.mkString(fileTypeToString(path.lstat().type));
}