Merge pull request ClickHouse#87479 from ClickHouse/backport/25.8/87181

Backport ClickHouse#87181 to 25.8: Make pathStartsWith only match paths under the prefix

Author: Algunenano

src/Common/filesystemHelpers.cpp

@@ -218,9 +218,8 @@ String getFilesystemName([[maybe_unused]] const String & mount_point)
 
 bool pathStartsWith(const std::filesystem::path & path, const std::filesystem::path & prefix_path)
 {
-    String absolute_path = std::filesystem::weakly_canonical(path);
-    String absolute_prefix_path = std::filesystem::weakly_canonical(prefix_path);
-    return absolute_path.starts_with(absolute_prefix_path);
+    auto rel = fs::relative(path, prefix_path);
+    return (!rel.empty() && (rel.native() == "." || rel.native()[0] != '.'));
 }
 
 static bool fileOrSymlinkPathStartsWith(const std::filesystem::path & path, const std::filesystem::path & prefix_path)
@@ -230,11 +229,8 @@ static bool fileOrSymlinkPathStartsWith(const std::filesystem::path & path, cons
     /// `.` and `..` and extra `/`. Path is not canonized because otherwise path will
     /// not be a path of a symlink itself.
 
-    String absolute_path = std::filesystem::absolute(path);
-    absolute_path = fs::path(absolute_path).lexically_normal(); /// Normalize path.
-    String absolute_prefix_path = std::filesystem::absolute(prefix_path);
-    absolute_prefix_path = fs::path(absolute_prefix_path).lexically_normal(); /// Normalize path.
-    return absolute_path.starts_with(absolute_prefix_path);
+    auto rel = fs::absolute(path).lexically_normal().lexically_relative(fs::absolute(prefix_path).lexically_normal());
+    return (!rel.empty() && (rel.native() == "." || rel.native()[0] != '.'));
 }
 
 bool pathStartsWith(const String & path, const String & prefix_path)

tests/queries/0_stateless/03624_proper_path_starts_with.reference

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+CUR_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CUR_DIR"/../shell_config.sh
+
+BAD_PATH_PARENT=$(echo "${USER_FILES_PATH}" | sed 's:/*$::')/../BAD
+# Remove the trailing slashes and add extra characters to the folder name
+BAD_PATH_EXTRA=$(echo "${USER_FILES_PATH}" | sed 's:/*$::')_BAD
+
+$CLICKHOUSE_CLIENT --query "CREATE TABLE t (a UInt64) ENGINE=File('CSV', '${BAD_PATH_PARENT}') -- { serverError DATABASE_ACCESS_DENIED }"
+$CLICKHOUSE_CLIENT --query "CREATE TABLE t (a UInt64) ENGINE=File('CSV', '${BAD_PATH_EXTRA}') -- { serverError DATABASE_ACCESS_DENIED }"