filesystem.h

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/*
  Copyright (c) 2015, 2024, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
  This program is designed to work with certain software (including
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  as designated in a particular file or component or in included license
  documentation.  The authors of MySQL hereby grant you an additional
  permission to link the program and your derivative works with the
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef MYSQL_HARNESS_FILESYSTEM_INCLUDED
#define MYSQL_HARNESS_FILESYSTEM_INCLUDED
 
#include "harness_export.h"
 
#include <memory>
#include <ostream>
#include <stdexcept>
#include <string>
#include <string_view>
#include <system_error>
#include <vector>
 
#ifndef _WIN32
#include <fcntl.h>
#endif
 
#include "mysql/harness/access_rights.h"
#include "mysql/harness/stdx/expected.h"
 
namespace mysql_harness {
 
/**
 * @defgroup Filesystem Platform-independent file system operations
 *
 * This module contain platform-independent file system operations.
 */
 
/**
 * Class representing a path in a file system.
 *
 * @ingroup Filesystem
 *
 * Paths are used to access files in the file system and can be either
 * relative or absolute. Absolute paths have a slash (`/`) first in
 * the path, otherwise, the path is relative.
 */
class HARNESS_EXPORT Path {
  friend std::ostream &operator<<(std::ostream &out, const Path &path) {
    out << path.path_;
    return out;
  }
 
 public:
  /**
   * Enum used to identify file types.
   */
 
  enum class FileType {
    /** An error occurred when trying to get file type, but it is *not*
     * that the file was not found. */
    STATUS_ERROR,
 
    /** Empty path was given */
    EMPTY_PATH,
 
    /** The file was not found. */
    FILE_NOT_FOUND,
 
    /** The file is a regular file. */
    REGULAR_FILE,
 
    /** The file is a directory. */
    DIRECTORY_FILE,
 
    /** The file is a symbolic link. */
    SYMLINK_FILE,
 
    /** The file is a block device */
    BLOCK_FILE,
 
    /** The file is a character device */
    CHARACTER_FILE,
 
    /** The file is a FIFO */
    FIFO_FILE,
 
    /** The file is a UNIX socket */
    SOCKET_FILE,
 
    /** The type of the file is unknown, either because it was not
     * fetched yet or because stat(2) reported something else than the
     * above. */
    TYPE_UNKNOWN,
  };
 
  friend HARNESS_EXPORT std::ostream &operator<<(std::ostream &out,
                                                 FileType type);
 
  Path() noexcept;
 
  /**
   * Construct a path
   *
   * @param path Non-empty string denoting the path.
   * @throws std::invalid_argument
   */
  Path(std::string path);
 
  Path(std::string_view path) : Path(std::string(path)) {}
  Path(const char *path) : Path(std::string(path)) {}
 
  /**
   * Create a path from directory, basename, and extension.
   */
  static Path make_path(const Path &directory, const std::string &basename,
                        const std::string &extension);
 
  bool operator==(const Path &rhs) const;
  bool operator!=(const Path &rhs) const { return !(*this == rhs); }
 
  /**
   * Path ordering operator.
   *
   * This is mainly used for ordered containers. The paths are ordered
   * lexicographically.
   */
  bool operator<(const Path &rhs) const;
 
  /**
   * Get the file type.
   *
   * The file type is normally cached so if the file type under a path
   * changes it is necessary to force a refresh.
   *
   * @param refresh Set to `true` if the file type should be
   * refreshed, default to `false`.
   *
   * @return The type of the file.
   */
  FileType type(bool refresh = false) const;
 
  /**
   * Check if the file is a directory.
   */
  bool is_directory() const;
 
  /**
   * Check if the file is a regular file.
   */
  bool is_regular() const;
 
  /**
   * Check if the path is absolute or not
   *
   * The path is considered absolute if it starts with one of:
   *   Unix:    '/'
   *   Windows: '/' or '\' or '.:' (where . is any character)
   * else:
   *   it's considered relative (empty path is also relative in such respect)
   */
  bool is_absolute() const;
 
  /**
   * Check if path exists
   */
  bool exists() const;
 
  /*
   * @brief Checks if path exists and can be opened for reading.
   *
   * @return true if path exists and can be opened for reading,
   *         false otherwise.
   */
  bool is_readable() const;
 
  /**
   * Get the directory name of the path.
   *
   * This will strip the last component of a path, assuming that the
   * what remains is a directory name. If the path is a relative path
   * that do not contain any directory separators, a dot will be
   * returned (denoting the current directory).
   *
   * @note No checking of the components are done, this is just simple
   * path manipulation.
   *
   * @return A new path object representing the directory portion of
   * the path.
   */
  Path dirname() const;
 
  /**
   * Get the basename of the path.
   *
   * Return the basename of the path: the path without the directory
   * portion.
   *
   * @note No checking of the components are done, this is just simple
   * path manipulation.
   *
   * @return A new path object representing the basename of the path.
   * the path.
   */
  Path basename() const;
 
  /**
   * Append a path component to the current path.
   *
   * This function will append a path component to the path using the
   * appropriate directory separator.
   *
   * @param other Path component to append to the path.
   */
  void append(const Path &other);
 
  /**
   * Join two path components to form a new path.
   *
   * This function will join the two path components using a
   * directory separator.
   *
   * @note This will return a new `Path` object. If you want to modify
   * the existing path object, you should use `append` instead.
   *
   * @param other Path component to be appended to the path
   */
  Path join(const Path &other) const;
 
  /**
   * Returns the canonical form of the path, resolving relative paths.
   */
  Path real_path() const;
 
  /**
   * Get a C-string representation to the path.
   *
   * @note This will return a pointer to the internal representation
   * of the path and hence will become a dangling pointer when the
   * `Path` object is destroyed.
   *
   * @return Pointer to a null-terminated C-string.
   */
  const char *c_str() const { return path_.c_str(); }
 
  /**
   * Get a string representation of the path.
   *
   * @return Instance of std::string containing the path.
   */
  const std::string &str() const noexcept { return path_; }
 
  /**
   * Test if path is set
   *
   * @return Test result
   */
  bool is_set() const noexcept { return (type_ != FileType::EMPTY_PATH); }
 
  /**
   * Directory separator string.
   *
   * @note This is platform-dependent and defined in the appropriate
   * source file.
   */
  static const char *const directory_separator;
 
  /**
   * Root directory string.
   *
   * @note This is platform-dependent and defined in the appropriate
   * source file.
   */
  static const char *const root_directory;
 
  operator bool() const noexcept { return is_set(); }
 
 private:
  void validate_non_empty_path() const;  // throws std::invalid_argument
 
  std::string path_;
  mutable FileType type_;
};
 
/**
 * Class representing a directory in a file system.
 *
 * @ingroup Filesystem
 *
 * In addition to being a refinement of `Path`, it also have functions
 * that make it act like a container of paths and support iterating
 * over the entries in a directory.
 *
 * An example of how it could be used is:
 * @code
 * for (auto&& entry: Directory(path))
 *   std::cout << entry << std::endl;
 * @endcode
 */
class HARNESS_EXPORT Directory : public Path {
 public:
  /**
   * Directory iterator for iterating over directory entries.
   *
   * A directory iterator is an input iterator.
   */
  class HARNESS_EXPORT DirectoryIterator {
    friend class Directory;
 
   public:
    using value_type = Path;
    using iterator_category = std::input_iterator_tag;
    using difference_type = std::ptrdiff_t;
    using pointer = value_type *;
    using reference = value_type &;
 
    DirectoryIterator(const Path &path,
                      const std::string &pattern = std::string());
 
    // Create an end iterator
    DirectoryIterator();
 
    /**
     * Destructor.
     *
     * @note We need this *declared* because the default constructor
     * try to generate a default constructor for shared_ptr on State
     * below, which does not work since it is not visible. The
     * destructor need to be *defined* in the corresponding .cc file
     * since the State type is visible there (but you can use a
     * default definition).
     */
    ~DirectoryIterator();
 
    // We need these since the default move/copy constructor is
    // deleted when you define a destructor.
#if !defined(_MSC_VER) || (_MSC_VER >= 1900)
    DirectoryIterator(DirectoryIterator &&);
    DirectoryIterator(const DirectoryIterator &);
#endif
 
    /** Standard iterator operators */
    /** @{ */
    Path operator*() const;
    DirectoryIterator &operator++();
    Path operator->() { return this->operator*(); }
    bool operator!=(const DirectoryIterator &other) const;
 
    // This avoids C2678 (no binary operator found) in MSVC,
    // MSVC's std::copy implementation (used by TestFilesystem) uses operator==
    // (while GCC's implementation uses operator!=).
    bool operator==(const DirectoryIterator &other) const {
      return !(this->operator!=(other));
    }
    /** @} */
 
   private:
    /**
     * Path to the root of the directory
     */
    const Path path_;
 
    /**
     * Pattern that matches entries iterated over.
     */
    std::string pattern_;
 
    /*
     * Platform-dependent container for iterator state.
     *
     * The definition of this class is different for different
     * platforms, meaning that it is not defined here at all but
     * rather in the corresponding `filesystem-<platform>.cc` file.
     *
     * The directory iterator is the most critical piece since it holds
     * an iteration state for the platform: something that requires
     * different types on the platforms.
     */
    class State;
    std::shared_ptr<State> state_;
  };
 
  /**
   * Construct a directory instance.
   *
   * Construct a directory instance in different ways depending on the
   * version of the constructor used.
   */
  Directory(const std::string &path)  // NOLINT(runtime/explicit)
      : Path(path) {}                 // throws std::invalid_argument
 
  /** @overload */              // throws std::invalid_argument
  Directory(const Path &path);  // NOLINT(runtime/explicit)
 
  Directory(const Directory &) = default;
  Directory &operator=(const Directory &) = default;
  ~Directory();
 
  /**
   * Iterator to first entry.
   *
   * @return Returns an iterator pointing to the first entry.
   */
  DirectoryIterator begin();
 
  DirectoryIterator begin() const { return cbegin(); }
 
  /**
   * Constant iterator to first entry.
   *
   * @return Returns a constant iterator pointing to the first entry.
   */
  DirectoryIterator cbegin() const;
 
  /**
   * Iterator past-the-end of entries.
   *
   * @return Returns an iterator pointing *past-the-end* of the entries.
   */
  DirectoryIterator end();
 
  DirectoryIterator end() const { return cend(); }
 
  /**
   * Constant iterator past-the-end of entries.
   *
   * @return Returns a constant iterator pointing *past-the-end* of the entries.
   */
  DirectoryIterator cend() const;
 
  /**
   * Check if the directory is empty.
   *
   * @retval true Directory is empty.
   * @retval false Directory is no empty.
   */
  bool is_empty() const;
 
  /**
   * Recursively list all paths in a directory.
   *
   * Recursively create a list of relative paths from a directory. Path will
   * be relative to the given directory. Empty directories are also listed.
   *
   * @return Recursive list of paths from a directory.
   */
  std::vector<Path> list_recursive() const;
 
  /**
   * Iterate over entries matching a glob.
   */
  DirectoryIterator glob(const std::string &glob);
};
 
////////////////////////////////////////////////////////////////////////////////
//
// Utility free functions
//
////////////////////////////////////////////////////////////////////////////////
 
/** @brief Removes a directory.
 *
 * @ingroup Filesystem
 *
 * @param dir path of the directory to be removed; this directory must be empty
 *
 * @return void on success, error_code on failure
 */
HARNESS_EXPORT
stdx::expected<void, std::error_code> delete_dir(
    const std::string &dir) noexcept;
 
/** @brief Removes a file.
 *
 * @ingroup Filesystem
 *
 * @param path of the file to be removed
 *
 * @return void on success, error_code on failure
 */
HARNESS_EXPORT
stdx::expected<void, std::error_code> delete_file(
    const std::string &path) noexcept;
 
/** @brief Removes directory and all its contents.
 *
 * @ingroup Filesystem
 *
 * @param dir path of the directory to be removed
 *
 * @return void on success, error_code on failure
 */
HARNESS_EXPORT
stdx::expected<void, std::error_code> delete_dir_recursive(
    const std::string &dir) noexcept;
 
/** @brief Creates a temporary directory with partially-random name and returns
 * its path.
 *
 * Creates a directory with a name of form {prefix}-{6 random alphanumerals}.
 * For example, a possible directory name created by a call to
 * get_tmp_dir("foo") might be: foo-3f9x0z
 *
 * Such directory is usually meant to be used as a temporary directory (thus the
 * "_tmp_" in the name of this function).
 *
 * @ingroup Filesystem
 *
 * @param name name to be used as a directory name prefix
 *
 * @return path to the created directory
 *
 * @throws std::runtime_error if operation failed
 */
HARNESS_EXPORT
std::string get_tmp_dir(const std::string &name = "router");
 
// TODO: description
// TODO: move to some other place?
HARNESS_EXPORT
std::string get_plugin_dir(const std::string &runtime_dir);
 
HARNESS_EXPORT
std::string get_tests_data_dir(const std::string &runtime_dir);
 
#ifndef _WIN32
using perm_mode = mode_t;
HARNESS_EXPORT
extern const perm_mode kStrictDirectoryPerm;
#else
using perm_mode = int;
HARNESS_EXPORT
extern const perm_mode kStrictDirectoryPerm;
#endif
 
/** @brief Creates a directory
 * *
 * @param dir       name (or path) of the directory to create
 * @param mode      permission mode for the created directory
 * @param recursive if true then imitate unix `mkdir -p` recursively
 *                  creating parent directories if needed
 * @retval 0 operation succeeded
 * @retval -1 operation failed because of wrong parameters
 * @retval > 0 errno for failure to mkdir() system call
 */
HARNESS_EXPORT
int mkdir(const std::string &dir, perm_mode mode, bool recursive = false);
 
/**
 * Changes file access permissions to be fully accessible by all users.
 *
 * On Unix, the function sets file permission mask to 777.
 * On Windows, Everyone group is granted full access to the file.
 *
 * @param[in] file_name File name.
 *
 * @throw std::exception Failed to change file permissions.
 */
void HARNESS_EXPORT make_file_public(const std::string &file_name);
 
#ifdef _WIN32
/**
 * Changes file access permissions to be readable by all users.
 *
 * On Windows, Everyone group is granted read access to the file.
 *
 * @param[in] file_name File name.
 *
 * @throw std::exception Failed to change file permissions.
 */
void make_file_readable_for_everyone(const std::string &file_name);
#endif
 
/**
 * Changes file access permissions to be accessible only by a limited set of
 * users.
 *
 * On Unix, the function sets file permission mask to 600.
 * On Windows, all permissions to this file are removed for Everyone group,
 * LocalService account gets read (and optionally write) access.
 *
 * @param[in] file_name File name.
 * @param[in] read_only_for_local_service Weather the LocalService user on
 * Windows should get only the read access (if false will grant write access
 * too). Not used on non-Windows.
 *
 * @throw std::exception Failed to change file permissions.
 */
void HARNESS_EXPORT
make_file_private(const std::string &file_name,
                  const bool read_only_for_local_service = true);
 
/**
 * Changes file access permissions to be read only.
 *
 * On Unix, the function sets file permission mask to 555.
 * On Windows, all permissions to this file are read access only for Everyone
 * group, LocalService account gets read access.
 *
 * @param[in] file_name File name.
 *
 * @throw std::exception Failed to change file permissions.
 */
void HARNESS_EXPORT make_file_readonly(const std::string &file_name);
 
/**
 * Verifies access permissions of a file.
 *
 * On Unix systems it throws if file's permissions differ from 600.
 * On Windows it throws if file can be accessed by Everyone group.
 *
 * @param[in] file_name File to be verified.
 *
 * @throw std::exception File access rights are too permissive or
 *                        an error occurred.
 * @throw std::system_error OS and/or filesystem doesn't support file
 *                           permissions.
 */
 
void HARNESS_EXPORT check_file_access_rights(const std::string &file_name);
 
}  // namespace mysql_harness
 
#endif /* MYSQL_HARNESS_FILESYSTEM_INCLUDED */