transmission/libtransmission/file.h

620 lines
22 KiB
C++

// This file Copyright 2013-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#pragma once
#include <cstddef> // size_t
#include <cstdint> // uint64_t
#include <ctime> // time_t
#include <optional>
#include <string>
#include <string_view>
#ifdef _WIN32
#include <windows.h>
#endif
#include "tr-macros.h"
struct tr_error;
/**
* @addtogroup file_io File IO
* @{
*/
#ifndef _WIN32
/** @brief Platform-specific file descriptor type. */
using tr_sys_file_t = int;
/** @brief Platform-specific invalid file descriptor constant. */
#define TR_BAD_SYS_FILE (-1)
/** @brief Platform-specific directory descriptor type. */
using tr_sys_dir_t = void*;
/** @brief Platform-specific end-of-line sequence. */
#define TR_NATIVE_EOL_STR "\n"
/** @brief Platform-specific end-of-line sequence length. */
#define TR_NATIVE_EOL_STR_SIZE 1
#else
using tr_sys_file_t = HANDLE;
#define TR_BAD_SYS_FILE INVALID_HANDLE_VALUE
struct tr_sys_dir_win32;
using tr_sys_dir_t = tr_sys_dir_win32*;
#define TR_NATIVE_EOL_STR "\r\n"
#define TR_NATIVE_EOL_STR_SIZE 2
#endif
/** @brief Platform-specific invalid directory descriptor constant. */
#define TR_BAD_SYS_DIR ((tr_sys_dir_t) nullptr)
enum tr_std_sys_file_t
{
TR_STD_SYS_FILE_IN,
TR_STD_SYS_FILE_OUT,
TR_STD_SYS_FILE_ERR
};
enum tr_sys_file_open_flags_t
{
TR_SYS_FILE_READ = (1 << 0),
TR_SYS_FILE_WRITE = (1 << 1),
TR_SYS_FILE_CREATE = (1 << 2),
TR_SYS_FILE_APPEND = (1 << 3),
TR_SYS_FILE_TRUNCATE = (1 << 4),
TR_SYS_FILE_SEQUENTIAL = (1 << 5)
};
enum tr_sys_file_lock_flags_t
{
TR_SYS_FILE_LOCK_SH = (1 << 0),
TR_SYS_FILE_LOCK_EX = (1 << 1),
TR_SYS_FILE_LOCK_NB = (1 << 2),
TR_SYS_FILE_LOCK_UN = (1 << 3)
};
enum tr_sys_path_get_info_flags_t
{
TR_SYS_PATH_NO_FOLLOW = (1 << 0)
};
enum tr_sys_file_advice_t
{
TR_SYS_FILE_ADVICE_WILL_NEED,
TR_SYS_FILE_ADVICE_DONT_NEED
};
enum tr_sys_file_preallocate_flags_t
{
TR_SYS_FILE_PREALLOC_SPARSE = (1 << 0)
};
enum tr_sys_dir_create_flags_t
{
TR_SYS_DIR_CREATE_PARENTS = (1 << 0)
};
enum tr_sys_path_type_t
{
TR_SYS_PATH_IS_FILE,
TR_SYS_PATH_IS_DIRECTORY,
TR_SYS_PATH_IS_OTHER
};
struct tr_sys_path_info
{
tr_sys_path_type_t type = {};
uint64_t size = {};
time_t last_modified_at = {};
[[nodiscard]] constexpr auto isFile() const noexcept
{
return type == TR_SYS_PATH_IS_FILE;
}
[[nodiscard]] constexpr auto isFolder() const noexcept
{
return type == TR_SYS_PATH_IS_DIRECTORY;
}
};
/**
* @name Platform-specific wrapper functions
*
* Following functions accept paths in UTF-8 encoding and convert them to native
* encoding internally if needed.
* Descriptors returned (@ref tr_sys_file_t and @ref tr_sys_dir_t) may have
* different type depending on platform and should generally not be passed to
* native functions, but to wrapper functions instead.
*
* @{
*/
/* Path-related wrappers */
/**
* @brief Portability wrapper for various in-kernel file copy functions, with a
* fallback to a userspace read/write loop.
*
* @param[in] src_path Path to source file.
* @param[in] dst_path Path to destination file.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_path_copy(char const* src_path, char const* dst_path, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `stat()`.
*
* @param[in] path Path to file or directory.
* @param[in] flags Combination of @ref tr_sys_path_get_info_flags_t values.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return info on success, or nullopt with `error` set accordingly.
*/
[[nodiscard]] std::optional<tr_sys_path_info> tr_sys_path_get_info(
std::string_view path,
int flags = 0,
tr_error** error = nullptr);
/**
* @brief Portability wrapper for `access()`.
*
* @param[in] path Path to file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` if path exists, `false` otherwise. Note that `false` will also
* be returned in case of error; if you need to distinguish the two,
* check if `error` is `nullptr` afterwards.
*/
bool tr_sys_path_exists(char const* path, struct tr_error** error = nullptr);
template<typename T, typename = decltype(&T::c_str)>
bool tr_sys_path_exists(T const& path, struct tr_error** error = nullptr)
{
return tr_sys_path_exists(path.c_str(), error);
}
/**
* @brief Check whether path is relative.
*
* This function only analyzes the string, so no error reporting is needed.
*
* @param[in] path Path to file or directory.
*
* @return `True` if path is relative, `false` otherwise
*/
bool tr_sys_path_is_relative(std::string_view path);
/**
* @brief Test to see if the two filenames point to the same file.
*
* @param[in] path1 Path to first file or directory.
* @param[in] path2 Path to second file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` if two paths point to the same file or directory, `false`
* otherwise. Note that `false` will also be returned in case of error;
* if you need to distinguish the two, check if `error` is `nullptr`
* afterwards.
*/
bool tr_sys_path_is_same(char const* path1, char const* path2, struct tr_error** error = nullptr);
template<typename T, typename U, typename = decltype(&T::c_str), typename = decltype(&U::c_str)>
bool tr_sys_path_is_same(T const& path1, U const& path2, struct tr_error** error = nullptr)
{
return tr_sys_path_is_same(path1.c_str(), path2.c_str(), error);
}
/**
* @brief Portability wrapper for `realpath()`.
*
* @param[in] path Path to file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return Full path with symbolic links, `.` and `..` resolved on success,
* or an empty string otherwise (with `error` set accordingly).
*/
std::string tr_sys_path_resolve(std::string_view path, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `basename()`.
*
* @param[in] path Path to file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return base name (last path component; parent path removed) on success,
* or empty string otherwise (with `error` set accordingly).
*/
std::string_view tr_sys_path_basename(std::string_view path, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `dirname()`.
*
* @param[in] path Path to file or directory.
*
* @return parent path substring of `path` (last path component removed) on
* success, or empty string otherwise with `error` set accordingly).
*/
std::string_view tr_sys_path_dirname(std::string_view path);
/**
* @brief Portability wrapper for `rename()`.
*
* @param[in] src_path Path to source file or directory.
* @param[in] dst_path Path to destination file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
* Rename will generally only succeed if both source and destination are
* on the same partition.
*/
bool tr_sys_path_rename(char const* src_path, char const* dst_path, struct tr_error** error = nullptr);
template<typename T, typename U, typename = decltype(&T::c_str), typename = decltype(&U::c_str)>
bool tr_sys_path_rename(T const& src_path, U const& dst_path, struct tr_error** error = nullptr)
{
return tr_sys_path_rename(src_path.c_str(), dst_path.c_str(), error);
}
/**
* @brief Portability wrapper for `remove()`.
*
* @param[in] path Path to file or directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
* Directory removal will only succeed if it is empty (contains no other
* files and directories).
*/
bool tr_sys_path_remove(char const* path, struct tr_error** error = nullptr);
template<typename T, typename = decltype(&T::c_str)>
bool tr_sys_path_remove(T const& path, struct tr_error** error = nullptr)
{
return tr_sys_path_remove(path.c_str(), error);
}
/**
* @brief Transform path separators to native ones, in-place.
*
* @param[in,out] path Path to transform.
*
* @return Same path but with native (and uniform) separators.
*/
char* tr_sys_path_native_separators(char* path);
/* File-related wrappers */
/**
* @brief Get handle to one of standard I/O files.
*
* @param[in] std_file Standard file identifier.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return Opened file descriptor on success, `TR_BAD_SYS_FILE` otherwise (with
* `error` set accordingly). DO NOT pass this descriptor to
* @ref tr_sys_file_close (unless you know what you are doing).
*/
tr_sys_file_t tr_sys_file_get_std(tr_std_sys_file_t std_file, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `open()`.
*
* @param[in] path Path to file.
* @param[in] flags Combination of @ref tr_sys_file_open_flags_t values.
* @param[in] permissions Permissions to create file with (in case
@ref TR_SYS_FILE_CREATE is used). Not used on Windows.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return Opened file descriptor on success, `TR_BAD_SYS_FILE` otherwise (with
* `error` set accordingly).
*/
tr_sys_file_t tr_sys_file_open(char const* path, int flags, int permissions, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `mkstemp()`.
*
* @param[in,out] path_template Template path to file. Should end with at least
* six 'X' characters. Upon success, trailing 'X'
* characters are replaced with actual random
* characters used to form a unique path to
* temporary file.
* @param[out] error Pointer to error object. Optional, pass `nullptr`
* if you are not interested in error details.
*
* @return Opened file descriptor on success, `TR_BAD_SYS_FILE` otherwise (with
* `error` set accordingly).
*/
tr_sys_file_t tr_sys_file_open_temp(char* path_template, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `close()`.
*
* @param[in] handle Valid file descriptor.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_close(tr_sys_file_t handle, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `read()`.
*
* @param[in] handle Valid file descriptor.
* @param[out] buffer Buffer to store read data to.
* @param[in] size Number of bytes to read.
* @param[out] bytes_read Number of bytes actually read. Optional, pass `nullptr`
* if you are not interested.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_read(
tr_sys_file_t handle,
void* buffer,
uint64_t size,
uint64_t* bytes_read,
struct tr_error** error = nullptr);
/**
* @brief Like `pread()`, except that the position is undefined afterwards.
* Not thread-safe.
*
* @param[in] handle Valid file descriptor.
* @param[out] buffer Buffer to store read data to.
* @param[in] size Number of bytes to read.
* @param[in] offset File offset in bytes to start reading from.
* @param[out] bytes_read Number of bytes actually read. Optional, pass `nullptr`
* if you are not interested.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_read_at(
tr_sys_file_t handle,
void* buffer,
uint64_t size,
uint64_t offset,
uint64_t* bytes_read,
struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `write()`.
*
* @param[in] handle Valid file descriptor.
* @param[in] buffer Buffer to get data being written from.
* @param[in] size Number of bytes to write.
* @param[out] bytes_written Number of bytes actually written. Optional, pass
* `nullptr` if you are not interested.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_write(
tr_sys_file_t handle,
void const* buffer,
uint64_t size,
uint64_t* bytes_written,
struct tr_error** error = nullptr);
/**
* @brief Like `pwrite()`, except that the position is undefined afterwards.
* Not thread-safe.
*
* @param[in] handle Valid file descriptor.
* @param[in] buffer Buffer to get data being written from.
* @param[in] size Number of bytes to write.
* @param[in] offset File offset in bytes to start writing from.
* @param[out] bytes_written Number of bytes actually written. Optional, pass
* `nullptr` if you are not interested.
* @param[out] error Pointer to error object. Optional, pass `nullptr`
* if you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_write_at(
tr_sys_file_t handle,
void const* buffer,
uint64_t size,
uint64_t offset,
uint64_t* bytes_written,
struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `fsync()`.
*
* @param[in] handle Valid file descriptor.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_flush(tr_sys_file_t handle, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `ftruncate()`.
*
* @param[in] handle Valid file descriptor.
* @param[in] size Number of bytes to truncate (or extend) file to.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_truncate(tr_sys_file_t handle, uint64_t size, struct tr_error** error = nullptr);
/**
* @brief Tell system to prefetch or discard some part of file which is [not] to be read soon.
*
* @param[in] handle Valid file descriptor.
* @param[in] offset Offset in file to prefetch from.
* @param[in] size Number of bytes to prefetch.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_advise(
tr_sys_file_t handle,
uint64_t offset,
uint64_t size,
tr_sys_file_advice_t advice,
struct tr_error** error = nullptr);
/**
* @brief Preallocate file to specified size in full or sparse mode.
*
* @param[in] handle Valid file descriptor.
* @param[in] size Number of bytes to preallocate file to.
* @param[in] flags Combination of @ref tr_sys_file_preallocate_flags_t values.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_preallocate(tr_sys_file_t handle, uint64_t size, int flags, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `flock()`.
*
* Don't try to upgrade or downgrade the lock unless you know what you are
* doing, as behavior varies a bit between platforms.
*
* @param[in] handle Valid file descriptor.
* @param[in] operation Combination of @ref tr_sys_file_lock_flags_t values.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_lock(tr_sys_file_t handle, int operation, struct tr_error** error = nullptr);
/* File-related wrappers (utility) */
/**
* @brief Portability wrapper for `fputs()`, appending EOL internally.
*
* Special care should be taken when writing to one of standard output streams
* (@ref tr_std_sys_file_t) since no UTF-8 conversion is currently being made.
*
* Writing to other streams (files, pipes) also leaves data untouched, so it
* should already be in UTF-8 encoding, or whichever else you expect.
*
* @param[in] handle Valid file descriptor.
* @param[in] buffer String to write.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_file_write_line(tr_sys_file_t handle, std::string_view buffer, struct tr_error** error = nullptr);
/* Directory-related wrappers */
/**
* @brief Portability wrapper for `getcwd()`.
*
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you are
* not interested in error details.
*
* @return current directory on success, or an empty string otherwise
* (with `error` set accordingly).
*/
std::string tr_sys_dir_get_current(struct tr_error** error = nullptr);
/**
* @brief Like `mkdir()`, but makes parent directories if needed.
*
* @param[in] path Path to directory.
* @param[in] flags Combination of @ref tr_sys_dir_create_flags_t values.
* @param[in] permissions Permissions to create directory with. Not used on
Windows.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if
* you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_dir_create(char const* path, int flags, int permissions, struct tr_error** error = nullptr);
template<typename T, typename = decltype(&T::c_str)>
bool tr_sys_dir_create(T const& path, int flags, int permissions, struct tr_error** error = nullptr)
{
return tr_sys_dir_create(path.c_str(), flags, permissions, error);
}
/**
* @brief Portability wrapper for `mkdtemp()`.
*
* @param[in,out] path_template Template path to directory. Should end with at
* least six 'X' characters. Upon success, trailing
* 'X' characters are replaced with actual random
* characters used to form a unique path to
* temporary directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr`
* if you are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_dir_create_temp(char* path_template, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `opendir()`.
*
* @param[in] path Path to directory.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you are
* not interested in error details.
*
* @return Opened directory descriptor on success, `TR_BAD_SYS_DIR` otherwise
* (with `error` set accordingly).
*/
tr_sys_dir_t tr_sys_dir_open(char const* path, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `readdir()`.
*
* @param[in] handle Valid directory descriptor.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return Pointer to next directory entry name (stored internally, DO NOT free
* it) on success, `nullptr` otherwise (with `error` set accordingly).
* Note that `nullptr` will also be returned in case of end of directory.
* If you need to distinguish the two, check if `error` is `nullptr`
* afterwards.
*/
char const* tr_sys_dir_read_name(tr_sys_dir_t handle, struct tr_error** error = nullptr);
/**
* @brief Portability wrapper for `closedir()`.
*
* @param[in] handle Valid directory descriptor.
* @param[out] error Pointer to error object. Optional, pass `nullptr` if you
* are not interested in error details.
*
* @return `True` on success, `false` otherwise (with `error` set accordingly).
*/
bool tr_sys_dir_close(tr_sys_dir_t handle, struct tr_error** error = nullptr);
/** @} */
/** @} */