os0file.h

Go to the documentation of this file.

/***********************************************************************
 
Copyright (c) 1995, 2026, Oracle and/or its affiliates.
Copyright (c) 2009, Percona Inc.
 
Portions of this file contain modifications contributed and copyrighted
by Percona Inc.. Those modifications are
gratefully acknowledged and are described briefly in the InnoDB
documentation. The contributions by Percona Inc. are incorporated with
their permission, and subject to the conditions contained in the file
COPYING.Percona.
 
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
but not limited to OpenSSL) that is licensed under separate terms,
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
separately licensed software that they have either included with
the program or referenced in the documentation.
 
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, version 2.0, 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
 
***********************************************************************/
 
/** @file include/os0file.h
 The interface to the operating system file io
 
 Created 10/21/1995 Heikki Tuuri
 *******************************************************/
 
#ifndef os0file_h
#define os0file_h
 
#include "my_dbug.h"
#include "my_io.h"
 
#include "os/file.h"
#include "os0atomic.h"
#include "os0enc.h"
 
#ifndef _WIN32
#include <dirent.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <time.h>
#else
#include <Strsafe.h>
#include <locale>
#include <string>
#endif /* !_WIN32 */
 
#include <functional>
#include <stack>
 
/** Prefix all files and directory created under data directory with special
string so that it never conflicts with MySQL schema directory. */
#define OS_FILE_PREFIX "#"
 
/** File node of a tablespace or the log data space */
class fil_node_t;
 
extern bool os_was_file_write_error_reported;
 
/** Number of retries for partial I/O's */
constexpr size_t NUM_RETRIES_ON_PARTIAL_IO = 10;
 
/** Number of pending read operations */
extern std::atomic<ulint> os_n_pending_reads;
/** Number of pending write operations */
extern std::atomic<ulint> os_n_pending_writes;
 
/* Flush after each os_fsync_threshold bytes */
extern unsigned long long os_fsync_threshold;
 
/** File offset in bytes */
typedef uint64_t os_offset_t;
 
namespace file {
/** Blocks for doing IO, used in the transparent compression
and encryption code. */
struct Block {
  /** Default constructor */
  Block() noexcept : m_ptr(nullptr), m_in_use() {}
 
  /** Free the given memory block.
  @param[in]  obj  the memory block to be freed. */
  static void free(file::Block *obj) noexcept;
 
  /** Pointer to the memory block. */
  byte *m_ptr;
  /** Size of the data in memory block. This may be not UNIV_PAGE_SIZE if the
  data was compressed before encryption. */
  size_t m_size;
  /** This padding is needed to avoid false sharing. TBD: of what exactly? We
  can't use alignas because std::vector<Block> uses std::allocator which in
  C++14 doesn't have to handle overaligned types. (see § 20.7.9.1.5 of N4140
  draft) */
  byte pad[ut::INNODB_CACHE_LINE_SIZE];
  std::atomic<bool> m_in_use;
};
}  // namespace file
 
/** Raw file handle. */
using os_fd_t = int;
 
static constexpr os_fd_t OS_FD_CLOSED = -1;
 
#ifdef _WIN32
 
typedef HANDLE os_file_dir_t; /*!< directory stream */
 
/** Use unbuffered I/O */
#define UNIV_NON_BUFFERED_IO
 
/** Windows file handle */
using os_file_t = HANDLE;
 
static const os_file_t OS_FILE_CLOSED = INVALID_HANDLE_VALUE;
 
/** Convert a C file descriptor to a native file handle
@param fd file descriptor
@return native file handle */
#define OS_FILE_FROM_FD(fd) (HANDLE) _get_osfhandle(fd)
 
/** Associates a C file descriptor with an existing native file handle
@param[in]      file    native file handle
@return C file descriptor */
#define OS_FD_FROM_FILE(file) _open_osfhandle((intptr_t)file, _O_RDONLY)
 
/** Closes the file associated with C file descriptor fd
@param[in]      fd      C file descriptor
@return 0 if success */
#define OS_FILE_CLOSE_FD(fd) _close(fd)
 
#else /* _WIN32 */
 
/** File handle */
using os_file_t = os_fd_t;
 
static constexpr os_fd_t OS_FILE_CLOSED = OS_FD_CLOSED;
 
/** Convert a C file descriptor to a native file handle
@param fd file descriptor
@return native file handle */
#define OS_FILE_FROM_FD(fd) fd
 
/** C file descriptor from an existing native file handle
@param[in]      file    native file handle
@return C file descriptor */
#define OS_FD_FROM_FILE(file) file
 
/** Closes the file associated with C file descriptor fd
@param[in]      fd      C file descriptor
@return 0 if success */
#define OS_FILE_CLOSE_FD(fd) (os_file_close(fd) ? 0 : OS_FD_CLOSED)
 
#endif /* _WIN32 */
 
/** Common file descriptor for file IO instrumentation with PFS
on windows and other platforms */
struct pfs_os_file_t {
#ifdef UNIV_PFS_IO
  struct PSI_file *m_psi;
#else  /* UNIV_PFS_IO */
  pfs_os_file_t &operator=(os_file_t file) {
    m_file = file;
    return (*this);
  }
#endif /* UNIV_PFS_IO */
 
  os_file_t m_file;
};
 
/** The next value should be smaller or equal to the smallest sector size used
on any disk. A log block is required to be a portion of disk which is written
so that if the start and the end of a block get written to disk, then the
whole block gets written. This should be true even in most cases of a crash:
if this fails for a log block, then it is equivalent to a media failure in the
log. */
 
constexpr uint32_t OS_FILE_LOG_BLOCK_SIZE = 512;
 
/** Options for os_file_create_func @{ */
enum os_file_create_t {
  OS_FILE_OPEN = 51,   /*!< to open an existing file (if
                       doesn't exist, error) */
  OS_FILE_CREATE,      /*!< to create new file (if
                       exists, error) */
  OS_FILE_OPEN_RAW,    /*!< to open a raw device or disk
                       partition */
  OS_FILE_CREATE_PATH, /*!< to create the directories */
  OS_FILE_OPEN_RETRY,  /*!< open with retry */
 
  /** Flags that can be combined with the above values. Please ensure
  that the above values stay below 128. */
 
  OS_FILE_ON_ERROR_NO_EXIT = 128, /*!< do not exit on unknown errors */
  OS_FILE_ON_ERROR_SILENT = 256   /*!< don't print diagnostic messages to
                                  the log unless it is a fatal error,
                                  this flag is only used if
                                  ON_ERROR_NO_EXIT is set */
};
 
static const ulint OS_FILE_READ_ONLY = 333;
static const ulint OS_FILE_READ_WRITE = 444;
 
/** Used by MySQLBackup */
static const ulint OS_FILE_READ_ALLOW_DELETE = 555;
/** @} */
 
/** Types for file create @{ */
static const ulint OS_DATA_FILE = 100;
static const ulint OS_LOG_FILE = 101;
static const ulint OS_LOG_FILE_RESIZING = 102;
/* Don't use this for Data files, Log files. Use it for smaller files
or if number of bytes to write are not multiple of sector size.
With this flag, writes to file will be always buffered and ignores the value
of innodb_flush_method. */
static const ulint OS_BUFFERED_FILE = 103;
static const ulint OS_CLONE_DATA_FILE = 104;
static const ulint OS_CLONE_LOG_FILE = 105;
static const ulint OS_DBLWR_FILE = 106;
static const ulint OS_DATA_FILE_FOR_SPACE_ID_READ = 107;
/** @} */
 
/** Error codes from os_file_get_and_log_last_error @{ */
static const ulint OS_FILE_NOT_FOUND = 71;
static const ulint OS_FILE_DISK_FULL = 72;
static const ulint OS_FILE_ALREADY_EXISTS = 73;
static const ulint OS_FILE_PATH_ERROR = 74;
 
/** wait for OS aio resources to become available again */
static const ulint OS_FILE_AIO_RESOURCES_RESERVED = 75;
 
static const ulint OS_FILE_SHARING_VIOLATION = 76;
static const ulint OS_FILE_ERROR_NOT_SPECIFIED = 77;
static const ulint OS_FILE_INSUFFICIENT_RESOURCE = 78;
static const ulint OS_FILE_AIO_INTERRUPTED = 79;
static const ulint OS_FILE_OPERATION_ABORTED = 80;
static const ulint OS_FILE_ACCESS_VIOLATION = 81;
static const ulint OS_FILE_NAME_TOO_LONG = 82;
static const ulint OS_FILE_TOO_MANY_OPENED = 83;
 
static const ulint OS_FILE_ERROR_MAX = 100;
/** @} */
 
/** Types for AIO operations @{ */
 
/**
The IO Context that is passed down to the low level IO code */
class IORequest {
 public:
  /** Flags that can be used to specify the IORequest mode and additional
  options, to be used as bitmask type. */
  enum class Type : uint16_t {
    UNSET = 0,
    READ = 1 << 0,
    WRITE = 1 << 1,
 
    /** Enumerations below can be ORed to READ/WRITE above*/
 
    /** Request for page IO during double-write buffer recovery. Setting this
    option will silence some corruption or decompression errors, will cause to
    use a safer decompression methods and will cause the `fil` subsystem to not
    validate the tablespace file, as we may have not yet recovered the first
    page with the FSP header from the double-write buffer. */
    DBLWR = 1 << 2,
 
    /** Data file */
    DATA_FILE = 1 << 3,
 
    /** Log file request*/
    LOG = 1 << 4,
 
    /** Disable partial read warnings */
    DISABLE_PARTIAL_IO_WARNINGS = 1 << 5,
 
    /** Do not to wake i/o-handler threads, but the caller will do
    the waking explicitly later, in this way the caller can post
    several requests in a batch; NOTE that the batch must not be
    so big that it exhausts the slots in AIO arrays! NOTE that
    a simulated batch may introduce hidden chances of deadlocks,
    because I/Os are not actually handled until all
    have been posted: use with great caution! */
    DO_NOT_WAKE = 1 << 6,
 
    /** Ignore failed reads of non-existent pages */
    IGNORE_MISSING = 1 << 7,
 
    /** Use punch hole if available, only makes sense if
    compression algorithm != NONE. Ignored if not set */
    PUNCH_HOLE = 1 << 8,
 
    /** Force raw read, do not try to compress/decompress.
    This can be used to force a read and write without any
    compression e.g., for redo log, merge sort temporary files
    and the truncate redo log. */
    NO_COMPRESSION = 1 << 9,
 
    /** Row log used in online DDL */
    ROW_LOG = 1 << 10,
 
    /** We optimise cases where punch hole is not done if the compressed length
    of the page is the same as the original size of the page. Ignore such
    optimisations if this flag is set. */
    DISABLE_PUNCH_HOLE_OPTIMISATION = 1 << 11,
 
    /** We want async ibuf requests to be performed on a separate IO queue as
    the default one might get saturated by waits for ibuf reads completions,
    leading to deadlock. */
    IBUF = 1 << 12,
 
    /** Force raw write, do not try to compress or encrypt. */
    NO_WRITE_TRANSFORMATIONS = 1 << 13
  };
 
  /** Default constructor */
  IORequest() = delete;
 
  /**
  @param[in]    type            Request type, can be a value that is
                                  ORed from the above enum */
  explicit IORequest(Type type)
      : m_block_size(UNIV_SECTOR_SIZE),
        m_type(type),
        m_compression(),
        m_encryption(),
        m_elen(0) {
    if (is_log() || is_row_log()) {
      disable_compression();
    }
 
    if (!is_punch_hole_supported()) {
      clear_punch_hole();
    }
  }
 
  /** @return true if it is a read request */
  [[nodiscard]] bool is_ibuf() const {
    return ((m_type & Type::IBUF) == Type::IBUF);
  }
 
  /** @return true if it is a read request */
  [[nodiscard]] bool is_read() const {
    return (m_type & Type::READ) == Type::READ;
  }
 
  /** @return true if it is a write request */
  [[nodiscard]] bool is_write() const {
    return (m_type & Type::WRITE) == Type::WRITE;
  }
 
  /** @return true if it is a redo log write */
  [[nodiscard]] bool is_log() const {
    return (m_type & Type::LOG) == Type::LOG;
  }
 
  /** @return true if it is a row log entry used in online DDL */
  [[nodiscard]] bool is_row_log() const {
    return (m_type & Type::ROW_LOG) == Type::ROW_LOG;
  }
 
  /** @return true if the simulated AIO thread should be woken up */
  [[nodiscard]] bool is_wake() const {
    return (m_type & Type::DO_NOT_WAKE) != Type::DO_NOT_WAKE;
  }
 
  /** @return true if partial read warning disabled */
  [[nodiscard]] bool is_partial_io_warning_disabled() const {
    return (m_type & Type::DISABLE_PARTIAL_IO_WARNINGS) ==
           Type::DISABLE_PARTIAL_IO_WARNINGS;
  }
 
  /** Disable partial read warnings */
  void disable_partial_io_warnings() {
    m_type |= Type::DISABLE_PARTIAL_IO_WARNINGS;
  }
 
  /** @return true if missing files should be ignored */
  [[nodiscard]] bool ignore_missing() const {
    return (m_type & Type::IGNORE_MISSING) == Type::IGNORE_MISSING;
  }
 
  /** @return true if punch hole should be used */
  [[nodiscard]] bool is_punch_hole_requested() const {
    return (m_type & Type::PUNCH_HOLE) == Type::PUNCH_HOLE;
  }
 
  /** @return true if punch hole needs to be done always if it's supported and
  if the page is to be compressed. */
  [[nodiscard]] bool is_punch_hole_optimisation_disabled() const {
    ut_ad(is_compression_requested() && is_punch_hole_requested());
 
    return (m_type & Type::DISABLE_PUNCH_HOLE_OPTIMISATION) ==
           Type::DISABLE_PUNCH_HOLE_OPTIMISATION;
  }
 
  /** @return true if the read should be validated */
  [[nodiscard]] bool validate() const {
    ut_ad(is_read() ^ is_write());
 
    return (!is_read() || !is_punch_hole_requested());
  }
 
  /** Set the punch hole flag */
  void set_punch_hole() {
    if (is_punch_hole_supported()) {
      m_type |= Type::PUNCH_HOLE;
    }
  }
 
  /** Set the force punch hole flag */
  void disable_punch_hole_optimisation() {
    if (is_punch_hole_supported()) {
      m_type |= Type::DISABLE_PUNCH_HOLE_OPTIMISATION;
    }
  }
 
  void set_ibuf() { m_type |= Type::IBUF; }
 
  /** Clear the do not wake flag */
  void clear_do_not_wake() { m_type &= ~Type::DO_NOT_WAKE; }
 
  /** Clear the punch hole flag */
  void clear_punch_hole() { m_type &= ~Type::PUNCH_HOLE; }
 
  /** @return the block size to use for IO */
  [[nodiscard]] ulint block_size() const { return m_block_size; }
 
  /** Set the block size for IO
  @param[in] block_size         Block size to set */
  void block_size(ulint block_size) {
    m_block_size = static_cast<uint32_t>(block_size);
  }
 
  /** Returns original size of the IO to make. If one was not specified, then 0
  is returned. */
  uint32_t get_original_size() const { return m_original_size; }
 
  void set_original_size(uint32_t original_size) {
    m_original_size = original_size;
  }
 
  /** Clear all compression related flags */
  void clear_compressed() {
    clear_punch_hole();
 
    m_compression.m_type = Compression::NONE;
  }
 
  /** Compare two requests
  @return true if the are equal */
  bool operator==(const IORequest &rhs) const { return m_type == rhs.m_type; }
 
  /** Set compression algorithm
  @param[in]    type    The compression algorithm to use */
  void compression_algorithm(Compression::Type type) {
    if (type == Compression::NONE) {
      return;
    }
 
    set_punch_hole();
 
    m_compression.m_type = type;
  }
 
  /** Get the compression algorithm.
  @return the compression algorithm */
  [[nodiscard]] Compression compression_algorithm() const {
    return m_compression;
  }
 
  /** @return true if the page should be compressed */
  [[nodiscard]] bool is_compression_requested() const {
    ut_ad(is_write());
    return compression_algorithm().m_type != Compression::NONE;
  }
 
  /** @return true if the page read/write should not be decompressed/compressed.
   */
  [[nodiscard]] bool is_compression_enabled() const {
    return (m_type & Type::NO_COMPRESSION) != Type::NO_COMPRESSION;
  }
 
  /** Disable transformations. */
  void disable_compression() { m_type |= Type::NO_COMPRESSION; }
 
  /** @return true iff transformations (compression and/or encryption) should be
  performed on the buffer in case this is a write operation and the tablespace
  seems to use them. */
  [[nodiscard]] bool are_write_transformations_enabled() const {
    return (m_type & Type::NO_WRITE_TRANSFORMATIONS) !=
           Type::NO_WRITE_TRANSFORMATIONS;
  }
 
  /** Disable transformations. */
  void disable_write_transformations() {
    m_type |= Type::NO_WRITE_TRANSFORMATIONS;
  }
 
  /** Get the encryption algorithm.
  @return the encryption algorithm */
  [[nodiscard]] Encryption encryption_algorithm() const { return m_encryption; }
 
  /** @return true if the page should be encrypted. */
  [[nodiscard]] bool is_encryption_requested() const {
    ut_ad(is_write());
    return m_encryption.get_type() != Encryption::NONE;
  }
 
  /** Clear all encryption related flags */
  void clear_encrypted() {
    m_encryption.set_key(nullptr);
    m_encryption.set_key_length(0);
    m_encryption.set_initial_vector(nullptr);
    m_encryption.set_type(Encryption::NONE);
  }
 
  /** @return true if the request is for page for the double-write buffer
  recovery. */
  [[nodiscard]] bool is_dblwr() const {
    return (m_type & Type::DBLWR) == Type::DBLWR;
  }
 
  /** @return true if punch hole is supported */
  static bool is_punch_hole_supported() {
    /* In this debugging mode, we act as if punch hole is supported,
    and then skip any calls to actually punch a hole here.
    In this way, Transparent Page Compression is still being tested. */
    DBUG_EXECUTE_IF("ignore_punch_hole", return true;);
 
#if defined(HAVE_FALLOC_PUNCH_HOLE_AND_KEEP_SIZE) || defined(_WIN32)
    return true;
#else
    return false;
#endif /* HAVE_FALLOC_PUNCH_HOLE_AND_KEEP_SIZE || _WIN32 */
  }
 
  /** @return string representation. */
  std::string to_string() const {
    std::ostringstream os;
    os << "bs: " << m_block_size << " flags: ";
    if ((m_type & Type::READ) == Type::READ) {
      os << "READ";
    } else if ((m_type & Type::WRITE) == Type::WRITE) {
      os << "WRITE";
    } else {
      os << "UNSET";
    }
 
    /* Enumerations below can be ORed to READ/WRITE above. */
 
#define PRINT_MASK_ELEMENT(flag)             \
  if ((m_type & Type::flag) == Type::flag) { \
    os << " | " #flag;                       \
  }
 
    PRINT_MASK_ELEMENT(DATA_FILE);
    PRINT_MASK_ELEMENT(DBLWR);
    PRINT_MASK_ELEMENT(LOG);
    PRINT_MASK_ELEMENT(ROW_LOG);
    PRINT_MASK_ELEMENT(PUNCH_HOLE);
    PRINT_MASK_ELEMENT(NO_COMPRESSION);
    PRINT_MASK_ELEMENT(DISABLE_PUNCH_HOLE_OPTIMISATION);
    PRINT_MASK_ELEMENT(DO_NOT_WAKE);
    PRINT_MASK_ELEMENT(IGNORE_MISSING);
    PRINT_MASK_ELEMENT(DISABLE_PARTIAL_IO_WARNINGS);
    PRINT_MASK_ELEMENT(NO_WRITE_TRANSFORMATIONS);
#undef PRINT_MASK_ELEMENT
 
    os << ", comp: " << m_compression.to_string();
    os << ", enc: " << m_encryption.to_string(m_encryption.get_type());
    return (os.str());
  }
 
  /** Get a reference to the underlying encryption information.
  @return reference to the encryption information. */
  [[nodiscard]] Encryption &get_encryption_info() noexcept {
    return m_encryption;
  }
 
 private:
  /* File system best block size */
  uint32_t m_block_size{};
 
  /** Request type bit flags */
  Type m_type{};
 
  /** Compression algorithm */
  Compression m_compression{};
 
  /** Encryption algorithm */
  Encryption m_encryption{};
 
  /** The length of data in encrypted block. */
  uint32_t m_elen{};
 
  /** Length of the original IO size.
  For reads it is an expected uncompressed length.
  For writes it is a length up to which the write is to be extended with a punch
  hole, if supported. */
  uint32_t m_original_size{};
 
  friend constexpr IORequest::Type operator~(const IORequest::Type type);
  friend constexpr IORequest::Type operator&(const IORequest::Type a,
                                             const IORequest::Type b);
  friend constexpr IORequest::Type &operator|=(IORequest::Type &a,
                                               const IORequest::Type b);
  friend constexpr IORequest::Type &operator&=(IORequest::Type &a,
                                               const IORequest::Type b);
};
 
/** @} */
 
constexpr IORequest::Type operator~(const IORequest::Type type) {
  return static_cast<IORequest::Type>(~static_cast<uint16_t>(type));
}
 
constexpr IORequest::Type operator|(const IORequest::Type a,
                                    const IORequest::Type b) {
  return static_cast<IORequest::Type>(static_cast<uint16_t>(a) |
                                      static_cast<uint16_t>(b));
}
constexpr IORequest::Type operator&(const IORequest::Type a,
                                    const IORequest::Type b) {
  return static_cast<IORequest::Type>(static_cast<uint16_t>(a) &
                                      static_cast<uint16_t>(b));
}
constexpr IORequest::Type &operator|=(IORequest::Type &a,
                                      const IORequest::Type b) {
  return a = a | b;
}
constexpr IORequest::Type &operator&=(IORequest::Type &a,
                                      const IORequest::Type b) {
  return a = a & b;
}
 
/** Sparse file size information. */
struct os_file_size_t {
  /** Total size of file in bytes */
  os_offset_t m_total_size;
 
  /** If it is a sparse file then this is the number of bytes
  actually allocated for the file. */
  os_offset_t m_alloc_size;
};
 
/** Win NT does not allow more than 64 */
static const ulint OS_AIO_N_PENDING_IOS_PER_THREAD = 32;
 
/** Modes for aio operations @{ */
enum class AIO_mode : size_t {
  /** Normal asynchronous i/o not for ibuf pages or ibuf bitmap pages */
  NORMAL = 21,
 
  /**  Asynchronous i/o for ibuf pages or ibuf bitmap pages */
  IBUF = 22,
};
/** @} */
 
extern ulint os_n_file_reads;
extern ulint os_n_file_writes;
extern ulint os_n_fsyncs;
 
/* File types for directory entry data type */
 
enum os_file_type_t {
  /** Get status failed. */
  OS_FILE_TYPE_FAILED,
 
  /** stat() failed, with ENAMETOOLONG */
  OS_FILE_TYPE_NAME_TOO_LONG,
 
  /** stat() failed with EACCESS */
  OS_FILE_PERMISSION_ERROR,
 
  /** File doesn't exist. */
  OS_FILE_TYPE_MISSING,
 
  /** File exists but type is unknown. */
  OS_FILE_TYPE_UNKNOWN,
 
  /** Ordinary file. */
  OS_FILE_TYPE_FILE,
 
  /** Directory. */
  OS_FILE_TYPE_DIR,
 
  /** Symbolic link. */
  OS_FILE_TYPE_LINK,
 
  /** Block device. */
  OS_FILE_TYPE_BLOCK
};
 
/* Maximum path string length in bytes when referring to tables with in the
'./databasename/tablename.ibd' path format; we can allocate at least 2 buffers
of this size from the thread stack; that is why this should not be made much
bigger than 4000 bytes.  The maximum path length used by any storage engine
in the server must be at least this big. */
constexpr uint32_t OS_FILE_MAX_PATH = 4000;
static_assert(FN_REFLEN_SE >= OS_FILE_MAX_PATH,
              "(FN_REFLEN_SE < OS_FILE_MAX_PATH)");
 
/** Struct used in fetching information of a file in a directory */
struct os_file_stat_t {
  char name[OS_FILE_MAX_PATH]; /*!< path to a file */
  os_file_type_t type;         /*!< file type */
  os_offset_t size;            /*!< file size in bytes */
  os_offset_t alloc_size;      /*!< Allocated size for
                               sparse files in bytes */
  uint32_t block_size;         /*!< Block size to use for IO
                               in bytes*/
  time_t ctime;                /*!< creation time */
  time_t mtime;                /*!< modification time */
  time_t atime;                /*!< access time */
};
 
#ifndef UNIV_HOTBACKUP
/** Create a temporary file. This function is like tmpfile(3). It will create
the file in the MySQL server configuration parameter (--tmpdir).
@return temporary file handle, or NULL on error */
FILE *os_file_create_tmpfile();
#endif /* !UNIV_HOTBACKUP */
 
/** This function attempts to create a directory named pathname. The new
directory gets default permissions. On Unix the permissions are
(0770 & ~umask). If the directory exists already, nothing is done and
the call succeeds, unless the fail_if_exists arguments is true.
If another error occurs, such as a permission error, this does not crash,
but reports the error and returns false.
@param[in]      pathname        directory name as null-terminated string
@param[in]      fail_if_exists  if true, pre-existing directory is treated as
                                an error.
@return true if call succeeds, false on error */
bool os_file_create_directory(const char *pathname, bool fail_if_exists);
 
/** Callback function type to be implemented by caller. It is called for each
entry in directory.
@param[in]      path    path to the file
@param[in]      name    name of the file */
typedef std::function<void(const char *path, const char *name)> os_dir_cbk_t;
 
/** This function scans the contents of a directory and invokes the callback
for each entry.
@param[in]      path            directory name as null-terminated string
@param[in]      scan_cbk        use callback to be called for each entry
@param[in]      is_drop         attempt to drop the directory after scan
@return true if call succeeds, false on error */
bool os_file_scan_directory(const char *path, os_dir_cbk_t scan_cbk,
                            bool is_drop);
 
/** Clang on Windows warns about umask not found. */
MY_COMPILER_DIAGNOSTIC_PUSH()
#ifdef _WIN32
MY_COMPILER_CLANG_DIAGNOSTIC_IGNORE("-Wdocumentation")
#endif
 
/** NOTE! Use the corresponding macro
os_file_create_simple_no_error_handling(), not directly this function!
A simple function to open or create a file.
@param[in]      name            name of the file or path as a
null-terminated string
@param[in]      create_mode     create mode
@param[in]      access_type     OS_FILE_READ_ONLY, OS_FILE_READ_WRITE, or
                                OS_FILE_READ_ALLOW_DELETE; the last option
                                is used by a backup program reading the file
@param[in]      umask           UNIX access permission to be set when creating a
                                file. Use os_umask_default to use global default
                                umask.
@param[out]     success         true if succeeded
@return own: handle to the file, not defined if error, error number
        can be retrieved with os_file_get_and_log_last_error */
[[nodiscard]] pfs_os_file_t os_file_create_simple_no_error_handling_func(
    const char *name, ulint create_mode, ulint access_type,
#ifndef _WIN32
    mode_t umask,
#endif
    bool *success);
MY_COMPILER_DIAGNOSTIC_POP()
 
/** Tries to disable OS caching on an opened file descriptor.
@param[in]      fd              file descriptor to alter
@param[in]      file_name       file name, used in the diagnostic message
@param[in]      operation_name  "open" or "create"; used in the diagnostic
                                message
@param[in]      on_error_silent if true then don't print any message to the log
*/
void os_file_set_nocache(int fd, const char *file_name,
                         const char *operation_name,
                         bool on_error_silent = false);
/** NOTE! Use the corresponding macro os_file_create(), not directly
this function!
Opens an existing file or creates a new.
@param[in]      name              name of the file or path as a null-terminated
                                  string
@param[in]      create_mode       create mode
@param[in]      purpose           OS_DATA_FILE, OS_LOG_FILE etc.
@param[in]      read_only         if true read only mode checks are enforced
@param[out]     success           true if succeeded
@return own: handle to the file, not defined if error, error number
        can be retrieved with os_file_get_and_log_last_error */
[[nodiscard]] pfs_os_file_t os_file_create_func(const char *name,
                                                ulint create_mode,
                                                ulint purpose, bool read_only,
                                                bool *success);
 
/** Deletes a file. The file has to be closed before calling this.
@param[in]      name            file path as a null-terminated string
@return true if success */
bool os_file_delete_func(const char *name);
 
/** Deletes a file if it exists. The file has to be closed before calling
this.
@param[in]      name            file path as a null-terminated string
@param[out]     exist           indicate if file pre-exist
@return true if success */
bool os_file_delete_if_exists_func(const char *name, bool *exist);
 
/** NOTE! Use the corresponding macro os_file_rename(), not directly
this function!
Renames a file (can also move it to another directory). It is safest that the
file is closed before calling this function.
@param[in]      oldpath         old file path as a null-terminated string
@param[in]      newpath         new file path
@return true if success */
bool os_file_rename_func(const char *oldpath, const char *newpath);
 
/** NOTE! Use the corresponding macro os_file_close(), not directly
this function!
Closes a file handle. In case of error, error number can be retrieved with
os_file_get_and_log_last_error.
@param[in]      file            Handle to a file
@return true if success */
bool os_file_close_func(os_file_t file);
 
#ifdef UNIV_PFS_IO
 
/* Keys to register InnoDB I/O with performance schema */
extern mysql_pfs_key_t innodb_log_file_key;
extern mysql_pfs_key_t innodb_temp_file_key;
extern mysql_pfs_key_t innodb_dblwr_file_key;
extern mysql_pfs_key_t innodb_arch_file_key;
extern mysql_pfs_key_t innodb_clone_file_key;
extern mysql_pfs_key_t innodb_data_file_key;
 
/* Following four macros are instrumentations to register
various file I/O operations with performance schema.
1) register_pfs_file_open_begin() and register_pfs_file_open_end() are
used to register file creation, opening and closing.
2) register_pfs_file_rename_begin() and  register_pfs_file_rename_end()
are used to register file renaming.
3) register_pfs_file_io_begin() and register_pfs_file_io_end() are
used to register actual file read, write and flush
4) register_pfs_file_close_begin() and register_pfs_file_close_end()
are used to register file deletion operations*/
#define register_pfs_file_open_begin(state, locker, key, op, name,           \
                                     src_location)                           \
  do {                                                                       \
    locker = PSI_FILE_CALL(get_thread_file_name_locker)(state, key.m_value,  \
                                                        op, name, &locker);  \
    if (locker != nullptr) {                                                 \
      PSI_FILE_CALL(start_file_open_wait)                                    \
      (locker, src_location.filename, static_cast<uint>(src_location.line)); \
    }                                                                        \
  } while (0)
 
#define register_pfs_file_open_end(locker, file, result)              \
  do {                                                                \
    if (locker != nullptr) {                                          \
      file.m_psi = PSI_FILE_CALL(end_file_open_wait)(locker, result); \
    }                                                                 \
  } while (0)
 
#define register_pfs_file_rename_begin(state, locker, key, op, from, to,    \
                                       src_location)                        \
  do {                                                                      \
    locker = PSI_FILE_CALL(get_thread_file_name_locker)(state, key.m_value, \
                                                        op, from, &locker); \
    if (locker != nullptr) {                                                \
      PSI_FILE_CALL(start_file_rename_wait)                                 \
      (locker, (size_t)0, from, to, src_location.filename,                  \
       static_cast<uint>(src_location.line));                               \
    }                                                                       \
  } while (0)
 
#define register_pfs_file_rename_end(locker, from, to, result)       \
  do {                                                               \
    if (locker != nullptr) {                                         \
      PSI_FILE_CALL(end_file_rename_wait)(locker, from, to, result); \
    }                                                                \
  } while (0)
 
#define register_pfs_file_close_begin(state, locker, key, op, name,          \
                                      src_location)                          \
  do {                                                                       \
    locker = PSI_FILE_CALL(get_thread_file_name_locker)(state, key.m_value,  \
                                                        op, name, &locker);  \
    if (locker != nullptr) {                                                 \
      PSI_FILE_CALL(start_file_close_wait)                                   \
      (locker, src_location.filename, static_cast<uint>(src_location.line)); \
    }                                                                        \
  } while (0)
 
#define register_pfs_file_close_end(locker, result)       \
  do {                                                    \
    if (locker != nullptr) {                              \
      PSI_FILE_CALL(end_file_close_wait)(locker, result); \
    }                                                     \
  } while (0)
 
#define register_pfs_file_io_begin(state, locker, file, count, op,           \
                                   src_location)                             \
  do {                                                                       \
    locker =                                                                 \
        PSI_FILE_CALL(get_thread_file_stream_locker)(state, file.m_psi, op); \
    if (locker != nullptr) {                                                 \
      PSI_FILE_CALL(start_file_wait)                                         \
      (locker, count, src_location.filename,                                 \
       static_cast<uint>(src_location.line));                                \
    }                                                                        \
  } while (0)
 
#define register_pfs_file_io_end(locker, count)    \
  do {                                             \
    if (locker != nullptr) {                       \
      PSI_FILE_CALL(end_file_wait)(locker, count); \
    }                                              \
  } while (0)
 
/* Following macros/functions are file I/O APIs that would be performance
schema instrumented if "UNIV_PFS_IO" is defined. They would point to
wrapper functions with performance schema instrumentation in such case.
 
os_file_create
os_file_create_simple_no_error_handling
os_file_close
os_file_rename
os_aio
os_file_read
os_file_read_no_error_handling
os_file_read_no_error_handling_int_fd
os_file_write
 
The wrapper functions have the prefix of "innodb_". */
 
#define os_file_create(key, name, create, purpose, read_only, success)    \
  pfs_os_file_create_func(key, name, create, purpose, read_only, success, \
                          UT_LOCATION_HERE)
 
#ifndef _WIN32
#define os_file_create_simple_no_error_handling(key, name, create_mode, \
                                                access, success)        \
  pfs_os_file_create_simple_no_error_handling_func(                     \
      key, name, create_mode, access, os_innodb_umask_default, success, \
      UT_LOCATION_HERE)
 
#define os_file_create_simple_no_error_handling_with_umask( \
    key, name, create_mode, access, umask, success)         \
  pfs_os_file_create_simple_no_error_handling_func(         \
      key, name, create_mode, access, umask, success, UT_LOCATION_HERE)
#else
#define os_file_create_simple_no_error_handling(key, name, create_mode, \
                                                access, success)        \
  pfs_os_file_create_simple_no_error_handling_func(                     \
      key, name, create_mode, access, success, UT_LOCATION_HERE)
#endif
 
#define os_file_close_pfs(file) pfs_os_file_close_func(file, UT_LOCATION_HERE)
 
#define os_aio(type, mode, name, file, buf, offset, n, callback)    \
  pfs_os_aio_func(type, mode, name, file, buf, offset, n, callback, \
                  UT_LOCATION_HERE)
 
#define os_file_read_pfs(type, file_name, file, buf, offset, n) \
  pfs_os_file_read_func(type, file_name, file, buf, offset, n, UT_LOCATION_HERE)
 
#define os_file_read_first_page_pfs(type, file_name, file, buf, n_pages) \
  pfs_os_file_read_first_page_func(type, file_name, file, buf, n_pages,  \
                                   UT_LOCATION_HERE)
 
#define os_file_copy_pfs(src, src_offset, dest, dest_offset, size) \
  pfs_os_file_copy_func(src, src_offset, dest, dest_offset, size,  \
                        UT_LOCATION_HERE)
 
#define os_file_read_no_error_handling_pfs(type, file_name, file, buf, offset, \
                                           n, o)                               \
  pfs_os_file_read_no_error_handling_func(type, file_name, file, buf, offset,  \
                                          n, o, UT_LOCATION_HERE)
 
#define os_file_read_no_error_handling_int_fd(type, file_name, file, buf, \
                                              offset, n, o)               \
  pfs_os_file_read_no_error_handling_int_fd_func(                         \
      type, file_name, file, buf, offset, n, o, UT_LOCATION_HERE)
 
#define os_file_write_pfs(type, name, file, buf, offset, n) \
  pfs_os_file_write_func(type, name, file, buf, offset, n, UT_LOCATION_HERE)
 
#define os_file_write_int_fd(type, name, file, buf, offset, n)    \
  pfs_os_file_write_int_fd_func(type, name, file, buf, offset, n, \
                                UT_LOCATION_HERE)
 
#define os_file_flush_pfs(file) pfs_os_file_flush_func(file, UT_LOCATION_HERE)
 
#define os_file_rename(key, oldpath, newpath) \
  pfs_os_file_rename_func(key, oldpath, newpath, UT_LOCATION_HERE)
 
#define os_file_delete(key, name) \
  pfs_os_file_delete_func(key, name, UT_LOCATION_HERE)
 
#define os_file_delete_if_exists(key, name, exist) \
  pfs_os_file_delete_if_exists_func(key, name, exist, UT_LOCATION_HERE)
 
/** Clang on Windows warns about umask not found. */
MY_COMPILER_DIAGNOSTIC_PUSH()
#ifdef _WIN32
MY_COMPILER_CLANG_DIAGNOSTIC_IGNORE("-Wdocumentation")
#endif
 
/** NOTE! Please use the corresponding macro
os_file_create_simple_no_error_handling(), not directly this function!
A performance schema instrumented wrapper function for
os_file_create_simple_no_error_handling(). Add instrumentation to
monitor file creation/open.
@param[in]      key             Performance Schema Key
@param[in]      name            name of the file or path as a null-terminated
                                string
@param[in]      create_mode     create mode
@param[in]      access_type     OS_FILE_READ_ONLY, OS_FILE_READ_WRITE, or
                                OS_FILE_READ_ALLOW_DELETE; the last option is
                                used by a backup program reading the file
@param[in]      umask           UNIX access permission to be set when creating a
                                file. Use os_umask_default to use global default
                                umask.
@param[out]     success         true if succeeded
@param[in]      src_location    location where func invoked
@return own: handle to the file, not defined if error, error number
        can be retrieved with os_file_get_and_log_last_error */
[[nodiscard]] static inline pfs_os_file_t
pfs_os_file_create_simple_no_error_handling_func(
    mysql_pfs_key_t key, const char *name, ulint create_mode, ulint access_type,
#ifndef _WIN32
    mode_t umask,
#endif
    bool *success, ut::Location src_location);
MY_COMPILER_DIAGNOSTIC_POP()
 
/** NOTE! Please use the corresponding macro os_file_create(), not directly
this function!
A performance schema wrapper function for os_file_create().
Add instrumentation to monitor file creation/open.
@param[in]      key               Performance Schema Key
@param[in]      name              name of the file or path as a null-terminated
                                  string
@param[in]      create_mode       create mode
@param[in]      purpose           OS_DATA_FILE, OS_LOG_FILE etc.
@param[in]      read_only         if true read only mode checks are enforced
@param[out]     success           true if succeeded
@param[in]      src_location      location where func invoked
@return own: handle to the file, not defined if error, error number
        can be retrieved with os_file_get_and_log_last_error */
[[nodiscard]] static inline pfs_os_file_t pfs_os_file_create_func(
    mysql_pfs_key_t key, const char *name, ulint create_mode, ulint purpose,
    bool read_only, bool *success, ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_close(), not directly
this function!
A performance schema instrumented wrapper function for os_file_close().
@param[in]      file            handle to a file
@param[in]      src_location    location where func invoked
@return true if success */
static inline bool pfs_os_file_close_func(pfs_os_file_t file,
                                          ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_read(), not directly
this function!
This is the performance schema instrumented wrapper function for
os_file_read() which requests a synchronous read operation.
@param[in, out] type            IO request context
@param[in]  file_name file name
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
static inline dberr_t pfs_os_file_read_func(const IORequest &type,
                                            const char *file_name,
                                            pfs_os_file_t file, byte *buf,
                                            os_offset_t offset, ulint n,
                                            ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_read_first_page(),
not directly this function!
This is the performance schema instrumented wrapper function for
os_file_read_first_page() which requests a synchronous read operation for first
@p n_pages pages of the @p file, using the page size stored on the first page.
It does not uncompress nor decrypt any pages.
@param[in, out] type            IO request context
@param[in]      file_name       file name
@param[in]      file            Open file handle
@param[in,out]  buf             Buffer where to read data to. It must be
                                aligned to OS device block size, it should be
                                safe to use 4KB alignment. It must have length
                                of at least `UNIV_PAGE_SIZE_MAX * n_pages`.
@param[in]      n_pages         How many pages to read.
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
static inline dberr_t pfs_os_file_read_first_page_func(
    IORequest &type, const char *file_name, pfs_os_file_t file, byte *buf,
    page_no_t n_pages, ut::Location src_location);
 
/** copy data from one file to another file. Data is read/written
at current file offset.
@param[in]      src             file handle to copy from
@param[in]      src_offset      offset to copy from
@param[in]      dest            file handle to copy to
@param[in]      dest_offset     offset to copy to
@param[in]      size            number of bytes to copy
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if successful */
static inline dberr_t pfs_os_file_copy_func(pfs_os_file_t src,
                                            os_offset_t src_offset,
                                            pfs_os_file_t dest,
                                            os_offset_t dest_offset, uint size,
                                            ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_read_no_error_handling(),
not directly this function!
This is the performance schema instrumented wrapper function for
os_file_read_no_error_handling_func() which requests a synchronous
read operation.
@param[in, out] type            IO request context
@param[in]  file_name file name
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[out]     o               number of bytes actually read
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
static inline dberr_t pfs_os_file_read_no_error_handling_func(
    IORequest &type, const char *file_name, pfs_os_file_t file, byte *buf,
    os_offset_t offset, ulint n, ulint *o, ut::Location src_location);
 
/** NOTE! Please use the corresponding macro
os_file_read_no_error_handling_int_fd(), not directly this function!
This is the performance schema instrumented wrapper function for
os_file_read_no_error_handling_int_fd_func() which requests a
synchronous read operation on files with int type descriptors.
@param[in, out] type            IO request context
@param[in]      file_name       file name
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[out]     o               number of bytes actually read
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
 
static inline dberr_t pfs_os_file_read_no_error_handling_int_fd_func(
    IORequest &type, const char *file_name, int file, byte *buf,
    os_offset_t offset, ulint n, ulint *o, ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_aio(), not directly this
function!
Performance schema wrapper function of os_aio() which requests
an asynchronous I/O operation.
@param[in]      type            IO request context
@param[in]      mode            IO mode
@param[in]      name            Name of the file or path as NUL terminated
                                string
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               how many bytes to read or write; this
must not cross a file boundary; in AIO this must be a block size multiple
@param[in]      callback        A lambda to be called when the result of this
                                operation is known. It may be a success if the
                                read or write succeeded or a subset of `dberr_t`
                                errors if the write or read could not be
                                executed or if it failed. It will be executed
                                asynchronously from another thread, before or
                                after this call returns.
@param[in]      location    location where func invoked
@return DB_SUCCESS if request was queued successfully, false if fail */
static inline dberr_t pfs_os_aio_func(IORequest &type, AIO_mode mode,
                                      const char *name, pfs_os_file_t file,
                                      byte *buf, os_offset_t offset, ulint n,
                                      std::function<void(dberr_t)> callback,
                                      ut::Location location);
 
/** NOTE! Please use the corresponding macro os_file_write(), not directly
this function!
This is the performance schema instrumented wrapper function for
os_file_write() which requests a synchronous write operation.
@param[in, out] type            IO request context
@param[in]      name            Name of the file or path as NUL terminated
                                string
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
static inline dberr_t pfs_os_file_write_func(IORequest &type, const char *name,
                                             pfs_os_file_t file,
                                             const byte *buf,
                                             os_offset_t offset, ulint n,
                                             ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_write(), not
directly this function!
This is the performance schema instrumented wrapper function for
os_file_write() which requests a synchronous write operation
on files with int type descriptors.
@param[in, out] type            IO request context
@param[in]      name            Name of the file or path as NUL terminated
                                string
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[in]      src_location    location where func invoked
@return DB_SUCCESS if request was successful */
static inline dberr_t pfs_os_file_write_int_fd_func(IORequest &type,
                                                    const char *name, int file,
                                                    const byte *buf,
                                                    os_offset_t offset, ulint n,
                                                    ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_flush(), not directly
this function!
This is the performance schema instrumented wrapper function for
os_file_flush() which flushes the write buffers of a given file to the disk.
Flushes the write buffers of a given file to the disk.
@param[in]      file            Open file handle
@param[in]      src_location    location where func invoked
@return true if success */
static inline bool pfs_os_file_flush_func(pfs_os_file_t file,
                                          ut::Location src_location);
 
/** NOTE! Please use the corresponding macro os_file_rename(), not directly
this function!
This is the performance schema instrumented wrapper function for
os_file_rename()
@param[in]      key             Performance Schema Key
@param[in]      oldpath         old file path as a null-terminated string
@param[in]      newpath         new file path
@param[in]      src_location    location where func invoked
@return true if success */
static inline bool pfs_os_file_rename_func(mysql_pfs_key_t key,
                                           const char *oldpath,
                                           const char *newpath,
                                           ut::Location src_location);
 
/**
NOTE! Please use the corresponding macro os_file_delete(), not directly
this function!
This is the performance schema instrumented wrapper function for
os_file_delete()
@param[in]      key             Performance Schema Key
@param[in]      name            old file path as a null-terminated string
@param[in]      src_location    location where func invoked
@return true if success */
static inline bool pfs_os_file_delete_func(mysql_pfs_key_t key,
                                           const char *name,
                                           ut::Location src_location);
 
/**
NOTE! Please use the corresponding macro os_file_delete_if_exists(), not
directly this function!
This is the performance schema instrumented wrapper function for
os_file_delete_if_exists()
@param[in]      key             Performance Schema Key
@param[in]      name            old file path as a null-terminated string
@param[in]      exist           indicate if file pre-exist
@param[in]      src_location    location where func invoked
@return true if success */
static inline bool pfs_os_file_delete_if_exists_func(mysql_pfs_key_t key,
                                                     const char *name,
                                                     bool *exist,
                                                     ut::Location src_location);
 
#else /* UNIV_PFS_IO */
 
/* If UNIV_PFS_IO is not defined, these I/O APIs point
to original un-instrumented file I/O APIs */
 
#define os_file_create(key, name, create, purpose, read_only, success) \
  os_file_create_func(name, create, purpose, read_only, success)
 
#ifndef _WIN32
 
#define os_file_create_simple_no_error_handling(key, name, create_mode, \
                                                access, success)        \
  os_file_create_simple_no_error_handling_func(                         \
      name, create_mode, access, os_innodb_umask_default, success)
 
#define os_file_create_simple_no_error_handling_with_umask(               \
    key, name, create_mode, access, umask, success)                       \
  os_file_create_simple_no_error_handling_func(name, create_mode, access, \
                                               umask, success)
 
#else
 
#define os_file_create_simple_no_error_handling(key, name, create_mode,   \
                                                access, success)          \
  os_file_create_simple_no_error_handling_func(name, create_mode, access, \
                                               success)
 
#endif
 
#define os_file_close_pfs(file) os_file_close_func(file)
 
#define os_aio(type, mode, name, file, buf, offset, n, callback) \
  os_aio_func(type, mode, name, file, buf, offset, n, callback)
 
#define os_file_read_pfs(type, file_name, file, buf, offset, n) \
  os_file_read_func(type, file_name, file, buf, offset, n)
 
#define os_file_read_first_page_pfs(type, file_name, file, buf, n_pages) \
  os_file_read_first_page_func(type, file_name, file, buf, n_pages)
 
#define os_file_copy_pfs(src, src_offset, dest, dest_offset, size) \
  os_file_copy_func(src, src_offset, dest, dest_offset, size)
 
#define os_file_read_no_error_handling_pfs(type, file_name, file, buf, offset, \
                                           n, o)                               \
  os_file_read_no_error_handling_func(type, file_name, file, buf, offset, n, o)
 
#define os_file_read_no_error_handling_int_fd(type, file_name, file, buf,     \
                                              offset, n, o)                   \
  os_file_read_no_error_handling_func(type, file_name, OS_FILE_FROM_FD(file), \
                                      buf, offset, n, o)
 
#define os_file_write_pfs(type, name, file, buf, offset, n) \
  os_file_write_func(type, name, file, buf, offset, n)
 
#define os_file_write_int_fd(type, name, file, buf, offset, n) \
  os_file_write_func(type, name, OS_FILE_FROM_FD(file), buf, offset, n)
 
#define os_file_flush_pfs(file) os_file_flush_func(file)
 
#define os_file_rename(key, oldpath, newpath) \
  os_file_rename_func(oldpath, newpath)
 
#define os_file_delete(key, name) os_file_delete_func(name)
 
#define os_file_delete_if_exists(key, name, exist) \
  os_file_delete_if_exists_func(name, exist)
 
#endif /* UNIV_PFS_IO */
 
#ifdef UNIV_PFS_IO
#define os_file_close(file) os_file_close_pfs(file)
#else
#define os_file_close(file) os_file_close_pfs((file).m_file)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_read(type, file_name, file, buf, offset, n) \
  os_file_read_pfs(type, file_name, file, buf, offset, n)
#else
#define os_file_read(type, file_name, file, buf, offset, n) \
  os_file_read_pfs(type, file_name, (file).m_file, buf, offset, n)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_read_first_page(type, file_name, file, buf, n_pages) \
  os_file_read_first_page_pfs(type, file_name, file, buf, n_pages)
#else
#define os_file_read_first_page(type, file_name, file, buf, n_pages) \
  os_file_read_first_page_pfs(type, file_name, (file).m_file, buf, n_pages)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_flush(file) os_file_flush_pfs(file)
#else
#define os_file_flush(file) os_file_flush_pfs((file).m_file)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_write(type, name, file, buf, offset, n) \
  os_file_write_pfs(type, name, file, buf, offset, n)
#else
#define os_file_write(type, name, file, buf, offset, n) \
  os_file_write_pfs(type, name, (file).m_file, buf, offset, n)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_copy(src, src_offset, dest, dest_offset, size) \
  os_file_copy_pfs(src, src_offset, dest, dest_offset, size)
#else
#define os_file_copy(src, src_offset, dest, dest_offset, size) \
  os_file_copy_pfs(src.m_file, src_offset, (dest).m_file, dest_offset, size)
#endif
 
#ifdef UNIV_PFS_IO
#define os_file_read_no_error_handling(type, file_name, file, buf, offset, n, \
                                       o)                                     \
  os_file_read_no_error_handling_pfs(type, file_name, file, buf, offset, n, o)
#else
#define os_file_read_no_error_handling(type, file_name, file, buf, offset, n, \
                                       o)                                     \
  os_file_read_no_error_handling_pfs(type, file_name, (file).m_file, buf,     \
                                     offset, n, o)
#endif
 
#ifdef UNIV_HOTBACKUP
/** Closes a file handle.
@param[in] file         handle to a file
@return true if success */
bool os_file_close_no_error_handling(os_file_t file);
#endif /* UNIV_HOTBACKUP */
 
/** Gets a file size.
@param[in]      filename        Full path to the filename to check
@return file size if OK, else set m_total_size to ~0 and m_alloc_size to
        errno. */
[[nodiscard]] os_file_size_t os_file_get_size(const char *filename);
 
/** Gets a file size.
@param[in]      file            Handle to a file
@return file size, or (os_offset_t) -1 on failure */
[[nodiscard]] os_offset_t os_file_get_size(pfs_os_file_t file);
 
/** Write the specified number of zeros to a file from specific offset, if the
end offset is beyond the end of file, the file will be resized to this offset.
If the file was or might have been opened in unbuffered mode, then the @p offset
and @p length must be aligned to UNIV_SECTOR_SIZE, and user should ensure these
restriction hold.
@param[in]      name             name of the file or path as a null-terminated
                                 string
@param[in]      file             handle to the file
@param[in]      offset           file offset from which to start writing zeros
@param[in]      length           number of bytes to zero
@param[in]      flush            flush file periodically if os_fsync_threshold
                                 is enabled or after the write is complete, to
                                 sync the range written and the file size
                                 metadata.
@param[in]      force_raw_writes Forces to use regular write calls to clear the
                                 range. The fallocate is still used, on systems
                                 that support it, as it has a side-effect of
                                 keeping OS from over-allocating additional
                                 space for the file as it grows. That is, on
                                 systems that do not support fallocate, this
                                 flag has no effect. */
[[nodiscard]] dberr_t os_file_fill_range_with_zeros(
    const char *name, pfs_os_file_t file, os_offset_t offset,
    os_offset_t length, bool flush, bool force_raw_writes);
 
/** Truncates a file at its current position.
@param[in,out]  file    file to be truncated
@return true if success */
bool os_file_set_eof(FILE *file); /*!< in: file to be truncated */
 
/** Truncates a file to a specified size in bytes.
Do nothing if the size to preserve is greater or equal to the current
size of the file.
@param[in]      pathname        file path
@param[in]      file            file to be truncated
@param[in]      size            size to preserve in bytes
@return true if success */
[[nodiscard]] bool os_file_truncate(const char *pathname, pfs_os_file_t file,
                                    os_offset_t size);
 
/** Set read/write position of a file handle to specific offset.
@param[in]      pathname        file path
@param[in]      file            file handle
@param[in]      offset          read/write offset
@return true if success */
bool os_file_seek(const char *pathname, os_file_t file, os_offset_t offset);
 
/** NOTE! Use the corresponding macro os_file_flush(), not directly this
function!
Flushes the write buffers of a given file to the disk.
@param[in]      file            handle to a file
@return true if success */
bool os_file_flush_func(os_file_t file);
 
/** Retrieves the last error number if an OS error occurs in a file IO function.
The number should be retrieved before any other OS calls (because they may
overwrite the error number). If the number is not known to this program,
the OS error number + 100 is returned. The error will also be logged to the
Server log.
@return error number, or OS error number + 100 */
[[nodiscard]] ulint os_file_get_and_log_last_error();
 
/** Logs the last error number if an OS error occurs in a file IO function.
The number should be retrieved before any other OS calls (because they may
overwrite the error number). The error will be logged to the Server log. */
void os_file_log_last_error();
 
/** NOTE! Use the corresponding macro os_file_read(), not directly
this function!
Requests a synchronous read operation of page 0 of IBD file.
@param[in]      type            IO request context
@param[in]      file_name       file name
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@return DB_SUCCESS if request was successful, DB_IO_ERROR on failure */
[[nodiscard]] dberr_t os_file_read_func(const IORequest &type,
                                        const char *file_name, os_file_t file,
                                        byte *buf, os_offset_t offset, ulint n);
 
/** NOTE! Use the corresponding macro os_file_read_first_page(),
not directly this function!
Requests a synchronous read operation for first @p n_pages pages of the @p file,
using the page size stored on the first page. It does not uncompress nor decrypt
any pages.
@param[in, out] type            IO request context
@param[in]      file_name       file name
@param[in]      file            Open file handle
@param[in,out]  buf             Buffer where to read data to. It must be
                                aligned to OS device block size, it should be
                                safe to use 4KB alignment. It must have length
                                of at least `UNIV_PAGE_SIZE_MAX * n_pages`.
@param[in]      n_pages         How many pages to read.
@return DB_SUCCESS if request was successful, DB_IO_ERROR on failure */
[[nodiscard]] dberr_t os_file_read_first_page_func(IORequest &type,
                                                   const char *file_name,
                                                   os_file_t file, byte *buf,
                                                   page_no_t n_pages);
 
/** Copy data from one file to another file. Data is read/written
at current file offset.
@param[in]      src_file        file handle to copy from
@param[in]      src_offset      offset to copy from
@param[in]      dest_file       file handle to copy to
@param[in]      dest_offset     offset to copy to
@param[in]      size            number of bytes to copy
@return DB_SUCCESS if successful */
[[nodiscard]] dberr_t os_file_copy_func(os_file_t src_file,
                                        os_offset_t src_offset,
                                        os_file_t dest_file,
                                        os_offset_t dest_offset, uint size);
 
/** Rewind file to its start, read at most size - 1 bytes from it to str, and
NUL-terminate str. All errors are silently ignored. This function is
mostly meant to be used with temporary files.
@param[in,out]  file            File to read from
@param[in,out]  str             Buffer where to read
@param[in]      size            Size of buffer */
void os_file_read_string(FILE *file, char *str, ulint size);
 
/** NOTE! Use the corresponding macro os_file_read_no_error_handling(),
not directly this function!
Requests a synchronous positioned read operation. This function does not do
any error handling. In case of error it returns false.
@param[in]      type            IO request context
@param[in]      file_name       file name
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@param[out]     o               number of bytes actually read
@return DB_SUCCESS or error code */
[[nodiscard]] dberr_t os_file_read_no_error_handling_func(
    IORequest &type, const char *file_name, os_file_t file, byte *buf,
    os_offset_t offset, ulint n, ulint *o);
 
/** NOTE! Use the corresponding macro os_file_write(), not directly this
function!
Requests a synchronous write operation.
@param[in,out]  type            IO request context
@param[in]      name            name of the file or path as a null-terminated
                                string
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               number of bytes to read
@return DB_SUCCESS if request was successful */
[[nodiscard]] dberr_t os_file_write_func(IORequest &type, const char *name,
                                         os_file_t file, const byte *buf,
                                         os_offset_t offset, ulint n);
 
/** Check the existence and usefulness of a given path.
@param[in]  path  path name
@retval true if the path definitely exists and can be used
@retval false if the path does not exist or if the path is
unusable due to access or other issue */
[[nodiscard]] bool os_file_exists(const char *path);
 
/** Checks the existence and type (dir, file, link, unknown) of given path.
Might fail in various ways (path might be too long, io might fail, access could
be blocked etc). Usually the file type is fed to the following helper methods:
- os_file_status_is_conclusive()
- os_file_exists()
- os_file_is_missing()
In case of failure os_file_status_is_conclusive(returned_type) would return
false, since existence or type might not be established therefore,
os_file_exists(returned_type) and os_file_is_missing(returned_type) will also
return false
@param[in]   path    pathname of the file
@return type of the file */
[[nodiscard]] os_file_type_t os_file_type(const char *path);
 
/** A helper method that usually is feed the file_type returned by the
os_file_type() method. It concludes the file status as following :
- File exists and there are no access, invalid path or other issues.
- File does not exist therefore it could be created.
@param  type  OS file type
@return true  file status is conclusive
@return false Otherwise */
[[nodiscard]] bool os_file_status_is_conclusive(os_file_type_t type);
 
/** A helper method that usually is feed the file_type returned by the
os_file_type() method. It indicates that file exists and there are no access,
invalid path or other issues.
@param  type  OS file type
@return true  file definitely exists and usable
@return false Otherwise */
[[nodiscard]] bool os_file_exists(os_file_type_t type);
 
/** A helper method that usually is feed the file_type returned by the
os_file_type() method. It indicates that file is definitely missing.
@param  type  OS file type
@return true  file is definitely missing
@return false Otherwise */
[[nodiscard]] bool os_file_is_missing(os_file_type_t type);
 
/** Create all missing subdirectories along the given path.
@return DB_SUCCESS if OK, otherwise error code. */
[[nodiscard]] dberr_t os_file_create_subdirs_if_needed(const char *path);
 
#ifdef UNIV_ENABLE_UNIT_TEST_GET_PARENT_DIR
/* Test the function os_file_get_parent_dir. */
void unit_test_os_file_get_parent_dir();
#endif /* UNIV_ENABLE_UNIT_TEST_GET_PARENT_DIR */
 
#ifdef UNIV_HOTBACKUP
/** Deallocates the "Blocks" in block_cache */
void meb_free_block_cache();
#endif /* UNIV_HOTBACKUP */
 
/** Creates and initializes block_cache. Creates array of MAX_BLOCKS
and allocates the memory in each block to hold UNIV_PAGE_SIZE bytes of data.
 
This function is called by InnoDB during srv_start().
It is also called by MEB while applying the redo logs on TDE tablespaces,
the "Blocks" allocated in this block_cache are used to hold the decrypted
page data. */
void os_create_block_cache();
 
#ifndef UNIV_HOTBACKUP
 
/** Initializes the asynchronous io system.
Creates an array for ibuf i/o (if not in read-only mode).
Also creates one array each for read and write where each
array is divided logically into n_readers and n_writers
respectively. The caller must create an i/o handler thread for each
segment in these arrays by calling os_aio_start_threads().
 
@param[in]      n_readers       number of reader threads
@param[in]      n_writers       number of writer threads */
[[nodiscard]] bool os_aio_init(ulint n_readers, ulint n_writers);
 
/** Starts one thread for each segment created in os_aio_init */
void os_aio_start_threads();
 
/**
Frees the asynchronous io system. */
void os_aio_free();
 
/**
NOTE! Use the corresponding macro os_aio(), not directly this function!
Requests an asynchronous i/o operation.
@param[in]      type            IO request context
@param[in]      aio_mode        IO mode
@param[in]      name            Name of the file or path as NUL terminated
  string
@param[in]      file            Open file handle
@param[out]     buf             buffer where to read
@param[in]      offset          file offset where to read
@param[in]      n               how many bytes to read or write; this
  must not cross a file boundary; in AIO this must be a block size multiple
@param[in]      callback        A lambda to be called when the result of this
                                operation is known. It may be a success if the
                                read or write succeeded or a subset of `dberr_t`
                                errors if the write or read could not be
                                executed or if it failed. It will be executed
                                asynchronously from another thread, before or
                                after this call returns.
@return DB_SUCCESS or error code */
[[nodiscard]] dberr_t os_aio_func(IORequest &type, AIO_mode aio_mode,
                                  const char *name, pfs_os_file_t file,
                                  byte *buf, os_offset_t offset, ulint n,
                                  std::function<void(dberr_t)> callback);
 
/** Wakes up all async i/o threads so that they know to exit themselves in
shutdown. */
void os_aio_wake_all_threads_at_shutdown();
 
/** Waits until there are no pending writes in os_aio_write_array. There can
be other, synchronous, pending writes. */
void os_aio_wait_until_no_pending_writes();
 
/** Wakes up simulated aio i/o-handler threads if they have something to do.
 */
void os_aio_simulated_wake_handler_threads();
 
/** This function can be called if one wants to post a batch of reads and
prefers an i/o-handler thread to handle them all at once later. You must
call os_aio_simulated_wake_handler_threads later to ensure the threads
are not left sleeping! */
void os_aio_simulated_put_read_threads_to_sleep();
 
/** Waits for an AIO operation to complete. This function is used to wait the
for completed requests. After the IO completes this method returns the IO
metadata and callback specified when issuing the IO, to allow the IO completion
routines to be called. It may return before any AIO completes, but only in case
the InnoDB is shutting down. In such case the DB_SHUTTING_DOWN is returned. The
AIO array of pending requests is divided into segments. The thread specifies
which segment or slot it wants to wait for. NOTE: this function will also take
care of freeing the AIO slot, therefore no other thread is allowed to do the
freeing!
@param[in]      segment         The number of the segment in the AIO arrays to
                                wait for; segment 0 is the ibuf I/O thread,
                                then follow the non-ibuf read threads, and as
                                the last are the non-ibuf write threads
@param[out]     callback        The callback specified when issuing the AIO
                                operation. It should be called as part of IO
                                completion routines. It will not be set if the
                                returned error code is DB_SHUTTING_DOWN.
@param[out]     request         The IO request metadata specified when issuing
                                the AIO operation. It will not be set if the
                                returned error code is DB_SHUTTING_DOWN.
@return DB_SUCCESS, DB_SHUTTING_DOWN or error code of result of the IO
operation. */
[[nodiscard]] dberr_t os_aio_handler(ulint segment,
                                     std::function<void(dberr_t)> &callback,
                                     IORequest *request);
 
/** Prints info of the aio arrays.
@param[in,out]  file            file where to print */
void os_aio_print(FILE *file);
 
/** Refreshes the statistics used to print per-second averages. */
void os_aio_refresh_stats();
 
/** Checks that all slots in the system have been freed, that is, there are
no pending io operations. */
[[nodiscard]] bool os_aio_all_slots_free();
 
#ifdef UNIV_DEBUG
 
/** Prints all pending IO
@param[in]      file            File where to print */
void os_aio_print_pending_io(FILE *file);
 
#endif /* UNIV_DEBUG */
#endif /* !UNIV_HOTBACKUP */
 
/** Get available free space on disk
@param[in]      path            pathname of a directory or file in disk
@param[out]     free_space      free space available in bytes
@return DB_SUCCESS if all OK */
[[nodiscard]] dberr_t os_get_free_space(const char *path, uint64_t &free_space);
 
/** Stores information about access modes to the resource permitted to the
caller at the moment of checking them. */
struct Access_permissions {
  bool has_read_access;
  bool has_write_access;
};
 
/** This function checks if we have read and/or write permissions at the time of
checking. These are not just the FS-related file permissions, as they are not
enough in case the file is locked for read and/or write.
@param[in]      path             pathname of the file
@param[in]      is_raw_device    true if the path is specified to a raw device.
@return Access modes possible for the path at the time of checking. */
[[nodiscard]] Access_permissions os_file_check_access(const char *path,
                                                      bool is_raw_device);
 
/** This function returns information about the specified file
@param[in]      path            pathname of the file
@param[out]     stat_info       information of a file in a directory
@return DB_SUCCESS if all OK */
[[nodiscard]] dberr_t os_file_get_status(const char *path,
                                         os_file_stat_t *stat_info);
 
/** Check if a file can be opened in read-write mode.
 @param[in]   name          filename to check
 @param[in]   is_raw_device true if the path is specified to a raw device.
 @param[in]   read_only     true if check for read-only mode only
 @retval true   if file can be opened in the specified mode (rw or ro);
                or file does not exist
 @retval false  if file exists and can't be opened in the specified mode */
[[nodiscard]] bool os_file_check_mode(const char *name, bool is_raw_device,
                                      bool read_only);
 
#ifndef UNIV_HOTBACKUP
 
/** return any of the tmpdir path */
[[nodiscard]] char *innobase_mysql_tmpdir();
 
/** Creates a temporary file in the location specified by the parameter
path. If the path is NULL, then it will be created in --tmpdir.
@param[in]      path    location for creating temporary file
@return temporary file descriptor, or OS_FD_CLOSED on error */
[[nodiscard]] os_fd_t innobase_mysql_tmpfile(const char *path);
 
#endif /* !UNIV_HOTBACKUP */
 
/** If it is a compressed page return the compressed page data + footer size
@param[in]      buf             Buffer to check, must include header + 10
bytes
@return ULINT_UNDEFINED if the page is not a compressed page or length
        of the compressed data (including footer) if it is a compressed page
*/
[[nodiscard]] ulint os_file_compressed_page_size(const byte *buf);
 
#ifndef _WIN32
/** Set the global file create umask. This value is to be set once, at startup
and never modified.
@param[in]      umask           The umask to use for all InnoDB file creation.
*/
void os_file_set_umask(mode_t umask);
 
/** A magic constant for the umask parameter that indicates caller wants the
`os_innodb_umask` value to be used. The `os_innodb_umask` is a static value,
private to this module, and to the file creation methods, so it should not be
used directly. */
constexpr mode_t os_innodb_umask_default = std::numeric_limits<mode_t>::max();
 
#endif
 
/** Free storage space associated with a section of the file.
@param[in]      fh              Open file handle
@param[in]      off             Starting offset (SEEK_SET)
@param[in]      len             Size of the hole
@return DB_SUCCESS or error code */
[[nodiscard]] dberr_t os_file_punch_hole(os_file_t fh, os_offset_t off,
                                         os_offset_t len);
 
/** Decompress the page data contents. Page type must be FIL_PAGE_COMPRESSED,
if not then the source contents are left unchanged and DB_SUCCESS is returned.
@param[in]      dblwr_read      true of double write recovery in progress
@param[in,out]  src             Data read from disk, decompressed data will be
                                copied to this page
@param[in,out]  dst             Scratch area to use for decompression or
                                nullptr.
@param[in]      dst_len         If dst is valid, then size of the scratch area
                                in bytes
@return DB_SUCCESS or error code */
[[nodiscard]] dberr_t os_file_decompress_page(bool dblwr_read, byte *src,
                                              byte *dst, ulint dst_len);
 
/** Compress a data page
@param[in]      compression     Compression algorithm
@param[in]      block_size      File system block size
@param[in]      src             Source contents to compress
@param[in]      src_len         Length in bytes of the source
@param[out]     dst             Compressed page contents
@param[out]     dst_len         Length in bytes of dst contents
@return buffer data, dst_len will have the length of the data */
[[nodiscard]] byte *os_file_compress_page(Compression compression,
                                          ulint block_size, byte *src,
                                          ulint src_len, byte *dst,
                                          ulint *dst_len);
 
/** Determine if O_DIRECT is supported.
@retval true    if O_DIRECT is supported.
@retval false   if O_DIRECT is not supported. */
[[nodiscard]] bool os_is_o_direct_supported();
 
#ifndef UNIV_NONINL
/** Class to scan the directory hierarchy using a depth first scan. */
class Dir_Walker {
 public:
  using Path = std::string;
 
  /** Check if the path is a directory. The file/directory must exist.
  @param[in]    path            The path to check
  @return true if it is a directory */
  static bool is_directory(const Path &path);
 
  /** Depth first traversal of the directory starting from basedir
  @param[in]  basedir    Start scanning from this directory
  @param[in]  recursive  `true` if scan should be recursive
  @param[in]  f          Function to call for each entry */
  template <typename F>
  static void walk(const Path &basedir, bool recursive, F &&f) {
#ifdef _WIN32
    walk_win32(basedir, recursive, [&](const Path &path, size_t) { f(path); });
#else
    walk_posix(basedir, recursive, [&](const Path &path, size_t) { f(path); });
#endif /* _WIN32 */
  }
 
 private:
  /** Directory names for the depth first directory scan. */
  struct Entry {
    /** Constructor
    @param[in]  path            Directory to traverse
    @param[in]  depth           Relative depth to the base
                                    directory in walk() */
    Entry(const Path &path, size_t depth) : m_path(path), m_depth(depth) {}
 
    /** Path to the directory */
    Path m_path;
 
    /** Relative depth of m_path */
    size_t m_depth;
  };
 
  using Function = std::function<void(const Path &, size_t)>;
 
  /** Depth first traversal of the directory starting from basedir
  @param[in]  basedir     Start scanning from this directory
  @param[in]  recursive  `true` if scan should be recursive
  @param[in]  f           Function to call for each entry */
#ifdef _WIN32
  static void walk_win32(const Path &basedir, bool recursive, Function &&f);
#else
  static void walk_posix(const Path &basedir, bool recursive, Function &&f);
#endif /* _WIN32 */
};
 
/** Allocate a page for sync IO
@return pointer to page */
[[nodiscard]] file::Block *os_alloc_block() noexcept;
 
/** Get the sector aligned frame pointer.
@param[in]  block   the memory block containing the page frame.
@return the sector aligned frame pointer. */
[[nodiscard]] byte *os_block_get_frame(const file::Block *block) noexcept;
 
/** Free a page after sync IO
@param[in,out]  block           The block to free/release */
void os_free_block(file::Block *block) noexcept;
 
inline void file::Block::free(file::Block *obj) noexcept { os_free_block(obj); }
 
/** Encrypt a page content when write it to disk.
@param[in]      type            IO flags
@param[out]     buf             buffer to read or write
@param[in]      n               number of bytes to read/write, starting from
                                offset
@return pointer to the encrypted page */
file::Block *os_file_encrypt_page(const IORequest &type, byte *&buf, ulint n);
 
/** Allocate the buffer for IO on a transparently compressed table.
@param[in]      type            IO flags
@param[out]     buf             buffer to read or write
@param[in,out]  n               number of bytes to read/write, starting from
                                offset
@return pointer to allocated page, compressed data is written to the offset
        that is aligned on the disk sector size */
file::Block *os_file_compress_page(IORequest &type, byte *&buf, ulint *n);
 
/** This is a wrapper function for the os_file_write() function call.  The
purpose of this wrapper function is to retry on i/o error. On I/O error
(perhaps because of disk full situation) keep retrying the write operation
till it succeeds.
@param[in]  type     IO flags
@param[in]  name     name of the file or path as a null-terminated string
@param[in]  file     handle to an open file
@param[out] buf      buffer from which to write
@param[in]  offset   file offset from the start where to read
@param[in]  n        number of bytes to read, starting from offset
@return DB_SUCCESS if request was successful, false if fail */
dberr_t os_file_write_retry(IORequest &type, const char *name,
                            pfs_os_file_t file, const byte *buf,
                            os_offset_t offset, ulint n);
 
/** Helper class for doing synchronous file IO. Currently, the objective
is to hide the OS specific code, so that the higher level functions aren't
peppered with "#ifdef". Makes the code flow difficult to follow.  */
class SyncFileIO {
 public:
  /** Constructor
  @param[in]    fh      File handle
  @param[in,out]        buf     Buffer to read/write
  @param[in]    n       Number of bytes to read/write
  @param[in]    offset  Offset where to read or write */
  SyncFileIO(os_file_t fh, void *buf, ulint n, os_offset_t offset)
      : m_fh(fh),
        m_buf(buf),
        m_n(static_cast<ssize_t>(n)),
        m_offset(offset),
        m_orig_bytes(n) {
    ut_ad(m_n > 0);
  }
 
  /** Destructor */
  ~SyncFileIO() = default;
 
  /** Do the read/write
  @param[in]    request The IO context and type
  @return the number of bytes read/written or negative value on error */
  ssize_t execute(const IORequest &request);
 
  /** Do the read/write with retry.
  @param[in] request The IO context and type
  @param[in] max_retries  the maximum number of retries on partial i/o.
  @return DB_SUCCESS on success, an error code on failure. */
  dberr_t execute_with_retry(
      const IORequest &request,
      const size_t max_retries = NUM_RETRIES_ON_PARTIAL_IO);
 
  /** Move the read/write offset up to where the partial IO succeeded.
  @param[in]    n_bytes The number of bytes to advance */
  void advance(ssize_t n_bytes) {
    m_offset += n_bytes;
 
    ut_ad(m_n >= n_bytes);
 
    m_n -= n_bytes;
 
    m_buf = reinterpret_cast<uchar *>(m_buf) + n_bytes;
  }
 
 private:
  /** Open file handle */
  os_file_t m_fh;
 
  /** Buffer to read/write */
  void *m_buf;
 
  /** Number of bytes to read/write */
  ssize_t m_n;
 
  /** Offset from where to read/write */
  os_offset_t m_offset;
 
  /** The total number of bytes to be read/written. */
  const size_t m_orig_bytes;
};
 
#include "os0file.ic"
#endif /* UNIV_NONINL */
 
#endif /* os0file_h */