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MMIOINFO structure

The MMIOINFO structure contains the current state of a file opened by using the mmioOpen function.

Syntax

typedef struct {
  DWORD      dwFlags;
  FOURCC     fccIOProc;
  LPMMIOPROC pIOProc;
  UINT       wErrorRet;
  HTASK      hTask;
  LONG       cchBuffer;
  HPSTR      pchBuffer;
  HPSTR      pchNext;
  HPSTR      pchEndRead;
  HPSTR      pchEndWrite;
  LONG       lBufOffset;
  LONG       lDiskOffset;
  DWORD      adwInfo[4];
  DWORD      dwReserved1;
  DWORD      dwReserved2;
  HMMIO      hmmio;
} MMIOINFO;

Members

  • dwFlags
    Flags specifying how a file was opened. The following values are defined:

    Name Description
    MMIO_ALLOCBUF

    File's I/O buffer was allocated by the mmioOpen or mmioSetBuffer function.

    MMIO_CREATE

    The mmioOpen function was directed to create the file (or truncate it to zero length if it already existed).

    MMIO_DIRTY

    The I/O buffer has been modified.

    MMIO_EXIST

    Checks for the existence of the file.

    MMIO_GETTEMP

    A temporary name was retrieved by the mmioOpen function.

    MMIO_PARSE

    The new file's path is returned.

     

    The following values may be set when the file is opened in share mode (identified by using the MMIO_SHAREMODE bit mask):

    Name Description
    MMIO_COMPAT

    File was opened with compatibility mode, allowing any process on a given machine to open the file any number of times.

    MMIO_DENYNONE

    Other processes are not denied read or write access to the file.

    MMIO_DENYREAD

    Other processes are denied read access to the file.

    MMIO_DENYWRITE

    Other processes are denied write access to the file.

    MMIO_EXCLUSIVE

    Other processes are denied read and write access to the file.

     

    The following values may be set when the file is opened in read/write mode (identified by using the MMIO_RWMODE bit mask):

    Name Description
    MMIO_READ

    File was opened only for reading.

    MMIO_READWRITE

    File was opened for reading and writing.

    MMIO_WRITE

    File was opened only for writing.

     

  • fccIOProc
    Four-character code identifying the file's I/O procedure. If the I/O procedure is not an installed I/O procedure, this member is NULL.

  • pIOProc
    Pointer to file's IO procedure.

  • wErrorRet
    Extended error value from the mmioOpen function if it returns NULL. This member is not used to return extended error information from any other functions.

  • hTask
    Handle to a local I/O procedure. Media Control Interface (MCI) devices that perform file I/O in the background and need an I/O procedure can locate a local I/O procedure with this handle.

  • cchBuffer
    Size, in bytes, of the file's I/O buffer. If the file does not have an I/O buffer, this member is zero.

  • pchBuffer
    Pointer to the file's I/O buffer. If the file is unbuffered, this member is NULL.

  • pchNext
    Pointer to the next location in the I/O buffer to be read or written. If no more bytes can be read without calling the mmioAdvance or mmioRead function, this member points to the pchEndRead member. If no more bytes can be written without calling the mmioAdvance or mmioWrite function, this member points to the pchEndWrite member.

  • pchEndRead
    Pointer to the location that is 1 byte past the last location in the buffer that can be read.

  • pchEndWrite
    Pointer to the location that is 1 byte past the last location in the buffer that can be written.

  • lBufOffset
    Reserved.

  • lDiskOffset
    Current file position, which is an offset, in bytes, from the beginning of the file. I/O procedures are responsible for maintaining this member.

  • adwInfo
    State information maintained by the I/O procedure. I/O procedures can also use these members to transfer information from the application to the I/O procedure when the application opens a file.

  • dwReserved1
    Reserved.

  • dwReserved2
    Reserved.

  • hmmio
    Handle to the open file, as returned by the mmioOpen function. I/O procedures can use this handle when calling other multimedia file I/O functions.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Mmsystem.h (include Windows.h)

See also

mmioAdvance

mmioOpen

mmioRead

mmioSetBuffer

mmioWrite