mutagen/_util.py
def delete_bytes(fobj, size, offset, BUFFER_SIZE=2**16):
    """Delete size bytes of empty space starting at offset.

    fobj must be an open file object, open rb+ or
    equivalent. Mutagen tries to use mmap to resize the file, but
    falls back to a significantly slower method if mmap fails.
    """

    locked = False
    assert 0 < size
    assert 0 <= offset
    fobj.seek(0, 2)
    filesize = fobj.tell()
    movesize = filesize - offset - size
    assert 0 <= movesize
    try:
        if movesize > 0:
            fobj.flush()
            try:
                import mmap
                file_map = mmap.mmap(fobj.fileno(), filesize)
                try:
                    file_map.move(offset, offset + size, movesize)
                finally:
                    file_map.close()
            except (ValueError, EnvironmentError, ImportError):
                # handle broken mmap scenarios
                locked = lock(fobj)
                fobj.seek(offset + size)
                buf = fobj.read(BUFFER_SIZE)
                while buf:
                    fobj.seek(offset)
                    fobj.write(buf)
                    offset += len(buf)
                    fobj.seek(offset + size)
                    buf = fobj.read(BUFFER_SIZE)
        fobj.truncate(filesize - size)
        fobj.flush()
    finally:
        if locked:
            unlock(fobj)
def delete_bytes(fobj, size, offset, BUFFER_SIZE=2**16):
    """Delete size bytes of empty space starting at offset.

    fobj must be an open file object, open rb+ or
    equivalent. Mutagen tries to use mmap to resize the file, but
    falls back to a significantly slower method if mmap fails.
    """

    locked = False
    assert 0 < size
    assert 0 <= offset
    fobj.seek(0, 2)
    filesize = fobj.tell()
    movesize = filesize - offset - size
    assert 0 <= movesize
    try:
        if movesize > 0:
            fobj.flush()
            try:
                import mmap
                file_map = mmap.mmap(fobj.fileno(), filesize)
                try:
                    file_map.move(offset, offset + size, movesize)
                finally:
                    file_map.close()
            except (ValueError, EnvironmentError, ImportError):
                # handle broken mmap scenarios
                locked = lock(fobj)
                fobj.seek(offset + size)
                buf = fobj.read(BUFFER_SIZE)
                while buf:
                    fobj.seek(offset)
                    fobj.write(buf)
                    offset += len(buf)
                    fobj.seek(offset + size)
                    buf = fobj.read(BUFFER_SIZE)
        fobj.truncate(filesize - size)
        fobj.flush()
    finally:
        if locked:
            unlock(fobj)
Delete size bytes of empty space starting at offset.

    fobj must be an open file object, open rb+ or
    equivalent. Mutagen tries to use mmap to resize the file, but
    falls back to a significantly slower method if mmap fails.