DosWrite
Bindings: C, MASM
This call transfers the specified number of bytes from a buffer to the
specified file, synchronously with respect to the requesting process's
execution.
DosWrite (FileHandle, BufferArea, BufferLength, BytesWritten)
FileHandle (HFILE) - input
File handle from DosOpen.
BufferArea (PVOID) - input
Address of the output buffer.
BufferLength (USHORT) - input
Number of bytes to write.
BytesWritten (PUSHORT) - output
Address of the number of bytes written.
rc (USHORT) - return
Return code descriptions are:
0 NO_ERROR
5 ERROR_ACCESS_DENIED
6 ERROR_INVALID_HANDLE
26 ERROR_NOT_DOS_DISK
33 ERROR_LOCK_VIOLATION
109 ERROR_BROKEN_PIPE
Remarks
On output, BytesWritten is the number of bytes actually written. If
BytesWritten is different from BufferLength, this usually indicates
insufficient disk space.
A BufferLength value of 0 is not considered an error. No data transfer
occurs. There is no effect on the file or the file pointer.
Buffers that are multiples of the hardware's base physical unit for data
written to the file on these base boundaries, are written directly to the
device. (The base physical unit is defined as the smallest block that
can be physically written to the device.) Other buffer sizes force some
I/O to go through an internal system buffer and greatly reduce the
efficiency of I/O operation.
The file pointer is moved by read and write operations. It can be moved
to a desired position by calling DosChgFilePtr.
If the file is read-only, the write to the file is not performed.
Family API Considerations
Some options operate differently in the DOS mode than in OS/2 mode.
Therefore, the following restriction applies to DosWrite when coding for
the DOS mode.
o Only single-byte DosWrite requests can be made to the COM device,
because the COM device driver for the DOS environment does not support
multiple-byte I/O.
Named Pipe Considerations
DosWrite is also used to write bytes or messages to a named pipe.
Each write to a message pipe writes a message whose size is the length of
the write; DosWrite automatically encodes message lengths in the pipe, so
applications need not encode this information in the buffer being
written.
Writes in blocking mode always write all requested bytes before
returning. In non-blocking mode, if the message size is bigger than the
buffer size, the write blocks. If the message size is smaller than the
pipe but not enough space is left in the pipe, the write returns
immediately with a value of zero, indicating no bytes were written.
In the case of a byte pipe, if the number of bytes to be written exceeds
the space available in the pipe, DosWrite writes as many bytes as it can
and returns with the number of bytes actually written.
An attempt to write to a pipe whose other end has been closed returns
ERROR_BROKEN_PIPE.
Created using Inf-PHP v.2 (c) 2003 Yuri Prokushev
Created using Inf-HTML v.0.9b (c) 1995 Peter Childs