Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

◄Changes►                                             ◄Up► ◄Next► ◄Previous►
────────────────────────────────────────────────────────────────────────────
 
#define INCL_DOSQUEUES
 
USHORT DosMakePipe(phfRead, phfWrite, cbPipe)
PHFILE phfRead;     /* pointer to variable for read handle  */
PHFILE phfWrite;    /* pointer to variable for write handle */
USHORT cbPipe;      /* number of bytes reserved for pipe    */
 
The DosMakePipe function creates a pipe. The function creates the pipe,
assigning the specified pipe size to the storage buffer, and also creates
handles that the process can use to read from and write to the buffer in
subsequent calls to the DosRead and DosWrite functions.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
phfRead    Points to the variable that receives the read handle for the
           pipe.
 
phfWrite   Points to the variable that receives the write handle for the
           pipe.
 
cbPipe     Specifies the size (in bytes) to allocate for the storage buffer
           for this pipe. This can be any value up to 65,536 minus the size
           of the pipe header, which is currently 32 bytes. If this
           parameter is zero, the default buffer size is used. (The buffer
           size is advisory only. MS OS/2 may allocate more or less space.)
 
Return Value
 
The return value is zero if the function is successful. Otherwise, it is an
error value, which may be one of the following:
 
     ERROR_NOT_ENOUGH_MEMORY
     ERROR_TOO_MANY_OPEN_FILES
 
Comments
 
Pipes are typically used by a pair of processes. One process creates the
pipe and passes a handle to the other process. This lets one process write
into the pipe and the other read from the pipe. Since MS OS/2 provides no
permission checks on pipes, the cooperating processes must ensure that they
do not attempt to write to or read from the pipe at the same time.
 
When all of a pipe's handles are closed by using the DosClose function, MS
OS/2 deletes that pipe. If two processes are communicating by using a pipe
and the process that is reading the pipe ends, the next call to the
DosWrite function for that pipe returns the "broken pipe" error value.
 
MS OS/2 temporarily blocks any call to the DosWrite function that would
write more data to the pipe than can fit in the storage buffer. The system
removes the block as soon as enough data is read from the pipe to make room
for the remaining unwritten data.
 
See Also
 
DosClose, DosDupHandle, DosRead, DosWrite
 
                                      ♦