DosMakeMailslot or Dos32MakeMailslot

The DosMakeMailslot API creates a mailslot and returns its handle.

Restrictions

This API can be called from DLS and OS/2 workstations. A call to this API must be issued locally.

Mailslot names must be unique; no two mailslots on any one computer can have the same name.

Mailslot handles cannot be passed to other processes by way of the OS/2 DosExecPgm function. Mailslot handles can be shared, however, among threads in a single process. Thus, multiple threads can use the same handle to read or write data to the mailslot.

Syntax

#include <netcons.h>
#include <mailslot.h>
 
DosMakeMailslot(pMailslotName, messagesize,
               mailslotsize, pMailslotHandle);     /* 16 bit */
 
Dos32MakeMailslot(pMailslotName, messagesize,
               mailslotsize, pMailslotHandle);     /* 32 bit */

Parameters

See Common Parameter Definitions for descriptions of parameters not defined here.

pMailslotName

(const unsigned char) points to an ASCIIZ string containing the name for the mailslot. Use the format \mailslot\name.
messagesize
(16-bit unsigned short or 32-bit unsigned long) specifies the maximum message size (in bytes) the mailslot can accept. Generally, mailslots cannot accept messages larger than 65475 bytes.
mailslotsize
(16-bit unsigned short or 32-bit unsigned long) specifies the size (in bytes) of the mailslot. The value of mailslotsize must be equal to or greater than the value of messagesize.
pMailslotHandle
(unsigned long LSFAR *) points to an unsigned integer that is the returned handle for the mailslot.
Return Codes

The following table lists the return codes most significant to this API. (See API Return Codes for a complete list of return codes.) ┌────────────────────────┬───────┬─────────────────────────────────────────────┐│SYMBOLICCONSTANT │VALUE│MEANING │
├────────────────────────┼───────┼─────────────────────────────────────────────┤
│ NERR_Success │ 0 │ No errors were encountered. │
├────────────────────────┼───────┼─────────────────────────────────────────────┤
│ ERROR_PATH_NOT_FOUND │ 3 │ The path was not found. │
├────────────────────────┼───────┼─────────────────────────────────────────────┤
│ ERROR_NOT_ENOUGH_MEMORY│ 8 │ Sufficient memory is not available. │
├────────────────────────┼───────┼─────────────────────────────────────────────┤
│ ERROR_INVALID_PARAMETER│ 87 │ At least one parameter value is not valid. │
└────────────────────────┴───────┴─────────────────────────────────────────────┘


Other codes could be returned from the following functions:

• DosAllocShrSeg
  
• DosExitList

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