mmioDetermineSSIOProc

The mmioDetermineSSIOProc function determines the storage system I/O procedure (SSIOProc) required for a media data object. It identifies the storage system based on the provided file name or information in the MMIOINFO structure.

Syntax

#define INCL_MMIOOS2
#include <os2.h>

ULONG mmioDetermineSSIOProc(PSZ pszFileName, PMMIOINFO pmmioinfo, PFOURCC pfccStorageSystem, PSZ pszParsedRemainder);

Parameters

pszFileName (PSZ) - input: The file name of the media object to be evaluated. This parameter can be NULL if the information is provided in the `pmmioinfo` structure.

pmmioinfo (PMMIOINFO) - input: A pointer to an MMIOINFO structure. This structure may contain additional data needed to identify the storage system, particularly for compound-file elements that are not fully valid.

pfccStorageSystem (PFOURCC) - in/out: A pointer to a FOURCC variable. Upon successful completion, this field is filled with the FOURCC of the identified storage system.

pszParsedRemainder (PSZ) - in/out: A pointer to a buffer where the function returns the "parsed" portion of the file name. This typically includes the characters following a separator (like a compound-file delimiter).

Return Values

rc (ULONG)

Returns a code indicating success or failure:

MMIO_SUCCESS: The function succeeded (0).
MMIO_ERROR: Unable to determine the storage system FOURCC.
MMIOERR_INVALID_PARAMETER: An invalid parameter was passed.

Detailed DOS file errors may be found in the `ulErrorRet` field of the MMIOINFO structure.

Remarks

The function follows a specific logic to identify the storage system:

MMIOINFO Check: It first checks the `fccChildIOProc` field of the `pmmioinfo` structure. If it is not NULL, that value is returned as the storage system FOURCC.
Filename Parsing: If no I/O procedure is specified in the structure, the function parses `pszFileName` from left to right, looking for a separator character (e.g., `+`).
Conversion: If a separator is found, the file extension before the separator is converted to a FOURCC, and the remainder of the string (following the separator) is returned in `pszParsedRemainder`.

Example Code

The following example demonstrates how to determine the storage system and sub-element name from a compound file path string:

   MMIOINFO mmioinfo;
   FOURCC   fccStorage;
   char     szRemainder[CCHMAXPATH];
   ULONG    rc;

   /* Example path: A bundle file containing a wave element */
   rc = mmioDetermineSSIOProc("DAN.BND+SUE.WAV",
                              &mmioinfo,
                              &fccStorage,
                              szRemainder);

   if (rc == MMIO_SUCCESS) {
      /* fccStorage now contains FOURCC_BND ('BND ') */
      /* szRemainder now contains "SUE.WAV" */
   } else {
      /* Handle error */
   }

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