This function reads from a file opened by mmioOpen and updates the file position.

#define INCL_MMIOOS2
#include <os2.h>

HMMIO    hmmio;      /*  Open file handle. */
PCHAR    pchBuffer;  /*  Buffer to read to. */
LONG     cBytes;     /*  Number of bytes read. */
LONG     rc;         /*  Return codes. */

rc = mmioRead(hmmio, pchBuffer, cBytes);