1.0  Open a file (extended) 
             ____ _ ____ __________



                                   **********
                                   * fopenx *
                                   **********



        NAME:   fopenx -- Open a file (extended) 


        SYNOPSIS:  


                FILE *
                fopenx(name, mode, inisiz, recsiz);
                char            *name;  /* File to open         */
                char            *mode;  /* Open modes           */
                int             inisiz; /* initial size of file */
                int             recsiz; /* record size for random access
                files */


        DESCRIPTION:  

                Fopenx  is  an  extended  version of the standard DecusC
                fopen routine.  It opens a new or existing file  in  the
                indicated mode:  

                        r       Read the existing file sequentially
                        w       Create and write the file sequentially
                        a       Append to the file
                        n       Not record oriented
                        u       RSX-mode "unbuffered i/o"

                "eXtended" modes are:  

                        m       Open existing file for modification
                        p       Preallocate file size
                        x       Open file as a random access file
                        s       Open file for shared access

                Either  "r", "w", "a" or "m" must be given.  "n" and "u"
                are optional.  "n" should be given for  "binary"  files.
                Note  that  "n"  mode will create fixed-block records on
                RSX systems with record size 512.  

                Inisiz must be 0 unless the "p" option is given, then it
                should be the initial number of blocks to  be  allocated
                for  the  file.   A positive value for inisiz requests a
                contiguous file, a negative value gives a non-contiguous
                file.  

                Recsiz must be 0 unless the "x" option is given, then it
                is the record size for a random access file.   The  size
                should be given in bytes.  
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        fopenx  Open a file (extended)



                The  "p"  and "x" options are only valid when creating a
                new file.  

                Note  that "n", "u", "m", "p" and "x" are not compatible
                with other Unix systems.  

        IMPLEMENTATION DETAILS:  

                On  RSX,  "u"  mode  files  will  be  created  with  the
                "variable-length" attribute.  

                On  RSX, if the record type bits in the record attribute
                byte (F.RATT in the FDB) is zero, the file will be  read
                as if the "n" was specified.  Files created with the "x"
                option also have the F.RATT byte set to 0.   Note  that,
                if   the   file   contains   carriage-return   line-feed
                sequences, the entire sequence will  be  passed  to  the
                user's    program.     If    record    attributes    are
                understandable, the carriage-return will be deleted from
                <CR><LF> sequences.  

                Don't  use  fopenx  on non-disk devices, the results are
                unpredicatable.  

                Fopenx()  returns NULL on errors -- $$ferr gets an error
                code.  On RSX, this will be the FCS error code.  

                Note that "no buffer space available" (IE.NBF or E$$NSP)
                and "invalid lun" (IE.ILU or E$$NOC) may be generated by
                fopen.  

                The  same  file  may  not  be  used for both reading and
                writing except if the program writes  a  disk  file  and
                uses  fgetb  and  fputb.   As  with  the standard DecusC
                fopen, using regular sequential io (fget,fput) will work
                only  if  you write, then repositions and reads it using
                ftell()/fseek().  In this case, the program should  call
                rewind()  or  freopen()  to reinitialize the file before
                using fseek().  

                You  can  get the status block info from FCS by defining
                $$stbk as an external  word  array.   Look  in  the  FCS
                manual for the meaning of each word.  Note this value is
                volatile, the next fopenx overwrites it.  

        BUGS:  

                Only  works  with  RSX FCS.  You need to known what your
                doing.