CRTL, creat, Arguments
*Conan The Librarian
file_spec A null-terminated string containing any valid file specification. mode An unsigned value that specifies the file-protection mode. The compiler performs a bitwise AND operation on the mode and the complement of the current protection mode. You can construct modes by using the bitwise OR operator (|) to create mode combinations. The modes are as follows: 0400 OWNER:READ 0200 OWNER:WRITE 0100 OWNER:EXECUTE 0040 GROUP:READ 0020 GROUP:WRITE 0010 GROUP:EXECUTE 0004 WORLD:READ 0002 WORLD:WRITE 0001 WORLD:EXECUTE The system is given the same privileges as the owner. A WRITE privilege implies a DELETE privilege. NOTE To create files with OpenVMS RMS default protections using the UNIX system-call functions umask, mkdir, creat, and open, call mkdir, creat, and open with a file-protection mode argument of 0777 in a program that never specifically calls umask. These default protections include correctly establishing protections based on ACLs, previous versions of files, and so on. In programs that do vfork/exec calls, the new process image inherits whether umask has ever been called or not from the calling process image. The umask setting and whether the umask function has ever been called are both inherited attributes. . . . An optional argument list of character strings of the following form: "keyword = value", . . . ,"keyword = value" Or in the case of "acc" or "err", this form: "keyword" Here, keyword is an RMS field in the file access block (FAB) or record access block (RAB); value is valid for assignment to that field. Some fields permit you to specify more than one value. In these cases, the values are separated by commas. The RMS callback keywords "acc" and "err" are the only keywords that do not take values. Instead, they are followed by a pointer to the callback routine to be used, followed by a pointer to a user-specified value to be used as the first argument of the callback routine. For example, to set up an access callback routine called acc_callback whose first argument is a pointer to the integer variable first_arg in a call to open, you can use the following statement: open("file.dat", O_RDONLY, 0 ,"acc", acc_callback, &first_arg) The second and third arguments to the callback routine must be pointers to a FAB and RAB, respectively, and the routine must have a return type of int. If the callback returns a value less than 0, the open, creat, or fopen fails. The error callback can correct the error condition and return a status greater than or equal to 0 to continue the creat call. Assuming the previous open statement, the function prototype for acc_callback would be similar to the following statement: #include <rms.h> int acc_callback(int *first_arg, struct FAB *fab, struct RAB *rab); FAB and RAB are defined in the <rms.h> header file, and the actual pointers passed to the routine are pointers to the RAB and FAB being used to open the file file.dat. If an access callback routine is established, then it will be called in the open-type routine immediately before the call to the RMS function sys$create or sys$open. If an error callback routine is established and an error status is returned from the sys$create or sys$open function, then the callback routine will be invoked immediately after the status is checked and the error value is discovered. NOTE Any manipulation of the RAB or FAB in a callback function could lead to serious problems in later calls to the Compaq C RTL I/O functions. RMS Valid Keywords and Values describes the RMS keywords and values. Table REF-3 RMS Valid Keywords and Values Keyword Value Description "acc" callbacAccess callback routine. "alq = n" decimalAllocation quantity. "bls = n" decimalBlock size. "ctx = bin" string No translation of '\n' to the terminal. Use this for writing binary data to files. "ctx=cvt" string Negates a previous setting of "ctx=nocvt". This is the default. "ctx = string No conversion of Fortran carriage-control nocvt" bytes. "ctx = rec" string Force record mode access. "ctx = stm" string Force stream mode access. "ctx=xplct" string Causes records to be written only when explicitly specified by a call to fflush, close, or fclose. "deq = n" decimalDefault extension quantity. "dna = string Default file-name string. filespec" "err" callbacError callback routine. "fop = val, File-processing options: val , . . . " ctg Contiguous. cbt Contiguous-best-try. dfw Deferred write; only applicable to files opened for shared access. dlt Delete file on close. tef Truncate at end-of-file. cif Create if nonexistent. sup Supersede. scf Submit as command file on close. spl Spool to system printer on close. tmd Temporary delete. tmp Temporary (no file directory). nef Not end-of-file. rck Read check compare operation. wck Write check compare operation. mxv Maximize version number. rwo Rewind file on open. pos Current position. rwc Rewind file on close. sqo File can only be processed in a sequential manner. "fsz = n" decimalFixed header size. "gbc = n" decimalThe requested number of global buffers for a file. "mbc = n" decimalMultiblock count. "mbf = n" decimalMultibuffer count. "mrs = n" decimalMaximum record size. "pmt=usr- string Prompts for terminal input. Any RMS input prmpt" from a terminal device will be preceded by "usr-prmpt" when this option and "rop=pmt" are specified. "rat = val, Record attributes: val . . . " cr Carriage-return control. blk Disallow records to span block boundaries. ftn FORTRAN print control. none Explicitly forces no carriage control. prn Print file format. "rfm = val" Record format: fix Fixed-length record format. stm RMS stream record format. stmlf Stream format with line-feed terminator. stmcr Stream format with carriage-return terminator. var Variable-length record format. vfc Variable-length record with fixed control. udf Undefined. "rop = val, Record-processing operations: val . . . " asy Asynchronous I/O. cco Cancel Ctrl/O (used with Terminal I/O). cvt Capitalizes characters on a read from the terminal. eof Positions the record stream to the end-of- file for the connect operation only. nlk Do not lock record. pmt Enables use of the prompt specified by "pmt=usr-prmpt" on input from the terminal. pta Eliminates any information in the type- ahead buffer on a read from the terminal. rea Locks record for a read operation for this process, while allowing other accessors to read the record. rlk Locks record for write. rne Suppresses echoing of input data on the screen as it is entered on the keyboard. rnf Indicates that Ctrl/U, Ctrl/R, and DELETE are not to be considered control commands on terminal input, but are to be passed to the application program. rrl Reads regardless of lock. syncstsReturns success status of RMS$_SYNCH if the requested service completes its task immediately. tmo Timeout I/O. tpt Allows put/write services using sequential record access mode to occur at any point in the file, truncating the file at that point. ulk Prohibits RMS from automatically unlocking records. wat Wait until record is available, if currently locked by another stream. rah Read ahead. wbh Write behind. "rtv=n" decimalThe number of retrieval pointers that RMS has to maintain in memory (0 to 127,255). "shr = val, File sharing options: val, . . . " del Allows users to delete. get Allows users to read. mse Allows multi-stream connects. nil Prohibits file sharing. put Allows users to write. upd Allows users to update. upi Allows one or more writers. nql No query locking (file level). "tmo = n" decimalI/O timeout value. In addition to these options, any option that takes a key value (such as "fop" or "rat") can be negated by prefixing the value with "no". For example, specify "fop=notmp" to clear the "tmp" bit in the "fop" field. NOTES o While these options provide much flexibility and functionality, many of them can also cause severe problems if not used correctly. o You cannot share the default Compaq C for OpenVMS stream file I/O. If you wish to share files, you must specify "ctx=rec" to force record access mode. You must also specify the appropriate "shr" options depending on the type of access you want. o If you intend to share a file opened for append, you must specify appropriate share and record-locking options, to allow other accessors to read the record. The reason for doing this: the file is positioned at end-of-file through reading records in a loop until end-of-file is reached. For more information on these options, see the OpenVMS Record Management Services Reference Manual manual.