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CMS Low-Level I/O Functions

Introduction

The library provides a set of functions that perform CMS disk file input and output operations. These functions are characterized as low-level I/O functions because they use the CMS file system directly. The library provides a second set of functions that can perform I/O operations on files in XEDIT storage. These functions are known as the XEDIT low-level I/O functions.

This chapter covers the low-level I/O functions as well as three utility functions that can be used with the I/O functions. Note that these functions are not portable.

The CMS low-level I/O functions are as follows:
cmsstate verifies the existence of a CMS disk file
cmsopen opens a CMS disk file
cmsread reads a record from a CMS disk file
cmswrite writes a record to a CMS disk file
cmspoint changes the current record pointer for a CMS disk file
cmsclose closes a CMS disk file
cmserase erases a CMS disk file.

The low-level XEDIT I/O functions are as follows:
cmsxflst verifies the existence of an XEDIT file
cmsxflrd reads a record from XEDIT storage
cmsxflwr writes a record to XEDIT storage
cmsxflpt moves the current line pointer in an XEDIT file.

The related utility functions are as follows:
cmspid tokenizes a filename string in "cms" or "xed" style
cmsdfind finds a file identifier that matches a pattern
cmsdnext finds the next file identifier that matches a pattern.


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