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Length: 13312 (0x3400) Types: Ada Source Notes: 03_class, FILE, R1k_Segment, e3_tag, package Os_Files, seg_04b958
└─⟦8527c1e9b⟧ Bits:30000544 8mm tape, Rational 1000, Arrival backup of disks in PAM's R1000 └─ ⟦cfc2e13cd⟧ »Space Info Vol 2« └─⟦this⟧
-- This is the interface file between machine-independent text_io, direct_io -- and sequential_io implementation and the actual physical i/o device(s). -- All Ada I/O can be reimplemented to work with a new device by reimplementing -- the body of this single package. -- -- Direct_io files are implemented (currently) with fixed-size elements. -- -- The phrase "normally will be called only" will appear below - it means that -- for VADS software, the statement is true. However, these files are public -- and may be used to write a low-level portable file handling system. Some -- users may have done this, and may therefore use these functions in ways -- that are not anticipated by our limited usage. If you wish to support these -- users, you may wish to generalize your support (our support is generalized -- where practical.) with System; use System; with A_Strings; package Os_Files is type File_Descriptor is new Integer; -- "file_descriptor" is used to identify the device-specific -- information control block associated with the specific file. -- it may be any type, but is typically either an integer (for -- cross systems and Unix) or a control block address (VMS). type File_Styles is (Text, Sequential, Direct, Special); -- "file_styles" identifies the Ada nature of the file. "text" means -- the file is an Ada text_io file, sequential means a sequential_io -- file, direct means a direct_io file, and special means one of -- standard_input, standard_output or standard_error (all used with -- text_io.) Default_Buffer_Size : Integer := 1024; -- Text_io is buffered. The buffer size may be set by calling -- file_support.setup_buffer, but will default on open/create to -- a buffer of this size. May be reset by user. subtype Name_String is String (1 .. 1024); -- mjs@6/23/93 -- Subtype needs to be constant range -- -- file names are restricted to being no longer than a single buffer -- in length. In some implementations, one or more special characters -- such as a closing CR are required in every text string, including -- file names, so these must be allowed for. type Open_Flags is new Integer; O_Rdonly : constant Open_Flags := 8#0000#; O_Wronly : constant Open_Flags := 8#0001#; O_Rdwr : constant Open_Flags := 8#0002#; O_Ndelay : constant Open_Flags := 8#0004#; O_Append : constant Open_Flags := 8#0010#; -- ATT 3B System V Unix. -- IBM PS2 AIX. -- IBM RT AIX. -- IBM RS/6000 AIX. -- Motorola 88K conforming to 88open Binary Compatibility Standard. -- i386 System V Unix. O_Sync : constant Open_Flags := 8#0020#; O_Creat : constant Open_Flags := 8#0400#; O_Trunc : constant Open_Flags := 8#1000#; O_Excl : constant Open_Flags := 8#2000#; subtype Permission is Integer range 0 .. 8#7777#; function "+" (Left, Right : Open_Flags) return Open_Flags; function "-" (Left, Right : Open_Flags) return Open_Flags; -- The open_flags constants are really an enumeration with a -- representation, but for historical reasons are left as a set -- of constants. They are used to form a bit mask of allowed or -- requested properties for files. They are not related to any -- specific external file representation, although they conform to -- Unix meanings. type File_Id_Ptr is private; Invalid : constant File_Id_Ptr; -- The file_id is a machine-dependent data structure that provides -- information that UNIQUELY identifies each external file. This -- information is used to determine if a given external file is already -- open via a different file descriptor. Typically, file names and -- directories can be aliased/abbreviated and so the file names are -- not themselves useful in uniquely identifying the physical file. -- On Unix, we use the inode/device numbers. On VMS, we are forced -- to use the "canonicalized" file name, as there are no accessible -- unique internal file ids. The "invalid" value is a file_id for an -- unopen file. Stdin_Fd : File_Descriptor; Stdout_Fd : File_Descriptor; Stderr_Fd : File_Descriptor; -- the machine-dependent file_descriptors of the special files function Std_Input_Name return String; function Std_Output_Name return String; function Std_Error_Name return String; -- the machine-dependent names for the special files. Always_Flush_Files : Boolean; -- Because text_io is buffered, it may be desirable that output -- appear immediately in the physical file. If this global is set, -- then all files opened while it is set will be flushed at the end -- of each user transaction. For example, if a user calls: -- put("what? "); -- Then the six characters "what? " would normally just be placed into -- the buffer - writing would only happen if the buffer happened to -- fill at one of those characters, and would then happen only up to -- the specific character that filled it. If the output file is -- being read by a person or program as it appears, or is to be mixed -- with output from other tasks or programs, it is desirable that the -- output appear immediately. Note that os_files_b.a implementations -- should turn on always_flush for any file that is known to be -- shared, or that is writing to a terminal. function Get_File_Id (Fd : File_Descriptor) return File_Id_Ptr; -- returns the pointer to the unique file identifier information -- used normally only with os_files itself, to see if external files -- are already in use in this program function File_Size (Fd : File_Descriptor; Elem_Size : Integer) return Integer; -- returns the size of the external file, in number of elements -- (use normally only for direct_io files.) function Is_Interactive (Fd : File_Descriptor) return Boolean; -- returns true iff file is associated with an interactive external -- device, such as a terminal; is used to set always_flush. procedure Position_File (Fd : File_Descriptor; To, Size : Integer); -- used to establish the external file information to read/write -- at the "to"th element. The first element is numbered 0. -- normally used only for direct_io files. "size" is the element_size -- for the file elements (constant.) procedure Skip_In_File (Fd : File_Descriptor; To : Integer); -- used to skip ahead "to" BYTEs. Normally called only for -- sequential_io files, to skip past padding bytes to the start of -- the next element. function Read (Fd : File_Descriptor; Addr : System.Long_Address; Cnt : Integer) return Integer; -- used to read up to "cnt" BYTEs from the file named by "fd" to the -- buffer memory at "addr". It will retry on Unix or VMS, as interrupts -- may cause timeouts and so forth. The actual number of characters, -- adjusted by "fix_end_of_record" is returned. If "fix_end_of_record" -- does nothing, then the actual number of characters read is returned; -- an end-of-file condition is represented by a 0. If, however, -- "fix_end_of_record" changes the record, then the number returned -- must be adjusted in a way to cooperate - a "-1" might be returned -- to signal EOF if it is known that fix_end_of_record will always -- add an end-of-record character such as a LF. See below. procedure Write (Fd : File_Descriptor; Addr : System.Long_Address; Cnt : Integer); -- used to write "cnt" BYTEs into the current position of the file -- named by "fd", from the buffer memory at "addr". It should keep -- attempting to write until all the bytes are written. It should -- assume that the bytes are already in the correct format for the -- external file. function Same_Id (F1, F2 : File_Id_Ptr) return Boolean; -- returns true if the two file_ids name the same file. function At_End_Of_File (Fd : File_Descriptor) return Boolean; -- returns true iff the associated external file is at EOF. procedure Fix_End_Of_Record (File : System.Long_Address; Actual : in out Integer); -- takes a buffer and count of bytes that has presumably just been read -- and converts them into the format expected by Ada. In Ada, lines -- of text are always terminated by an ASCII.LF (line feed); -- however, on systems such as VMS a CR (carriage return) may be -- represented implicitly in the external file. For VMS, then, this -- routine adds a LF on to the end of each line read, adjusting the -- "actual" to include the LF. Note that if a VMS EOF is read, -- our implementation on VMS expects an actual of -1, and adds the LF -- anyway - leaving an actual of 0, correctly indicating EOF. function Ok_To_Write (File : System.Long_Address) return Boolean; -- on most systems, buffers are always "ok_to_write". But on some -- systems, only certain kinds of lines can be output. For example, -- on VMS only lines that end in ASCII.LF should be output because -- VMS is record-oriented - every output is considered to be a line. -- Note that this routine is given access to the entire file_type -- object. It can therefore make changes directly in the associated -- buffer for the file. These changes are typically the inverse of -- the changes done after reading a line by "fix_end_of_record". function Flushable (Fd : File_Descriptor) return Boolean; -- Some operating systems, for example VMS, have non-trivial -- ok_to_write semantics. When it is not possible to flush buffers -- arbitrarily, this function should return FALSE. This prevents -- non-flushable files from being opened under two different file -- variables - and then having a confused input/output due to buffering. procedure Open (File : System.Long_Address; Style : File_Styles; Mode : Open_Flags); -- opens the named external file; raises NAME_ERROR or USE_ERROR -- as appropriate for Ada semantics. File should be opened with -- the given requested properties. Note that files will normally be -- requested in READ/WRITE mode unless READ mode is specifically -- denied them. procedure Close (Fd : File_Descriptor); -- closes the given external file. Note that if the program ends in -- an exception, ada_exit will eventually call close_all.a, which will -- step through the list of open files and close them. procedure Truncate (Fd : File_Descriptor); -- truncates the given external file procedure Delete (Fd : File_Descriptor; Name : A_Strings.A_String); -- delete named file (for VMS, name is required) function Get_Tempname (Root : String) return A_Strings.A_String; -- return string representing unique temporary file for this program. -- (on many hosts, a process id can be used with a count). function Get_Full_Name (Name : String; Style : File_Styles) return A_Strings.A_String; -- return string representing "canonical" full name of file, -- including directory, etc. procedure Free_File_Id (Id_Ptr : in out File_Id_Ptr); -- pragma inline(position_file, read, write, at_end_of_file); private type File_Id_Type; type File_Id_Ptr is access File_Id_Type; Invalid : constant File_Id_Ptr := null; end Os_Files;
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