PosixFileDescr

Import List

    C
    Channel
    Msg
    Time
 
Class List
Channel
ErrorContext
Reader
Writer
Class Summary: Channel [Detail]
  +---Channel.Channel
       |
       +--PosixFileDescr.Channel
Field Summary
fd-: int

          
Inherited Fields

From Channel.Channel:

          open, readable, res, writable

Constructor Summary
Init(Channel, FileDescriptor, SHORTINT)

          Attach channel ch to file descriptor fd.
Method Summary
Close()

          Flushes all buffers associated with ch, closes the channel, and frees all system resources allocated to it.
Flush()

          Flushes all buffers related to this channel.
GetModTime(VAR TimeStamp)

          Retrieves the modification time of the data accessed by the given channel.
Length(): LONGINT

          Result is the number of bytes of data that this channel refers to.
NewReader(): Reader

          Attaches a new reader to the channel ch.
NewWriter(): Writer

          Attaches a new writer to the channel ch.
Inherited Methods

From Channel.Channel:

          ClearError, Close, Flush, GetModTime, Length, NewReader, NewWriter

 
Class Summary: ErrorContext [Detail]
  +---Msg.Context
       |
       +---Channel.ErrorContext
            |
            +--PosixFileDescr.ErrorContext
Inherited Fields

From Msg.Context:

          id

Method Summary
GetTemplate(Msg, VAR LString)

          Translates this module's error codes into strings.
Inherited Methods

From Channel.ErrorContext:

          GetTemplate

 
Class Summary: Reader [Detail]
  +---Channel.Reader
       |
       +--PosixFileDescr.Reader
Inherited Fields

From Channel.Reader:

          base, bytesRead, positionable, res

Constructor Summary
InitReader(Reader, Channel)

          
Method Summary
Available(): LONGINT

          Returns the number of bytes available for the next reading operation.
Pos(): LONGINT

          Returns the current reading position associated with the reader r in channel r.base, i.e.
ReadByte(VAR BYTE)

          Reads a single byte from the channel r.base at the reading position associated with r and places it in x.
ReadBytes(VAR ARRAY OF BYTE, LONGINT, LONGINT)

          Reads n bytes from the channel r.base at the reading position associated with r and places them in x, starting at index start.
SetPos(LONGINT)

          Sets the reading position to newPos.
Inherited Methods

From Channel.Reader:

          Available, ClearError, Pos, ReadByte, ReadBytes, SetPos

 
Class Summary: Writer [Detail]
  +---Channel.Writer
       |
       +--PosixFileDescr.Writer
Inherited Fields

From Channel.Writer:

          base, bytesWritten, positionable, res

Constructor Summary
InitWriter(Writer, Channel)

          
Method Summary
Pos(): LONGINT

          Returns the current writing position associated with the writer w in channel w.base, i.e.
SetPos(LONGINT)

          Sets the writing position to newPos.
WriteByte(BYTE)

          Writes a single byte x to the channel w.base at the writing position associated with w.
WriteBytes(ARRAY OF BYTE, LONGINT, LONGINT)

          Writes n bytes from x, starting at position start, to the channel w.base at the writing position associated with w.
Inherited Methods

From Channel.Writer:

          ClearError, Pos, SetPos, WriteByte, WriteBytes

 
Type Summary
[FileDescriptor] = int

          
Result = Result

          
Procedure Summary
Truncate(Writer, LONGINT)

          Causes the file associated with w to have the specified length.
Constant Summary
blockBuffer

          
channelClosed

          
closeError

          
done

          
freeErrorCode

          
invalidChannel

          
invalidFormat

          
lineBuffer

          
noBuffer

          
noLength

          
noModTime

          
noPosition

          
noReadAccess

          
noRoom

          
noTmpName

          
noWriteAccess

          
outOfRange

          
readAfterEnd

          
readError

          
readOnly

          
readWrite

          
stderrFileno

          
stdinFileno

          
stdoutFileno

          
writeError

          
writeOnly

          

Class Detail: Channel
Field Detail

fd

FIELD fd-: int
Constructor Detail

Init

PROCEDURE Init(ch: Channel; 
               fd: FileDescriptor; 
               mode: SHORTINT)

Attach channel ch to file descriptor fd. mode specifies whether the descriptor should be treated as read only, write only, or read/write. It's a bad idea to pass a duplicated file descriptor to fd, all kinds of unexpected things might happen.

Method Detail

Close

PROCEDURE (ch: Channel) Close()

Flushes all buffers associated with ch, closes the channel, and frees all system resources allocated to it. This invalidates all riders attached to ch, and they can't be used further. On success, i.e. if all read and write operations (including flush) completed successfully, ch.res is set to done. An opened channel can only be closed once, successive calls of Channel.Close are undefined. Note that unlike the Oberon System all opened channels have to be closed explicitly. Otherwise resources allocated to them will remain blocked.

[Description inherited from Close]

Redefines: Close


Flush

PROCEDURE (ch: Channel) Flush()

Flushes all buffers related to this channel. Any pending write operations are passed to the underlying OS and all buffers are marked as invalid. The next read operation will get its data directly from the channel instead of the buffer. If a writing error occurs during flushing, the field ch.res will be changed to writeError, otherwise it's assigned done. Note that you have to check the channel's Channel.res flag after an explicit flush yourself, since none of the attached writers will notice any write error in this case.

[Description inherited from Flush]

Redefines: Flush


GetModTime

PROCEDURE (ch: Channel) GetModTime(VAR mtime: TimeStamp)

Retrieves the modification time of the data accessed by the given channel. If no such information is avaiblable, ch.res is set to noModTime, otherwise to done.

[Description inherited from GetModTime]

Redefines: GetModTime


Length

PROCEDURE (ch: Channel) Length(): LONGINT

Result is the number of bytes of data that this channel refers to. If ch represents a file, then this value is the file's size. If ch has no fixed length (e.g. because it's interactive), the result is noLength.

[Description inherited from Length]

Redefines: Length


NewReader

PROCEDURE (ch: Channel) NewReader(): Reader

Attaches a new reader to the channel ch. It is placed at the very start of the channel, and its Reader.res field is initialized to done. ch.res is set to done on success and the new reader is returned. Otherwise result is NIL and ch.res is changed to indicate the error cause. Note that always the same reader is returned if the channel does not support multiple reading positions.

[Description inherited from NewReader]

Redefines: NewReader


NewWriter

PROCEDURE (ch: Channel) NewWriter(): Writer

Attaches a new writer to the channel ch. It is placed at the very start of the channel, and its Writer.res field is initialized to done. ch.res is set to done on success and the new writer is returned. Otherwise result is NIL and ch.res is changed to indicate the error cause. Note that always the same reader is returned if the channel does not support multiple writing positions.

[Description inherited from NewWriter]

Redefines: NewWriter

 
Class Detail: ErrorContext
Method Detail

GetTemplate

PROCEDURE (context: ErrorContext) GetTemplate(msg: Msg; 
                      VAR templ: LString)

Translates this module's error codes into strings. The string usually contains a short error description, possibly followed by some attributes to provide additional information for the problem.

The method should not be called directly by the user. It is invoked by `res.GetText()' or `res.GetLText'.

[Description inherited from GetTemplate]

Redefines: GetTemplate, GetTemplate

 
Class Detail: Reader
Constructor Detail

InitReader

PROCEDURE InitReader(r: Reader; 
                     ch: Channel)
Method Detail

Available

PROCEDURE (r: Reader) Available(): LONGINT

Returns the number of bytes available for the next reading operation. For a file this is the length of the channel r.base minus the current reading position, for an sequential channel (or a channel designed to handle slow transfer rates) this is the number of bytes that can be accessed without additional waiting. The result is `-1' if Channel.Close was called for the channel, or no more byte are available and the remote end of the channel has been closed. Note that the number of bytes returned is always a lower approximation of the number that could be read at once; for some channels or systems it might be as low as `1' even if tons of bytes are waiting to be processed.

[Description inherited from Available]

Redefines: Available


Pos

PROCEDURE (r: Reader) Pos(): LONGINT

Returns the current reading position associated with the reader r in channel r.base, i.e. the index of the first byte that is read by the next call to Reader.ReadByte resp. Reader.ReadBytes. This procedure will return noPosition if the reader has no concept of a reading position (e.g. if it corresponds to input from keyboard), otherwise the result is not negative.

[Description inherited from Pos]

Redefines: Pos


ReadByte

PROCEDURE (r: Reader) ReadByte(VAR x: BYTE)

Reads a single byte from the channel r.base at the reading position associated with r and places it in x. The reading position is moved forward by one byte on success, otherwise r.res is changed to indicate the error cause. Calling this procedure with the reader r placed at the end (or beyond the end) of the channel will set r.res to readAfterEnd. r.bytesRead will be `1' on success and `0' on failure. Calls to this procedure while `r.res # done' will be ignored.

[Description inherited from ReadByte]

Redefines: ReadByte


ReadBytes

PROCEDURE (r: Reader) ReadBytes(VAR x: ARRAY OF BYTE; 
                    start: LONGINT; 
                    n: LONGINT)

Reads n bytes from the channel r.base at the reading position associated with r and places them in x, starting at index start. The reading position is moved forward by n bytes on success, otherwise r.res is changed to indicate the error cause. Calling this procedure with the reader r placed less than n bytes before the end of the channel will will set r.res to readAfterEnd. r.bytesRead will hold the number of bytes that were actually read (being equal to n on success). Calls to this procedure while `r.res # done' will be ignored.

Pre-condition: `(n >= 0) & (0 <= start) & (start+n <= LEN (x))'

[Description inherited from ReadBytes]

Redefines: ReadBytes


SetPos

PROCEDURE (r: Reader) SetPos(newPos: LONGINT)

Sets the reading position to newPos. A negative value of newPos or calling this procedure for a reader that doesn't allow positioning will set r.res to outOfRange. A value larger than the channel's length is legal, but the following read operation will most likely fail with an readAfterEnd error unless the channel has grown beyond this position in the meantime. Calls to this procedure while `r.res # done' will be ignored, in particular a call with `r.res.code = readAfterEnd' error will not reset Reader.res to done.

[Description inherited from SetPos]

Redefines: SetPos

 
Class Detail: Writer
Constructor Detail

InitWriter

PROCEDURE InitWriter(w: Writer; 
                     ch: Channel)
Method Detail

Pos

PROCEDURE (w: Writer) Pos(): LONGINT

Returns the current writing position associated with the writer w in channel w.base, i.e. the index of the first byte that is written by the next call to Writer.WriteByte or Writer.WriteBytes. This procedure will return noPosition if the writer has no concept of a writing position (e.g. if it corresponds to output to terminal), otherwise the result is not negative.

[Description inherited from Pos]

Redefines: Pos


SetPos

PROCEDURE (w: Writer) SetPos(newPos: LONGINT)

Sets the writing position to newPos. A negative value of newPos or calling this procedure for a writer that doesn't allow positioning will set `w.res' to outOfRange. A value larger than the channel's length is legal, the following write operation will fill the gap between the end of the channel and this position with zero bytes. Calls to this procedure while `w.res # done' will be ignored.

[Description inherited from SetPos]

Redefines: SetPos


WriteByte

PROCEDURE (w: Writer) WriteByte(x: BYTE)

Writes a single byte x to the channel w.base at the writing position associated with w. The writing position is moved forward by one byte on success, otherwise w.res is changed to indicate the error cause. w.bytesWritten will be `1' on success and `0' on failure. Calls to this procedure while `w.res # done' will be ignored.

[Description inherited from WriteByte]

Redefines: WriteByte


WriteBytes

PROCEDURE (w: Writer) WriteBytes(x: ARRAY OF BYTE; 
                     start: LONGINT; 
                     n: LONGINT)

Writes n bytes from x, starting at position start, to the channel w.base at the writing position associated with w. The writing position is moved forward by n bytes on success, otherwise w.res is changed to indicate the error cause. w.bytesWritten will hold the number of bytes that were actually written (being equal to n on success). Calls to this procedure while `w.res # done' will be ignored.

Pre-condition: `(n >= 0) & (0 <= start) & (start+n <= LEN (x))'

[Description inherited from WriteBytes]

Redefines: WriteBytes

 
Type Detail

FileDescriptor

TYPE [FileDescriptor] = int

Result

TYPE Result = Result
Procedure Detail

Truncate

PROCEDURE Truncate(w: Writer; 
                   newLength: LONGINT)

Causes the file associated with w to have the specified length. If the file was previously larger than newLength, the extra data is lost. If it was previously shorter, bytes between the old and new lengths are read as zeros. The writer's position is not modified. Note: On systems that do not support shortening files directly it is implemented as a partial file copy. This procedure should always be called through Files.Writer.Truncate.

Availability: Unix.

Constant Detail

blockBuffer

CONST blockBuffer 

channelClosed

CONST channelClosed 

closeError

CONST closeError 

done

CONST done 

freeErrorCode

CONST freeErrorCode 

invalidChannel

CONST invalidChannel 

invalidFormat

CONST invalidFormat 

lineBuffer

CONST lineBuffer 

noBuffer

CONST noBuffer 

noLength

CONST noLength 

noModTime

CONST noModTime 

noPosition

CONST noPosition 

noReadAccess

CONST noReadAccess 

noRoom

CONST noRoom 

noTmpName

CONST noTmpName 

noWriteAccess

CONST noWriteAccess 

outOfRange

CONST outOfRange 

readAfterEnd

CONST readAfterEnd 

readError

CONST readError 

readOnly

CONST readOnly 

readWrite

CONST readWrite 

stderrFileno

CONST stderrFileno 

stdinFileno

CONST stdinFileno 

stdoutFileno

CONST stdoutFileno 

writeError

CONST writeError 

writeOnly

CONST writeOnly