OP(2) OP(2)
NAME
Op, Rmsg, Tmsg, dir2text, istmsg, packdir, packdirsize,
readmsg, qid2text, unpackdir - interface to the Op file
protocol
SYNOPSIS
include "op.m";
op := load Op Op->PATH;
# Message types
Tattach, # 1
Rattach,
Terror, # 3 illegal
Rerror,
Tflush, # 5
Rflush,
Tput, # 7
Rput,
Tget, # 9
Rget,
Tremove, # 11
Rremove,
Tmax: con 1+iota;
NOFD: con int ~0;
MAXDATA: con 16*1024; # `reasonable' iounit (size of .data fields)
ODATA: con int 1 <<1; # put/get data
OSTAT: con int 1 <<2; # put/get stat
OCREATE: con int 1 <<3; # create the file (or truncate)
OMORE: con int 1 <<4; # more data going/comming later
OREMOVEC: con int 1 <<5; # remove after final put.
Tmsg: adt {
tag: int;
pick {
Readerror =>
error: string; # tag is unused in this case
Attach =>
uname: string; # user name responsible for rpcs
path: string; # subtree we want to attach to.
Flush =>
oldtag: int; # tag for flushed request
Put =>
path: string; # of file
fd: int; # for file
mode : int; # bit-or of OSTAT|ODATA|OCREATE|OMORE
stat: Sys->Dir; # for file
offset: big; # for data
data: array of byte;
OP(2) OP(2)
Get =>
path: string; # of file
fd: int; # of file
mode: int; # bit-or of OSTAT|ODATA|OMORE
nmsgs: int; # max number of Rgets for reply. 0==unlimited.
offset: big; # byte offset (ignored for dirs)
count: int; # max data expected per message
Remove =>
path: string; # of file
}
read: fn(fd: ref Sys->FD, msize: int): ref Tmsg;
unpack: fn(a: array of byte): (int, ref Tmsg);
pack: fn(nil: self ref Tmsg): array of byte;
packedsize: fn(nil: self ref Tmsg): int;
text: fn(nil: self ref Tmsg): string;
mtype: fn(nil: self ref Tmsg): int;
};
Rmsg: adt {
tag: int;
pick {
Readerror =>
error: string; # tag is unused in this case
Error =>
ename: string;
Attach or Flush =>
Put =>
fd: int;
count: int;
qid: Sys->Qid;
mtime: int;
Get =>
fd: int;
mode: int; # bit or of OSTAT|ODATA|OMORE
stat: Sys->Dir;
data: array of byte;
Remove =>
}
read: fn(fd: ref Sys->FD, msize: int): ref Rmsg;
unpack: fn(a: array of byte): (int, ref Rmsg);
pack: fn(nil: self ref Rmsg): array of byte;
packedsize: fn(nil: self ref Rmsg): int;
text: fn(nil: self ref Rmsg): string;
mtype: fn(nil: self ref Rmsg): int;
};
init: fn();
readmsg: fn(fd: ref Sys->FD, msize: int): (array of byte, string);
OP(2) OP(2)
istmsg: fn(f: array of byte): int;
packdirsize: fn(d: Sys->Dir): int;
packdir: fn(d: Sys->Dir): array of byte;
unpackdir: fn(f: array of byte): (int, Sys->Dir);
dir2text: fn(d: Sys->Dir): string;
qid2text: fn(q: Sys->Qid): string;
DESCRIPTION
Op provides a Limbo interface for speaking the Octopus File
Protocol, Op. See intro(O) for a description of the proto-
col.
Init initializes and prepares the module for operation.
Readmsg reads an Op message from fd (a maximum of msize
bytes), and returns it as an array of bytes. The second mem-
ber of the tuple returned is the error status (nil for no
error). When msize is zero, a reasonable default is chosen
by the module.
Istmsg returns non-zero if the array of bytes f corresponds
to an Op Tmsg. Tmsg.read is similar to readmsg, but reads
an Op Tmsg and unpacks it using Tmsg.unpack.
The converse of Tmsg.unpack is Tmsg.pack. It packs a Tmsg
into network format, and returns the resulting array of
bytes. The function Tmsg.packedsize may be used to obtain
the size of a Tmsg while packed.
The function Tmsg.text returns a string with a printable
representation of the message, for debugging.
In general, the adt for a Tmsg suffices. However, mtype
returns a different (small) integer for different Tmsgs ,
representing its type.
The same set of operations are available for Rmsgs (they are
not described again here).
As an aid, packdir packages a directory entry, packdirsize
reports the size in bytes of a packed directory, and
unpackdir unpacks a directory entry. These functions are
only necessary for reading directories. Othersize, the stat
fields in Tmsgs and Rmsgs suffice.
Dir2text and qid2text return printable strings for directory
entries and qids, also for debugging purposes.
The meaning of the various constants defined is explained in
section O of this manual. In general, directories and qids
OP(2) OP(2)
use the same name (and meaning) used in Styx.
SOURCE
/usr/octopus/port/lib/op.b
SEE ALSO
intro(O), opmux(2), and intro(5).