From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <f51978c6a85f48d5386bc77ed61297d9@mail.gmx.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] i need someone to pinpoint a sample program for me : )
From: "Sascha Retzki" <sretzki@gmx.de>
Date: Tue,  5 Sep 2006 22:25:30 +0200
In-Reply-To: <44F699AA.7010802@enerla.net>
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> Ahoi all...
> Im like lets starts something basic (basic might be a relative term), 
> like a server that exports a ctl and a data file,
> every line written to ctl can be read from data with the letters sorted.


I did something like this some long time ago, I was told that using 9p(2)/9pfile(2) for such tiny things, which file structure does not change much is not suggested - I actually did not get that.

Anyway, this may not even compile, I copied out of a source-tree. You want to read it and understand every line, anyway, do you? ;)

#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>

Srv *daefs;

/*
our file layout. Note that the enum Qstatus is
used in daefsfiles_create() to determine the size
of the array. Either fix the function or add files 
(in any) before Qstatus.
*/
enum {
	Qctl,
	Qout,
	Qstatus,
};
struct {
	char name[20]; /* name of the file */
	ulong mode;	/* permission mode */
	File *file;		/* File-struct used by createfile() */
	char *data;	/* The data this file contains */
} daefsfiles[] = {
	"ctl",		0666, nil, nil,
	"output",	0444, nil, nil,
	"status",	0444, nil, nil,
};



void daefs_write(Req *r) {
	int i, myQid = (int)r->fid->file->qid.path;

	if(myQid > Qstatus)
			sysfatal("unknown Qid %d in write-call\n",myQid);

	for(i=0;i+r->ifcall.offset < FILESIZE && i < r->ifcall.count;i++) {
		daefsfiles[myQid].data[i+r->ifcall.offset] = r->ifcall.data[i];
		r->ofcall.count++;
	}
	daefsfiles[myQid].file->length = r->ifcall.offset + r->ifcall.count;

	
	if(myQid == Qctl) {
		char *msg = daefsfiles[Qctl].data;
		// Do your processing...

		// Copy the string
		strcpy(daefsfiles[Qstatus].data,msg);
		// Do not forget to set the new length of the file, for stat(5) etc.
		daefsfiles[Qstatus].file->length =  strlen(msg);
	}

	respond(r,nil);
}

void daefs_read(Req *r) {
	readstr(r,daefsfiles[(int)r->fid->file->qid.path].data);
	respond(r,nil);	
}


void daefsfiles_create(void) {
	int i;

	if((daefs->tree = alloctree("daefs","daefs",DMDIR|0777,nil)) == nil)
		sysfatal("daefs: daefsfiles_create(): alloctree() == nil");

	for(i=0;i<=Qstatus;i++) {

		daefsfiles[i].data = emalloc9p(FILESIZE);

		if((daefsfiles[i].file = createfile(daefs->tree->root, daefsfiles[i].name,"daefs", daefsfiles[i].mode,(void *)daefsfiles[i].data)) == nil)
			sysfatal("daefs: daefsfiles_create() for file \"%s\": createfile() == nil\n",daefsfiles[i].name);

	}

	daefs_status("ready\n");
}

void main(int argc, char **argv) {
	char *mtpt = "/n/daefs/";
	daefs = emalloc9p(sizeof(Srv));
	daefs->write = daefs_write;
	daefs->read = daefs_read;
	daefsfiles_create();
	threadpostmountsrv(daefs,"daefs",mtpt,0);
}