plumb.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

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

#include "dat.h"
#include "fns.h"

static int		plumbsendfd;
static int		plumbwebfd;
static Channel	*plumbchan;

static void	plumbwebproc(void*);
static void	plumbwebthread(void*);
static void plumbsendproc(void*);

void
plumbinit(void)
{
	plumbsendfd = plumbopen("send", OWRITE|OCEXEC);
	plumbwebfd = plumbopen("web", OREAD|OCEXEC);
}

void
plumbstart(void)
{
	plumbchan = chancreate(sizeof(Plumbmsg*), 0);
	proccreate(plumbwebproc, nil, STACK);
	threadcreate(plumbwebthread, nil, STACK);
}

static void
plumbwebthread(void*)
{
	char *base;
	Plumbmsg *m;

	for(;;){
		m = recvp(plumbchan);
		if(m == nil)
			threadexits(nil);
		base = plumblookup(m->attr, "baseurl");
		if(base == nil)
			base = m->wdir;
		plumburl(m->data, base);
		plumbfree(m);
	}
}

static void
plumbwebproc(void*)
{
	Plumbmsg *m;

	for(;;){
		m = plumbrecv(plumbwebfd);
		sendp(plumbchan, m);
		if(m == nil)
			threadexits(nil);
	}
}

static void
addattr(Plumbmsg *m, char *name, char *value)
{
	Plumbattr *a;

	a = malloc(sizeof(Plumbattr));
	a->name = name;
	a->value = value;
	a->next = m->attr;
	m->attr = a;
}

static void
freeattrs(Plumbmsg *m)
{
	Plumbattr *a, *next;

	a = m->attr;
	while(a != nil) {
		next = a->next;
		free(a);
		a = next;
	}
}

static struct
{
	char	*ctype;
	char	*ext;
}
ctypes[] =
{
	{ "application/msword", "doc" },
	{ "application/pdf", "pdf" },
	{ "application/postscript", "ps" },
	{ "application/rtf", "rtf" },
	{ "image/gif", "gif" },
	{ "image/jpeg", "jpg" },
	{ "image/png", "png" },
	{ "image/ppm", "ppm" },
	{ "image/tiff", "tiff" },
	{ "text/html", "html" },
	{ "text/plain", "txt" },
	{ "text/xml", "xml" },
};

void
replumb(Client *c)
{
	int i;
	Plumbmsg *m;
	char name[128], *ctype, *ext, *p;

	if(!c->plumbed)
		return;
	m = emalloc(sizeof(Plumbmsg));
	m->src = "webfs";
	m->dst = nil;
	m->wdir = "/";
	m->type = "text";
	m->attr = nil;
	addattr(m, "url", c->url->url);
	ctype = c->contenttype;
	ext = nil;
	if(ctype != nil) {
		addattr(m, "content-type", ctype);
		for(i = 0; i < nelem(ctypes); i++) {
			if(strcmp(ctype, ctypes[i].ctype) == 0) {
				ext = ctypes[i].ext;
				break;
			}
		}
	}
	if(ext == nil) {
		p = strrchr(c->url->url, '/');
		if(p != nil)
			p = strrchr(p+1, '.');
		if(p != nil && strlen(p) <= 5)
			ext = p+1;
		else
			ext = "txt";		/* punt */
	}
	c->ext = ext;
if(0)fprint(2, "content type %s -> extension .%s\n", ctype, ext);
	m->ndata = snprint(name, sizeof name, "/mnt/web/%d/body.%s", c->num, ext);
	m->data = estrdup(name);
	proccreate(plumbsendproc, m, STACK);	/* separate proc to avoid a deadlock */
}

static void
plumbsendproc(void *x)
{
	Plumbmsg *m;

	m = x;
	plumbsend(plumbsendfd, m);
	freeattrs(m);
	free(m->data);
	free(m);
}