mbox.c

来自「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」· C语言 代码 · 共 814 行 · 第 1/2 页

}

int
emptyImp(char *mbox)
{
	Dir *d;
	long mode;
	int fd;

	fd = cdCreate(mboxDir, impName(mbox), OWRITE, 0664);
	if(fd < 0)
		return -1;
	d = cdDirstat(mboxDir, mbox);
	if(d == nil){
		close(fd);
		return -1;
	}
	fprint(fd, "%s%.*lud %.*lud\n", IMPMAGIC, NUid, d->mtime, NUid, 1UL);
	mode = d->mode & 0777;
	nulldir(d);
	d->mode = mode;
	dirfwstat(fd, d);
	free(d);
	return fd;
}

/*
 * try to match permissions with mbox
 */
static int
createImp(Box *box, Qid *qid)
{
	Dir *d;
	long mode;
	int fd;

	fd = cdCreate(mboxDir, box->imp, OREAD, 0664);
	if(fd < 0)
		return -1;
	d = cdDirstat(mboxDir, box->name);
	if(d != nil){
		mode = d->mode & 0777;
		nulldir(d);
		d->mode = mode;
		dirfwstat(fd, d);
		free(d);
	}
	if(fqid(fd, qid) < 0){
		close(fd);
		return -1;
	}

	return fd;
}

/*
 * read or re-read a .imp file.
 * this is tricky:
 *	messages can be deleted by another agent
 *	we might still have a Msg for an expunged message,
 *		because we haven't told the client yet.
 *	we can have a Msg without a .imp entry.
 *	flag information is added at the end of the .imp by copy & append
 *	there can be duplicate messages (same digests).
 *
 * look up existing messages based on uid.
 * look up new messages based on in order digest matching.
 *
 * note: in the face of duplicate messages, one of which is deleted,
 * two active servers may decide different ones are valid, and so return
 * different uids for the messages.  this situation will stablize when the servers exit.
 */
static int
parseImp(Biobuf *b, Box *box)
{
	Msg *m, *mm = nil;
	char *s, *t, *toks[3];
	ulong uid, u;
	int match, n;

	m = box->msgs;
	s = Brdline(b, '\n');
	if(s == nil || Blinelen(b) != STRLEN(IMPMAGIC)
	|| strncmp(s, IMPMAGIC, STRLEN(IMPMAGIC)) != 0)
		return 0;

	s = Brdline(b, '\n');
	if(s == nil || Blinelen(b) != 2*NUid + 2)
		return 0;
	s[2*NUid + 1] = '\0';
	u = strtoul(s, &t, 10);
	if(u != box->uidvalidity && box->uidvalidity != 0)
		return 0;
	box->uidvalidity = u;
	if(*t != ' ' || t != s + NUid)
		return 0;
	t++;
	u = strtoul(t, &t, 10);
	if(box->uidnext > u)
		return 0;
	box->uidnext = u;
	if(t != s + 2*NUid+1 || box->uidnext == 0)
		return 0;

	uid = ~0;
	while(m != nil){
		s = Brdline(b, '\n');
		if(s == nil)
			break;
		n = Blinelen(b) - 1;
		if(n != NDigest + NUid + NFlags + 2
		|| s[NDigest] != ' ' || s[NDigest + NUid + 1] != ' ')
			return 0;
		toks[0] = s;
		s[NDigest] = '\0';
		toks[1] = s + NDigest + 1;
		s[NDigest + NUid + 1] = '\0';
		toks[2] = s + NDigest + NUid + 2;
		s[n] = '\0';
		t = toks[1];
		u = strtoul(t, &t, 10);
		if(*t != '\0' || uid != ~0 && (uid >= u && u || u && !uid))
			return 0;
		uid = u;

		/*
		 * zero uid => added by append or copy, only flags valid
		 * can only match messages without uids, but this message
		 * may not be the next one, and may have been deleted.
		 */
		if(!uid){
			for(; m != nil && m->uid; m = m->next)
				;
			for(mm = m; mm != nil; mm = mm->next){
				if(mm->info[IDigest] != nil &&
				    strcmp(mm->info[IDigest], toks[0]) == 0){
					if(!mm->uid)
						mm->flags = 0;
					if(!impFlags(box, mm, toks[2]))
						return 0;
					m = mm->next;
					break;
				}
			}
			continue;
		}

		/*
		 * ignore expunged messages,
		 * and messages already assigned uids which don't match this uid.
		 * such messages must have been deleted by another imap server,
		 * which updated the mailbox and .imp file since we read the mailbox,
		 * or because upas/fs got confused by consecutive duplicate messages,
		 * the first of which was deleted by another imap server.
		 */
		for(; m != nil && (m->expunged || m->uid && m->uid < uid); m = m->next)
			;
		if(m == nil)
			break;

		/*
		 * only check for digest match on the next message,
		 * since it comes before all other messages, and therefore
		 * must be in the .imp file if they should be.
		 */
		match = mm != nil && mm->info[IDigest] != nil &&
			strcmp(m->info[IDigest], toks[0]) == 0;
		if(uid && (m->uid == uid || !m->uid && match)){
			if(!match)
				bye("inconsistent uid");

			/*
			 * wipe out recent flag if some other server saw this new message.
			 * it will be read from the .imp file if is really should be set,
			 * ie the message was only seen by a status command.
			 */
			if(!m->uid)
				m->flags = 0;

			if(!impFlags(box, m, toks[2]))
				return 0;
			m->uid = uid;
			m = m->next;
		}
	}
	return 1;
}

/*
 * parse .imp flags
 */
static int
impFlags(Box *box, Msg *m, char *flags)
{
	int i, f;

	f = 0;
	for(i = 0; i < NFlags; i++){
		if(flags[i] == '-')
			continue;
		if(flags[i] != flagChars[i].name[0])
			return 0;
		f |= flagChars[i].v;
	}

	/*
	 * recent flags are set until the first time message's box is selected or examined.
	 * it may be stored in the file as a side effect of a status or subscribe command;
	 * if so, clear it out.
	 */
	if((f & MRecent) && strcmp(box->fs, "imap") == 0)
		box->dirtyImp = 1;
	f |= m->flags & MRecent;

	/*
	 * all old messages with changed flags should be reported to the client
	 */
	if(m->uid && m->flags != f){
		box->sendFlags = 1;
		m->sendFlags = 1;
	}
	m->flags = f;
	return 1;
}

/*
 * assign uids to any new messages
 * which aren't already in the .imp file.
 * sum up totals for flag values.
 */
static void
boxFlags(Box *box)
{
	Msg *m;

	box->recent = 0;
	for(m = box->msgs; m != nil; m = m->next){
		if(m->uid == 0){
			box->dirtyImp = 1;
			box->uidnext = uidRenumber(m, box->uidnext, 0);
		}
		if(m->flags & MRecent)
			box->recent++;
	}
}

static ulong
uidRenumber(Msg *m, ulong uid, int force)
{
	for(; m != nil; m = m->next){
		if(!force && m->uid != 0)
			bye("uid renumbering with a valid uid");
		m->uid = uid++;
	}
	return uid;
}

void
closeBox(Box *box, int opened)
{
	Msg *m, *next;

	/*
	 * make sure to leave the mailbox directory so upas/fs can close the mailbox
	 */
	myChdir(mboxDir);

	if(box->writable){
		deleteMsgs(box);
		if(expungeMsgs(box, 0))
			closeImp(box, checkBox(box, 1));
	}

	if(fprint(fsCtl, "close %s", box->fs) < 0 && opened)
		bye("can't talk to mail server");
	for(m = box->msgs; m != nil; m = next){
		next = m->next;
		freeMsg(m);
	}
	free(box->name);
	free(box->fs);
	free(box->fsDir);
	free(box->imp);
	free(box);
}

int
deleteMsgs(Box *box)
{
	Msg *m;
	char buf[BufSize], *p, *start;
	int ok;

	if(!box->writable)
		return 0;

	/*
	 * first pass: delete messages; gang the writes together for speed.
	 */
	ok = 1;
	start = seprint(buf, buf + sizeof(buf), "delete %s", box->fs);
	p = start;
	for(m = box->msgs; m != nil; m = m->next){
		if((m->flags & MDeleted) && !m->expunged){
			m->expunged = 1;
			p = seprint(p, buf + sizeof(buf), " %lud", m->id);
			if(p + 32 >= buf + sizeof(buf)){
				if(write(fsCtl, buf, p - buf) < 0)
					bye("can't talk to mail server");
				p = start;
			}
		}
	}
	if(p != start && write(fsCtl, buf, p - buf) < 0)
		bye("can't talk to mail server");

	return ok;
}

/*
 * second pass: remove the message structure,
 * and renumber message sequence numbers.
 * update messages counts in mailbox.
 * returns true if anything changed.
 */
int
expungeMsgs(Box *box, int send)
{
	Msg *m, *next, *last;
	ulong n;

	n = 0;
	last = nil;
	for(m = box->msgs; m != nil; m = next){
		m->seq -= n;
		next = m->next;
		if(m->expunged){
			if(send)
				Bprint(&bout, "* %lud expunge\r\n", m->seq);
			if(m->flags & MRecent)
				box->recent--;
			n++;
			if(last == nil)
				box->msgs = next;
			else
				last->next = next;
			freeMsg(m);
		}else
			last = m;
	}
	if(n){
		box->max -= n;
		box->dirtyImp = 1;
	}
	return n;
}

static void
fsInit(void)
{
	if(fsCtl >= 0)
		return;
	fsCtl = open("/mail/fs/ctl", ORDWR);
	if(fsCtl < 0)
		bye("can't open mail file system");
	if(fprint(fsCtl, "close mbox") < 0)
		bye("can't initialize mail file system");
}

static char *stoplist[] =
{
	"mbox",
	"pipeto",
	"forward",
	"names",
	0
};

/*
 * reject bad mailboxes based on mailbox name
 */
int
okMbox(char *path)
{
	char *name;
	int i;

	name = strrchr(path, '/');
	if(name == nil)
		name = path;
	else
		name++;
	if(strlen(name) + STRLEN(".imp") >= MboxNameLen)
		return 0;
	for(i = 0; stoplist[i]; i++)
		if(strcmp(name, stoplist[i]) == 0)
			return 0;
	if(isprefix("L.", name) || isprefix("imap-tmp.", name)
	|| issuffix(".imp", name)
	|| strcmp("imap.subscribed", name) == 0
	|| isdotdot(name) || name[0] == '/')
		return 0;

	return 1;

}