lib9p: remove Srv.srvfd, make postsrv() and threadpostsrv() return the mountable file descriptor, update documentation

Now that we have these new functions,
we can also make them return an error
instead of calling sysfatal() like
postmountsrv().

Remove the confusing Srv.srvfd, as it
is only temporarily used and return
it from postsrv() instead.

sys/include/9p.h

@@ -214,7 +214,6 @@ struct Srv {
 
 	int		infd;
 	int		outfd;
-	int		srvfd;
 	char*	keyspec;
 
 /* below is implementation-specific; don't use */
@@ -243,13 +242,13 @@ void		srvforker(void (*)(void*), void*, int);
 void		threadsrvforker(void (*)(void*), void*, int);
 
 void		srv(Srv*);
-void		postsrv(Srv*, char*);
+int		postsrv(Srv*, char*);
 void		postmountsrv(Srv*, char*, char*, int);
 void		postsharesrv(Srv*, char*, char*, char*);
 void		listensrv(Srv*, char*);
 
 void		threadsrv(Srv*);
-void		threadpostsrv(Srv*, char*);
+int		threadpostsrv(Srv*, char*);
 void		threadpostmountsrv(Srv*, char*, char*, int);
 void		threadpostsharesrv(Srv*, char*, char*, char*);
 void		threadlistensrv(Srv *s, char *addr);

sys/man/2/9p

@@ -63,7 +63,6 @@ typedef struct Srv {
 
 	int		infd;
 	int		outfd;
-	int		srvfd;
 
 	void		(*forker)(void (*fn)(void*), void *arg, int flags);
 } Srv;
@@ -73,12 +72,12 @@ typedef struct Srv {
 .ft L
 .ta \w'\fLvoid* 'u
 void	srv(Srv *s)
-void	postsrv(Srv *s, char *name);
+int	postsrv(Srv *s, char *name);
 void	postmountsrv(Srv *s, char *name, char *mtpt, int flag)
 void	postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
 void	listensrv(Srv *s, char *addr)
 void	threadsrv(Srv *s)
-void	threadpostsrv(Srv *s, char *name);
+int	threadpostsrv(Srv *s, char *name);
 void	threadpostmountsrv(Srv *s, char *name, char *mtpt, int flag)
 void	threadpostsharesrv(Srv *s, char *name, char *mtpt, char *desc)
 void	threadlistensrv(Srv *s, char *addr)
@@ -193,14 +192,26 @@ or
 (see
 .IR thread (2)).
 .PP
-.I Postmountsrv
+
+.I Postsrv
 and
-.I threadpostmountsrv
+.I threadpostsrv
 are wrappers that create a separate process in which to run
 .IR srv .
 They do the following:
 .IP
 Initialize
+.IB s -> infd
+and
+.IB s -> outfd
+to be one end of a freshly allocated pipe.
+.IP
+If
+.B name
+is non-nil, post the other end file descriptor under the name
+.BI /srv/ name .
+.IP
+Initialize
 .IB s -> forker
 to eigther
 .I srvforker
@@ -208,24 +219,6 @@ or
 .I threadsrvforker
 unless already initialized to a non-nil value.
 .IP
-Initialize
-.IB s -> infd
-and
-.IB s -> outfd
-to be one end of a freshly allocated pipe,
-with
-.IB s -> srvfd
-initialized as the other end.
-.IP
-If
-.B name
-is non-nil, post the file descriptor
-.IB s -> srvfd
-under the name
-.BI /srv/ name
-using a call to
-.IR postsrv .
-.IP
 Fork a child process via
 .IB s -> forker
 using the
@@ -248,27 +241,37 @@ flag. This way, the service loop will share the original
 file descriptor table with previously created child
 processes of the caller.
 .IP
-The child process then calls
-.IB close( s -> srvfd )
-and then
-.IB srv( s ) \fR;
-it will exit once
-.I srv
-returns.
+The child process then closes the other end file descriptor
+and calls
+.IR srv .
 .IP
-If
+The parent process returns from the function with the
+mountable file descriptor
+.IR sfd .
+On error,
+.I postsrv
+and
+.I threadpostsrv
+return a file descriptor of
+.BR -1
+with error string set.
+.PP
+.I Postmountsrv
+and
+.I threadpostmntsrv
+call
+.I postsrv
+with
+.I name
+and then if
 .I mtpt
 is non-nil,
 call
-.BI amount( s -> srvfd,
+.BI amount( sfd ,
 .IB mtpt ,
 .IB flag ,
 \fB"")\fR;
-otherwise, close
-.IB s -> srvfd \fR.
-.IP
-The parent returns to the caller.
-.LP
+otherwise, close the file descriptor.
 If any error occurs during
 this process, the entire process is terminated by calling
 .I sysfatal

sys/src/cmd/aux/wacom.c

@@ -329,7 +329,6 @@ main()
 	
 	pipe(fd);
 	tabletsrv.infd = tabletsrv.outfd = fd[0];
-	tabletsrv.srvfd = fd[1];
 	tabletsrv.tree = alloctree(getuser(), getuser(), 0555, 0);
 	tfile = createfile(tabletsrv.tree->root, "tablet", getuser(), 0400, 0);
 	if(rfork(RFPROC | RFMEM | RFNOWAIT | RFNOTEG) > 0) exits(nil);

sys/src/lib9p/listen.c

@@ -18,7 +18,7 @@ listensrv(Srv *os, char *addr)
 	*s = *os;
 
 	s->addr = estrdup9p(addr);
-	s->infd = s->outfd = s->srvfd = -1;
+	s->infd = s->outfd = -1;
 	s->fpool = nil;
 	s->rpool = nil;
 	s->msize = 0;

sys/src/lib9p/mount.c

@@ -8,12 +8,15 @@
 void
 postmountsrv(Srv *s, char *name, char *mtpt, int flag)
 {
-	postsrv(s, name);
+	int sfd;
 
+	sfd = postsrv(s, name);
+	if(sfd < 0)
+		sysfatal("postsrv: %r");
 	if(mtpt != nil){
-		if(amount(s->srvfd, mtpt, flag, "") == -1)
+		if(amount(sfd, mtpt, flag, "") == -1)
 			sysfatal("mount %s: %r", mtpt);
-		/* mount closed s->srvfd */
+		/* mount closed sfd */
 	} else
-		close(s->srvfd);
+		close(sfd);
 }

sys/src/lib9p/post.c

@@ -8,43 +8,41 @@ static void
 postproc(void *v)
 {
 	Srv *s = v;
-	rendezvous(0, 0);
-	close(s->srvfd);
+	close((int)(uintptr)rendezvous(s, 0));
 	srv(s);
 }
 
-void
+int
 postsrv(Srv *s, char *name)
 {
-	char buf[80];
-	int fd[2];
-	int cfd;
+	int fd[2], cfd;
 
 	if(pipe(fd) < 0)
-		sysfatal("pipe: %r");
-	s->infd = s->outfd = fd[1];
-	s->srvfd = fd[0];
-
+		return -1;
 	if(name != nil){
+		char buf[80];
+
 		snprint(buf, sizeof buf, "/srv/%s", name);
-		if((cfd = create(buf, OWRITE|ORCLOSE|OCEXEC, 0600)) < 0)
-			sysfatal("create %s: %r", buf);
-		if(fprint(cfd, "%d", s->srvfd) < 0)
-			sysfatal("write %s: %r", buf);
+		if((cfd = create(buf, OWRITE|ORCLOSE|OCEXEC, 0600)) < 0
+		|| fprint(cfd, "%d", fd[0]) < 0){
+			close(fd[0]);
+			fd[0] = -1;
+			goto Out;
+		}
 	} else
 		cfd = -1;
 
+	/* now we are commited */
+	s->infd = s->outfd = fd[1];
 	if(s->forker == nil)
 		s->forker = srvforker;
 	(*s->forker)(postproc, s, RFNAMEG|RFNOTEG);
 
 	rfork(RFFDG);
-	rendezvous(0, 0);
-
-	close(s->infd);
-	if(s->infd != s->outfd)
-		close(s->outfd);
-
+	rendezvous(s, (void*)(uintptr)fd[0]);
+Out:
 	if(cfd >= 0)
 		close(cfd);
+	close(fd[1]);
+	return fd[0];
 }

sys/src/lib9p/share.c

@@ -8,7 +8,7 @@ void
 postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
 {
 	char buf[80];
-	int cfd;
+	int cfd, sfd;
 
 	if(mtpt != nil && desc != nil){
 		snprint(buf, sizeof buf, "#σc/%s", mtpt);
@@ -21,12 +21,13 @@ postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
 	} else
 		cfd = -1;
 
-	postsrv(s, name);
-
+	sfd = postsrv(s, name);
+	if(sfd < 0)
+		sysfatal("postsrv: %r");
 	if(cfd >= 0){
-		if(fprint(cfd, "%d\n", s->srvfd) < 0)
+		if(fprint(cfd, "%d\n", sfd) < 0)
 			sysfatal("write %s: %r", buf);
 		close(cfd);
 	}
-	close(s->srvfd);
+	close(sfd);
 }

sys/src/lib9p/threadpostsrv.c

@@ -4,10 +4,10 @@
 #include <thread.h>
 #include <9p.h>
 
-void
+int
 threadpostsrv(Srv *s, char *name)
 {
 	if(s->forker == nil)
 		s->forker = threadsrvforker;
-	postsrv(s, name);
+	return postsrv(s, name);
 }