From f6509078ed9d03b71c945b19cdda5c882cb1e78d Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sat, 1 May 2021 16:37:00 +0200
Subject: [PATCH] lib9p: expose Srv.forker handler and srvforker(),
 threadsrvforker() and threadsrv() functions

To use srvrease()/srvaquire() we need to have a way to spawn
new processes to handle the service loop. This functionality
was provided by the internal _forker() function which was
eigther rfork or libthread based implementation depending on
if postmountsrv() or threadpostmountsrv() where called.

For servers who want to use srv() directly, _forker would not
be initialized so srvrelease() could not be used.

To untangle this, we get rid of the global _forker handler
and put the handler in the Srv structure. Which will get
initialized (when nil) to eigther srvforker() or threadsrvforker()
depending on if the thread or non-thread entry points where used.

For symmetry, we provde new threadsrv() and threadpostsrv()
functions which handle the default initialization of Srv.forker.

This also allows a user to provide his own forker function,
maybe to conserve stack space.

To avoid dead code, we put each of these function in their
own object file. Note, this also allows a user to define its
own srvforker() symbol.
---
 sys/include/9p.h                   | 20 ++++++-----
 sys/man/2/9p                       | 53 +++++++++++++++++++++++-------
 sys/src/lib9p/listen.c             | 10 +++---
 sys/src/lib9p/mkfile               | 17 +++++++---
 sys/src/lib9p/mount.c              | 19 +++++++++++
 sys/src/lib9p/post.c               | 52 +++--------------------------
 sys/src/lib9p/rfork.c              | 25 ++------------
 sys/src/lib9p/share.c              | 33 +++++++++++++++++++
 sys/src/lib9p/srv.c                |  7 ++--
 sys/src/lib9p/thread.c             | 25 ++------------
 sys/src/lib9p/threadlistensrv.c    | 13 ++++++++
 sys/src/lib9p/threadpostmountsrv.c | 13 ++++++++
 sys/src/lib9p/threadpostsharesrv.c | 13 ++++++++
 sys/src/lib9p/threadpostsrv.c      | 13 ++++++++
 sys/src/lib9p/threadsrv.c          | 13 ++++++++
 15 files changed, 201 insertions(+), 125 deletions(-)
 create mode 100644 sys/src/lib9p/mount.c
 create mode 100644 sys/src/lib9p/share.c
 create mode 100644 sys/src/lib9p/threadlistensrv.c
 create mode 100644 sys/src/lib9p/threadpostmountsrv.c
 create mode 100644 sys/src/lib9p/threadpostsharesrv.c
 create mode 100644 sys/src/lib9p/threadpostsrv.c
 create mode 100644 sys/src/lib9p/threadsrv.c

diff --git a/sys/include/9p.h b/sys/include/9p.h
index 949476232..1a51ffeab 100644
--- a/sys/include/9p.h
+++ b/sys/include/9p.h
@@ -235,23 +235,29 @@ struct Srv {
 
 	int	spid;	/* pid of srv() caller */
 
+	void	(*forker)(void (*)(void*), void*, int);
 	void	(*free)(Srv*);
 };
 
+void		srvforker(void (*)(void*), void*, int);
+void		threadsrvforker(void (*)(void*), void*, int);
+
 void		srv(Srv*);
+void		postsrv(Srv*, char*);
 void		postmountsrv(Srv*, char*, char*, int);
-void		_postmountsrv(Srv*, char*, char*, int);
 void		postsharesrv(Srv*, char*, char*, char*);
-void		_postsharesrv(Srv*, char*, char*, char*);
 void		listensrv(Srv*, char*);
-void		_listensrv(Srv*, char*);
-int		chatty9p;
-void		respond(Req*, char*);
-void		responderror(Req*);
+
+void		threadsrv(Srv*);
+void		threadpostsrv(Srv*, char*);
 void		threadpostmountsrv(Srv*, char*, char*, int);
 void		threadpostsharesrv(Srv*, char*, char*, char*);
 void		threadlistensrv(Srv *s, char *addr);
 
+int		chatty9p;
+void		respond(Req*, char*);
+void		responderror(Req*);
+
 /*
  * Helper.  Assumes user is same as group.
  */
@@ -276,8 +282,6 @@ void		authwrite(Req*);
 void		authdestroy(Fid*);
 int		authattach(Req*);
 
-extern void (*_forker)(void (*)(void*), void*, int);
-
 void		srvacquire(Srv *);
 void		srvrelease(Srv *);
 
diff --git a/sys/man/2/9p b/sys/man/2/9p
index 9a110e292..d68fbaa2c 100644
--- a/sys/man/2/9p
+++ b/sys/man/2/9p
@@ -9,16 +9,21 @@ estrdup9p,
 listensrv,
 postmountsrv,
 postsharesrv,
+postsrv,
 readbuf,
 readstr,
 respond,
 responderror,
+srv
 srvacquire,
+srvforker,
 srvrelease,
 threadlistensrv,
 threadpostmountsrv,
 threadpostsharesrv,
-srv \- 9P file service
+threadpostsrv,
+threadsrv,
+threadsrvforker - 9P file service
 .SH SYNOPSIS
 .ft L
 .nf
@@ -59,6 +64,8 @@ typedef struct Srv {
 	int		infd;
 	int		outfd;
 	int		srvfd;
+
+	void		(*forker)(void (*fn)(void*), void *arg, int flags);
 } Srv;
 .fi
 .PP
@@ -66,12 +73,17 @@ typedef struct Srv {
 .ft L
 .ta \w'\fLvoid* 'u
 void	srv(Srv *s)
+void	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);
 void	threadpostmountsrv(Srv *s, char *name, char *mtpt, int flag)
 void	threadpostsharesrv(Srv *s, char *name, char *mtpt, char *desc)
-void	listensrv(Srv *s, char *addr)
 void	threadlistensrv(Srv *s, char *addr)
+void	srvforker(void (*fn)(void*), void *arg, int flags)
+void	threadsrvforker(void (*fn)(void*), void *arg, int flags)
 void	respond(Req *r, char *error)
 void	responderror(Req*)
 void	readstr(Req *r, char *src)
@@ -106,7 +118,9 @@ extern int chatty9p;
 .SH DESCRIPTION
 The function
 .I srv
-serves a 9P session by reading requests from
+and
+.I threadsrv
+serve a 9P session by reading requests from
 .BR s->infd ,
 dispatching them to the function pointers kept in 
 .BR Srv ,
@@ -166,6 +180,19 @@ but abort the program if they run out of memory.
 If alternate behavior is desired, clients can link against
 alternate implementations of these functions.
 .PP
+The functions
+.I srvforker
+and
+.I threadsrvforker
+handle the creation of new processes on a connection which use
+.I rfork
+(see
+.IR fork (2))
+or
+.I procrfork
+(see
+.IR thread (2)).
+.PP
 .I Postmountsrv
 and
 .I threadpostmountsrv
@@ -174,6 +201,14 @@ are wrappers that create a separate process in which to run
 They do the following:
 .IP
 Initialize
+.IB s -> forker
+to eigther
+.I srvforker
+or
+.I threadsrvforker
+unless already initialized to a non-nil value.
+.IP
+Initialize
 .IB s -> infd
 and
 .IB s -> outfd
@@ -187,16 +222,12 @@ If
 is non-nil, post the file descriptor
 .IB s -> srvfd
 under the name
-.BI /srv/ name .
+.BI /srv/ name
+using a call to
+.IR postsrv .
 .IP
 Fork a child process via
-.I rfork
-(see
-.IR fork (2))
-or
-.I procrfork
-(see
-.IR thread (2)),
+.IB s -> forker
 using the
 .BR RFPROC ,
 .BR RFNOWAIT ,
diff --git a/sys/src/lib9p/listen.c b/sys/src/lib9p/listen.c
index 89b2f322d..59082f594 100644
--- a/sys/src/lib9p/listen.c
+++ b/sys/src/lib9p/listen.c
@@ -11,7 +11,7 @@ static void srvfree(Srv *);
 static char *getremotesys(char*);
 
 void
-_listensrv(Srv *os, char *addr)
+listensrv(Srv *os, char *addr)
 {
 	Srv *s;
 
@@ -33,9 +33,9 @@ _listensrv(Srv *os, char *addr)
 	s->spid = 0;
 	s->free = nil;
 
-	if(_forker == nil)
-		sysfatal("no forker");
-	_forker(listenproc, s, 0);
+	if(s->forker == nil)
+		s->forker = srvforker;
+	(*s->forker)(listenproc, s, 0);
 }
 
 static void
@@ -72,7 +72,7 @@ listenproc(void *v)
 		s->addr = getremotesys(ndir);
 		s->infd = s->outfd = data;
 		s->free = srvfree;
-		_forker(srvproc, s, 0);
+		(*s->forker)(srvproc, s, 0);
 	}
 	free(os->addr);
 	free(os);
diff --git a/sys/src/lib9p/mkfile b/sys/src/lib9p/mkfile
index 78129109b..6ec968a88 100644
--- a/sys/src/lib9p/mkfile
+++ b/sys/src/lib9p/mkfile
@@ -7,17 +7,24 @@ OFILES=\
 	fid.$O\
 	file.$O\
 	intmap.$O\
-	listen.$O\
 	mem.$O\
 	req.$O\
 	parse.$O\
-	post.$O\
 	queue.$O\
-	rfork.$O\
-	srv.$O\
-	thread.$O\
 	uid.$O\
 	util.$O\
+	srv.$O\
+	post.$O\
+	mount.$O\
+	share.$O\
+	listen.$O\
+	rfork.$O\
+	thread.$O\
+	threadsrv.$O\
+	threadpostsrv.$O\
+	threadpostmountsrv.$O\
+	threadpostsharesrv.$O\
+	threadlistensrv.$O\
 
 HFILES=/sys/include/9p.h
 
diff --git a/sys/src/lib9p/mount.c b/sys/src/lib9p/mount.c
new file mode 100644
index 000000000..1adc90bed
--- /dev/null
+++ b/sys/src/lib9p/mount.c
@@ -0,0 +1,19 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+#include <auth.h>
+
+void
+postmountsrv(Srv *s, char *name, char *mtpt, int flag)
+{
+	postsrv(s, name);
+
+	if(mtpt != nil){
+		if(amount(s->srvfd, mtpt, flag, "") == -1)
+			sysfatal("mount %s: %r", mtpt);
+		/* mount closed s->srvfd */
+	} else
+		close(s->srvfd);
+}
diff --git a/sys/src/lib9p/post.c b/sys/src/lib9p/post.c
index ba4265494..803d7646d 100644
--- a/sys/src/lib9p/post.c
+++ b/sys/src/lib9p/post.c
@@ -8,15 +8,13 @@
 static void
 postproc(void *v)
 {
-	Srv *s;
-
-	s = v;
+	Srv *s = v;
 	rendezvous(0, 0);
 	close(s->srvfd);
 	srv(s);
 }
 
-static void
+void
 postsrv(Srv *s, char *name)
 {
 	char buf[80];
@@ -37,9 +35,9 @@ postsrv(Srv *s, char *name)
 	} else
 		cfd = -1;
 
-	if(_forker == nil)
-		sysfatal("no forker");
-	_forker(postproc, s, RFNAMEG|RFNOTEG);
+	if(s->forker == nil)
+		s->forker = srvforker;
+	(*s->forker)(postproc, s, RFNAMEG|RFNOTEG);
 
 	rfork(RFFDG);
 	rendezvous(0, 0);
@@ -51,43 +49,3 @@ postsrv(Srv *s, char *name)
 	if(cfd >= 0)
 		close(cfd);
 }
-
-void
-_postmountsrv(Srv *s, char *name, char *mtpt, int flag)
-{
-	postsrv(s, name);
-
-	if(mtpt != nil){
-		if(amount(s->srvfd, mtpt, flag, "") == -1)
-			sysfatal("mount %s: %r", mtpt);
-		/* mount closed s->srvfd */
-	} else
-		close(s->srvfd);
-}
-
-void
-_postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
-{
-	char buf[80];
-	int cfd;
-
-	if(mtpt != nil && desc != nil){
-		snprint(buf, sizeof buf, "#σc/%s", mtpt);
-		if((cfd = create(buf, OREAD, DMDIR|0700)) >= 0)
-			close(cfd);
-
-		snprint(buf, sizeof buf, "#σc/%s/%s", mtpt, desc);
-		if((cfd = create(buf, OWRITE|ORCLOSE|OCEXEC, 0600)) < 0)
-			sysfatal("create %s: %r", buf);
-	} else
-		cfd = -1;
-
-	postsrv(s, name);
-
-	if(cfd >= 0){
-		if(fprint(cfd, "%d\n", s->srvfd) < 0)
-			sysfatal("write %s: %r", buf);
-		close(cfd);
-	}
-	close(s->srvfd);
-}
diff --git a/sys/src/lib9p/rfork.c b/sys/src/lib9p/rfork.c
index 45bf59365..32621d57f 100644
--- a/sys/src/lib9p/rfork.c
+++ b/sys/src/lib9p/rfork.c
@@ -4,8 +4,8 @@
 #include <thread.h>
 #include <9p.h>
 
-static void
-rforker(void (*fn)(void*), void *arg, int flag)
+void
+srvforker(void (*fn)(void*), void *arg, int flag)
 {
 	switch(rfork(RFPROC|RFMEM|RFNOWAIT|flag)){
 	case -1:
@@ -17,24 +17,3 @@ rforker(void (*fn)(void*), void *arg, int flag)
 		_exits(0);
 	}
 }
-
-void
-listensrv(Srv *s, char *addr)
-{
-	_forker = rforker;
-	_listensrv(s, addr);
-}
-
-void
-postmountsrv(Srv *s, char *name, char *mtpt, int flag)
-{
-	_forker = rforker;
-	_postmountsrv(s, name, mtpt, flag);
-}
-
-void
-postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
-{
-	_forker = rforker;
-	_postsharesrv(s, name, mtpt, desc);
-}
diff --git a/sys/src/lib9p/share.c b/sys/src/lib9p/share.c
new file mode 100644
index 000000000..f33d62b1e
--- /dev/null
+++ b/sys/src/lib9p/share.c
@@ -0,0 +1,33 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+#include <auth.h>
+
+void
+postsharesrv(Srv *s, char *name, char *mtpt, char *desc)
+{
+	char buf[80];
+	int cfd;
+
+	if(mtpt != nil && desc != nil){
+		snprint(buf, sizeof buf, "#σc/%s", mtpt);
+		if((cfd = create(buf, OREAD, DMDIR|0700)) >= 0)
+			close(cfd);
+
+		snprint(buf, sizeof buf, "#σc/%s/%s", mtpt, desc);
+		if((cfd = create(buf, OWRITE|ORCLOSE|OCEXEC, 0600)) < 0)
+			sysfatal("create %s: %r", buf);
+	} else
+		cfd = -1;
+
+	postsrv(s, name);
+
+	if(cfd >= 0){
+		if(fprint(cfd, "%d\n", s->srvfd) < 0)
+			sysfatal("write %s: %r", buf);
+		close(cfd);
+	}
+	close(s->srvfd);
+}
diff --git a/sys/src/lib9p/srv.c b/sys/src/lib9p/srv.c
index f3039e012..5e82b5603 100644
--- a/sys/src/lib9p/srv.c
+++ b/sys/src/lib9p/srv.c
@@ -5,8 +5,6 @@
 #include <thread.h>
 #include <9p.h>
 
-void (*_forker)(void(*)(void*), void*, int);
-
 static char Ebadattach[] = "unknown specifier in attach";
 static char Ebadoffset[] = "bad offset";
 static char Ebadcount[] = "bad count";
@@ -813,7 +811,7 @@ srvrelease(Srv *srv)
 {
 	if(decref(&srv->sref) == 0){
 		incref(&srv->sref);
-		_forker(srvwork, srv, 0);
+		(*srv->forker)(srvwork, srv, 0);
 	}
 	qunlock(&srv->slock);
 }
@@ -843,6 +841,9 @@ srv(Srv *srv)
 	if(srv->start)
 		srv->start(srv);
 
+	if(srv->forker == nil)
+		srv->forker = srvforker;
+
 	incref(&srv->sref);
 	srvwork(srv);
 }
diff --git a/sys/src/lib9p/thread.c b/sys/src/lib9p/thread.c
index 445791be4..0e536ba5b 100644
--- a/sys/src/lib9p/thread.c
+++ b/sys/src/lib9p/thread.c
@@ -4,29 +4,8 @@
 #include <thread.h>
 #include <9p.h>
 
-static void
-tforker(void (*fn)(void*), void *arg, int rflag)
+void
+threadsrvforker(void (*fn)(void*), void *arg, int rflag)
 {
 	procrfork(fn, arg, 32*1024, rflag);
 }
-
-void
-threadlistensrv(Srv *s, char *addr)
-{
-	_forker = tforker;
-	_listensrv(s, addr);
-}
-
-void
-threadpostmountsrv(Srv *s, char *name, char *mtpt, int flag)
-{
-	_forker = tforker;
-	_postmountsrv(s, name, mtpt, flag);
-}
-
-void
-threadpostsharesrv(Srv *s, char *name, char *mtpt, char *desc)
-{
-	_forker = tforker;
-	_postsharesrv(s, name, mtpt, desc);
-}
diff --git a/sys/src/lib9p/threadlistensrv.c b/sys/src/lib9p/threadlistensrv.c
new file mode 100644
index 000000000..65be4e51e
--- /dev/null
+++ b/sys/src/lib9p/threadlistensrv.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+void
+threadlistensrv(Srv *s, char *addr)
+{
+	if(s->forker == nil)
+		s->forker = threadsrvforker;
+	listensrv(s, addr);
+}
diff --git a/sys/src/lib9p/threadpostmountsrv.c b/sys/src/lib9p/threadpostmountsrv.c
new file mode 100644
index 000000000..025459b65
--- /dev/null
+++ b/sys/src/lib9p/threadpostmountsrv.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+void
+threadpostmountsrv(Srv *s, char *name, char *mtpt, int flag)
+{
+	if(s->forker == nil)
+		s->forker = threadsrvforker;
+	postmountsrv(s, name, mtpt, flag);
+}
diff --git a/sys/src/lib9p/threadpostsharesrv.c b/sys/src/lib9p/threadpostsharesrv.c
new file mode 100644
index 000000000..383852c4a
--- /dev/null
+++ b/sys/src/lib9p/threadpostsharesrv.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+void
+threadpostsharesrv(Srv *s, char *name, char *mtpt, char *desc)
+{
+	if(s->forker == nil)
+		s->forker = threadsrvforker;
+	postsharesrv(s, name, mtpt, desc);
+}
diff --git a/sys/src/lib9p/threadpostsrv.c b/sys/src/lib9p/threadpostsrv.c
new file mode 100644
index 000000000..abdb882e8
--- /dev/null
+++ b/sys/src/lib9p/threadpostsrv.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+void
+threadpostsrv(Srv *s, char *name)
+{
+	if(s->forker == nil)
+		s->forker = threadsrvforker;
+	postsrv(s, name);
+}
diff --git a/sys/src/lib9p/threadsrv.c b/sys/src/lib9p/threadsrv.c
new file mode 100644
index 000000000..f892f5195
--- /dev/null
+++ b/sys/src/lib9p/threadsrv.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+void
+threadsrv(Srv *s)
+{
+	if(s->forker == nil)
+		s->forker = threadsrvforker;
+	srv(s);
+}