_9pfs: add darwin build

pkgs/tools/filesystems/9pfs/default.nix

@@ -10,6 +10,10 @@ stdenv.mkDerivation {
     sha256 = "007s2idsn6bspmfxv1qabj39ggkgvn6gwdbhczwn04lb4c6gh3xc";
   };
 
+  # Upstream development has stopped and is no longer accepting patches
+  # https://github.com/mischief/9pfs/pull/3
+  patches = [ ./fix-darwin-build.patch ];
+
   preConfigure =
     ''
       substituteInPlace Makefile --replace '-g bin' ""
@@ -25,7 +29,7 @@ stdenv.mkDerivation {
     homepage = "https://github.com/mischief/9pfs";
     description = "FUSE-based client of the 9P network filesystem protocol";
     maintainers = [ lib.maintainers.eelco ];
-    platforms = lib.platforms.linux;
+    platforms = lib.platforms.unix;
     license = with lib.licenses; [ lpl-102 bsd2 ];
   };
 }

pkgs/tools/filesystems/9pfs/fix-darwin-build.patch

@@ -0,0 +1,47 @@
+From 6b7863b51c97f8ecd9a93fc4347f8938f9b5c05f Mon Sep 17 00:00:00 2001
+From: midchildan <git@midchildan.org>
+Date: Tue, 30 Mar 2021 22:21:51 +0900
+Subject: [PATCH] build: fix build for macOS
+
+---
+ 9pfs.c | 4 ++--
+ libc.h | 4 ++++
+ 2 files changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/9pfs.c b/9pfs.c
+index 2c481bd..f5c487c 100644
+--- a/9pfs.c
++++ b/9pfs.c
+@@ -30,7 +30,7 @@
+ enum
+ {
+ 	CACHECTLSIZE = 8, /* sizeof("cleared\n") - 1 */
+-	MSIZE = 8192
++	MSIZE_9P = 8192
+ };
+ 
+ void	dir2stat(struct stat*, Dir*);
+@@ -505,7 +505,7 @@ main(int argc, char *argv[])
+ 		freeaddrinfo(ainfo);
+ 
+ 	init9p();
+-	msize = _9pversion(MSIZE);
++	msize = _9pversion(MSIZE_9P);
+ 	if(doauth){
+ 		authfid = _9pauth(AUTHFID, user, NULL);
+ 		ai = auth_proxy(authfid, auth_getkey, "proto=p9any role=client");
+diff --git a/libc.h b/libc.h
+index 099adba..aac03c5 100644
+--- a/libc.h
++++ b/libc.h
+@@ -61,6 +61,10 @@ typedef unsigned char uchar;
+ typedef unsigned long long uvlong;
+ typedef long long vlong;
+ 
++#ifndef __GLIBC__
++typedef unsigned long ulong;
++#endif
++
+ typedef
+ struct Qid
+ {