[src/trunk]: src Add mkfifo{, at}(2) mode in mknod{, at}(2) as requested by POSIX

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/071c6389f7df
branches:  trunk
changeset: 842211:071c6389f7df
user:      kamil <kamil%NetBSD.org@localhost>
date:      Thu Jun 20 03:31:53 2019 +0000

description:
Add mkfifo{,at}(2) mode in mknod{,at}(2) as requested by POSIX

mknod with mode & S_IFIFO and dev=0 shall behave like mkfifo.

Update the documentation to reflect this state.

Add ATF tests.

This is an in-kernel implementation as typically user-space programs use
mkfifo(2) directly, however whenever there is need to bypass libc (like in
valgrind) then portable POSIX software calls the mknod syscall.

Noted on tech-kern@ by Greg Troxel.

diffstat:

 lib/libc/sys/mknod.2                  |  38 +++++++++++++++++++++++++++++++---
 sys/compat/netbsd32/netbsd32_netbsd.c |   8 +++---
 sys/kern/vfs_syscalls.c               |  26 ++++++++++++++++++-----
 sys/sys/vfs_syscalls.h                |   3 +-
 tests/lib/libc/c063/t_mkfifoat.c      |  31 ++++++++++++++++++++++++++-
 tests/lib/libc/sys/t_mkfifo.c         |  33 ++++++++++++++++++++++++++++-
 6 files changed, 120 insertions(+), 19 deletions(-)

diffs (truncated from 304 to 300 lines):

diff -r 80a5f0475843 -r 071c6389f7df lib/libc/sys/mknod.2
--- a/lib/libc/sys/mknod.2      Thu Jun 20 03:31:29 2019 +0000
+++ b/lib/libc/sys/mknod.2      Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: mknod.2,v 1.29 2017/11/20 17:03:31 uwe Exp $
+.\"    $NetBSD: mknod.2,v 1.30 2019/06/20 03:31:54 kamil Exp $
 .\"
 .\" Copyright (c) 1980, 1991, 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"     @(#)mknod.2    8.1 (Berkeley) 6/4/93
 .\"
-.Dd July 29, 2013
+.Dd June 20, 2019
 .Dt MKNOD 2
 .Os
 .Sh NAME
@@ -47,7 +47,28 @@
 .Ft int
 .Fn mknodat "int fd" "const char *path" "mode_t mode" "dev_t dev"
 .Sh DESCRIPTION
-The device special file
+.Nm
+with
+.Dv S_IFIFO
+specified in
+.Fa mode
+and 0 in
+.Fa dev
+makes a fifo file.
+This call is respectively a portable alias for
+.Xr mkfifo 2
+and
+.Xr mkfifoat 2 .
+.Pp
+.Nm
+with
+.Dv S_IFCHR
+or
+.Dv S_IFBLK
+in
+.Fa mode
+makes a device special file.
+The file
 .Fa path
 is created with the major and minor
 device numbers specified by
@@ -87,7 +108,7 @@
 in order to specify the current directory.
 .Pp
 .Fn mknod
-requires super-user privileges.
+requires super-user privileges for creating device special files.
 .Sh RETURN VALUES
 .Rv -std mknod mknodat
 .Sh ERRORS
@@ -138,6 +159,8 @@
 A component of the path prefix is not a directory.
 .It Bq Er EPERM
 The process's effective user ID is not super-user.
+.It Bq Er EOPNOTSUPP
+The kernel has not been configured to support fifo's.
 .It Bq Er EROFS
 The named file resides on a read-only file system.
 .El
@@ -178,3 +201,10 @@
 .Fn mknod
 function call appeared in
 .At v6 .
+.Pp
+The alias mode for
+.Xr mkfifo 2
+and
+.Xr mkfifoat 2
+first appeared in
+.Nx 9 .
diff -r 80a5f0475843 -r 071c6389f7df sys/compat/netbsd32/netbsd32_netbsd.c
--- a/sys/compat/netbsd32/netbsd32_netbsd.c     Thu Jun 20 03:31:29 2019 +0000
+++ b/sys/compat/netbsd32/netbsd32_netbsd.c     Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: netbsd32_netbsd.c,v 1.227 2019/06/18 22:34:25 kamil Exp $      */
+/*     $NetBSD: netbsd32_netbsd.c,v 1.228 2019/06/20 03:31:54 kamil Exp $      */
 
 /*
  * Copyright (c) 1998, 2001, 2008, 2018 Matthew R. Green
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: netbsd32_netbsd.c,v 1.227 2019/06/18 22:34:25 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: netbsd32_netbsd.c,v 1.228 2019/06/20 03:31:54 kamil Exp $");
 
 /*
  * below are all the standard NetBSD system calls, in the 32bit
@@ -297,8 +297,8 @@
                syscallarg(netbsd32_dev_t) dev;
        } */
 
-       return do_sys_mknod(l, SCARG_P32(uap, path), SCARG(uap, mode),
-           SCARG(uap, dev), UIO_USERSPACE);
+       return do_posix_mknodat(l, AT_FDCWD, SCARG_P32(uap, path),
+           SCARG(uap, mode), SCARG(uap, dev));
 }
 
 int
diff -r 80a5f0475843 -r 071c6389f7df sys/kern/vfs_syscalls.c
--- a/sys/kern/vfs_syscalls.c   Thu Jun 20 03:31:29 2019 +0000
+++ b/sys/kern/vfs_syscalls.c   Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_syscalls.c,v 1.530 2019/06/19 14:16:06 kamil Exp $ */
+/*     $NetBSD: vfs_syscalls.c,v 1.531 2019/06/20 03:31:54 kamil Exp $ */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.530 2019/06/19 14:16:06 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.531 2019/06/20 03:31:54 kamil Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_fileassoc.h"
@@ -2151,6 +2151,20 @@
        return error;
 }
 
+int
+do_posix_mknodat(struct lwp *l, int fdat, const char *pathname, mode_t mode,
+    dev_t dev)
+{
+
+       if ((mode & S_IFIFO) && dev == 0)
+               return do_sys_mkfifoat(l, fdat, pathname, mode);
+       else if (mode & (S_IFCHR | S_IFBLK))
+               return do_sys_mknodat(l, fdat, pathname, mode, dev,
+                   UIO_USERSPACE);
+       else
+               return EINVAL;
+}
+
 /*
  * Create a special file.
  */
@@ -2164,8 +2178,8 @@
                syscallarg(mode_t) mode;
                syscallarg(dev_t) dev;
        } */
-       return do_sys_mknodat(l, AT_FDCWD, SCARG(uap, path),
-           SCARG(uap, mode), SCARG(uap, dev), UIO_USERSPACE);
+       return do_posix_mknodat(l, AT_FDCWD, SCARG(uap, path),
+           SCARG(uap, mode), SCARG(uap, dev));
 }
 
 int
@@ -2180,8 +2194,8 @@
                syscallarg(dev_t) dev;
        } */
 
-       return do_sys_mknodat(l, SCARG(uap, fd), SCARG(uap, path),
-           SCARG(uap, mode), SCARG(uap, dev), UIO_USERSPACE);
+       return do_posix_mknodat(l, SCARG(uap, fd), SCARG(uap, path),
+           SCARG(uap, mode), SCARG(uap, dev));
 }
 
 int
diff -r 80a5f0475843 -r 071c6389f7df sys/sys/vfs_syscalls.h
--- a/sys/sys/vfs_syscalls.h    Thu Jun 20 03:31:29 2019 +0000
+++ b/sys/sys/vfs_syscalls.h    Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_syscalls.h,v 1.24 2019/06/18 22:34:26 kamil Exp $        */
+/*     $NetBSD: vfs_syscalls.h,v 1.25 2019/06/20 03:31:54 kamil Exp $        */
 
 /*
  * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -70,6 +70,7 @@
 int    do_sys_linkat(struct lwp *, int, const char *, int, const char *, int, register_t *);
 int    do_sys_unlink(const char *, enum uio_seg);
 int    do_sys_rename(const char *, const char *, enum uio_seg, int);
+int    do_posix_mknodat(struct lwp *, int, const char *, mode_t, dev_t);
 int    do_sys_mknod(struct lwp *, const char *, mode_t, dev_t, enum uio_seg);
 int    do_sys_mknodat(struct lwp *, int, const char *, mode_t, dev_t, enum uio_seg);
 int    do_sys_chmodat(struct lwp *, int, const char *, int, int);
diff -r 80a5f0475843 -r 071c6389f7df tests/lib/libc/c063/t_mkfifoat.c
--- a/tests/lib/libc/c063/t_mkfifoat.c  Thu Jun 20 03:31:29 2019 +0000
+++ b/tests/lib/libc/c063/t_mkfifoat.c  Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: t_mkfifoat.c,v 1.4 2017/01/14 20:55:26 christos Exp $ */
+/*     $NetBSD: t_mkfifoat.c,v 1.5 2019/06/20 03:31:53 kamil Exp $ */
 
 /*-
  * Copyright (c) 2012 The NetBSD Foundation, Inc.
@@ -29,7 +29,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_mkfifoat.c,v 1.4 2017/01/14 20:55:26 christos Exp $");
+__RCSID("$NetBSD: t_mkfifoat.c,v 1.5 2019/06/20 03:31:53 kamil Exp $");
 
 #include <atf-c.h>
 #include <errno.h>
@@ -108,6 +108,32 @@
        ATF_REQUIRE(mkfifoat(-1, FIFO, mode) == -1);
 }
 
+ATF_TC(mknodat_s_ififo);
+ATF_TC_HEAD(mknodat_s_ififo, tc)
+{
+       atf_tc_set_md_var(tc, "descr", "Test mknodat(2) with S_IFIFO");
+}
+
+ATF_TC_BODY(mknodat_s_ififo, tc)
+{
+       struct stat st;
+       int dfd;
+       mode_t mode = S_IFIFO | 0600;
+
+       (void)memset(&st, 0, sizeof(struct stat));
+
+       ATF_REQUIRE(mkdir(DIR, 0755) == 0);
+       ATF_REQUIRE((dfd = open(DIR, O_RDONLY, 0)) != -1);
+       ATF_REQUIRE(mknodat(dfd, BASEFIFO, mode, 0) != -1);
+       ATF_REQUIRE(access(FIFO, F_OK) == 0);
+       ATF_REQUIRE(stat(FIFO, &st) == 0);
+
+       if (S_ISFIFO(st.st_mode) == 0)
+               atf_tc_fail("invalid mode from mknodat(2) with S_IFIFO");
+
+       (void)close(dfd);
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 
@@ -115,6 +141,7 @@
        ATF_TP_ADD_TC(tp, mkfifoat_fdcwd);
        ATF_TP_ADD_TC(tp, mkfifoat_fdcwderr);
        ATF_TP_ADD_TC(tp, mkfifoat_fderr);
+       ATF_TP_ADD_TC(tp, mknodat_s_ififo);
 
        return atf_no_error();
 }
diff -r 80a5f0475843 -r 071c6389f7df tests/lib/libc/sys/t_mkfifo.c
--- a/tests/lib/libc/sys/t_mkfifo.c     Thu Jun 20 03:31:29 2019 +0000
+++ b/tests/lib/libc/sys/t_mkfifo.c     Thu Jun 20 03:31:53 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: t_mkfifo.c,v 1.2 2011/11/02 06:04:48 jruoho Exp $ */
+/* $NetBSD: t_mkfifo.c,v 1.3 2019/06/20 03:31:54 kamil Exp $ */
 
 /*-
  * Copyright (c) 2011 The NetBSD Foundation, Inc.
@@ -29,7 +29,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_mkfifo.c,v 1.2 2011/11/02 06:04:48 jruoho Exp $");
+__RCSID("$NetBSD: t_mkfifo.c,v 1.3 2019/06/20 03:31:54 kamil Exp $");
 
 #include <sys/stat.h>
 #include <sys/wait.h>
@@ -263,6 +263,34 @@
        (void)unlink(path);
 }
 
+ATF_TC_WITH_CLEANUP(mknod_s_ififo);
+ATF_TC_HEAD(mknod_s_ififo, tc)
+{
+       atf_tc_set_md_var(tc, "descr", "Test mknod(2) with S_IFIFO");
+}
+
+ATF_TC_BODY(mknod_s_ififo, tc)
+{
+       struct stat st;
+
+       support();
+
+       (void)memset(&st, 0, sizeof(struct stat));
+
+       ATF_REQUIRE(mknod(path, S_IFIFO | 0600, 0) == 0);
+       ATF_REQUIRE(stat(path, &st) == 0);
+
+       if (S_ISFIFO(st.st_mode) == 0)
+               atf_tc_fail("invalid mode from mknod(2) with S_IFIFO");
+
+       ATF_REQUIRE(unlink(path) == 0);
+}
+
+ATF_TC_CLEANUP(mknod_s_ififo, tc)
+{
+       (void)unlink(path);
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 
@@ -271,6 +299,7 @@
        ATF_TP_ADD_TC(tp, mkfifo_nonblock);
        ATF_TP_ADD_TC(tp, mkfifo_perm);
        ATF_TP_ADD_TC(tp, mkfifo_stat);