There is an optimization in chmod(1), that makes it not to call chmod(2)

if the new file mode is the same as it was before; however, this
optimization must be disabled for filesystems that support NFSv4 ACLs.
Chmod uses pathconf(2) to determine whether this is the case - however,
pathconf(2) always follows symbolic links, while the 'chmod -h' doesn't.

This change adds lpathconf(3) to make it possible to solve that problem
in a clean way.

Reviewed by:	rwatson (earlier version)
Approved by:	re (kib)

7 files changed, 31 insertions, 7 deletions

diff --git a/sys/bsm/audit_kevents.h b/sys/bsm/audit_kevents.h
index c583718..8808095 100644
--- a/sys/bsm/audit_kevents.h
+++ b/sys/bsm/audit_kevents.h
@@ -597,6 +597,7 @@
 #define	AUE_PWRITE		43193	/* Darwin/FreeBSD. */
 #define	AUE_FSCTL		43194	/* Darwin. */
 #define	AUE_FFSCTL		43195	/* Darwin. */
+#define	AUE_LPATHCONF		43196	/* FreeBSD. */
 
 /*
  * Darwin BSM uses a number of AUE_O_* definitions, which are aliased to the
diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master
index 6e0f886..66731fc 100644
--- a/sys/compat/freebsd32/syscalls.master
+++ b/sys/compat/freebsd32/syscalls.master
@@ -900,3 +900,4 @@
 				    struct msqid_ds32 *buf); }
 512	AUE_SHMCTL	STD	{ int freebsd32_shmctl(int shmid, int cmd, \
 				    struct shmid_ds32 *buf); }
+513	AUE_LPATHCONF	STD	{ int lpathconf(char *path, int name); }
diff --git a/sys/compat/svr4/svr4_stat.c b/sys/compat/svr4/svr4_stat.c
index 9ef94be..cfb8276 100644
--- a/sys/compat/svr4/svr4_stat.c
+++ b/sys/compat/svr4/svr4_stat.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/jail.h>
 #include <sys/kernel.h>
 #include <sys/malloc.h>
+#include <sys/namei.h>
 #include <sys/unistd.h>
 #include <sys/time.h>
 #include <sys/syscallsubr.h>
@@ -669,7 +670,7 @@ svr4_sys_pathconf(td, uap)
 		return (0);
 	default:
 		CHECKALTEXIST(td, uap->path, &path);
-		error = kern_pathconf(td, path, UIO_SYSSPACE, name);
+		error = kern_pathconf(td, path, UIO_SYSSPACE, name, FOLLOW);
 		free(path, M_TEMP);
 		return (error);
 	}
diff --git a/sys/i386/ibcs2/ibcs2_misc.c b/sys/i386/ibcs2/ibcs2_misc.c
index 94fe50f..23c617d 100644
--- a/sys/i386/ibcs2/ibcs2_misc.c
+++ b/sys/i386/ibcs2/ibcs2_misc.c
@@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <sys/file.h>			/* Must come after sys/malloc.h */
 #include <sys/mutex.h>
+#include <sys/namei.h>
 #include <sys/priv.h>
 #include <sys/reboot.h>
 #include <sys/resourcevar.h>
@@ -763,7 +764,7 @@ ibcs2_pathconf(td, uap)
 
 	CHECKALTEXIST(td, uap->path, &path);
 	uap->name++;	/* iBCS2 _PC_* defines are offset by one */
-	error = kern_pathconf(td, path, UIO_SYSSPACE, uap->name);
+	error = kern_pathconf(td, path, UIO_SYSSPACE, uap->name, FOLLOW);
 	free(path, M_TEMP);
 	return (error);
 }
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index 940f13d..4e2e99c 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -910,5 +910,6 @@
 				    struct msqid_ds *buf); }
 512	AUE_SHMCTL	NOSTD	{ int shmctl(int shmid, int cmd, \
 				    struct shmid_ds *buf); }
+513	AUE_LPATHCONF	STD	{ int lpathconf(char *path, int name); }
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 7252c47..28d95e2e 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -2506,17 +2506,36 @@ pathconf(td, uap)
 	} */ *uap;
 {
 
-	return (kern_pathconf(td, uap->path, UIO_USERSPACE, uap->name));
+	return (kern_pathconf(td, uap->path, UIO_USERSPACE, uap->name, FOLLOW));
+}
+
+#ifndef _SYS_SYSPROTO_H_
+struct lpathconf_args {
+	char	*path;
+	int	name;
+};
+#endif
+int
+lpathconf(td, uap)
+	struct thread *td;
+	register struct lpathconf_args /* {
+		char *path;
+		int name;
+	} */ *uap;
+{
+
+	return (kern_pathconf(td, uap->path, UIO_USERSPACE, uap->name, NOFOLLOW));
 }
 
 int
-kern_pathconf(struct thread *td, char *path, enum uio_seg pathseg, int name)
+kern_pathconf(struct thread *td, char *path, enum uio_seg pathseg, int name,
+    u_long flags)
 {
 	struct nameidata nd;
 	int error, vfslocked;
 
-	NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
-	    AUDITVNODE1, pathseg, path, td);
+	NDINIT(&nd, LOOKUP, LOCKSHARED | LOCKLEAF | MPSAFE | AUDITVNODE1 |
+	    flags, pathseg, path, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	vfslocked = NDHASGIANT(&nd);
diff --git a/sys/sys/syscallsubr.h b/sys/sys/syscallsubr.h
index 7e5c15d..d0f209c 100644
--- a/sys/sys/syscallsubr.h
+++ b/sys/sys/syscallsubr.h
@@ -145,7 +145,7 @@ int	kern_open(struct thread *td, char *path, enum uio_seg pathseg,
 int	kern_openat(struct thread *td, int fd, char *path,
 	    enum uio_seg pathseg, int flags, int mode);
 int	kern_pathconf(struct thread *td, char *path, enum uio_seg pathseg,
-	    int name);
+	    int name, u_long flags);
 int	kern_pipe(struct thread *td, int fildes[2]);
 int	kern_preadv(struct thread *td, int fd, struct uio *auio, off_t offset);
 int	kern_ptrace(struct thread *td, int req, pid_t pid, void *addr,