Our implementation of pipes does not provide useful values for st_dev
and st_ino when stat(2) is done on an anonymous pipe. It was noted by the
people outside the project, e.g. Perl contains a workaround in one
of its modules, submitted by Debian/kFreeBSD developers, see
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=537555
and the commit 16f708c9bc0dc48713b200 in the Perl git.
I think this is a non-conformance, since SUSv4 explicitely states
in the description of stat(2)
For all other file types defined in this volume of POSIX.1-2008, the
structure members st_mode, st_ino, st_dev, st_uid, st_gid, st_atim,
st_ctim, and st_mtim shall have meaningful values
Patch below implements the requirement, by the cost of the small overhead
at the pipe creation time, and slightly bigger cost at the destruction.
Any comments ?
diff --git a/sys/fs/devfs/devfs_devs.c b/sys/fs/devfs/devfs_devs.c
index a2d3222..a111527 100644
--- a/sys/fs/devfs/devfs_devs.c
+++ b/sys/fs/devfs/devfs_devs.c
@@ -171,8 +171,7 @@ devfs_free(struct cdev *cdev)
cdp = cdev2priv(cdev);
if (cdev-si_cred != NULL)
crfree(cdev-si_cred);
- if (cdp-cdp_inode 0)
- free_unr(devfs_inos, cdp-cdp_inode);
+ devfs_free_cdp_inode(cdp-cdp_inode);
if (cdp-cdp_maxdirent 0)
free(cdp-cdp_dirents, M_DEVFS2);
free(cdp, M_CDEVP);
@@ -394,7 +393,7 @@ devfs_delete(struct devfs_mount *dm, struct devfs_dirent
*de, int flags)
mac_devfs_destroy(de);
#endif
if (de-de_inode DEVFS_ROOTINO) {
- free_unr(devfs_inos, de-de_inode);
+ devfs_free_cdp_inode(de-de_inode);
de-de_inode = 0;
}
if (DEVFS_DE_DROP(de))
@@ -685,6 +684,21 @@ devfs_destroy(struct cdev *dev)
devfs_generation++;
}
+ino_t
+devfs_alloc_cdp_inode(void)
+{
+
+ return (alloc_unr(devfs_inos));
+}
+
+void
+devfs_free_cdp_inode(ino_t ino)
+{
+
+ if (ino 0)
+ free_unr(devfs_inos, ino);
+}
+
static void
devfs_devs_init(void *junk __unused)
{
diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
index b7ae521..2edecf2 100644
--- a/sys/kern/sys_pipe.c
+++ b/sys/kern/sys_pipe.c
@@ -93,6 +93,7 @@ __FBSDID($FreeBSD$);
#include sys/param.h
#include sys/systm.h
+#include sys/conf.h
#include sys/fcntl.h
#include sys/file.h
#include sys/filedesc.h
@@ -224,6 +225,8 @@ static int pipe_zone_init(void *mem, int size, int flags);
static voidpipe_zone_fini(void *mem, int size);
static uma_zone_t pipe_zone;
+static struct unrhdr *pipeino_unr;
+static ino_t pipedev_ino;
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
@@ -235,6 +238,10 @@ pipeinit(void *dummy __unused)
pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
UMA_ALIGN_PTR, 0);
KASSERT(pipe_zone != NULL, (pipe_zone not initialized));
+ pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
+ KASSERT(pipeino_unr != NULL, (pipe fake inodes not initialized));
+ pipedev_ino = devfs_alloc_cdp_inode();
+ KASSERT(pipedev_ino 0, (pipe dev inode not initialized));
}
static int
@@ -562,6 +569,12 @@ pipe_create(pipe, backing)
/* If we're not backing this pipe, no need to do anything. */
error = 0;
}
+ if (error == 0) {
+ pipe-pipe_ino = alloc_unr(pipeino_unr);
+ if (pipe-pipe_ino == -1)
+ /* pipeclose will clear allocated kva */
+ error = ENOMEM;
+ }
return (error);
}
@@ -1408,9 +1421,10 @@ pipe_stat(fp, ub, active_cred, td)
ub-st_ctim = pipe-pipe_ctime;
ub-st_uid = fp-f_cred-cr_uid;
ub-st_gid = fp-f_cred-cr_gid;
+ ub-st_dev = pipedev_ino;
+ ub-st_ino = pipe-pipe_ino;
/*
-* Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
-* XXX (st_dev, st_ino) should be unique.
+* Left as 0: st_nlink, st_rdev, st_flags, st_gen.
*/
return (0);
}
@@ -1463,6 +1477,7 @@ pipeclose(cpipe)
{
struct pipepair *pp;
struct pipe *ppipe;
+ ino_t ino;
KASSERT(cpipe != NULL, (pipeclose: cpipe == NULL));
@@ -1521,6 +1536,12 @@ pipeclose(cpipe)
knlist_destroy(cpipe-pipe_sel.si_note);
/*
+* Postpone the destroy of the fake inode number allocated for
+* our end, until pipe mtx is unlocked.
+*/
+ ino = cpipe-pipe_ino;
+
+ /*
* If both endpoints are now closed, release the memory for the
* pipe pair. If not, unlock.
*/
@@ -1532,6 +1553,9 @@ pipeclose(cpipe)
uma_zfree(pipe_zone, cpipe-pipe_pair);
} else
PIPE_UNLOCK(cpipe);
+
+ if (ino 0)
+ free_unr(pipeino_unr, cpipe-pipe_ino);
}
/*ARGSUSED*/
diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 08e1582..7acd2e0 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@
