On Sun, May 20, 2012 at 06:05:12PM +0200, Davidlohr Bueso wrote:
> On Sun, 2012-05-20 at 10:51 -0400, Dave Reisner wrote:
> > On Sun, May 20, 2012 at 04:06:00PM +0200, Davidlohr Bueso wrote:
> > > On Sat, 2012-05-19 at 20:39 -0400, Dave Reisner wrote:
> > > > While we're at it, expand this list of known pseudofs types.
> > > >
> > > > Signed-off-by: Dave Reisner <dreisner@xxxxxxxxxxxxx>
> > > > ---
> > > > libmount/src/utils.c | 68 +++++++++++++++++++++++++++++++-------------------
> > > > 1 file changed, 43 insertions(+), 25 deletions(-)
> > > >
> > > > diff --git a/libmount/src/utils.c b/libmount/src/utils.c
> > > > index b824edc..77557f2 100644
> > > > --- a/libmount/src/utils.c
> > > > +++ b/libmount/src/utils.c
> > > > @@ -72,6 +72,15 @@ int mnt_parse_offset(const char *str, size_t len, uintmax_t *res)
> > > > return rc;
> > > > }
> > > >
> > > > +/* used as a callback by bsearch in mnt_fstype_is_pseudofs() */
> > > > +static int fstype_cmp(const void *v1, const void *v2)
> > > > +{
> > > > + const char *s1 = *(const char **)v1;
> > > > + const char *s2 = *(const char **)v2;
> > > > +
> > > > + return strcmp(s1, s2);
> > > > +}
> > > > +
> > > > /* returns basename and keeps dirname in the @path, if @path is "/" (root)
> > > > * then returns empty string */
> > > > static char *stripoff_last_component(char *path)
> > > > @@ -214,31 +223,40 @@ char *mnt_unmangle(const char *str)
> > > > */
> > > > int mnt_fstype_is_pseudofs(const char *type)
> > > > {
> > > > - if (!type)
> > > > - return 0;
> > > > - if (strcmp(type, "none") == 0 ||
> > > > - strcmp(type, "proc") == 0 ||
> > > > - strcmp(type, "tmpfs") == 0 ||
> > > > - strcmp(type, "sysfs") == 0 ||
> > > > - strcmp(type, "autofs") == 0 ||
> > > > - strcmp(type, "devpts") == 0||
> > > > - strcmp(type, "cgroup") == 0 ||
> > > > - strcmp(type, "devtmpfs") == 0 ||
> > > > - strcmp(type, "devfs") == 0 ||
> > > > - strcmp(type, "dlmfs") == 0 ||
> > > > - strcmp(type, "cpuset") == 0 ||
> > > > - strcmp(type, "configfs") == 0 ||
> > > > - strcmp(type, "securityfs") == 0 ||
> > > > - strcmp(type, "hugetlbfs") == 0 ||
> > > > - strcmp(type, "rpc_pipefs") == 0 ||
> > > > - strcmp(type, "fusectl") == 0 ||
> > > > - strcmp(type, "mqueue") == 0 ||
> > > > - strcmp(type, "binfmt_misc") == 0 ||
> > > > - strcmp(type, "fuse.gvfs-fuse-daemon") == 0 ||
> > > > - strcmp(type, "debugfs") == 0 ||
> > > > - strcmp(type, "spufs") == 0)
> > > > - return 1;
> > > > - return 0;
> > > > + static const char *pseudofs[] = {
> > > > + "anon_inodefs",
> > > > + "autofs",
> > > > + "bdev",
> > > > + "binfmt_misc",
> > > > + "cgroup",
> > > > + "configfs",
> > > > + "cpuset",
> > > > + "debugfs",
> > > > + "devfs",
> > > > + "devpts",
> > > > + "devtmpfs",
> > > > + "dlmfs",
> > > > + "fuse.gvfs-fuse-daemon",
> > > > + "fusectl",
> > > > + "hugetlbfs",
> > > > + "mqueue",
> > > > + "nfsd",
> > > > + "none",
> > > > + "pipefs",
> > > > + "proc",
> > > > + "pstore",
> > > > + "ramfs",
> > > > + "rootfs",
> > > > + "rpc_pipefs",
> > > > + "securityfs",
> > > > + "sockfs",
> > > > + "spufs",
> > > > + "sysfs",
> > > > + "tmpfs"
> > > > + };
> > > > +
> > >
> > > What about applying sort (qsort(3)) before searching here? This would
> > > correct any manual string sorting that pseudofs[] imposes to the
> > > developer.
> > >
> >
> > Hmm, so the overhead from this seems to be negligible, but given that
> > this is running as part of a library, wouldn't we need a reentrant
> > version of qsort? qsort_r was added to glibc in 2.8, but I'm not
> > familiar with how portable this would be to other libc's.
>
> I normally worry about reentrancy when dealing with interrupt handling,
> like signals. Also consider that pseudofs[] isn't global.
>
qsort_r takes an extra param to the callback to hold an element while
its being swapped. The reentrancy of the function isn't guaranteed just
because it operates on a non-global var.
Regardless, I'm not really in favor of adding this. I think it's reasonable
to push a little responsibility on the developer and preemptively ensure
that this is sorted. Perhaps add a comment in the function would be
sufficient: "make sure this is sorted or Karel will come after you".
d
> >
> > > > + return !(bsearch(&type, pseudofs, ARRAY_SIZE(pseudofs),
> > > > + sizeof(char*), fstype_cmp) == NULL);
> > > > }
> > > >
> > > > /**
> > >
> > >
> > > --
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> >
>
>
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