Re: [libvirt] [PATCH v2] xen: Remove PATH_MAX sized stack allocation from block stats code

On Sat, Apr 09, 2011 at 12:05:17PM +0200, Matthias Bolte wrote: > --- >  src/xen/block_stats.c |   51 +++++++++++++++++++++++++------------------------ >  1 files changed, 26 insertions(+), 25 deletions(-) > > diff --git a/src/xen/block_stats.c b/src/xen/block_stats.c > index e7c80c9..1918257 100644 > --- a/src/xen/block_stats.c > +++ b/src/xen/block_stats.c > @@ -113,34 +113,35 @@ read_stat (const char *path) >  } > >  static int64_t > -read_bd_stat (int device, int domid, const char *str) > +read_bd_stat(int device, int domid, const char *str) >  { > -    char path[PATH_MAX]; > +    static const char *paths[] = { > +        "/sys/bus/xen-backend/devices/vbd-%d-%d/statistics/%s", > +        "/sys/bus/xen-backend/devices/tap-%d-%d/statistics/%s", > +        "/sys/devices/xen-backend/vbd-%d-%d/statistics/%s", > +        "/sys/devices/xen-backend/tap-%d-%d/statistics/%s" > +    }; > + > +    int i; > +    char *path; >      int64_t r; > > -    snprintf (path, sizeof path, > -              "/sys/bus/xen-backend/devices/vbd-%d-%d/statistics/%s", > -              domid, device, str); > -    r = read_stat (path); > -    if (r >= 0) return r; > - > -    snprintf (path, sizeof path, > -              "/sys/bus/xen-backend/devices/tap-%d-%d/statistics/%s", > -              domid, device, str); > -    r = read_stat (path); > -    if (r >= 0) return r; > - > -    snprintf (path, sizeof path, > -              "/sys/devices/xen-backend/vbd-%d-%d/statistics/%s", > -              domid, device, str); > -    r = read_stat (path); > -    if (r >= 0) return r; > - > -    snprintf (path, sizeof path, > -              "/sys/devices/xen-backend/tap-%d-%d/statistics/%s", > -              domid, device, str); > -    r = read_stat (path); > -    return r; > +    for (i = 0; i < ARRAY_CARDINALITY(paths); ++i) { > +        if (virAsprintf(&path, paths[i], domid, device, str) < 0) { > +            virReportOOMError(); > +            return -1; > +        } > + > +        r = read_stat(path); > + > +        VIR_FREE(path); > + > +        if (r >= 0) { > +            return r; > +        } > +    } > + > +    return -1; >  } > >  /* In Xenstore, /local/domain/0/backend/vbd/<domid>/<device>/state,  ACK, thanks ! Daniel