[Libguestfs] [PATCH] daemon: Rewrite prog_exists so it uses the actual PATH, not hard-coded list.
Richard W.M. Jones
rjones at redhat.com
Tue Jun 23 20:24:42 UTC 2015
On Tue, Jun 23, 2015 at 07:58:52PM +0200, Pino Toscano wrote:
> In data martedì 23 giugno 2015 14:34:18, Richard W.M. Jones ha scritto:
> > ---
> > daemon/guestfsd.c | 37 +++++++++++++++++++++++--------------
> > 1 file changed, 23 insertions(+), 14 deletions(-)
> >
> > diff --git a/daemon/guestfsd.c b/daemon/guestfsd.c
> > index 21b3600..c9cc8c5 100644
> > --- a/daemon/guestfsd.c
> > +++ b/daemon/guestfsd.c
> > @@ -243,9 +243,6 @@ main (int argc, char *argv[])
> > /* Set up a basic environment. After we are called by /init the
> > * environment is essentially empty.
> > * https://bugzilla.redhat.com/show_bug.cgi?id=502074#c5
> > - *
> > - * NOTE: if you change $PATH, you must also change 'prog_exists'
> > - * function below.
> > */
> > setenv ("PATH", "/sbin:/usr/sbin:/bin:/usr/bin", 1);
> > setenv ("SHELL", "/bin/sh", 1);
> > @@ -1440,22 +1437,34 @@ mountable_to_string (const mountable_t *mountable)
> > }
> > }
> >
> > -/* Check program exists and is executable on $PATH. Actually, we
> > - * just assume PATH contains the default entries (see main() above).
> > - */
> > +/* Check program exists and is executable on $PATH. */
> > int
> > prog_exists (const char *prog)
> > {
> > - static const char * const dirs[] =
> > - { "/sbin", "/usr/sbin", "/bin", "/usr/bin" };
> > - size_t i;
> > - char buf[1024];
> > -
> > - for (i = 0; i < sizeof dirs / sizeof dirs[0]; ++i) {
> > - snprintf (buf, sizeof buf, "%s/%s", dirs[i], prog);
> > - if (access (buf, X_OK) == 0)
> > + const char *pathc = getenv ("PATH");
> > +
> > + if (!pathc)
> > + return 0;
> > +
> > + const char *elem;
> > + char *saveptr;
> > + size_t len = strlen (pathc) + 1;
> > + char path[len];
> > + strcpy (path, pathc);
> > +
> > + elem = strtok_r (path, ":", &saveptr);
> > + while (elem) {
> > + size_t n = strlen (elem) + strlen (prog) + 2;
> > + char testprog[n];
> > +
> > + snprintf (testprog, n, "%s/%s", elem, prog);
> > + if (access (testprog, X_OK) == 0)
> > return 1;
> > +
> > + elem = strtok_r (NULL, ":", &saveptr);
> > }
> > +
> > + /* Not found. */
> > return 0;
> > }
>
> LGTM.
>
> The only minor note, "strlen (prog)" could be cached outside the while
> loop.
Yup. Kind of hoping that gcc would do that, but I just checked the
assembler output at -O2 and as best I can tell it doesn't :-(
I will modify the source ..
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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