Michael McConville wrote:
> Michael McConville wrote:
> > Maxim Pugachev wrote:
> > > In a case when the shell name is not specified (i.e. just "#!" without
> > > a path), don't run the heavy logic that checks shell, simply return
> > > ENOENT.
> >
> > I'm not sure whether this is a reasonable thing to do. Someone with more
> > kernel API experience will have to comment.
> >
> > > Also, as a tiny improvement: avoid a loop when calculating shell's
> > > args length.
> >
> > It seems like there's a simpler solution to this: strlen. Also, the
> > assignment that follows the for loop seems dead, as we know *cp will be
> > NUL.
> >
> > The below diff makes that change, removes the useless if condition you
> > noticed, and bumps a few variable initializations into the declaration
> > block.
>
> I just remembered that this was probably a perfomance concern as well.
> In that case, we could assign shellarg and shellarglen earlier in the
> function, right?
Is anyone willing to work with me on this? This cleanup should obviously
be done very carefully, but I think it's worth doing because this code
is... unfortunate. I'd be happy to submit and review in smaller chunks.
> > Index: sys/kern/exec_script.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/exec_script.c,v
> > retrieving revision 1.37
> > diff -u -p -r1.37 exec_script.c
> > --- sys/kern/exec_script.c 31 Dec 2015 18:55:33 -0000 1.37
> > +++ sys/kern/exec_script.c 10 Jan 2016 01:41:55 -0000
> > @@ -67,9 +67,9 @@
> > int
> > exec_script_makecmds(struct proc *p, struct exec_package *epp)
> > {
> > - int error, hdrlinelen, shellnamelen, shellarglen;
> > + int error, hdrlinelen, shellnamelen, shellarglen = 0;
> > char *hdrstr = epp->ep_hdr;
> > - char *cp, *shellname, *shellarg, *oldpnbuf;
> > + char *cp, *shellname = NULL, *shellarg = NULL, *oldpnbuf;
> > char **shellargp = NULL, **tmpsap;
> > struct vnode *scriptvp;
> > uid_t script_uid = -1;
> > @@ -110,10 +110,6 @@ exec_script_makecmds(struct proc *p, str
> > if (cp >= hdrstr + hdrlinelen)
> > return ENOEXEC;
> >
> > - shellname = NULL;
> > - shellarg = NULL;
> > - shellarglen = 0;
> > -
> > /* strip spaces before the shell name */
> > for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t';
> > cp++)
> > @@ -122,8 +118,6 @@ exec_script_makecmds(struct proc *p, str
> > /* collect the shell name; remember its length for later */
> > shellname = cp;
> > shellnamelen = 0;
> > - if (*cp == '\0')
> > - goto check_shell;
> > for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++)
> > shellnamelen++;
> > if (*cp == '\0')
> > @@ -142,9 +136,8 @@ exec_script_makecmds(struct proc *p, str
> > * behaviour.
> > */
> > shellarg = cp;
> > - for ( /* cp = cp */ ; *cp != '\0'; cp++)
> > - shellarglen++;
> > - *cp++ = '\0';
> > + shellarglen = strlen(shellarg);
> > + cp += shellarglen + 1;
> >
> > check_shell:
> > /*
> >
>
