[Toybox] [PATCH] Clean up xz a good amount

[enh]

On Tue, Feb 27, 2024 at 8:34 PM Rob Landley <rob at landley.net> wrote:
>
> On 2/27/24 21:27, Oliver Webb wrote:
> > 2 are help text, do_xzcat was due to replacing the case statement for error handling with a array
> > If I had to guess, xz_dec_run or xz_dec_bcj_reset
> >
> > It was the case statement I stripped out in xz_dec_bcj_reset, it works with the attached patch
>
> Let's see..
>
> > diff --git a/toys/pending/xzcat.c b/toys/pending/xzcat.c
> > index 5177f243..b50c9524 100644
> > --- a/toys/pending/xzcat.c
> > +++ b/toys/pending/xzcat.c
> > @@ -55,6 +55,7 @@ enum xz_ret {
> >    // truncated or otherwise corrupt.
> >  };
> >
> > +
> >  // Passing input and output buffers to XZ code
> >  // Only the contents of the output buffer from out[out_pos] onward, and
> >  // the variables in_pos and out_pos are modified by the XZ code.
>
> Whitespace change.
>
> > @@ -212,7 +213,7 @@ struct xz_dec_bcj {
> >  // in an x86 instruction.
> >  static int bcj_x86_test_msbyte(char b)
> >  {
> > -  return !b || !~b;
> > +  return !b || b == 0xFF;
> >  }
>
> NOP.
>
> >  static size_t bcj_x86(struct xz_dec_bcj *s, char *buf, size_t size)
> > @@ -639,6 +640,20 @@ enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s, struct xz_dec_lzma2 *lzma2,
> >   */
> >  enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, char id)
> >  {
> > +  switch (id) {
> > +  case BCJ_X86:
> > +  case BCJ_POWERPC:
> > +  case BCJ_IA64:
> > +  case BCJ_ARM:
> > +  case BCJ_ARMTHUMB:
> > +  case BCJ_SPARC:
> > +    break;
> > +
> > +  default:
> > +    /* Unsupported Filter ID */
> > +    return XZ_OPTIONS_ERROR;
> > +  }
> > +
> >    s->type = id;
> >    s->ret = XZ_OK;
> >    s->pos = 0;

ah, crap, that's another thing to put on the riscv64 to-do list...
(thanks for bringing that to light!)

> NOP unless you hit the error path, what are the values...
>
>   enum {
>     BCJ_X86 = 4,        /* x86 or x86-64 */
>     BCJ_POWERPC = 5,    /* Big endian only */
>     BCJ_IA64 = 6,       /* Big or little endian */
>     BCJ_ARM = 7,        /* Little endian only */
>     BCJ_ARMTHUMB = 8,   /* Little endian only */
>     BCJ_SPARC = 9       /* Big or little endian */
>   } type;
>
> Since id is char, which is unsigned in toybox, this is:
>
>   if ((id-4)>5) return XZ_OPTIONS_ERROR;
>
> > @@ -2860,16 +2875,17 @@ void do_xzcat(int fd, char *name)
> >      if (ret == XZ_OK || ret == XZ_UNSUPPORTED_CHECK)
> >        continue;
> >
> > -    else if (ret == XZ_STREAM_END) {
> > -      xz_dec_end(s);
> > -      return;
> > -    }
> > -
> >      if (fwrite(out, 1, b.out_pos, stdout) != b.out_pos) {
> >        msg = "Write error\n";
> >        goto error;
> >      }
> >
> > +    if (ret == XZ_STREAM_END) {
> > +      xz_dec_end(s);
> > +      return;
> > +    }
> > +
> > +
> >      msg = (ret-3 < ARRAY_LEN(errors)) ? errors[ret-3] : "Bug!";
> >      goto error;
> >    }
>
> There's the bug, moving a return before the fwrite().
>
> Rob
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