[PATCH] od_bloaty: fix floating point output

[Denys Vlasenko]

Applied, thanks!

On Wed, Jul 19, 2017 at 11:43 AM, Ron Yorston <rmy at pobox.com> wrote:
> Currently od_bloaty does this:
>
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | busybox od -f
>    od: invalid character 'F' in type string 'fF'
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | busybox od -t fD
>    od: invalid character 'D' in type string 'fD'
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | busybox od -t f
>    0000000
>    0000010
>
> The first two occur because the alphabetic length specifier isn't being
> properly skipped.  The third is due to the empty length specifier being
> treated as alphabetic so we fall off the end of the FDL_sizeof array with
> undetermined consequences.  Coreutils defaults to printing a double in
> this case.
>
> With this patch the output is:
>
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | ./busybox od -f
>    0000000   0.0000000e+00   0.0000000e+00
>    0000010
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | ./busybox od -t fD
>    0000000   0.000000000000000e+00
>    0000010
>    $ /bin/echo -en '\x00\x00\x00\x00\x00\x00\x00\x00' | ./busybox od -t f
>    0000000   0.000000000000000e+00
>    0000010
>
> I guess nobody uses BusyBox od to print floating point numbers.
>
> Signed-off-by: Ron Yorston <rmy at pobox.com>
> ---
>  coreutils/od_bloaty.c |  3 ++-
>  testsuite/od.tests    | 10 ++++++++++
>  2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/coreutils/od_bloaty.c b/coreutils/od_bloaty.c
> index f13bdfc11..fa0196ca4 100644
> --- a/coreutils/od_bloaty.c
> +++ b/coreutils/od_bloaty.c
> @@ -665,7 +665,7 @@ decode_one_format(const char *s_orig, const char *s, struct tspec *tspec)
>                 fmt = FLOATING_POINT;
>                 ++s;
>                 p = strchr(FDL, *s);
> -               if (!p) {
> +               if (!p || *p == '\0') {
>                         size = sizeof(double);
>                         if (isdigit(s[0])) {
>                                 size = bb_strtou(s, &end, 0);
> @@ -686,6 +686,7 @@ decode_one_format(const char *s_orig, const char *s, struct tspec *tspec)
>                         };
>
>                         size = FDL_sizeof[p - FDL];
> +                       s++; /* skip F/D/L */
>                 }
>
>                 size_spec = fp_type_size[size];
> diff --git a/testsuite/od.tests b/testsuite/od.tests
> index 7a9da3e97..0880e0d2f 100755
> --- a/testsuite/od.tests
> +++ b/testsuite/od.tests
> @@ -16,6 +16,16 @@ testing "od -b" \
>         "" "HELLO"
>  SKIP=
>
> +optional DESKTOP
> +testing "od -f" \
> +       "od -f" \
> +"\
> +0000000   0.0000000e+00   0.0000000e+00
> +0000010
> +" \
> +       "" "\x00\x00\x00\x00\x00\x00\x00\x00"
> +SKIP=
> +
>  optional DESKTOP LONG_OPTS
>  testing "od -b --traditional" \
>         "od -b --traditional" \
> --
> 2.13.3
>
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