Re: [PATCH] maint.mk: tighten "test a == b" check

[Eric Blake]

On 11/13/2010 02:45 AM, Jim Meyering wrote:
> I tried the latest gnulib in coreutils and saw these two
> false positives:
> 
>     src/copy.c:730:                 test below (*wp++ == 0) would read some 
> uninitialized bytes
>     src/stty.c:1339:     test would have been (ts_lines > 64k || ts_cols > 
> 64k || ts_cols == 0).
>     maint.mk: use "test x = x", not "test x == x"
>     make: *** [sc_prohibit_test_double_equal] Error 1
> 
> +
> +     maint.mk: tighten "test a == b" check
> +     * top/maint.mk (sc_prohibit_test_double_equal): Restrict this
> +     test to files that contain something like #!/bin/sh.
> +     Without this, coreutils would get two false positives in
> +     the comments of C source files.

Except that this weakens the test so that it no longer detects a real
bug in libivrt - a C source file that generated the equivalent of a
system() call where the embedded shell script used test.

src/nwfilter/nwfilter_ebiptables_driver.c:653:
                      "if [ \"${res}\" == \"\" ]; then "


> +
>  2010-11-12  Eric Blake  <address@hidden>
> 
>       bootstrap: fix typo in previous attempt
> diff --git a/top/maint.mk b/top/maint.mk
> index d51944b..65c2f80 100644
> --- a/top/maint.mk
> +++ b/top/maint.mk
> @@ -820,6 +820,7 @@ sc_prohibit_test_minus_ao:
>  # Avoid a test bashism.
>  sc_prohibit_test_double_equal:
>       @prohibit='(\<test| \[+) .+ == '                                \
> +     containing='^#! */bin/sh'                                       \

Maybe a compromise would be to revert this, but to tighten the prohibit
regex:

prohibit='(\<test| \[+) ("[^"]*"|[^ ]+) == '

which misses out on both false positives in coreutils, but still detects
the libvirt bug?

-- 
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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