Re: dash bug: double-quoted "\" breaks glob protection for next char

[Harald van Dijk]

On 2/21/18 2:50 PM, Denys Vlasenko wrote:

I propose replacing this:


Agreed, that looks better. Thanks!

Cheers,
Harald van Dijk
--
To unsubscribe from this list: send the line "unsubscribe dash" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: dash bug: double-quoted "\" breaks glob protection for next char

[Denys Vlasenko]

On Mon, Feb 19, 2018 at 11:13 PM, Harald van Dijk  wrote:
> On 2/18/18 11:50 PM, Harald van Dijk wrote:
>> On 2/14/18 11:50 PM, Harald van Dijk wrote:
>>> On 2/14/18 10:44 PM, Harald van Dijk wrote:
 On 2/14/18 9:03 PM, Harald van Dijk wrote:
> On 13/02/2018 14:53, Denys Vlasenko wrote:
>> $ >'\'
>> $ >'\'
>> $ dash -c 'echo "\*"'
>> \ \
>
>
> [...]
>
> Currently:
>
> $ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
> <>
>
> This is what I expect, and also what bash, ksh and posh do.
>
> With your patch:
>
> $ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
> 

 Does the attached look right as an alternative? It treats a quoted
 backslash the same way as if it were preceded by CTLESC in _rmescapes. It
 passes your test case and mine, but I'll do more extensive testing.
>>>
>>> It causes preglob's string to potentially grow larger than the original.
>>> When called with RMESCAPE_ALLOC, that can be handled by increasing the
>>> buffer size, but preglob also gets called without RMESCAPE_ALLOC to modify a
>>> string in-place. That's never going to work with this approach. Back to the
>>> drawing board...
>>
>> There is a way to make it work: ensure sufficient memory is always
>> available. Instead of inserting CTLESC, which caused problems,
>> CTLQUOTEMARK+CTLQUOTEMARK can be inserted instead. It's effectively a no-op
>> here.
>
> It required one obvious additional trivial change to the CHECKSTRSPACE
> invocation, but with that added, the attached passed all testing I could
> think of. Does this look okay to include, did I miss something, or is there
> perhaps a better alternative?

I propose replacing this:

if (*p == (char)CTLESC) {
p++;
+   goto escape;
+   } else if (*p == '\\') {
+   if (inquotes) {
+escape:
+   if (notescaped)
+   *q++ = '\\';
+   } else {
+   /* naked back slash */
+   notescaped = 0;
+   goto copy;
+   }

with equivalent

if (*p == (char)CTLESC) {
p++;
+   goto escape;
+   }
+   if (*p == '\\') {
+   if (!inquotes) {
+   /* naked back slash */
+   notescaped = 0;
+   goto copy;
+   }
+escape:
+   if (notescaped)
+   *q++ = '\\';
--
To unsubscribe from this list: send the line "unsubscribe dash" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html