[ccan] [PATCH 2/2] darray: Fix bug in the darray_remove() macro

[Damien Grassart]

Ugh, sorry about that, I forgot to run the tests after the last patch
fixing darray_remove(). I missed a backslash in that patch (darray: Fix bug
in the darray_remove() macro). I'll resend it with the missing parentheses
around the macro params. Thanks.

On Mon, Aug 28, 2017 at 4:48 AM, David Gibson <david at gibson.dropbear.id.au>
wrote:

> On Sun, Aug 27, 2017 at 11:26:24PM +0200, Damien Grassart wrote:
> > The memmove() call should be using the index argument to determine the
> > number of bytes to copy. To be consistent with the rest of the code,
> > we should also not evaluate the index parameter multiple
> > times. Calling this with rand() % arr.size would otherwise generally
> > segfault.
> >
> > Finally, we want to avoid using "index" as an identifier so as to not
> > shadow index(3) in the C library.
> >
> > Signed-off-by: Damien Grassart <damien at grassart.com>
>
> This breaks compile for me, though I can't quickly see why.
>
> $ make
> cc -g3 -ggdb -Wall -Wstrict-prototypes -Wold-style-definition -Wundef
> -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wwrite-strings
> -DCCAN_STR_DEBUG=1 -I.  -MMD -MP -MFccan/strgrp/strgrp.o.d
> -MTccan/strgrp/strgrp.o -c ccan/strgrp/strgrp.c -o ccan/strgrp/strgrp.o
> In file included from ccan/strgrp/strgrp.c:26:0:
> ./ccan/darray/darray.h:235:2: error: expected identifier or ‘(’ before ‘if’
>   if (index_ < arr.size-1)    \
>   ^~
> ./ccan/darray/darray.h:237:7: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or
> ‘__attribute__’ before ‘.’ token
>   (arr).size--;  \
>        ^
> ./ccan/darray/darray.h:238:2: error: expected identifier or ‘(’ before ‘}’
> token
>   } while(0)
>   ^
> ./ccan/darray/darray.h:238:4: error: expected identifier or ‘(’ before
> ‘while’
>   } while(0)
>     ^~~~~
>
> I also noticed that both this and the earlier patches use:
>         size_t index_ = i;
> in the macro, without parentheses around the 'i' macro paramater.
> That's not the cause of the error above, but it's not good practice as
> a rule.
>
> So, I've backed out these darray patches for now.  Can you debug the
> compile problem above and resend the whole lot as a single series.
>
> > ---
> >  ccan/darray/darray.h | 11 ++++++-----
> >  1 file changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/ccan/darray/darray.h b/ccan/darray/darray.h
> > index 82726c05..6787f14c 100644
> > --- a/ccan/darray/darray.h
> > +++ b/ccan/darray/darray.h
> > @@ -170,8 +170,8 @@ typedef darray(unsigned long)  darray_ulong;
> >               memmove((arr).item+1, (arr).item,
> ((arr).size-1)*sizeof(*(arr).item)); \
> >               (arr).item[0] = (__VA_ARGS__); \
> >       } while(0)
> > -#define darray_insert(arr, index, ...) do { \
> > -             size_t index_ = index; \
> > +#define darray_insert(arr, i, ...) do { \
> > +             size_t index_ = i; \
> >               darray_resize(arr, (arr).size+1); \
> >               memmove((arr).item+index_+1, (arr).item+index_,
> ((arr).size-index_-1)*sizeof(*(arr).item)); \
> >               (arr).item[index_] = (__VA_ARGS__); \
> > @@ -230,9 +230,10 @@ typedef darray(unsigned long)  darray_ulong;
> >  #define darray_pop(arr) ((arr).item[--(arr).size])
> >  #define darray_pop_check(arr) ((arr).size ? darray_pop(arr) : NULL)
> >  /* Warning, slow: Requires copying all elements after removed item. */
> > -#define darray_remove(arr, index) do { \
> > -     if (index < arr.size-1)    \
> > -             memmove(&(arr).item[index], &(arr).item[index+1],
> ((arr).size-1-i)*sizeof(*(arr).item)); \
> > +#define darray_remove(arr, i) do { \
> > +     size_t index_ = i;
> > +     if (index_ < arr.size-1)    \
> > +             memmove(&(arr).item[index_], &(arr).item[index_+1],
> ((arr).size-1-index_)*sizeof(*(arr).item)); \
> >       (arr).size--;  \
> >       } while(0)
> >
>
> --
> David Gibson                    | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_
> _other_
>                                 | _way_ _around_!
> http://www.ozlabs.org/~dgibson
>
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