Re: [bootstrappable] Re: wip-full-source-bootstrap: from a 357-byte `hex0' to 'hello'

[Jan Nieuwenhuizen <janneke@gnu.org>]

Danny Milosavljevic writes:

Hi Danny,

> I propose to, instead, change mes libc to align stuff malloc returns like this:
>
> That should fix it.

That's great; I'd like to go test this.  Would you like to push to "wip"
when you're ready?

> diff --git a/include/stddef.h b/include/stddef.h
> index a597c9bb..a682d726 100644
> --- a/include/stddef.h
> +++ b/include/stddef.h
> @@ -37,6 +37,10 @@
>  #endif // !__MESC__
>  #endif // offsetof
>  
> +/* TODO: On armhf gcc, max_align_t is 16 Byte big instead.  Use that? */
> +
> +typedef double max_align_t;
> +
>  #endif // ! SYSTEM_LIBC

Is this something you can get more info on, or do we just try it like
this?

>  #endif // __MES_STDDEF_H
> diff --git a/lib/stdlib/malloc.c b/lib/stdlib/malloc.c
> index f4be4de1..aaf99886 100644
> --- a/lib/stdlib/malloc.c
> +++ b/lib/stdlib/malloc.c
> @@ -20,6 +20,8 @@
>  
>  #include <mes/lib.h>
>  #include <string.h>
> +#include <stddef.h>
> +#include <stdint.h>
>  
>  /* FIXME: We want bin/mes-mescc's x86-linux sha256sum to stay the same.
>     Therfore we cannot remove stdlib/malloc from libc_SOURCES, which is
> @@ -37,6 +39,8 @@ malloc (size_t size)
>  {
>    if (!__brk)
>      __brk = (char *) brk (0);
> +  /* align what we give back. */
> +  __brk = (char*) (((uintptr_t) __brk + sizeof(max_align_t) - 1) & -sizeof(max_align_t));
>    if (brk (__brk + size) == -1)
>      return 0;
>    char *p = __brk;

Very nice, thanks!!
Janneke

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