Re: [PATCH 8/8] Remove __morecore and __default_morecore

[DJ Delorie <dj@redhat.com>]

Siddhesh Poyarekar <siddhesh@sourceware.org> writes:
> Make the __morecore and __default_morecore symbols compat-only and
> remove their declarations from the API.

> diff --git a/NEWS b/NEWS
>  
> +* The __morecore and __after_morecore_hook malloc hooks and the default
> +  implementation __default_morecore have been removed from the API.  Existing
> +  applications will continue to link against these symbols but the interfaces
> +  no longer have any effect on malloc.
> +

Ok.

> diff --git a/include/stdlib.h b/include/stdlib.h
> index e2453c1896..c5cccce85c 100644
> --- a/include/stdlib.h
> +++ b/include/stdlib.h
> @@ -300,9 +300,6 @@ libc_hidden_proto (__qfcvt_r)
>  #  define MB_CUR_MAX (_NL_CURRENT_WORD (LC_CTYPE, _NL_CTYPE_MB_CUR_MAX))
>  # endif
>  
> -extern void *__default_morecore (ptrdiff_t) __THROW;
> -libc_hidden_proto (__default_morecore)
> -

Ok.

> diff --git a/malloc/arena.c b/malloc/arena.c
> -#if defined(SHARED) || defined(USE_MTAG)
> -static void *
> -__failing_morecore (ptrdiff_t d)
> -{
> -  return (void *) MORECORE_FAILURE;
> -}
> -#endif
> -

Ok.

> @@ -300,7 +292,7 @@ ptmalloc_init (void)
>  	 and that morecore does not support tagged regions, then
>  	 disable it.  */
>        if (__MTAG_SBRK_UNTAGGED)
> -	__morecore = __failing_morecore;
> +	__always_fail_morecore = true;

Ok.

> @@ -313,7 +305,7 @@ ptmalloc_init (void)
>       generic sbrk implementation also enforces this, but it is not
>       used on Hurd.  */
>    if (!__libc_initial)
> -    __morecore = __failing_morecore;
> +    __always_fail_morecore = true;
>  #endif

Ok.

> diff --git a/malloc/hooks.c b/malloc/hooks.c
>  
> +void *(*__morecore)(ptrdiff_t);
> +compat_symbol (libc, __morecore, __morecore, GLIBC_2_0);

Ok.

> diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
>  
>  #include <malloc-machine.h>
>  #include <malloc-sysdep.h>
> +#include <stdbool.h>

Ok.

> @@ -63,6 +64,8 @@
>  
>  #define top(ar_ptr) ((ar_ptr)->top)
>  
> +extern bool __always_fail_morecore attribute_hidden;
> +

Ok

> @@ -78,4 +81,6 @@ void __malloc_arena_thread_freeres (void) attribute_hidden;
>  /* Activate a standard set of debugging hooks. */
>  void __malloc_check_init (void) attribute_hidden;
>  
> +extern void *__glibc_morecore (ptrdiff_t) attribute_hidden;
> +

Ok.

> diff --git a/malloc/malloc.c b/malloc/malloc.c
>  
>  
>  /* Definition for getting more memory from the OS.  */
> -#define MORECORE         (*__morecore)
> +#define MORECORE         (*__glibc_morecore)
>  #define MORECORE_FAILURE 0
> -void * __default_morecore (ptrdiff_t);
> -void *(*__morecore)(ptrdiff_t) = __default_morecore;

Ok.

> diff --git a/malloc/malloc.h b/malloc/malloc.h
> @@ -76,14 +76,6 @@ extern void *valloc (size_t __size) __THROW __attribute_malloc__
>  extern void *pvalloc (size_t __size) __THROW __attribute_malloc__
>    __wur __attr_dealloc_free;
>  
> -/* Underlying allocation function; successive calls should return
> -   contiguous pieces of memory.  */
> -extern void *(*__morecore) (ptrdiff_t __size) __MALLOC_DEPRECATED;
> -
> -/* Default value of `__morecore'.  */
> -extern void *__default_morecore (ptrdiff_t __size)
> -__THROW __attribute_malloc__  __MALLOC_DEPRECATED;
> -

Ok.

> diff --git a/malloc/morecore.c b/malloc/morecore.c
> index 047228779b..c85a85c0eb 100644
> --- a/malloc/morecore.c
> +++ b/malloc/morecore.c
> @@ -38,16 +38,27 @@ libc_hidden_proto (__sbrk)
>  # define NULL 0
>  #endif
>  
> +#if defined(SHARED) || defined(USE_MTAG)
> +bool __always_fail_morecore = false;
> +#endif
> +

Ok.

>  /* Allocate INCREMENT more bytes of data space,
>     and return the start of data space, or NULL on errors.
>     If INCREMENT is negative, shrink data space.  */
>  void *
> -__default_morecore (ptrdiff_t increment)
> +__glibc_morecore (ptrdiff_t increment)
>  {
> +#if defined(SHARED) || defined(USE_MTAG)
> +  if (__always_fail_morecore)
> +    return NULL;
> +#endif
> +
>    void *result = (void *) __sbrk (increment);
>    if (result == (void *) -1)
>      return NULL;
>  
>    return result;
>  }
> -libc_hidden_def (__default_morecore)
> +#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
> +compat_symbol (libc, __glibc_morecore, __default_morecore, GLIBC_2_0);
> +#endif

Ok.

LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>