Backport of the following upstream commits:

commit ab5ac271e6210fa0af11cf3ca525ce573bc47c48

Author: Florian Weimer <fweimer@redhat.com>

Date:   Wed Sep 6 11:25:14 2017 +0200

    __libc_dynarray_emplace_enlarge: Add missing else

    Before, arrays of small elements received a starting allocation size of

    8, not 16.

commit 5898f4548efdcd7c0fd437a74eeb80facc51a117

Author: Florian Weimer <fweimer@redhat.com>

Date:   Wed Aug 30 20:10:56 2017 +0200

    dynarray: Set errno on overflow-induced allocation failure

    This allows the caller to return directly on such an error, with an

    appropriate errno value.

commit 5b83faf6a7ca57ef2bfbca2c77992cafc8daa0be

Author: Florian Weimer <fweimer@redhat.com>

Date:   Mon Jun 19 12:58:08 2017 +0200

    dynarray: Use libc_hidden_proto only for !_ISOMAC

    With this change, it is possible to use dynarray from non-internal

    tests.

commit f8bf87face3304f216bcd838081fa33bb4976ac6

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue Jun 13 17:03:56 2017 +0200

    dynarray: Implement begin/end functions in the spirit of C++

commit 990c32b93a29d8b8d599e10ebca19a260f84cbba

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Jun 9 14:08:57 2017 +0200

    malloc: Remove tst-dynarray, tst-dynarray-fail from test-srcs

    They are already covered through the tests variable.

commit 91b6eb1140eda6bab324821ee3785e5d0ca155b8

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Jun 2 11:59:28 2017 +0200

    Add internal facility for dynamic array handling

    This is intended as a type-safe alternative to obstacks and

    hand-written realloc constructs.  The implementation avoids

    writing function pointers to the heap.

malloc/tst-dynarray-at-fail.c has been adjusted to use __WORDSIZE

instead of SIZE_WIDTH.

malloc/Makefile has been adjusted to the changes in the build and test

process (no tests-internal in glibc 2.17, mtrace tests are handled

differently, there is no evaluate-test Makefile macro).

diff --git a/malloc/Makefile b/malloc/Makefile

index 38aa9e0993d4880c..63fc3291dcc4077a 100644

--- a/malloc/Makefile

+++ b/malloc/Makefile

@@ -34,6 +34,9 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \

 	 tst-interpose-static-nothread \

 	 tst-interpose-static-thread \

 	 tst-scratch_buffer \

+	 tst-dynarray \

+	 tst-dynarray-fail \

+	 tst-dynarray-at-fail \

 tests-static := \

 	 tst-interpose-static-nothread \

@@ -41,10 +44,17 @@ tests-static := \

 test-srcs = tst-mtrace

+generated += tst-dynarray-mem tst-dynarray-fail-mem

+

 routines = malloc morecore mcheck mtrace obstack \

   scratch_buffer_grow \

   scratch_buffer_grow_preserve \

   scratch_buffer_set_array_size \

+  dynarray_at_failure \

+  dynarray_emplace_enlarge \

+  dynarray_finalize \

+  dynarray_resize \

+  dynarray_resize_clear \

 install-lib := libmcheck.a

@@ -143,8 +153,7 @@ ifeq ($(run-built-tests),yes)

 ifeq (yes,$(build-shared))

 ifneq ($(PERL),no)

 tests: $(objpfx)tst-mtrace.out

-$(objpfx)tst-mtrace.out: tst-mtrace.sh $(objpfx)tst-mtrace

-	$(SHELL) $< $(common-objpfx) '$(run-program-prefix)'

+tests: $(objpfx)tst-dynarray-mem $(objpfx)tst-dynarray-fail-mem

 endif

 endif

 endif

@@ -194,3 +203,11 @@ $(objpfx)tst-interpose-static-thread: \

 # Compile the tests with a flag which suppresses the mallopt call in

 # the test skeleton.

 $(tests:%=$(objpfx)%.o): CPPFLAGS += -DTEST_NO_MALLOPT

+

+tst-dynarray-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray.mtrace

+$(objpfx)tst-dynarray-mem: $(objpfx)tst-dynarray.out

+	$(common-objpfx)malloc/mtrace $(objpfx)tst-dynarray.mtrace > $@

+

+tst-dynarray-fail-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray-fail.mtrace

+$(objpfx)tst-dynarray-fail-mem: $(objpfx)tst-dynarray-fail.out

+	$(common-objpfx)malloc/mtrace $(objpfx)tst-dynarray-fail.mtrace > $@

diff --git a/malloc/Versions b/malloc/Versions

index f3c3d8a0934bdcd3..16f9dab418a4e3f6 100644

--- a/malloc/Versions

+++ b/malloc/Versions

@@ -72,5 +72,12 @@ libc {

     __libc_scratch_buffer_grow;

     __libc_scratch_buffer_grow_preserve;

     __libc_scratch_buffer_set_array_size;

+

+    # dynarray support

+    __libc_dynarray_at_failure;

+    __libc_dynarray_emplace_enlarge;

+    __libc_dynarray_finalize;

+    __libc_dynarray_resize;

+    __libc_dynarray_resize_clear;

   }

 }

diff --git a/malloc/dynarray-skeleton.c b/malloc/dynarray-skeleton.c

new file mode 100644

index 0000000000000000..7ec58788087e80d3

--- /dev/null

+++ b/malloc/dynarray-skeleton.c

@@ -0,0 +1,521 @@

+/* Type-safe arrays which grow dynamically.

+   Copyright (C) 2017 Free Software Foundation, Inc.

+   This file is part of the GNU C Library.

+

+   The GNU C Library is free software; you can redistribute it and/or

+   modify it under the terms of the GNU Lesser General Public

+   License as published by the Free Software Foundation; either

+   version 2.1 of the License, or (at your option) any later version.

+

+   The GNU C Library is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <http://www.gnu.org/licenses/>.  */

+

+/* Pre-processor macros which act as parameters:

+

+   DYNARRAY_STRUCT

+      The struct tag of dynamic array to be defined.

+   DYNARRAY_ELEMENT

+      The type name of the element type.  Elements are copied

+      as if by memcpy, and can change address as the dynamic

+      array grows.

+   DYNARRAY_PREFIX

+      The prefix of the functions which are defined.

+

+   The following parameters are optional:

+

+   DYNARRAY_ELEMENT_FREE

+      DYNARRAY_ELEMENT_FREE (E) is evaluated to deallocate the

+      contents of elements. E is of type  DYNARRAY_ELEMENT *.

+   DYNARRAY_ELEMENT_INIT

+      DYNARRAY_ELEMENT_INIT (E) is evaluated to initialize a new

+      element.  E is of type  DYNARRAY_ELEMENT *.

+      If DYNARRAY_ELEMENT_FREE but not DYNARRAY_ELEMENT_INIT is

+      defined, new elements are automatically zero-initialized.

+      Otherwise, new elements have undefined contents.

+   DYNARRAY_INITIAL_SIZE

+      The size of the statically allocated array (default:

+      at least 2, more elements if they fit into 128 bytes).

+      Must be a preprocessor constant.  If DYNARRAY_INITIAL_SIZE is 0,

+      there is no statically allocated array at, and all non-empty

+      arrays are heap-allocated.

+   DYNARRAY_FINAL_TYPE

+      The name of the type which holds the final array.  If not

+      defined, is PREFIX##finalize not provided.  DYNARRAY_FINAL_TYPE

+      must be a struct type, with members of type DYNARRAY_ELEMENT and

+      size_t at the start (in this order).

+

+   These macros are undefined after this header file has been

+   included.

+

+   The following types are provided (their members are private to the

+   dynarray implementation):

+

+     struct DYNARRAY_STRUCT

+

+   The following functions are provided:

+

+     void DYNARRAY_PREFIX##init (struct DYNARRAY_STRUCT *);

+     void DYNARRAY_PREFIX##free (struct DYNARRAY_STRUCT *);

+     bool DYNARRAY_PREFIX##has_failed (const struct DYNARRAY_STRUCT *);

+     void DYNARRAY_PREFIX##mark_failed (struct DYNARRAY_STRUCT *);

+     size_t DYNARRAY_PREFIX##size (const struct DYNARRAY_STRUCT *);

+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##begin (const struct DYNARRAY_STRUCT *);

+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##end (const struct DYNARRAY_STRUCT *);

+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##at (struct DYNARRAY_STRUCT *, size_t);

+     void DYNARRAY_PREFIX##add (struct DYNARRAY_STRUCT *, DYNARRAY_ELEMENT);

+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##emplace (struct DYNARRAY_STRUCT *);

+     bool DYNARRAY_PREFIX##resize (struct DYNARRAY_STRUCT *, size_t);

+     void DYNARRAY_PREFIX##remove_last (struct DYNARRAY_STRUCT *);

+     void DYNARRAY_PREFIX##clear (struct DYNARRAY_STRUCT *);

+

+   The following functions are provided are provided if the

+   prerequisites are met:

+

+     bool DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,

+                                     DYNARRAY_FINAL_TYPE *);

+       (if DYNARRAY_FINAL_TYPE is defined)

+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,

+                                                  size_t *);

+       (if DYNARRAY_FINAL_TYPE is not defined)

+*/

+

+#include <malloc/dynarray.h>

+

+#include <errno.h>

+#include <stdlib.h>

+#include <string.h>

+

+#ifndef DYNARRAY_STRUCT

+# error "DYNARRAY_STRUCT must be defined"

+#endif

+

+#ifndef DYNARRAY_ELEMENT

+# error "DYNARRAY_ELEMENT must be defined"

+#endif

+

+#ifndef DYNARRAY_PREFIX

+# error "DYNARRAY_PREFIX must be defined"

+#endif

+

+#ifdef DYNARRAY_INITIAL_SIZE

+# if DYNARRAY_INITIAL_SIZE < 0

+#  error "DYNARRAY_INITIAL_SIZE must be non-negative"

+# endif

+# if DYNARRAY_INITIAL_SIZE > 0

+#  define DYNARRAY_HAVE_SCRATCH 1

+# else

+#  define DYNARRAY_HAVE_SCRATCH 0

+# endif

+#else

+/* Provide a reasonable default which limits the size of

+   DYNARRAY_STRUCT.  */

+# define DYNARRAY_INITIAL_SIZE \

+  (sizeof (DYNARRAY_ELEMENT) > 64 ? 2 : 128 / sizeof (DYNARRAY_ELEMENT))

+# define DYNARRAY_HAVE_SCRATCH 1

+#endif

+

+/* Public type definitions.  */

+

+/* All fields of this struct are private to the implementation.  */

+struct DYNARRAY_STRUCT

+{

+  union

+  {

+    struct dynarray_header dynarray_abstract;

+    struct

+    {

+      /* These fields must match struct dynarray_header.  */

+      size_t used;

+      size_t allocated;

+      DYNARRAY_ELEMENT *array;

+    } dynarray_header;

+  };

+

+#if DYNARRAY_HAVE_SCRATCH

+  /* Initial inline allocation.  */

+  DYNARRAY_ELEMENT scratch[DYNARRAY_INITIAL_SIZE];

+#endif

+};

+

+/* Internal use only: Helper macros.  */

+

+/* Ensure macro-expansion of DYNARRAY_PREFIX.  */

+#define DYNARRAY_CONCAT0(prefix, name) prefix##name

+#define DYNARRAY_CONCAT1(prefix, name) DYNARRAY_CONCAT0(prefix, name)

+#define DYNARRAY_NAME(name) DYNARRAY_CONCAT1(DYNARRAY_PREFIX, name)

+

+/* Address of the scratch buffer if any.  */

+#if DYNARRAY_HAVE_SCRATCH

+# define DYNARRAY_SCRATCH(list) (list)->scratch

+#else

+# define DYNARRAY_SCRATCH(list) NULL

+#endif

+

+/* Internal use only: Helper functions.  */

+

+/* Internal function.  Call DYNARRAY_ELEMENT_FREE with the array

+   elements.  Name mangling needed due to the DYNARRAY_ELEMENT_FREE

+   macro expansion.  */

+static inline void

+DYNARRAY_NAME (free__elements__) (DYNARRAY_ELEMENT *__dynarray_array,

+                                  size_t __dynarray_used)

+{

+#ifdef DYNARRAY_ELEMENT_FREE

+  for (size_t __dynarray_i = 0; __dynarray_i < __dynarray_used; ++__dynarray_i)

+    DYNARRAY_ELEMENT_FREE (&__dynarray_array[__dynarray_i]);

+#endif /* DYNARRAY_ELEMENT_FREE */

+}

+

+/* Internal function.  Free the non-scratch array allocation.  */

+static inline void

+DYNARRAY_NAME (free__array__) (struct DYNARRAY_STRUCT *list)

+{

+#if DYNARRAY_HAVE_SCRATCH

+  if (list->dynarray_header.array != list->scratch)

+    free (list->dynarray_header.array);

+#else

+  free (list->dynarray_header.array);

+#endif

+}

+

+/* Public functions.  */

+

+/* Initialize a dynamic array object.  This must be called before any

+   use of the object.  */

+__attribute__ ((nonnull (1)))

+static void

+DYNARRAY_NAME (init) (struct DYNARRAY_STRUCT *list)

+{

+  list->dynarray_header.used = 0;

+  list->dynarray_header.allocated = DYNARRAY_INITIAL_SIZE;

+  list->dynarray_header.array = DYNARRAY_SCRATCH (list);

+}

+

+/* Deallocate the dynamic array and its elements.  */

+__attribute__ ((unused, nonnull (1)))

+static void

+DYNARRAY_NAME (free) (struct DYNARRAY_STRUCT *list)

+{

+  DYNARRAY_NAME (free__elements__)

+    (list->dynarray_header.array, list->dynarray_header.used);

+  DYNARRAY_NAME (free__array__) (list);

+  DYNARRAY_NAME (init) (list);

+}

+

+/* Return true if the dynamic array is in an error state.  */

+__attribute__ ((nonnull (1)))

+static inline bool

+DYNARRAY_NAME (has_failed) (const struct DYNARRAY_STRUCT *list)

+{

+  return list->dynarray_header.allocated == __dynarray_error_marker ();

+}

+

+/* Mark the dynamic array as failed.  All elements are deallocated as

+   a side effect.  */

+__attribute__ ((nonnull (1)))

+static void

+DYNARRAY_NAME (mark_failed) (struct DYNARRAY_STRUCT *list)

+{

+  DYNARRAY_NAME (free__elements__)

+    (list->dynarray_header.array, list->dynarray_header.used);

+  DYNARRAY_NAME (free__array__) (list);

+  list->dynarray_header.array = DYNARRAY_SCRATCH (list);

+  list->dynarray_header.used = 0;

+  list->dynarray_header.allocated = __dynarray_error_marker ();

+}

+

+/* Return the number of elements which have been added to the dynamic

+   array.  */

+__attribute__ ((nonnull (1)))

+static inline size_t

+DYNARRAY_NAME (size) (const struct DYNARRAY_STRUCT *list)

+{

+  return list->dynarray_header.used;

+}

+

+/* Return a pointer to the array element at INDEX.  Terminate the

+   process if INDEX is out of bounds.  */

+__attribute__ ((nonnull (1)))

+static inline DYNARRAY_ELEMENT *

+DYNARRAY_NAME (at) (struct DYNARRAY_STRUCT *list, size_t index)

+{

+  if (__glibc_unlikely (index >= DYNARRAY_NAME (size) (list)))

+    __libc_dynarray_at_failure (DYNARRAY_NAME (size) (list), index);

+  return list->dynarray_header.array + index;

+}

+

+/* Return a pointer to the first array element, if any.  For a

+   zero-length array, the pointer can be NULL even though the dynamic

+   array has not entered the failure state.  */

+__attribute__ ((nonnull (1)))

+static inline DYNARRAY_ELEMENT *

+DYNARRAY_NAME (begin) (struct DYNARRAY_STRUCT *list)

+{

+  return list->dynarray_header.array;

+}

+

+/* Return a pointer one element past the last array element.  For a

+   zero-length array, the pointer can be NULL even though the dynamic

+   array has not entered the failure state.  */

+__attribute__ ((nonnull (1)))

+static inline DYNARRAY_ELEMENT *

+DYNARRAY_NAME (end) (struct DYNARRAY_STRUCT *list)

+{

+  return list->dynarray_header.array + list->dynarray_header.used;

+}

+

+/* Internal function.  Slow path for the add function below.  */

+static void

+DYNARRAY_NAME (add__) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)

+{

+  if (__glibc_unlikely

+      (!__libc_dynarray_emplace_enlarge (&list->dynarray_abstract,

+                                         DYNARRAY_SCRATCH (list),

+                                         sizeof (DYNARRAY_ELEMENT))))

+    {

+      DYNARRAY_NAME (mark_failed) (list);

+      return;

+    }

+

+  /* Copy the new element and increase the array length.  */

+  list->dynarray_header.array[list->dynarray_header.used++] = item;

+}

+

+/* Add ITEM at the end of the array, enlarging it by one element.

+   Mark *LIST as failed if the dynamic array allocation size cannot be

+   increased.  */

+__attribute__ ((unused, nonnull (1)))

+static inline void

+DYNARRAY_NAME (add) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)

+{

+  /* Do nothing in case of previous error.  */

+  if (DYNARRAY_NAME (has_failed) (list))

+    return;

+

+  /* Enlarge the array if necessary.  */

+  if (__glibc_unlikely (list->dynarray_header.used

+                        == list->dynarray_header.allocated))

+    {

+      DYNARRAY_NAME (add__) (list, item);

+      return;

+    }

+

+  /* Copy the new element and increase the array length.  */

+  list->dynarray_header.array[list->dynarray_header.used++] = item;

+}

+

+/* Internal function.  Building block for the emplace functions below.

+   Assumes space for one more element in *LIST.  */

+static inline DYNARRAY_ELEMENT *

+DYNARRAY_NAME (emplace__tail__) (struct DYNARRAY_STRUCT *list)

+{

+  DYNARRAY_ELEMENT *result

+    = &list->dynarray_header.array[list->dynarray_header.used];

+  ++list->dynarray_header.used;

+#if defined (DYNARRAY_ELEMENT_INIT)

+  DYNARRAY_ELEMENT_INIT (result);

+#elif defined (DYNARRAY_ELEMENT_FREE)

+  memset (result, 0, sizeof (*result));

+#endif

+  return result;

+}

+

+/* Internal function.  Slow path for the emplace function below.  */

+static DYNARRAY_ELEMENT *

+DYNARRAY_NAME (emplace__) (struct DYNARRAY_STRUCT *list)

+{

+  if (__glibc_unlikely

+      (!__libc_dynarray_emplace_enlarge (&list->dynarray_abstract,

+                                         DYNARRAY_SCRATCH (list),

+                                         sizeof (DYNARRAY_ELEMENT))))

+    {

+      DYNARRAY_NAME (mark_failed) (list);

+      return NULL;

+    }

+  return DYNARRAY_NAME (emplace__tail__) (list);

+}

+

+/* Allocate a place for a new element in *LIST and return a pointer to

+   it.  The pointer can be NULL if the dynamic array cannot be

+   enlarged due to a memory allocation failure.  */

+__attribute__ ((unused, warn_unused_result, nonnull (1)))

+static

+/* Avoid inlining with the larger initialization code.  */

+#if !(defined (DYNARRAY_ELEMENT_INIT) || defined (DYNARRAY_ELEMENT_FREE))

+inline

+#endif

+DYNARRAY_ELEMENT *

+DYNARRAY_NAME (emplace) (struct DYNARRAY_STRUCT *list)

+{

+  /* Do nothing in case of previous error.  */

+  if (DYNARRAY_NAME (has_failed) (list))

+    return NULL;

+

+  /* Enlarge the array if necessary.  */

+  if (__glibc_unlikely (list->dynarray_header.used

+                        == list->dynarray_header.allocated))

+    return (DYNARRAY_NAME (emplace__) (list));

+  return DYNARRAY_NAME (emplace__tail__) (list);

+}

+

+/* Change the size of *LIST to SIZE.  If SIZE is larger than the

+   existing size, new elements are added (which can be initialized).

+   Otherwise, the list is truncated, and elements are freed.  Return

+   false on memory allocation failure (and mark *LIST as failed).  */

+__attribute__ ((unused, nonnull (1)))

+static bool

+DYNARRAY_NAME (resize) (struct DYNARRAY_STRUCT *list, size_t size)

+{

+  if (size > list->dynarray_header.used)

+    {

+      bool ok;

+#if defined (DYNARRAY_ELEMENT_INIT)

+      /* The new elements have to be initialized.  */

+      size_t old_size = list->dynarray_header.used;

+      ok = __libc_dynarray_resize (&list->dynarray_abstract,

+                                   size, DYNARRAY_SCRATCH (list),

+                                   sizeof (DYNARRAY_ELEMENT));

+      if (ok)

+        for (size_t i = old_size; i < size; ++i)

+          {

+            DYNARRAY_ELEMENT_INIT (&list->dynarray_header.array[i]);

+          }

+#elif defined (DYNARRAY_ELEMENT_FREE)

+      /* Zero initialization is needed so that the elements can be

+         safely freed.  */

+      ok = __libc_dynarray_resize_clear

+        (&list->dynarray_abstract, size,

+         DYNARRAY_SCRATCH (list), sizeof (DYNARRAY_ELEMENT));

+#else

+      ok =  __libc_dynarray_resize (&list->dynarray_abstract,

+                                    size, DYNARRAY_SCRATCH (list),

+                                    sizeof (DYNARRAY_ELEMENT));

+#endif

+      if (__glibc_unlikely (!ok))

+        DYNARRAY_NAME (mark_failed) (list);

+      return ok;

+    }

+  else

+    {

+      /* The list has shrunk in size.  Free the removed elements.  */

+      DYNARRAY_NAME (free__elements__)

+        (list->dynarray_header.array + size,

+         list->dynarray_header.used - size);

+      list->dynarray_header.used = size;

+      return true;

+    }

+}

+

+/* Remove the last element of LIST if it is present.  */

+__attribute__ ((unused, nonnull (1)))

+static void

+DYNARRAY_NAME (remove_last) (struct DYNARRAY_STRUCT *list)

+{

+  /* used > 0 implies that the array is the non-failed state.  */

+  if (list->dynarray_header.used > 0)

+    {

+      size_t new_length = list->dynarray_header.used - 1;

+#ifdef DYNARRAY_ELEMENT_FREE

+      DYNARRAY_ELEMENT_FREE (&list->dynarray_header.array[new_length]);

+#endif

+      list->dynarray_header.used = new_length;

+    }

+}

+

+/* Remove all elements from the list.  The elements are freed, but the

+   list itself is not.  */

+__attribute__ ((unused, nonnull (1)))

+static void

+DYNARRAY_NAME (clear) (struct DYNARRAY_STRUCT *list)

+{

+  /* free__elements__ does nothing if the list is in the failed

+     state.  */

+  DYNARRAY_NAME (free__elements__)

+    (list->dynarray_header.array, list->dynarray_header.used);

+  list->dynarray_header.used = 0;

+}

+

+#ifdef DYNARRAY_FINAL_TYPE

+/* Transfer the dynamic array to a permanent location at *RESULT.

+   Returns true on success on false on allocation failure.  In either

+   case, *LIST is re-initialized and can be reused.  A NULL pointer is

+   stored in *RESULT if LIST refers to an empty list.  On success, the

+   pointer in *RESULT is heap-allocated and must be deallocated using

+   free.  */

+__attribute__ ((unused, warn_unused_result, nonnull (1, 2)))

+static bool

+DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list,

+                          DYNARRAY_FINAL_TYPE *result)

+{

+  struct dynarray_finalize_result res;

+  if (__libc_dynarray_finalize (&list->dynarray_abstract,

+                                DYNARRAY_SCRATCH (list),

+                                sizeof (DYNARRAY_ELEMENT), &res))

+    {

+      /* On success, the result owns all the data.  */

+      DYNARRAY_NAME (init) (list);

+      *result = (DYNARRAY_FINAL_TYPE) { res.array, res.length };

+      return true;

+    }

+  else

+    {

+      /* On error, we need to free all data.  */

+      DYNARRAY_NAME (free) (list);

+      errno = ENOMEM;

+      return false;

+    }

+}

+#else /* !DYNARRAY_FINAL_TYPE */

+/* Transfer the dynamic array to a heap-allocated array and return a

+   pointer to it.  The pointer is NULL if memory allocation fails, or

+   if the array is empty, so this function should be used only for

+   arrays which are known not be empty (usually because they always

+   have a sentinel at the end).  If LENGTHP is not NULL, the array

+   length is written to *LENGTHP.  *LIST is re-initialized and can be

+   reused.  */

+__attribute__ ((unused, warn_unused_result, nonnull (1)))

+static DYNARRAY_ELEMENT *

+DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list, size_t *lengthp)

+{

+  struct dynarray_finalize_result res;

+  if (__libc_dynarray_finalize (&list->dynarray_abstract,

+                                DYNARRAY_SCRATCH (list),

+                                sizeof (DYNARRAY_ELEMENT), &res))

+    {

+      /* On success, the result owns all the data.  */

+      DYNARRAY_NAME (init) (list);

+      if (lengthp != NULL)

+        *lengthp = res.length;

+      return res.array;

+    }

+  else

+    {

+      /* On error, we need to free all data.  */

+      DYNARRAY_NAME (free) (list);

+      errno = ENOMEM;

+      return NULL;

+    }

+}

+#endif /* !DYNARRAY_FINAL_TYPE */

+

+/* Undo macro definitions.  */

+

+#undef DYNARRAY_CONCAT0

+#undef DYNARRAY_CONCAT1

+#undef DYNARRAY_NAME

+#undef DYNARRAY_SCRATCH

+#undef DYNARRAY_HAVE_SCRATCH

+

+#undef DYNARRAY_STRUCT

+#undef DYNARRAY_ELEMENT

+#undef DYNARRAY_PREFIX

+#undef DYNARRAY_ELEMENT_FREE

+#undef DYNARRAY_ELEMENT_INIT

+#undef DYNARRAY_INITIAL_SIZE

+#undef DYNARRAY_FINAL_TYPE

diff --git a/malloc/dynarray.h b/malloc/dynarray.h

new file mode 100644

index 0000000000000000..5888bcbc1d4ae9bf

--- /dev/null

+++ b/malloc/dynarray.h

@@ -0,0 +1,179 @@

+/* Type-safe arrays which grow dynamically.  Shared definitions.

+   Copyright (C) 2017 Free Software Foundation, Inc.

+   This file is part of the GNU C Library.

+

+   The GNU C Library is free software; you can redistribute it and/or

+   modify it under the terms of the GNU Lesser General Public

+   License as published by the Free Software Foundation; either

+   version 2.1 of the License, or (at your option) any later version.

+

+   The GNU C Library is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <http://www.gnu.org/licenses/>.  */

+

+/* To use the dynarray facility, you need to include

+   <malloc/dynarray-skeleton.c> and define the parameter macros

+   documented in that file.

+

+   A minimal example which provides a growing list of integers can be

+   defined like this:

+

+     struct int_array

+     {

+       // Pointer to result array followed by its length,

+       // as required by DYNARRAY_FINAL_TYPE.

+       int *array;

+       size_t length;

+     };

+

+     #define DYNARRAY_STRUCT dynarray_int

+     #define DYNARRAY_ELEMENT int

+     #define DYNARRAY_PREFIX dynarray_int_

+     #define DYNARRAY_FINAL_TYPE struct int_array

+     #include <malloc/dynarray-skeleton.c>

+

+   To create a three-element array with elements 1, 2, 3, use this

+   code:

+

+     struct dynarray_int dyn;

+     dynarray_int_init (&dyn);

+     for (int i = 1; i <= 3; ++i)

+       {

+         int *place = dynarray_int_emplace (&dyn);

+         assert (place != NULL);

+         *place = i;

+       }

+     struct int_array result;

+     bool ok = dynarray_int_finalize (&dyn, &result);

+     assert (ok);

+     assert (result.length == 3);

+     assert (result.array[0] == 1);