base/SOURCES/glibc-rh677316-scratch_buffer.patch

Backport of the following upstream commits:

commit c04af6068b2c2c65c92b3360cbc4b51ad9843f21
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Apr 7 13:46:28 2016 +0200

    scratch_buffer_set_array_size: Include <limits.h>

    It is needed for CHAR_BIT.

commit dbb7600658d8ea633083ee99572622b04ef23a3f
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Oct 29 12:46:22 2015 +0000

    Use max_align_t from <stddef.h>.

    Now that we build with -std=gnu11 and can rely on a compiler providing
    max_align_t in <stddef.h>, we no longer need our own version
    libc_max_align_t.  This patch removes it and replaces the single user
    with a use of max_align_t.

    Tested for x86_64 and x86 (testsuite, and that installed stripped
    shared libraries are unchanged by the patch for x86_64; for x86, I see
    some code reordering of no significance).

            * include/libc-internal.h (libc_max_align_t): Remove typedef.
            * include/scratch_buffer.h: Include <stddef.h> instead of
            <libc-internal.h>.
            (struct scratch_buffer): Use max_align_t instead of
            libc_max_align_t.

(The above is a partial backport.  It depends on max_align_t addition to
<include/sys/cdefs.h> because glibc 2.17 is not compiled in C11 mode, so
GCC's <stddef.h> does not provide it.)

commit 2902af1631c0c74c2f0c0edd7a85a523370e5027
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Apr 9 17:12:42 2015 +0200

    scratch_buffer: Suppress truncation warning on 32-bit

commit 72301304a5655662baf2bae88a7aceeabc4a753e
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Apr 7 17:46:58 2015 +0200

    scratch_buffer_grow_preserve: Add missing #include <string.h>

commit cfcfd4614b8b01b2782ac4dcafb21d14d74d5184
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Apr 7 11:03:43 2015 +0200

    Add struct scratch_buffer and its internal helper functions

    These will be used from NSS modules, so they have to be exported.

diff --git a/include/scratch_buffer.h b/include/scratch_buffer.h
new file mode 100644
index 0000000000000000..dd17a4a7e13596aa
--- /dev/null
+++ b/include/scratch_buffer.h
@@ -0,0 +1,136 @@
+/* Variable-sized buffer with on-stack default allocation.
+   Copyright (C) 2015-2017 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/>.  */
+
+#ifndef _SCRATCH_BUFFER_H
+#define _SCRATCH_BUFFER_H
+
+/* Scratch buffers with a default stack allocation and fallback to
+   heap allocation.  It is expected that this function is used in this
+   way:
+
+     struct scratch_buffer tmpbuf;
+     scratch_buffer_init (&tmpbuf);
+
+     while (!function_that_uses_buffer (tmpbuf.data, tmpbuf.length))
+       if (!scratch_buffer_grow (&tmpbuf))
+	 return -1;
+
+     scratch_buffer_free (&tmpbuf);
+     return 0;
+
+   The allocation functions (scratch_buffer_grow,
+   scratch_buffer_grow_preserve, scratch_buffer_set_array_size) make
+   sure that the heap allocation, if any, is freed, so that the code
+   above does not have a memory leak.  The buffer still remains in a
+   state that can be deallocated using scratch_buffer_free, so a loop
+   like this is valid as well:
+
+     struct scratch_buffer tmpbuf;
+     scratch_buffer_init (&tmpbuf);
+
+     while (!function_that_uses_buffer (tmpbuf.data, tmpbuf.length))
+       if (!scratch_buffer_grow (&tmpbuf))
+	 break;
+
+     scratch_buffer_free (&tmpbuf);
+
+   scratch_buffer_grow and scratch_buffer_grow_preserve are guaranteed
+   to grow the buffer by at least 512 bytes.  This means that when
+   using the scratch buffer as a backing store for a non-character
+   array whose element size, in bytes, is 512 or smaller, the scratch
+   buffer only has to grow once to make room for at least one more
+   element.
+*/
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+/* Scratch buffer.  Must be initialized with scratch_buffer_init
+   before its use.  */
+struct scratch_buffer {
+  void *data;    /* Pointer to the beginning of the scratch area.  */
+  size_t length; /* Allocated space at the data pointer, in bytes.  */
+  char __space[1024]
+    __attribute__ ((aligned (__alignof__ (max_align_t))));
+};
+
+/* Initializes *BUFFER so that BUFFER->data points to BUFFER->__space
+   and BUFFER->length reflects the available space.  */
+static inline void
+scratch_buffer_init (struct scratch_buffer *buffer)
+{
+  buffer->data = buffer->__space;
+  buffer->length = sizeof (buffer->__space);
+}
+
+/* Deallocates *BUFFER (if it was heap-allocated).  */
+static inline void
+scratch_buffer_free (struct scratch_buffer *buffer)
+{
+  if (buffer->data != buffer->__space)
+    free (buffer->data);
+}
+
+/* Grow *BUFFER by some arbitrary amount.  The buffer contents is NOT
+   preserved.  Return true on success, false on allocation failure (in
+   which case the old buffer is freed).  On success, the new buffer is
+   larger than the previous size.  On failure, *BUFFER is deallocated,
+   but remains in a free-able state, and errno is set.  */
+bool __libc_scratch_buffer_grow (struct scratch_buffer *buffer);
+libc_hidden_proto (__libc_scratch_buffer_grow)
+
+/* Alias for __libc_scratch_buffer_grow.  */
+static __always_inline bool
+scratch_buffer_grow (struct scratch_buffer *buffer)
+{
+  return __glibc_likely (__libc_scratch_buffer_grow (buffer));
+}
+
+/* Like __libc_scratch_buffer_grow, but preserve the old buffer
+   contents on success, as a prefix of the new buffer.  */
+bool __libc_scratch_buffer_grow_preserve (struct scratch_buffer *buffer);
+libc_hidden_proto (__libc_scratch_buffer_grow_preserve)
+
+/* Alias for __libc_scratch_buffer_grow_preserve.  */
+static __always_inline bool
+scratch_buffer_grow_preserve (struct scratch_buffer *buffer)
+{
+  return __glibc_likely (__libc_scratch_buffer_grow_preserve (buffer));
+}
+
+/* Grow *BUFFER so that it can store at least NELEM elements of SIZE
+   bytes.  The buffer contents are NOT preserved.  Both NELEM and SIZE
+   can be zero.  Return true on success, false on allocation failure
+   (in which case the old buffer is freed, but *BUFFER remains in a
+   free-able state, and errno is set).  It is unspecified whether this
+   function can reduce the array size.  */
+bool __libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer,
+					   size_t nelem, size_t size);
+libc_hidden_proto (__libc_scratch_buffer_set_array_size)
+
+/* Alias for __libc_scratch_set_array_size.  */
+static __always_inline bool
+scratch_buffer_set_array_size (struct scratch_buffer *buffer,
+			       size_t nelem, size_t size)
+{
+  return __glibc_likely (__libc_scratch_buffer_set_array_size
+			 (buffer, nelem, size));
+}
+
+#endif /* _SCRATCH_BUFFER_H */
diff --git a/malloc/Makefile b/malloc/Makefile
index 70e3cefa7b06157e..38aa9e0993d4880c 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -33,6 +33,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
 	 tst-interpose-thread \
 	 tst-interpose-static-nothread \
 	 tst-interpose-static-thread \
+	 tst-scratch_buffer \
 
 tests-static := \
 	 tst-interpose-static-nothread \
@@ -40,7 +41,11 @@ tests-static := \
 
 test-srcs = tst-mtrace
 
-routines = malloc morecore mcheck mtrace obstack
+routines = malloc morecore mcheck mtrace obstack \
+  scratch_buffer_grow \
+  scratch_buffer_grow_preserve \
+  scratch_buffer_set_array_size \
+
 
 install-lib := libmcheck.a
 non-lib.a := libmcheck.a
diff --git a/malloc/Versions b/malloc/Versions
index 7ca9bdf25fcafdf2..f3c3d8a0934bdcd3 100644
--- a/malloc/Versions
+++ b/malloc/Versions
@@ -67,5 +67,10 @@ libc {
 
     # Internal destructor hook for libpthread.
     __libc_thread_freeres;
+
+    # struct scratch_buffer support
+    __libc_scratch_buffer_grow;
+    __libc_scratch_buffer_grow_preserve;
+    __libc_scratch_buffer_set_array_size;
   }
 }
diff --git a/malloc/scratch_buffer_grow.c b/malloc/scratch_buffer_grow.c
new file mode 100644
index 0000000000000000..22bae506a1946eb4
--- /dev/null
+++ b/malloc/scratch_buffer_grow.c
@@ -0,0 +1,52 @@
+/* Variable-sized buffer with on-stack default allocation.
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <scratch_buffer.h>
+#include <errno.h>
+
+bool
+__libc_scratch_buffer_grow (struct scratch_buffer *buffer)
+{
+  void *new_ptr;
+  size_t new_length = buffer->length * 2;
+
+  /* Discard old buffer.  */
+  scratch_buffer_free (buffer);
+
+  /* Check for overflow.  */
+  if (__glibc_likely (new_length >= buffer->length))
+    new_ptr = malloc (new_length);
+  else
+    {
+      __set_errno (ENOMEM);
+      new_ptr = NULL;
+    }
+
+  if (__glibc_unlikely (new_ptr == NULL))
+    {
+      /* Buffer must remain valid to free.  */
+      scratch_buffer_init (buffer);
+      return false;
+    }
+
+  /* Install new heap-based buffer.  */
+  buffer->data = new_ptr;
+  buffer->length = new_length;
+  return true;
+}
+libc_hidden_def (__libc_scratch_buffer_grow);
diff --git a/malloc/scratch_buffer_grow_preserve.c b/malloc/scratch_buffer_grow_preserve.c
new file mode 100644
index 0000000000000000..18543ef85b7a48e1
--- /dev/null
+++ b/malloc/scratch_buffer_grow_preserve.c
@@ -0,0 +1,63 @@
+/* Variable-sized buffer with on-stack default allocation.
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <scratch_buffer.h>
+#include <errno.h>
+#include <string.h>
+
+bool
+__libc_scratch_buffer_grow_preserve (struct scratch_buffer *buffer)
+{
+  size_t new_length = 2 * buffer->length;
+  void *new_ptr;
+
+  if (buffer->data == buffer->__space)
+    {
+      /* Move buffer to the heap.  No overflow is possible because
+	 buffer->length describes a small buffer on the stack.  */
+      new_ptr = malloc (new_length);
+      if (new_ptr == NULL)
+	return false;
+      memcpy (new_ptr, buffer->__space, buffer->length);
+    }
+  else
+    {
+      /* Buffer was already on the heap.  Check for overflow.  */
+      if (__glibc_likely (new_length >= buffer->length))
+	new_ptr = realloc (buffer->data, new_length);
+      else
+	{
+	  __set_errno (ENOMEM);
+	  new_ptr = NULL;
+	}
+
+      if (__glibc_unlikely (new_ptr == NULL))
+	{
+	  /* Deallocate, but buffer must remain valid to free.  */
+	  free (buffer->data);
+	  scratch_buffer_init (buffer);
+	  return false;
+	}
+    }
+
+  /* Install new heap-based buffer.  */
+  buffer->data = new_ptr;
+  buffer->length = new_length;
+  return true;
+}
+libc_hidden_def (__libc_scratch_buffer_grow_preserve);
diff --git a/malloc/scratch_buffer_set_array_size.c b/malloc/scratch_buffer_set_array_size.c
new file mode 100644
index 0000000000000000..8ab6d9d300d5c10d
--- /dev/null
+++ b/malloc/scratch_buffer_set_array_size.c
@@ -0,0 +1,60 @@
+/* Variable-sized buffer with on-stack default allocation.
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <scratch_buffer.h>
+#include <errno.h>
+#include <limits.h>
+
+bool
+__libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer,
+				      size_t nelem, size_t size)
+{
+  size_t new_length = nelem * size;
+
+  /* Avoid overflow check if both values are small. */
+  if ((nelem | size) >> (sizeof (size_t) * CHAR_BIT / 2) != 0
+      && nelem != 0 && size != new_length / nelem)
+    {
+      /* Overflow.  Discard the old buffer, but it must remain valid
+	 to free.  */
+      scratch_buffer_free (buffer);
+      scratch_buffer_init (buffer);
+      __set_errno (ENOMEM);
+      return false;
+    }
+
+  if (new_length <= buffer->length)
+    return true;
+
+  /* Discard old buffer.  */
+  scratch_buffer_free (buffer);
+
+  char *new_ptr = malloc (new_length);
+  if (new_ptr == NULL)
+    {
+      /* Buffer must remain valid to free.  */
+      scratch_buffer_init (buffer);
+      return false;
+    }
+
+  /* Install new heap-based buffer.  */
+  buffer->data = new_ptr;
+  buffer->length = new_length;
+  return true;
+}
+libc_hidden_def (__libc_scratch_buffer_set_array_size);
diff --git a/malloc/tst-scratch_buffer.c b/malloc/tst-scratch_buffer.c
new file mode 100644
index 0000000000000000..5c9f3442ae8d6ef9
--- /dev/null
+++ b/malloc/tst-scratch_buffer.c
@@ -0,0 +1,155 @@
+/*
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <scratch_buffer.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+static bool
+unchanged_array_size (struct scratch_buffer *buf, size_t a, size_t b)
+{
+  size_t old_length = buf->length;
+  if (!scratch_buffer_set_array_size (buf, a, b))
+    {
+      printf ("scratch_buffer_set_array_size failed: %zu %zu\n",
+	      a, b);
+      return false;
+    }
+  if (old_length != buf->length)
+    {
+      printf ("scratch_buffer_set_array_size did not preserve size: %zu %zu\n",
+	      a, b);
+      return false;
+    }
+  return true;
+}
+
+static bool
+array_size_must_fail (size_t a, size_t b)
+{
+  for (int pass = 0; pass < 2; ++pass)
+    {
+      struct scratch_buffer buf;
+      scratch_buffer_init (&buf);
+      if (pass > 0)
+	if (!scratch_buffer_grow (&buf))
+	  {
+	    printf ("scratch_buffer_grow in array_size_must_fail failed\n");
+	    return false;
+	  }
+      if (scratch_buffer_set_array_size (&buf, a, b))
+	{
+	  printf ("scratch_buffer_set_array_size passed: %d %zu %zu\n",
+		  pass, a, b);
+	  return false;
+	}
+      if (buf.data != buf.__space)
+	{
+	  printf ("scratch_buffer_set_array_size did not free: %d %zu %zu\n",
+		  pass, a, b);
+	  return false;
+	}
+    }
+  return true;
+}
+
+static int
+do_test (void)
+{
+  {
+    struct scratch_buffer buf;
+    scratch_buffer_init (&buf);
+    memset (buf.data, ' ', buf.length);
+    scratch_buffer_free (&buf);
+  }
+  {
+    struct scratch_buffer buf;
+    scratch_buffer_init (&buf);
+    memset (buf.data, ' ', buf.length);
+    size_t old_length = buf.length;
+    scratch_buffer_grow (&buf);
+    if (buf.length <= old_length)
+      {
+	printf ("scratch_buffer_grow did not enlarge buffer\n");
+	return 1;
+      }
+    memset (buf.data, ' ', buf.length);
+    scratch_buffer_free (&buf);
+  }
+  {
+    struct scratch_buffer buf;
+    scratch_buffer_init (&buf);
+    memset (buf.data, '@', buf.length);
+    strcpy (buf.data, "prefix");
+    size_t old_length = buf.length;
+    scratch_buffer_grow_preserve (&buf);
+    if (buf.length <= old_length)
+      {
+	printf ("scratch_buffer_grow_preserve did not enlarge buffer\n");
+	return 1;
+      }
+    if (strcmp (buf.data, "prefix") != 0)
+      {
+	printf ("scratch_buffer_grow_preserve did not copy buffer\n");
+	return 1;
+      }
+    for (unsigned i = 7; i < old_length; ++i)
+      if (((char *)buf.data)[i] != '@')
+	{
+	  printf ("scratch_buffer_grow_preserve did not copy buffer (%u)\n",
+		  i);
+	  return 1;
+	}
+    scratch_buffer_free (&buf);
+  }
+  {
+    struct scratch_buffer buf;
+    scratch_buffer_init (&buf);
+    for (int pass = 0; pass < 4; ++pass)
+      {
+	if (!(unchanged_array_size (&buf, 0, 0)
+	      && unchanged_array_size (&buf, 1, 0)
+	      && unchanged_array_size (&buf, 0, 1)
+	      && unchanged_array_size (&buf, -1, 0)
+	      && unchanged_array_size (&buf, 0, -1)
+	      && unchanged_array_size (&buf, 1ULL << 16, 0)
+	      && unchanged_array_size (&buf, 0, 1ULL << 16)
+	      && unchanged_array_size (&buf, (size_t) (1ULL << 32), 0)
+	      && unchanged_array_size (&buf, 0, (size_t) (1ULL << 32))))
+	  return 1;
+	if (!scratch_buffer_grow (&buf))
+	  {
+	    printf ("scratch_buffer_grow_failed (pass %d)\n", pass);
+	  }
+      }
+    scratch_buffer_free (&buf);
+  }
+  {
+    if (!(array_size_must_fail (-1, 1)
+	  && array_size_must_fail (-1, -1)
+	  && array_size_must_fail (1, -1)
+	  && array_size_must_fail (((size_t)-1) / 4, 4)
+	  && array_size_must_fail (4, ((size_t)-1) / 4)))
+	return 1;
+  }
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"