glibc/glibc-rh2248502-1.patch

Revert "stdlib: Remove use of mergesort on qsort (BZ 21719)"

This reverts commit 03bf8357e8291857a435afcc3048e0b697b6cc04.

diff --git a/include/stdlib.h b/include/stdlib.h
index 580da9be15adf0c1..0ed8271d9bd76896 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -149,6 +149,8 @@ extern int __posix_openpt (int __oflag) attribute_hidden;
 extern int __add_to_environ (const char *name, const char *value,
 			     const char *combines, int replace)
      attribute_hidden;
+extern void _quicksort (void *const pbase, size_t total_elems,
+			size_t size, __compar_d_fn_t cmp, void *arg);
 
 extern int __on_exit (void (*__func) (int __status, void *__arg), void *__arg);
 
diff --git a/manual/argp.texi b/manual/argp.texi
index b77ad68285ecb732..0023441812d4e584 100644
--- a/manual/argp.texi
+++ b/manual/argp.texi
@@ -735,7 +735,7 @@ for options, bad phase of the moon, etc.
 @c  hol_set_group ok
 @c   hol_find_entry ok
 @c  hol_sort @mtslocale @acucorrupt
-@c   qsort dup
+@c   qsort dup @acucorrupt
 @c    hol_entry_qcmp @mtslocale
 @c     hol_entry_cmp @mtslocale
 @c      group_cmp ok
diff --git a/manual/locale.texi b/manual/locale.texi
index f6afa5dc44a2a016..720e0ca952a665bd 100644
--- a/manual/locale.texi
+++ b/manual/locale.texi
@@ -253,7 +253,7 @@ The symbols in this section are defined in the header file @file{locale.h}.
 @c    calculate_head_size ok
 @c    __munmap ok
 @c    compute_hashval ok
-@c    qsort dup
+@c    qsort dup @acucorrupt
 @c     rangecmp ok
 @c    malloc @ascuheap @acsmem
 @c    strdup @ascuheap @acsmem
@@ -275,6 +275,7 @@ The symbols in this section are defined in the header file @file{locale.h}.
 @c      realloc @ascuheap @acsmem
 @c     realloc @ascuheap @acsmem
 @c     fclose @ascuheap @asulock @acsmem @acsfd @aculock
+@c     qsort @ascuheap @acsmem
 @c      alias_compare dup
 @c    libc_lock_unlock @aculock
 @c   _nl_explode_name @ascuheap @acsmem
diff --git a/manual/search.texi b/manual/search.texi
index a550858478f7fc83..5691bf2f2b2bb861 100644
--- a/manual/search.texi
+++ b/manual/search.texi
@@ -159,7 +159,7 @@ To sort an array using an arbitrary comparison function, use the
 
 @deftypefun void qsort (void *@var{array}, size_t @var{count}, size_t @var{size}, comparison_fn_t @var{compare})
 @standards{ISO, stdlib.h}
-@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{}}}
 The @code{qsort} function sorts the array @var{array}.  The array
 contains @var{count} elements, each of which is of size @var{size}.
 
@@ -199,8 +199,9 @@ Functions}):
 The @code{qsort} function derives its name from the fact that it was
 originally implemented using the ``quick sort'' algorithm.
 
-The implementation of @code{qsort} in this library is an in-place sort
-and uses a constant extra space (allocated on the stack).
+The implementation of @code{qsort} in this library might not be an
+in-place sort and might thereby use an extra amount of memory to store
+the array.
 @end deftypefun
 
 @node Search/Sort Example
diff --git a/stdlib/Makefile b/stdlib/Makefile
index 6af606136e557910..b99bb34ae8f23730 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -96,6 +96,7 @@ routines := \
   mbtowc \
   mrand48 \
   mrand48_r \
+  msort \
   nrand48 \
   nrand48_r \
   old_atexit  \
@@ -380,6 +381,7 @@ generated += \
   # generated
 
 CFLAGS-bsearch.c += $(uses-callbacks)
+CFLAGS-msort.c += $(uses-callbacks)
 CFLAGS-qsort.c += $(uses-callbacks)
 CFLAGS-system.c += -fexceptions
 CFLAGS-system.os = -fomit-frame-pointer
diff --git a/stdlib/msort.c b/stdlib/msort.c
new file mode 100644
index 0000000000000000..bbaa5e9f82a75b78
--- /dev/null
+++ b/stdlib/msort.c
@@ -0,0 +1,309 @@
+/* An alternative to qsort, with an identical interface.
+   This file is part of the GNU C Library.
+   Copyright (C) 1992-2023 Free Software Foundation, Inc.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <alloca.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <memcopy.h>
+#include <errno.h>
+#include <atomic.h>
+
+struct msort_param
+{
+  size_t s;
+  size_t var;
+  __compar_d_fn_t cmp;
+  void *arg;
+  char *t;
+};
+static void msort_with_tmp (const struct msort_param *p, void *b, size_t n);
+
+static void
+msort_with_tmp (const struct msort_param *p, void *b, size_t n)
+{
+  char *b1, *b2;
+  size_t n1, n2;
+
+  if (n <= 1)
+    return;
+
+  n1 = n / 2;
+  n2 = n - n1;
+  b1 = b;
+  b2 = (char *) b + (n1 * p->s);
+
+  msort_with_tmp (p, b1, n1);
+  msort_with_tmp (p, b2, n2);
+
+  char *tmp = p->t;
+  const size_t s = p->s;
+  __compar_d_fn_t cmp = p->cmp;
+  void *arg = p->arg;
+  switch (p->var)
+    {
+    case 0:
+      while (n1 > 0 && n2 > 0)
+	{
+	  if ((*cmp) (b1, b2, arg) <= 0)
+	    {
+	      *(uint32_t *) tmp = *(uint32_t *) b1;
+	      b1 += sizeof (uint32_t);
+	      --n1;
+	    }
+	  else
+	    {
+	      *(uint32_t *) tmp = *(uint32_t *) b2;
+	      b2 += sizeof (uint32_t);
+	      --n2;
+	    }
+	  tmp += sizeof (uint32_t);
+	}
+      break;
+    case 1:
+      while (n1 > 0 && n2 > 0)
+	{
+	  if ((*cmp) (b1, b2, arg) <= 0)
+	    {
+	      *(uint64_t *) tmp = *(uint64_t *) b1;
+	      b1 += sizeof (uint64_t);
+	      --n1;
+	    }
+	  else
+	    {
+	      *(uint64_t *) tmp = *(uint64_t *) b2;
+	      b2 += sizeof (uint64_t);
+	      --n2;
+	    }
+	  tmp += sizeof (uint64_t);
+	}
+      break;
+    case 2:
+      while (n1 > 0 && n2 > 0)
+	{
+	  unsigned long *tmpl = (unsigned long *) tmp;
+	  unsigned long *bl;
+
+	  tmp += s;
+	  if ((*cmp) (b1, b2, arg) <= 0)
+	    {
+	      bl = (unsigned long *) b1;
+	      b1 += s;
+	      --n1;
+	    }
+	  else
+	    {
+	      bl = (unsigned long *) b2;
+	      b2 += s;
+	      --n2;
+	    }
+	  while (tmpl < (unsigned long *) tmp)
+	    *tmpl++ = *bl++;
+	}
+      break;
+    case 3:
+      while (n1 > 0 && n2 > 0)
+	{
+	  if ((*cmp) (*(const void **) b1, *(const void **) b2, arg) <= 0)
+	    {
+	      *(void **) tmp = *(void **) b1;
+	      b1 += sizeof (void *);
+	      --n1;
+	    }
+	  else
+	    {
+	      *(void **) tmp = *(void **) b2;
+	      b2 += sizeof (void *);
+	      --n2;
+	    }
+	  tmp += sizeof (void *);
+	}
+      break;
+    default:
+      while (n1 > 0 && n2 > 0)
+	{
+	  if ((*cmp) (b1, b2, arg) <= 0)
+	    {
+	      tmp = (char *) __mempcpy (tmp, b1, s);
+	      b1 += s;
+	      --n1;
+	    }
+	  else
+	    {
+	      tmp = (char *) __mempcpy (tmp, b2, s);
+	      b2 += s;
+	      --n2;
+	    }
+	}
+      break;
+    }
+
+  if (n1 > 0)
+    memcpy (tmp, b1, n1 * s);
+  memcpy (b, p->t, (n - n2) * s);
+}
+
+
+void
+__qsort_r (void *b, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
+{
+  size_t size = n * s;
+  char *tmp = NULL;
+  struct msort_param p;
+
+  /* For large object sizes use indirect sorting.  */
+  if (s > 32)
+    size = 2 * n * sizeof (void *) + s;
+
+  if (size < 1024)
+    /* The temporary array is small, so put it on the stack.  */
+    p.t = __alloca (size);
+  else
+    {
+      /* We should avoid allocating too much memory since this might
+	 have to be backed up by swap space.  */
+      static long int phys_pages;
+      static int pagesize;
+
+      if (pagesize == 0)
+	{
+	  phys_pages = __sysconf (_SC_PHYS_PAGES);
+
+	  if (phys_pages == -1)
+	    /* Error while determining the memory size.  So let's
+	       assume there is enough memory.  Otherwise the
+	       implementer should provide a complete implementation of
+	       the `sysconf' function.  */
+	    phys_pages = (long int) (~0ul >> 1);
+
+	  /* The following determines that we will never use more than
+	     a quarter of the physical memory.  */
+	  phys_pages /= 4;
+
+	  /* Make sure phys_pages is written to memory.  */
+	  atomic_write_barrier ();
+
+	  pagesize = __sysconf (_SC_PAGESIZE);
+	}
+
+      /* Just a comment here.  We cannot compute
+	   phys_pages * pagesize
+	   and compare the needed amount of memory against this value.
+	   The problem is that some systems might have more physical
+	   memory then can be represented with a `size_t' value (when
+	   measured in bytes.  */
+
+      /* If the memory requirements are too high don't allocate memory.  */
+      if (size / pagesize > (size_t) phys_pages)
+	{
+	  _quicksort (b, n, s, cmp, arg);
+	  return;
+	}
+
+      /* It's somewhat large, so malloc it.  */
+      int save = errno;
+      tmp = malloc (size);
+      __set_errno (save);
+      if (tmp == NULL)
+	{
+	  /* Couldn't get space, so use the slower algorithm
+	     that doesn't need a temporary array.  */
+	  _quicksort (b, n, s, cmp, arg);
+	  return;
+	}
+      p.t = tmp;
+    }
+
+  p.s = s;
+  p.var = 4;
+  p.cmp = cmp;
+  p.arg = arg;
+
+  if (s > 32)
+    {
+      /* Indirect sorting.  */
+      char *ip = (char *) b;
+      void **tp = (void **) (p.t + n * sizeof (void *));
+      void **t = tp;
+      void *tmp_storage = (void *) (tp + n);
+
+      while ((void *) t < tmp_storage)
+	{
+	  *t++ = ip;
+	  ip += s;
+	}
+      p.s = sizeof (void *);
+      p.var = 3;
+      msort_with_tmp (&p, p.t + n * sizeof (void *), n);
+
+      /* tp[0] .. tp[n - 1] is now sorted, copy around entries of
+	 the original array.  Knuth vol. 3 (2nd ed.) exercise 5.2-10.  */
+      char *kp;
+      size_t i;
+      for (i = 0, ip = (char *) b; i < n; i++, ip += s)
+	if ((kp = tp[i]) != ip)
+	  {
+	    size_t j = i;
+	    char *jp = ip;
+	    memcpy (tmp_storage, ip, s);
+
+	    do
+	      {
+		size_t k = (kp - (char *) b) / s;
+		tp[j] = jp;
+		memcpy (jp, kp, s);
+		j = k;
+		jp = kp;
+		kp = tp[k];
+	      }
+	    while (kp != ip);
+
+	    tp[j] = jp;
+	    memcpy (jp, tmp_storage, s);
+	  }
+    }
+  else
+    {
+      if ((s & (sizeof (uint32_t) - 1)) == 0
+	  && ((uintptr_t) b) % __alignof__ (uint32_t) == 0)
+	{
+	  if (s == sizeof (uint32_t))
+	    p.var = 0;
+	  else if (s == sizeof (uint64_t)
+		   && ((uintptr_t) b) % __alignof__ (uint64_t) == 0)
+	    p.var = 1;
+	  else if ((s & (sizeof (unsigned long) - 1)) == 0
+		   && ((uintptr_t) b)
+		      % __alignof__ (unsigned long) == 0)
+	    p.var = 2;
+	}
+      msort_with_tmp (&p, b, n);
+    }
+  free (tmp);
+}
+libc_hidden_def (__qsort_r)
+weak_alias (__qsort_r, qsort_r)
+
+
+void
+qsort (void *b, size_t n, size_t s, __compar_fn_t cmp)
+{
+  return __qsort_r (b, n, s, (__compar_d_fn_t) cmp, NULL);
+}
+libc_hidden_def (qsort)
diff --git a/stdlib/qsort.c b/stdlib/qsort.c
index fd32a165e7313c3a..d5f205affc4371cb 100644
--- a/stdlib/qsort.c
+++ b/stdlib/qsort.c
@@ -19,6 +19,7 @@
    Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
    Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993.  */
 
+#include <alloca.h>
 #include <limits.h>
 #include <memswap.h>
 #include <stdlib.h>
@@ -264,8 +265,8 @@ insertion_sort_qsort_partitions (void *const pbase, size_t total_elems,
       stack size is needed (actually O(1) in this case)!  */
 
 void
-__qsort_r (void *const pbase, size_t total_elems, size_t size,
-	   __compar_d_fn_t cmp, void *arg)
+_quicksort (void *const pbase, size_t total_elems, size_t size,
+	    __compar_d_fn_t cmp, void *arg)
 {
   char *base_ptr = (char *) pbase;
 
@@ -397,12 +398,3 @@ __qsort_r (void *const pbase, size_t total_elems, size_t size,
   insertion_sort_qsort_partitions (pbase, total_elems, size, swap_type, cmp,
 				   arg);
 }
-libc_hidden_def (__qsort_r)
-weak_alias (__qsort_r, qsort_r)
-
-void
-qsort (void *b, size_t n, size_t s, __compar_fn_t cmp)
-{
-  return __qsort_r (b, n, s, (__compar_d_fn_t) cmp, NULL);
-}
-libc_hidden_def (qsort)