Imported from /home/lorry/working-area/delta_cvs-tarball/cvs-1.12.13.tar.bz2.HEADcvs-1.12.13master

1 files changed, 198 insertions, 0 deletions

diff --git a/lib/pagealign_alloc.c b/lib/pagealign_alloc.c
new file mode 100644
index 0000000..28e8209
--- /dev/null
+++ b/lib/pagealign_alloc.c
@@ -0,0 +1,198 @@
+/* Memory allocation aligned to system page boundaries.
+
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program 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
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+   USA.  */
+
+/* Written by Derek R. Price <derek@ximbiot.com>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "pagealign_alloc.h"
+
+#include <errno.h>
+#include <stdlib.h>
+
+#include <fcntl.h>
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#if HAVE_MMAP
+# include <sys/mman.h>
+#endif
+
+#include "error.h"
+#include "exit.h"
+#include "getpagesize.h"
+#include "xalloc.h"
+#include "gettext.h"
+
+#define _(str) gettext (str)
+
+#if HAVE_MMAP
+/* Define MAP_FILE when it isn't otherwise.  */
+# ifndef MAP_FILE
+#  define MAP_FILE 0
+# endif
+/* Define MAP_FAILED for old systems which neglect to.  */
+# ifndef MAP_FAILED
+#  define MAP_FAILED ((void *)-1)
+# endif
+#endif
+
+
+#if HAVE_MMAP || ! HAVE_POSIX_MEMALIGN
+
+# if HAVE_MMAP
+/* For each memory region, we store its size.  */
+typedef size_t info_t;
+# else
+/* For each memory region, we store the original pointer returned by
+   malloc().  */
+typedef void * info_t;
+# endif
+
+/* A simple linked list of allocated memory regions.  It is probably not the
+   most efficient way to store these, but anyway...  */
+typedef struct memnode_s memnode_t;
+struct memnode_s
+{
+  void *aligned_ptr;
+  info_t info;
+  memnode_t *next;
+};
+
+/* The list of currently allocated memory regions.  */
+static memnode_t *memnode_table = NULL;
+
+
+static void
+new_memnode (void *aligned_ptr, info_t info)
+{
+  memnode_t *new_node = (memnode_t *) xmalloc (sizeof (memnode_t));
+  new_node->aligned_ptr = aligned_ptr;
+  new_node->info = info;
+  new_node->next = memnode_table;
+  memnode_table = new_node;
+}
+
+
+/* Dispose of the memnode containing a map for the ALIGNED_PTR in question
+   and return the content of the node's INFO field.  */
+static info_t
+get_memnode (void *aligned_ptr)
+{
+  info_t ret;
+  memnode_t *c;
+  memnode_t **p_next = &memnode_table;
+
+  for (c = *p_next; c != NULL; p_next = &c->next, c = c->next)
+    if (c->aligned_ptr == aligned_ptr)
+      break;
+
+  if (c == NULL)
+    /* An attempt to free untracked memory.  A wrong pointer was passed
+       to pagealign_free().  */
+    abort ();
+
+  /* Remove this entry from the list, save the return value, and free it.  */
+  *p_next = c->next;
+  ret = c->info;
+  free (c);
+
+  return ret;
+}
+
+#endif /* HAVE_MMAP || !HAVE_POSIX_MEMALIGN */
+
+
+void *
+pagealign_alloc (size_t size)
+{
+  void *ret;
+#if HAVE_MMAP
+# ifdef HAVE_MAP_ANONYMOUS
+  const int fd = -1;
+  const int flags = MAP_ANONYMOUS | MAP_PRIVATE;
+# else /* !HAVE_MAP_ANONYMOUS */
+  static int fd = -1;  /* Only open /dev/zero once in order to avoid limiting
+			  the amount of memory we may allocate based on the
+			  number of open file descriptors.  */
+  const int flags = MAP_FILE | MAP_PRIVATE;
+  if (fd == -1)
+    {
+      fd = open ("/dev/zero", O_RDONLY, 0666);
+      if (fd < 0)
+	error (EXIT_FAILURE, errno, _("Failed to open /dev/zero for read"));
+    }
+# endif /* HAVE_MAP_ANONYMOUS */
+  ret = mmap (NULL, size, PROT_READ | PROT_WRITE, flags, fd, 0);
+  if (ret == MAP_FAILED)
+    return NULL;
+  new_memnode (ret, size);
+#elif HAVE_POSIX_MEMALIGN
+  int status = posix_memalign (&ret, getpagesize (), size);
+  if (status)
+    {
+      errno = status;
+      return NULL;
+    }
+#else /* !HAVE_MMAP && !HAVE_POSIX_MEMALIGN */
+  size_t pagesize = getpagesize ();
+  void *unaligned_ptr = malloc (size + pagesize - 1);
+  if (unaligned_ptr == NULL)
+    {
+      /* Set errno.  We don't know whether malloc already set errno: some
+	 implementations of malloc do, some don't.  */
+      errno = ENOMEM;
+      return NULL;
+    }
+  ret = (char *) unaligned_ptr
+        + ((- (unsigned long) unaligned_ptr) & (pagesize - 1));
+  new_memnode (ret, unaligned_ptr);
+#endif /* HAVE_MMAP && HAVE_POSIX_MEMALIGN */
+  return ret;
+}
+
+
+void *
+pagealign_xalloc (size_t size)
+{
+  void *ret;
+
+  ret = pagealign_alloc (size);
+  if (ret == NULL)
+    xalloc_die ();
+  return ret;
+}
+
+
+void
+pagealign_free (void *aligned_ptr)
+{
+#if HAVE_MMAP
+  if (munmap (aligned_ptr, get_memnode (aligned_ptr)) < 0)
+    error (EXIT_FAILURE, errno, "Failed to unmap memory");
+#elif HAVE_POSIX_MEMALIGN
+  free (aligned_ptr);
+#else
+  free (get_memnode (aligned_ptr));
+#endif
+}