New module 'eealloc'.

[gnulib.git] / lib / eealloc.h

diff --git a/lib/eealloc.h b/lib/eealloc.h
new file mode 100644 (file)
index 0000000..72476da
--- /dev/null
+++ b/lib/eealloc.h
@@ -0,0 +1,68 @@
+/* Memory allocation with expensive empty allocations.
+   Copyright (C) 2003 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2003,
+   based on prior work by Jim Meyering.
+
+   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#ifndef _EEALLOC_H
+#define _EEALLOC_H
+
+/* malloc() and realloc() are allowed to return NULL when asked to allocate
+   a memory block of 0 bytes; this is not an out-of-memory condition.
+   (See ISO C 99 section 7.20.3.)  In some places, this is not welcome,
+   because it requires extra checking (so as not to confuse a zero-sized
+   allocation with an out-of-memory condition).  This file provides
+   malloc()/realloc() workalikes which return non-NULL pointers for
+   succeeding zero-sized allocations.  GNU libc already defines malloc()
+   and realloc() this way; on such platforms the workalikes are aliased
+   to the original malloc()/realloc() functions.  */
+
+#include <stdlib.h>
+
+#if MALLOC_0_IS_NONNULL
+# define eemalloc malloc
+#else
+static inline void *
+eemalloc (size_t n)
+{
+  /* If n is zero, allocate a 1-byte block.  */
+  if (n == 0)
+    n = 1;
+  return malloc (n);
+}
+#endif
+
+#if REALLOC_0_IS_NONNULL
+# define eerealloc realloc
+#else
+static inline void *
+eerealloc (void *p, size_t n)
+{
+  /* If n is zero, allocate or keep a 1-byte block.  */
+  if (n == 0)
+    n = 1;
+  return realloc (p, n);
+}
+#endif
+
+/* Maybe we should also define variants
+    eenmalloc (size_t n, size_t s) - behaves like eemalloc (n * s)
+    eezalloc (size_t n) - like eemalloc followed by memset 0
+    eecalloc (size_t n, size_t s) - like eemalloc (n * s) followed by memset 0
+    eenrealloc (void *p, size_t n, size_t s) - like eerealloc (p, n * s)
+   If this would be useful in your application. please speak up.  */
+
+#endif /* _EEALLOC_H */