Implement aligned_alloc().

Implement aligned_alloc(), which was added in the C11 standard.  The
function is weakly specified to the point that a minimally compliant
implementation would be painful to use (size must be an integral
multiple of alignment!), which in practice makes posix_memalign() a
safer choice.

1 files changed, 35 insertions, 0 deletions

diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index 74da409..926deaf 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -30,6 +30,7 @@
     <refname>malloc</refname>
     <refname>calloc</refname>
     <refname>posix_memalign</refname>
+    <refname>aligned_alloc</refname>
     <refname>realloc</refname>
     <refname>free</refname>
     <refname>malloc_usable_size</refname>
@@ -74,6 +75,11 @@
           <paramdef>size_t <parameter>size</parameter></paramdef>
         </funcprototype>
         <funcprototype>
+          <funcdef>void *<function>aligned_alloc</function></funcdef>
+          <paramdef>size_t <parameter>alignment</parameter></paramdef>
+          <paramdef>size_t <parameter>size</parameter></paramdef>
+        </funcprototype>
+        <funcprototype>
           <funcdef>void *<function>realloc</function></funcdef>
           <paramdef>void *<parameter>ptr</parameter></paramdef>
           <paramdef>size_t <parameter>size</parameter></paramdef>
@@ -190,6 +196,14 @@
       <parameter>alignment</parameter> must be a power of 2 at least as large
       as <code language="C">sizeof(<type>void *</type>)</code>.</para>
 
+      <para>The <function>aligned_alloc<parameter/></function> function
+      allocates <parameter>size</parameter> bytes of memory such that the
+      allocation's base address is an even multiple of
+      <parameter>alignment</parameter>.  The requested
+      <parameter>alignment</parameter> must be a power of 2.  Behavior is
+      undefined if <parameter>size</parameter> is not an integral multiple of
+      <parameter>alignment</parameter>.</para>
+
       <para>The <function>realloc<parameter/></function> function changes the
       size of the previously allocated memory referenced by
       <parameter>ptr</parameter> to <parameter>size</parameter> bytes.  The
@@ -1789,6 +1803,27 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         </variablelist>
       </para>
 
+      <para>The <function>aligned_alloc<parameter/></function> function returns
+      a pointer to the allocated memory if successful; otherwise a
+      <constant>NULL</constant> pointer is returned and
+      <varname>errno</varname> is set.  The
+      <function>aligned_alloc<parameter/></function> function will fail if:
+        <variablelist>
+          <varlistentry>
+            <term><errorname>EINVAL</errorname></term>
+
+            <listitem><para>The <parameter>alignment</parameter> parameter is
+            not a power of 2.
+            </para></listitem>
+          </varlistentry>
+          <varlistentry>
+            <term><errorname>ENOMEM</errorname></term>
+
+            <listitem><para>Memory allocation error.</para></listitem>
+          </varlistentry>
+        </variablelist>
+      </para>
+
       <para>The <function>realloc<parameter/></function> function returns a
       pointer, possibly identical to <parameter>ptr</parameter>, to the
       allocated memory if successful; otherwise a <constant>NULL</constant>