Make the default option of zero realloc match the system allocator.
diff --git a/configure.ac b/configure.ac
index 5c7a8ef..f6d25f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -638,6 +638,7 @@
dnl definitions need to be seen before any headers are included, which is a pain
dnl to make happen otherwise.
default_retain="0"
+zero_realloc_default_free="0"
maps_coalesce="1"
DUMP_SYMS="${NM} -a"
SYM_PREFIX=""
@@ -684,6 +685,7 @@
if test "${LG_SIZEOF_PTR}" = "3"; then
default_retain="1"
fi
+ zero_realloc_default_free="1"
;;
*-*-linux*)
dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
@@ -698,6 +700,7 @@
if test "${LG_SIZEOF_PTR}" = "3"; then
default_retain="1"
fi
+ zero_realloc_default_free="1"
;;
*-*-kfreebsd*)
dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
@@ -773,6 +776,7 @@
if test "${LG_SIZEOF_PTR}" = "3"; then
default_retain="1"
fi
+ zero_realloc_default_free="1"
;;
*-*-nto-qnx)
abi="elf"
@@ -1395,6 +1399,11 @@
AC_DEFINE([JEMALLOC_RETAIN], [ ], [ ])
fi
+dnl Indicate whether realloc(ptr, 0) defaults to the "alloc" behavior.
+if test "x$zero_realloc_default_free" = "x1" ; then
+ AC_DEFINE([JEMALLOC_ZERO_REALLOC_DEFAULT_FREE], [ ], [ ])
+fi
+
dnl Enable allocation from DSS if supported by the OS.
have_dss="1"
dnl Check whether the BSD/SUSv1 sbrk() exists. If not, disable DSS support.
diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index fe4ded9..e28e8f3 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -1578,13 +1578,14 @@
<literal>r-</literal>
</term>
<listitem><para> Determines the behavior of
- <function>realloc()</function> when passed a value of zero for the new
- size. <quote>alloc</quote> treats this as an allocation of size zero
- (and returns a non-null result except in case of resource exhaustion).
- <quote>free</quote> treats this as a deallocation of the pointer, and
- returns <constant>NULL</constant> without setting
- <varname>errno</varname>. <quote>abort</quote> aborts the process if
- zero is passed. The default is <quote>alloc</quote>.</para>
+ <function>realloc()</function> when passed a value of zero for the new
+ size. <quote>alloc</quote> treats this as an allocation of size zero
+ (and returns a non-null result except in case of resource exhaustion).
+ <quote>free</quote> treats this as a deallocation of the pointer, and
+ returns <constant>NULL</constant> without setting
+ <varname>errno</varname>. <quote>abort</quote> aborts the process if
+ zero is passed. The default is <quote>free</quote> on Linux and
+ Windows, and <quote>alloc</quote> elsewhere.</para>
<para>There is considerable divergence of behaviors across
implementations in handling this case. Many have the behavior of
diff --git a/include/jemalloc/internal/jemalloc_internal_defs.h.in b/include/jemalloc/internal/jemalloc_internal_defs.h.in
index 0cb15d3..3588072 100644
--- a/include/jemalloc/internal/jemalloc_internal_defs.h.in
+++ b/include/jemalloc/internal/jemalloc_internal_defs.h.in
@@ -421,4 +421,7 @@
/* Darwin VM_MAKE_TAG support */
#undef JEMALLOC_HAVE_VM_MAKE_TAG
+/* If defined, realloc(ptr, 0) defaults to "free" instead of "alloc". */
+#undef JEMALLOC_ZERO_REALLOC_DEFAULT_FREE
+
#endif /* JEMALLOC_INTERNAL_DEFS_H_ */
diff --git a/src/jemalloc.c b/src/jemalloc.c
index 9c94425..7655de4 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -112,7 +112,12 @@
;
zero_realloc_action_t opt_zero_realloc_action =
- zero_realloc_action_alloc;
+#ifdef JEMALLOC_ZERO_REALLOC_DEFAULT_FREE
+ zero_realloc_action_free
+#else
+ zero_realloc_action_alloc
+#endif
+ ;
atomic_zu_t zero_realloc_count = ATOMIC_INIT(0);
