* include/ruby/ruby.h (ALLOCV): new API for exception-safe

  temporary buffer.  [ruby-core:34844]
* string.c (rb_alloc_tmp_buffer, rb_free_tmp_buffer):
  implementation of the API.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30661 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 38 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 659fd2e816..a7094d5fad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Jan 27 08:32:17 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/ruby.h (ALLOCV): new API for exception-safe
+	  temporary buffer.  [ruby-core:34844]
+
+	* string.c (rb_alloc_tmp_buffer, rb_free_tmp_buffer):
+	  implementation of the API.
+
 Thu Jan 27 08:22:49 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* dln_find.c (dln_find_1): use rb_warning and return immediately
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 4e15517377..aca517ca61 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1028,6 +1028,18 @@ NUM2CHR(VALUE x)
 
 #define ALLOCA_N(type,n) (type*)alloca(sizeof(type)*(n))
 
+void *rb_alloc_tmp_buffer(volatile VALUE *store, long len);
+void rb_free_tmp_buffer(volatile VALUE *store);
+/* allocates _n_ bytes temporary buffer and stores VALUE including it
+ * in _v_.  _n_ may be evaluated twice. */
+#ifdef C_ALLOCA
+# define ALLOCV(v, n) rb_alloc_tmp_buffer(&(v), (n))
+#else
+# define ALLOCV(v, n) ((n) < 1024 ? (RB_GC_GUARD(v) = 0, alloca(n)) : rb_alloc_tmp_buffer(&(v), (n)))
+#endif
+#define ALLOCV_N(type, v, n) (type*)ALLOCV((v), sizeof(type)*(n))
+#define ALLOCV_END(v) rb_free_tmp_buffer(&(v))
+
 #define MEMZERO(p,type,n) memset((p), 0, sizeof(type)*(n))
 #define MEMCPY(p1,p2,type,n) memcpy((p1), (p2), sizeof(type)*(n))
 #define MEMMOVE(p1,p2,type,n) memmove((p1), (p2), sizeof(type)*(n))
diff --git a/string.c b/string.c
index f7c0ff7762..d4d1c9f7da 100644
--- a/string.c
+++ b/string.c
@@ -45,6 +45,8 @@
 #undef rb_str_buf_cat2
 #undef rb_str_cat2
 
+static VALUE rb_str_clear(VALUE str);
+
 VALUE rb_cString;
 VALUE rb_cSymbol;
 
@@ -765,6 +767,22 @@ rb_str_tmp_new(long len)
     return str_new(0, 0, len);
 }
 
+void *
+rb_alloc_tmp_buffer(volatile VALUE *store, long len)
+{
+    VALUE s = rb_str_tmp_new(len);
+    *store = s;
+    return RSTRING_PTR(s);
+}
+
+void
+rb_free_tmp_buffer(volatile VALUE *store)
+{
+    VALUE s = *store;
+    *store = 0;
+    if (s) rb_str_clear(s);
+}
+
 void
 rb_str_free(VALUE str)
 {