Issue 4474: On platforms with sizeof(wchar_t) == 4 and

sizeof(Py_UNICODE) == 2, PyUnicode_FromWideChar now converts
each character outside the BMP to the appropriate surrogate pair.

Thanks Victor Stinner for the patch.

(backport of r70452 from py3k to trunk)

1 files changed, 58 insertions, 0 deletions

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 03bccaf..079eebf 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -529,6 +529,60 @@ PyObject *PyUnicode_FromString(const char *u)
 
 #ifdef HAVE_WCHAR_H
 
+#if (Py_UNICODE_SIZE == 2) && defined(SIZEOF_WCHAR_T) && (SIZEOF_WCHAR_T == 4)
+# define CONVERT_WCHAR_TO_SURROGATES
+#endif
+
+#ifdef CONVERT_WCHAR_TO_SURROGATES
+
+/* Here sizeof(wchar_t) is 4 but Py_UNICODE_SIZE == 2, so we need
+   to convert from UTF32 to UTF16. */
+
+PyObject *PyUnicode_FromWideChar(register const wchar_t *w,
+                                 Py_ssize_t size)
+{
+    PyUnicodeObject *unicode;
+    register Py_ssize_t i;
+    Py_ssize_t alloc;
+    const wchar_t *orig_w;
+
+    if (w == NULL) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
+
+    alloc = size;
+    orig_w = w;
+    for (i = size; i > 0; i--) {
+        if (*w > 0xFFFF)
+            alloc++;
+        w++;
+    }
+    w = orig_w;
+    unicode = _PyUnicode_New(alloc);
+    if (!unicode)
+        return NULL;
+
+    /* Copy the wchar_t data into the new object */
+    {
+        register Py_UNICODE *u;
+        u = PyUnicode_AS_UNICODE(unicode);
+        for (i = size; i > 0; i--) {
+            if (*w > 0xFFFF) {
+                wchar_t ordinal = *w++;
+                ordinal -= 0x10000;
+                *u++ = 0xD800 | (ordinal >> 10);
+                *u++ = 0xDC00 | (ordinal & 0x3FF);
+            }
+            else
+                *u++ = *w++;
+        }
+    }
+    return (PyObject *)unicode;
+}
+
+#else
+
 PyObject *PyUnicode_FromWideChar(register const wchar_t *w,
                                  Py_ssize_t size)
 {
@@ -559,6 +613,10 @@ PyObject *PyUnicode_FromWideChar(register const wchar_t *w,
     return (PyObject *)unicode;
 }
 
+#endif /* CONVERT_WCHAR_TO_SURROGATES */
+
+#undef CONVERT_WCHAR_TO_SURROGATES
+
 static void
 makefmt(char *fmt, int longflag, int size_tflag, int zeropad, int width, int precision, char c)
 {