python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Python/mysnprintf.c

@@ -0,0 +1,104 @@
+#include "Python.h"
+
+/* snprintf() wrappers.  If the platform has vsnprintf, we use it, else we
+   emulate it in a half-hearted way.  Even if the platform has it, we wrap
+   it because platforms differ in what vsnprintf does in case the buffer
+   is too small:  C99 behavior is to return the number of characters that
+   would have been written had the buffer not been too small, and to set
+   the last byte of the buffer to \0.  At least MS _vsnprintf returns a
+   negative value instead, and fills the entire buffer with non-\0 data.
+
+   The wrappers ensure that str[size-1] is always \0 upon return.
+
+   PyOS_snprintf and PyOS_vsnprintf never write more than size bytes
+   (including the trailing '\0') into str.
+
+   If the platform doesn't have vsnprintf, and the buffer size needed to
+   avoid truncation exceeds size by more than 512, Python aborts with a
+   Py_FatalError.
+
+   Return value (rv):
+
+    When 0 <= rv < size, the output conversion was unexceptional, and
+    rv characters were written to str (excluding a trailing \0 byte at
+    str[rv]).
+
+    When rv >= size, output conversion was truncated, and a buffer of
+    size rv+1 would have been needed to avoid truncation.  str[size-1]
+    is \0 in this case.
+
+    When rv < 0, "something bad happened".  str[size-1] is \0 in this
+    case too, but the rest of str is unreliable.  It could be that
+    an error in format codes was detected by libc, or on platforms
+    with a non-C99 vsnprintf simply that the buffer wasn't big enough
+    to avoid truncation, or on platforms without any vsnprintf that
+    PyMem_Malloc couldn't obtain space for a temp buffer.
+
+   CAUTION:  Unlike C99, str != NULL and size > 0 are required.
+*/
+
+int
+PyOS_snprintf(char *str, size_t size, const  char  *format, ...)
+{
+    int rc;
+    va_list va;
+
+    va_start(va, format);
+    rc = PyOS_vsnprintf(str, size, format, va);
+    va_end(va);
+    return rc;
+}
+
+int
+PyOS_vsnprintf(char *str, size_t size, const char  *format, va_list va)
+{
+    int len;  /* # bytes written, excluding \0 */
+#ifdef HAVE_SNPRINTF
+#define _PyOS_vsnprintf_EXTRA_SPACE 1
+#else
+#define _PyOS_vsnprintf_EXTRA_SPACE 512
+    char *buffer;
+#endif
+    assert(str != NULL);
+    assert(size > 0);
+    assert(format != NULL);
+    /* We take a size_t as input but return an int.  Sanity check
+     * our input so that it won't cause an overflow in the
+     * vsnprintf return value or the buffer malloc size.  */
+    if (size > INT_MAX - _PyOS_vsnprintf_EXTRA_SPACE) {
+        len = -666;
+        goto Done;
+    }
+
+#ifdef HAVE_SNPRINTF
+    len = vsnprintf(str, size, format, va);
+#else
+    /* Emulate it. */
+    buffer = PyMem_MALLOC(size + _PyOS_vsnprintf_EXTRA_SPACE);
+    if (buffer == NULL) {
+        len = -666;
+        goto Done;
+    }
+
+    len = vsprintf(buffer, format, va);
+    if (len < 0)
+        /* ignore the error */;
+
+    else if ((size_t)len >= size + _PyOS_vsnprintf_EXTRA_SPACE)
+        Py_FatalError("Buffer overflow in PyOS_snprintf/PyOS_vsnprintf");
+
+    else {
+        const size_t to_copy = (size_t)len < size ?
+                                (size_t)len : size - 1;
+        assert(to_copy < size);
+        memcpy(str, buffer, to_copy);
+        str[to_copy] = '\0';
+    }
+    PyMem_FREE(buffer);
+#endif
+Done:
+    if (size > 0)
+        str[size-1] = '\0';
+    return len;
+#undef _PyOS_vsnprintf_EXTRA_SPACE
+}