Since the MAGIC number scheme is going to break on January 1st, document
what it is more carefully and point out some of the subtleties.
diff --git a/Python/import.c b/Python/import.c
index 9f668bf..0b4cd0f 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -30,10 +30,22 @@
/* Change for each incompatible change */
/* The value of CR and LF is incorporated so if you ever read or write
a .pyc file in text mode the magic number will be wrong; also, the
- Apple MPW compiler swaps their values, botching string constants */
+ Apple MPW compiler swaps their values, botching string constants.
+ XXX That probably isn't important anymore.
+*/
/* XXX Perhaps the magic number should be frozen and a version field
added to the .pyc file header? */
-/* New way to come up with the magic number: (YEAR-1995), MONTH, DAY */
+/* New way to come up with the low 16 bits of the magic number:
+ (YEAR-1995) * 10000 + MONTH * 100 + DAY
+ where MONTH and DAY are 1-based.
+ XXX Whatever the "old way" may have been isn't documented.
+ XXX This scheme breaks in 2002, as (2002-1995)*10000 = 70000 doesn't
+ fit in 16 bits.
+ XXX Later, sometimes 1 gets added to MAGIC in order to record that
+ the Unicode -U option is in use. IMO (Tim's), that's a Bad Idea
+ (quite apart from that the -U option doesn't work so isn't used
+ anyway).
+*/
#define MAGIC (60717 | ((long)'\r'<<16) | ((long)'\n'<<24))
/* Magic word as global; note that _PyImport_Init() can change the
@@ -63,7 +75,7 @@
{".py", "r", PY_SOURCE},
#ifdef MS_WIN32
{".pyw", "r", PY_SOURCE},
-#endif
+#endif
{".pyc", "rb", PY_COMPILED},
{0, 0}
};
@@ -739,7 +751,7 @@
return NULL;
}
#endif
- cpathname = make_compiled_pathname(pathname, buf,
+ cpathname = make_compiled_pathname(pathname, buf,
(size_t)MAXPATHLEN + 1);
if (cpathname != NULL &&
(fpc = check_compiled_module(pathname, mtime, cpathname))) {