Make test_zipfile pass.

The zipfile module now does all I/O in binary mode using bytes.
(Maybe we should support wrapping a TextIOWrapper around it
when text mode reading is requested?)
Even the password is a bytes array now.
Had to fix py_compile.py to use bytes while I was at it.
The _struct needed a patch to support bytes, str8 and str
for the 's' and 'p' formats.

Lib/py_compile.py

@@ -72,10 +72,10 @@ else:
 
 def wr_long(f, x):
     """Internal; write a 32-bit int to a file in little-endian order."""
-    f.write(chr( x        & 0xff))
-    f.write(chr((x >> 8)  & 0xff))
-    f.write(chr((x >> 16) & 0xff))
-    f.write(chr((x >> 24) & 0xff))
+    f.write(bytes([x        & 0xff,
+                   (x >> 8)  & 0xff,
+                   (x >> 16) & 0xff,
+                   (x >> 24) & 0xff]))
 
 def compile(file, cfile=None, dfile=None, doraise=False):
     """Byte-compile one Python source file to Python bytecode.
@@ -133,7 +133,7 @@ def compile(file, cfile=None, dfile=None, doraise=False):
     if cfile is None:
         cfile = file + (__debug__ and 'c' or 'o')
     fc = open(cfile, 'wb')
-    fc.write('\0\0\0\0')
+    fc.write(b'\0\0\0\0')
     wr_long(fc, timestamp)
     marshal.dump(codeobject, fc)
     fc.flush()

Modules/_struct.c

@@ -1635,27 +1635,57 @@ s_pack_internal(PyStructObject *soself, PyObject *args, int offset, char* buf)
 		const formatdef *e = code->fmtdef;
 		char *res = buf + code->offset;
 		if (e->format == 's') {
-			if (!PyString_Check(v)) {
+			int isstring;
+			void *p;
+			if (PyUnicode_Check(v)) {
+				v = _PyUnicode_AsDefaultEncodedString(v, NULL);
+				if (v == NULL)
+					return -1;
+			}
+			isstring = PyString_Check(v);
+			if (!isstring && !PyBytes_Check(v)) {
 				PyErr_SetString(StructError,
 						"argument for 's' must be a string");
 				return -1;
 			}
-			n = PyString_GET_SIZE(v);
+			if (isstring) {
+				n = PyString_GET_SIZE(v);
+				p = PyString_AS_STRING(v);
+			}
+			else {
+				n = PyBytes_GET_SIZE(v);
+				p = PyBytes_AS_STRING(v);
+			}
 			if (n > code->size)
 				n = code->size;
 			if (n > 0)
-				memcpy(res, PyString_AS_STRING(v), n);
+				memcpy(res, p, n);
 		} else if (e->format == 'p') {
-			if (!PyString_Check(v)) {
+			int isstring;
+			void *p;
+			if (PyUnicode_Check(v)) {
+				v = _PyUnicode_AsDefaultEncodedString(v, NULL);
+				if (v == NULL)
+					return -1;
+			}
+			isstring = PyString_Check(v);
+			if (!isstring && !PyBytes_Check(v)) {
 				PyErr_SetString(StructError,
 						"argument for 'p' must be a string");
 				return -1;
 			}
-			n = PyString_GET_SIZE(v);
+			if (isstring) {
+				n = PyString_GET_SIZE(v);
+				p = PyString_AS_STRING(v);
+			}
+			else {
+				n = PyBytes_GET_SIZE(v);
+				p = PyBytes_AS_STRING(v);
+			}
 			if (n > (code->size - 1))
 				n = code->size - 1;
 			if (n > 0)
-				memcpy(res + 1, PyString_AS_STRING(v), n);
+				memcpy(res + 1, p, n);
 			if (n > 255)
 				n = 255;
 			*res = Py_SAFE_DOWNCAST(n, Py_ssize_t, unsigned char);