py/modstruct: Fix struct.pack_into with unaligned offset of native type.

dpgeorge · dpgeorge · commit 24c3e9b283da · 2019-09-02T13:14:16.000+10:00
Following the same fix for unpack.
diff --git a/extmod/moductypes.c b/extmod/moductypes.c
@@ -305,7 +305,7 @@ static inline mp_obj_t get_unaligned(uint val_type, byte *p, int big_endian) {
 static inline void set_unaligned(uint val_type, byte *p, int big_endian, mp_obj_t val) {
     char struct_type = big_endian ? '>' : '<';
     static const char type2char[16] = "BbHhIiQq------fd";
-    mp_binary_set_val(struct_type, type2char[val_type], val, &p);
+    mp_binary_set_val(struct_type, type2char[val_type], val, p, &p);
 }
 
 static inline mp_uint_t get_aligned_basic(uint val_type, void *p) {
diff --git a/py/binary.c b/py/binary.c
@@ -250,14 +250,14 @@ void mp_binary_set_int(mp_uint_t val_sz, bool big_endian, byte *dest, mp_uint_t
     }
 }
 
-void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte **ptr) {
+void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte *p_base, byte **ptr) {
     byte *p = *ptr;
     mp_uint_t align;
 
     size_t size = mp_binary_get_size(struct_type, val_type, &align);
     if (struct_type == '@') {
-        // Make pointer aligned
-        p = (byte*)MP_ALIGN(p, (size_t)align);
+        // Align p relative to p_base
+        p = p_base + (uintptr_t)MP_ALIGN(p - p_base, (size_t)align);
         if (MP_ENDIANNESS_LITTLE) {
             struct_type = '<';
         } else {
diff --git a/py/binary.h b/py/binary.h
@@ -39,7 +39,7 @@ mp_obj_t mp_binary_get_val_array(char typecode, void *p, mp_uint_t index);
 void mp_binary_set_val_array(char typecode, void *p, mp_uint_t index, mp_obj_t val_in);
 void mp_binary_set_val_array_from_int(char typecode, void *p, mp_uint_t index, mp_int_t val);
 mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte *p_base, byte **ptr);
-void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte **ptr);
+void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte *p_base, byte **ptr);
 long long mp_binary_get_int(mp_uint_t size, bool is_signed, bool big_endian, const byte *src);
 void mp_binary_set_int(mp_uint_t val_sz, bool big_endian, byte *dest, mp_uint_t val);
 
diff --git a/py/modstruct.c b/py/modstruct.c
@@ -180,6 +180,7 @@ STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, c
     const char *fmt = mp_obj_str_get_str(fmt_in);
     char fmt_type = get_fmt_type(&fmt);
 
+    byte *p_base = p;
     size_t i;
     for (i = 0; i < n_args;) {
         mp_uint_t cnt = 1;
@@ -204,7 +205,7 @@ STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, c
         } else {
             // If we run out of args then we just finish; CPython would raise struct.error
             while (cnt-- && i < n_args) {
-                mp_binary_set_val(fmt_type, *fmt, args[i++], &p);
+                mp_binary_set_val(fmt_type, *fmt, args[i++], p_base, &p);
             }
         }
         fmt++;
diff --git a/tests/basics/struct_endian.py b/tests/basics/struct_endian.py
@@ -15,3 +15,10 @@
 print(struct.unpack_from('i', buf, 1))
 print(struct.unpack_from('@i', buf, 1))
 print(struct.unpack_from('@ii', buf, 1))
+
+# pack_into with unaligned native type
+buf = bytearray(b'>----<<<<<<<')
+struct.pack_into('i', buf, 1, 0x30313233)
+print(buf)
+struct.pack_into('@ii', buf, 3, 0x34353637, 0x41424344)
+print(buf)

Original file line number	Diff line number	Diff line change
`@@ -305,7 +305,7 @@ static inline mp_obj_t get_unaligned(uint val_type, byte *p, int big_endian) {`
`305`	`305`	`static inline void set_unaligned(uint val_type, byte *p, int big_endian, mp_obj_t val) {`
`306`	`306`	`char struct_type = big_endian ? '>' : '<';`
`307`	`307`	`static const char type2char[16] = "BbHhIiQq------fd";`
`308`		`- mp_binary_set_val(struct_type, type2char[val_type], val, &p);`
	`308`	`+ mp_binary_set_val(struct_type, type2char[val_type], val, p, &p);`
`309`	`309`	`}`
`310`	`310`
`311`	`311`	`static inline mp_uint_t get_aligned_basic(uint val_type, void *p) {`