Split `MRB_BINARY_FORMAT` to major and minor.

The minor versions should be upper compatible. So mere opcode, section
addition can be done without breaking compiled binary.

3 files changed, 16 insertions, 4 deletions

diff --git a/include/mruby/dump.h b/include/mruby/dump.h
index bad27fdf5..b8161e055 100644
--- a/include/mruby/dump.h
+++ b/include/mruby/dump.h
@@ -49,7 +49,12 @@ MRB_API mrb_irep *mrb_read_irep_buf(mrb_state*, const void*, size_t);
 
 /* Rite Binary File header */
 #define RITE_BINARY_IDENT              "RITE"
-#define RITE_BINARY_FORMAT_VER         "0007"
+/* Binary Format Version Major:Minor */
+/*   Major: Incompatible to prior versions */
+/*   Minor: Upper-compatible to prior versions */
+#define RITE_BINARY_MAJOR_VER          "01"
+#define RITE_BINARY_MINOR_VER          "00"
+#define RITE_BINARY_FORMAT_VER         RITE_BINARY_MAJOR_VER RITE_BINARY_MINOR_VER
 #define RITE_COMPILER_NAME             "MATZ"
 #define RITE_COMPILER_VERSION          "0000"
 
@@ -66,7 +71,8 @@ MRB_API mrb_irep *mrb_read_irep_buf(mrb_state*, const void*, size_t);
 /* binary header */
 struct rite_binary_header {
   uint8_t binary_ident[4];    /* Binary Identifier */
-  uint8_t binary_version[4];  /* Binary Format Version */
+  uint8_t major_version[2];   /* Binary Format Major Version */
+  uint8_t minor_version[2];   /* Binary Format Minor Version */
   uint8_t binary_crc[2];      /* Binary CRC */
   uint8_t binary_size[4];     /* Binary Size */
   uint8_t compiler_name[4];   /* Compiler name */
diff --git a/src/dump.c b/src/dump.c
index c0f0ca0a8..8cd69cd29 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -726,7 +726,8 @@ write_rite_binary_header(mrb_state *mrb, size_t binary_size, uint8_t *bin, uint8
   uint32_t offset;
 
   memcpy(header->binary_ident, RITE_BINARY_IDENT, sizeof(header->binary_ident));
-  memcpy(header->binary_version, RITE_BINARY_FORMAT_VER, sizeof(header->binary_version));
+  memcpy(header->major_version, RITE_BINARY_MAJOR_VER, sizeof(header->major_version));
+  memcpy(header->minor_version, RITE_BINARY_MAJOR_VER, sizeof(header->minor_version));
   memcpy(header->compiler_name, RITE_COMPILER_NAME, sizeof(header->compiler_name));
   memcpy(header->compiler_version, RITE_COMPILER_VERSION, sizeof(header->compiler_version));
   mrb_assert(binary_size <= UINT32_MAX);
diff --git a/src/load.c b/src/load.c
index 0dc6e93fe..2002af3ab 100644
--- a/src/load.c
+++ b/src/load.c
@@ -525,7 +525,12 @@ read_binary_header(const uint8_t *bin, size_t bufsize, size_t *bin_size, uint16_
     return MRB_DUMP_INVALID_FILE_HEADER;
   }
 
-  if (memcmp(header->binary_version, RITE_BINARY_FORMAT_VER, sizeof(header->binary_version)) != 0) {
+  /* if major version is different, they are incompatible */
+  if (memcmp(header->major_version, RITE_BINARY_MAJOR_VER, sizeof(header->major_version)) != 0) {
+    return MRB_DUMP_INVALID_FILE_HEADER;
+  }
+  /* if minor version is different, we can accept the older version */
+  if (memcmp(header->minor_version, RITE_BINARY_MINOR_VER, sizeof(header->minor_version)) <= 0) {
     return MRB_DUMP_INVALID_FILE_HEADER;
   }