From f7f16a29766c4df15d204015ce6d7f10df0a8833 Mon Sep 17 00:00:00 2001
From: Pascal Massimino <pascal.massimino@gmail.com>
Date: Wed, 18 Jul 2012 11:53:25 -0700
Subject: [PATCH] add ABI compatibility check

minor revision shouldn't matter, we only check major revision number.
Bumped all version numbers so that incompatibility starts *now*

Change-Id: Id06c20f03039845ae4cfb3fd121807b931d67ee4
---
 src/dec/vp8.c     | 17 +++++++++--------
 src/dec/webp.c    |  4 ++--
 src/mux/demux.c   |  2 +-
 src/mux/muxedit.c | 13 ++++++++-----
 src/mux/muxread.c |  4 +++-
 src/webp/decode.h |  2 +-
 src/webp/encode.h |  2 +-
 src/webp/mux.h    |  4 ++--
 src/webp/types.h  |  3 +++
 9 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/src/dec/vp8.c b/src/dec/vp8.c
index 904cc70b..5db7d546 100644
--- a/src/dec/vp8.c
+++ b/src/dec/vp8.c
@@ -35,9 +35,10 @@ static void SetOk(VP8Decoder* const dec) {
 }
 
 int VP8InitIoInternal(VP8Io* const io, int version) {
-  if (version != WEBP_DECODER_ABI_VERSION)
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
     return 0;  // mismatch error
-  if (io) {
+  }
+  if (io != NULL) {
     memset(io, 0, sizeof(*io));
   }
   return 1;
@@ -45,7 +46,7 @@ int VP8InitIoInternal(VP8Io* const io, int version) {
 
 VP8Decoder* VP8New(void) {
   VP8Decoder* const dec = (VP8Decoder*)calloc(1, sizeof(VP8Decoder));
-  if (dec) {
+  if (dec != NULL) {
     SetOk(dec);
     WebPWorkerInit(&dec->worker_);
     dec->ready_ = 0;
@@ -60,13 +61,13 @@ VP8StatusCode VP8Status(VP8Decoder* const dec) {
 }
 
 const char* VP8StatusMessage(VP8Decoder* const dec) {
-  if (!dec) return "no object";
+  if (dec == NULL) return "no object";
   if (!dec->error_msg_) return "OK";
   return dec->error_msg_;
 }
 
 void VP8Delete(VP8Decoder* const dec) {
-  if (dec) {
+  if (dec != NULL) {
     VP8Clear(dec);
     free(dec);
   }
@@ -136,7 +137,7 @@ int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
 // Header parsing
 
 static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
-  assert(hdr);
+  assert(hdr != NULL);
   hdr->use_segment_ = 0;
   hdr->update_map_ = 0;
   hdr->absolute_delta_ = 1;
@@ -147,8 +148,8 @@ static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
 // Paragraph 9.3
 static int ParseSegmentHeader(VP8BitReader* br,
                               VP8SegmentHeader* hdr, VP8Proba* proba) {
-  assert(br);
-  assert(hdr);
+  assert(br != NULL);
+  assert(hdr != NULL);
   hdr->use_segment_ = VP8Get(br);
   if (hdr->use_segment_) {
     hdr->update_map_ = VP8Get(br);
diff --git a/src/dec/webp.c b/src/dec/webp.c
index 21744e91..edd348cb 100644
--- a/src/dec/webp.c
+++ b/src/dec/webp.c
@@ -651,7 +651,7 @@ int WebPGetInfo(const uint8_t* data, size_t data_size,
 
 int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
                                   int version) {
-  if (version != WEBP_DECODER_ABI_VERSION) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
     return 0;   // version mismatch
   }
   if (config == NULL) {
@@ -667,7 +667,7 @@ VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
                                       WebPBitstreamFeatures* features,
                                       int version) {
   VP8StatusCode status;
-  if (version != WEBP_DECODER_ABI_VERSION) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
     return VP8_STATUS_INVALID_PARAM;   // version mismatch
   }
   if (features == NULL) {
diff --git a/src/mux/demux.c b/src/mux/demux.c
index 2ce553d6..4519f7d5 100644
--- a/src/mux/demux.c
+++ b/src/mux/demux.c
@@ -631,7 +631,7 @@ WebPDemuxer* WebPDemuxInternal(const WebPData* data, int allow_partial,
   MemBuffer mem;
   WebPDemuxer* dmux;
 
-  if (version != WEBP_DEMUX_ABI_VERSION) return NULL;
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DEMUX_ABI_VERSION)) return NULL;
   if (data == NULL || data->bytes_ == NULL || data->size_ == 0) return NULL;
 
   if (!InitMemBuffer(&mem, data->bytes_, data->size_)) return NULL;
diff --git a/src/mux/muxedit.c b/src/mux/muxedit.c
index 33dab625..59e08745 100644
--- a/src/mux/muxedit.c
+++ b/src/mux/muxedit.c
@@ -35,11 +35,14 @@ static void MuxInit(WebPMux* const mux) {
 }
 
 WebPMux* WebPNewInternal(int version) {
-  WebPMux* const mux = (version == WEBP_MUX_ABI_VERSION) ?
-                       (WebPMux*)malloc(sizeof(WebPMux)) : NULL;
-  // If mux is NULL MuxInit is a noop.
-  MuxInit(mux);
-  return mux;
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
+    return NULL;
+  } else {
+    WebPMux* const mux = (WebPMux*)malloc(sizeof(WebPMux));
+    // If mux is NULL MuxInit is a noop.
+    MuxInit(mux);
+    return mux;
+  }
 }
 
 static void DeleteAllChunks(WebPChunk** const chunk_list) {
diff --git a/src/mux/muxread.c b/src/mux/muxread.c
index 8d52cc99..351d9cd9 100644
--- a/src/mux/muxread.c
+++ b/src/mux/muxread.c
@@ -89,7 +89,9 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
   ChunkInit(&chunk);
 
   // Sanity checks.
-  if (version != WEBP_MUX_ABI_VERSION) return NULL;  // version mismatch
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
+    return NULL;  // version mismatch
+  }
   if (bitstream == NULL) return NULL;
 
   data = bitstream->bytes_;
diff --git a/src/webp/decode.h b/src/webp/decode.h
index c61849e7..74f1ee20 100644
--- a/src/webp/decode.h
+++ b/src/webp/decode.h
@@ -18,7 +18,7 @@
 extern "C" {
 #endif
 
-#define WEBP_DECODER_ABI_VERSION 0x0003
+#define WEBP_DECODER_ABI_VERSION 0x0100    // MAJOR(8b) + MINOR(8b)
 
 // Return the decoder's version number, packed in hexadecimal using 8bits for
 // each of major/minor/revision. E.g: v2.5.7 is 0x020507.
diff --git a/src/webp/encode.h b/src/webp/encode.h
index 1568ea65..4e34d467 100644
--- a/src/webp/encode.h
+++ b/src/webp/encode.h
@@ -18,7 +18,7 @@
 extern "C" {
 #endif
 
-#define WEBP_ENCODER_ABI_VERSION 0x0003
+#define WEBP_ENCODER_ABI_VERSION 0x0100    // MAJOR(8b) + MINOR(8b)
 
 // Return the encoder's version number, packed in hexadecimal using 8bits for
 // each of major/minor/revision. E.g: v2.5.7 is 0x020507.
diff --git a/src/webp/mux.h b/src/webp/mux.h
index 5c023077..ec132b35 100644
--- a/src/webp/mux.h
+++ b/src/webp/mux.h
@@ -51,7 +51,7 @@
 extern "C" {
 #endif
 
-#define WEBP_MUX_ABI_VERSION 0x0000
+#define WEBP_MUX_ABI_VERSION 0x0100        // MAJOR(8b) + MINOR(8b)
 
 // Error codes
 typedef enum {
@@ -461,7 +461,7 @@ WEBP_EXTERN(WebPMuxError) WebPMuxAssemble(WebPMux* mux,
 // Demux API.
 // Enables extraction of image and extended format data from WebP files.
 
-#define WEBP_DEMUX_ABI_VERSION 0x0000
+#define WEBP_DEMUX_ABI_VERSION 0x0100    // MAJOR(8b) + MINOR(8b)
 
 typedef struct WebPDemuxer WebPDemuxer;
 
diff --git a/src/webp/types.h b/src/webp/types.h
index 25c0e708..3e27190b 100644
--- a/src/webp/types.h
+++ b/src/webp/types.h
@@ -39,4 +39,7 @@ typedef long long int int64_t;
 #define WEBP_EXTERN(type) extern type
 #endif  /* WEBP_EXTERN */
 
+// Macro to check ABI compatibility (same major revision number)
+#define WEBP_ABI_IS_INCOMPATIBLE(a, b) (((a) >> 8) != ((b) >> 8))
+
 #endif  /* WEBP_WEBP_TYPES_H_ */