Fixed formatting in docs
[apps/agl-service-can-low-level.git] / pb_decode.c
index 0e55cbf..50a11c4 100644 (file)
@@ -23,7 +23,8 @@ typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void
 static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
     &pb_dec_varint,
     &pb_dec_svarint,
-    &pb_dec_fixed,
+    &pb_dec_fixed32,
+    &pb_dec_fixed64,
     
     &pb_dec_bytes,
     &pb_dec_string,
@@ -74,7 +75,7 @@ static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
 {
     uint64_t temp;
     bool status = pb_decode_varint(stream, &temp);
-    *dest = temp;
+    *dest = (uint32_t)temp;
     return status;
 }
 
@@ -116,12 +117,33 @@ bool checkreturn pb_skip_string(pb_istream_t *stream)
     return pb_read(stream, NULL, length);
 }
 
-/* Currently the wire type related stuff is kept hidden from
- * callbacks. They shouldn't need it. It's better for performance
- * to just assume the correct type and fail safely on corrupt message.
- */
+bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, int *tag, bool *eof)
+{
+    uint32_t temp;
+    *eof = false;
+    *wire_type = 0;
+    *tag = 0;
+    
+    if (!pb_decode_varint32(stream, &temp))
+    {
+        if (stream->bytes_left == 0)
+            *eof = true;
+
+        return false;
+    }
+    
+    if (temp == 0)
+    {
+        *eof = true; /* Special feature: allow 0-terminated messages. */
+        return false;
+    }
+    
+    *tag = temp >> 3;
+    *wire_type = (pb_wire_type_t)(temp & 7);
+    return true;
+}
 
-static bool checkreturn skip(pb_istream_t *stream, int wire_type)
+bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
 {
     switch (wire_type)
     {
@@ -163,7 +185,10 @@ static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire
     }
 }
 
-/* Decode string length from stream and return a substream with limited length */
+/* Decode string length from stream and return a substream with limited length.
+ * Before disposing the substream, remember to copy the substream->state back
+ * to stream->state.
+ */
 static bool checkreturn make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
 {
     uint32_t size;
@@ -193,7 +218,7 @@ static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, v
 {
     iter->start = iter->current = fields;
     iter->field_index = 0;
-    iter->pData = dest_struct + iter->current->data_offset;
+    iter->pData = (char*)dest_struct + iter->current->data_offset;
     iter->pSize = (char*)iter->pData + iter->current->size_offset;
     iter->dest_struct = dest_struct;
 }
@@ -239,7 +264,7 @@ static bool checkreturn pb_field_find(pb_field_iterator_t *iter, int tag)
  * Decode a single field *
  *************************/
 
-static bool checkreturn decode_field(pb_istream_t *stream, int wire_type, pb_field_iterator_t *iter)
+static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
 {
     pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
     
@@ -288,7 +313,7 @@ static bool checkreturn decode_field(pb_istream_t *stream, int wire_type, pb_fie
             pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
             
             if (pCallback->funcs.decode == NULL)
-                return skip(stream, wire_type);
+                return pb_skip_field(stream, wire_type);
             
             if (wire_type == PB_WT_STRING)
             {
@@ -302,6 +327,8 @@ static bool checkreturn decode_field(pb_istream_t *stream, int wire_type, pb_fie
                     if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
                         return false;
                 }
+                
+                stream->state = substream.state;
                 return true;
             }
             else
@@ -327,69 +354,81 @@ static bool checkreturn decode_field(pb_istream_t *stream, int wire_type, pb_fie
     }
 }
 
-/*********************
- * Decode all fields *
- *********************/
-
-bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
+/* Initialize message fields to default values, recursively */
+static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
 {
-    uint32_t fields_seen = 0; /* Used to check for required fields */
     pb_field_iterator_t iter;
-    int i;
-    
-    if (fields[0].tag == 0)
-    {
-        /* No fields -> nothing to do */
-        return pb_read(stream, NULL, stream->bytes_left);
-    }
-    
     pb_field_init(&iter, fields, dest_struct);
     
     /* Initialize size/has fields and apply default values */
     do
     {
+        if (iter.current->tag == 0)
+            continue;
+        
+        /* Initialize the size field for optional/repeated fields to 0. */
         if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
         {
             *(bool*)iter.pSize = false;
-            
-            /* Initialize to default value */
-            if (iter.current->ptr != NULL)
-                memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
-            else
-                memset(iter.pData, 0, iter.current->data_size);
         }
         else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
         {
             *(size_t*)iter.pSize = 0;
+            continue; /* Array is empty, no need to initialize contents */
         }
-        else if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED)
+        
+        /* Initialize field contents to default value */
+        if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
+        {
+            continue; /* Don't overwrite callback */
+        }
+        else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
+        {
+            pb_message_set_to_defaults(iter.current->ptr, iter.pData);
+        }
+        else if (iter.current->ptr != NULL)
+        {
+            memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
+        }
+        else
         {
             memset(iter.pData, 0, iter.current->data_size);
         }
     } while (pb_field_next(&iter));
+}
+
+/*********************
+ * Decode all fields *
+ *********************/
+
+bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
+{
+    uint32_t fields_seen = 0; /* Used to check for required fields */
+    pb_field_iterator_t iter;
+    int i;
+    
+    pb_message_set_to_defaults(fields, dest_struct);
+    
+    pb_field_init(&iter, fields, dest_struct);
     
     while (stream->bytes_left)
     {
-        uint32_t temp;
-        int tag, wire_type;
-        if (!pb_decode_varint32(stream, &temp))
+        int tag;
+        pb_wire_type_t wire_type;
+        bool eof;
+        
+        if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
         {
-            if (stream->bytes_left == 0)
-                break; /* It was EOF */
+            if (eof)
+                break;
             else
-                return false; /* It was error */
+                return false;
         }
         
-        if (temp == 0)
-            break; /* Special feature: allow 0-terminated messages. */
-        
-        tag = temp >> 3;
-        wire_type = temp & 7;
-        
         if (!pb_field_find(&iter, tag))
         {
             /* No match found, skip data */
-            if (!skip(stream, wire_type))
+            if (!pb_skip_field(stream, wire_type))
                 return false;
             continue;
         }
@@ -425,6 +464,7 @@ static void endian_copy(void *dest, void *src, size_t destsize, size_t srcsize)
 #ifdef __BIG_ENDIAN__
     memcpy(dest, (char*)src + (srcsize - destsize), destsize);
 #else
+    UNUSED(srcsize);
     memcpy(dest, src, destsize);
 #endif
 }
@@ -446,17 +486,45 @@ bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, v
     return status;
 }
 
-bool checkreturn pb_dec_fixed(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
+{
+#ifdef __BIG_ENDIAN__
+    uint8_t bytes[4] = {0};
+    bool status = pb_read(stream, bytes, 4);
+    if (status) {
+        uint8_t *d = (uint8_t*)dest;
+        d[0] = bytes[3];
+        d[1] = bytes[2];
+        d[2] = bytes[1];
+        d[3] = bytes[0];
+    }
+    return status;
+#else
+    UNUSED(field);
+    return pb_read(stream, (uint8_t*)dest, 4);
+#endif
+}
+
+bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
 #ifdef __BIG_ENDIAN__
     uint8_t bytes[8] = {0};
-    bool status = pb_read(stream, bytes, field->data_size);
-    uint8_t bebytes[8] = {bytes[7], bytes[6], bytes[5], bytes[4], 
-                          bytes[3], bytes[2], bytes[1], bytes[0]};
-    endian_copy(dest, lebytes, field->data_size, 8);
+    bool status = pb_read(stream, bytes, 8);
+    if (status) {
+        uint8_t *d = (uint8_t*)dest;
+        d[0] = bytes[7];
+        d[1] = bytes[6];
+        d[2] = bytes[5]; 
+        d[3] = bytes[4];
+        d[4] = bytes[3];
+        d[5] = bytes[2];
+        d[6] = bytes[1];
+        d[7] = bytes[0];
+    }
     return status;
 #else
-    return pb_read(stream, (uint8_t*)dest, field->data_size);
+    UNUSED(field);
+    return pb_read(stream, (uint8_t*)dest, 8);
 #endif
 }
 
@@ -469,7 +537,8 @@ bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, voi
         return false;
     x->size = temp;
     
-    if (x->size > field->data_size)
+    /* Check length, noting the space taken by the size_t header. */
+    if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
         return false;
     
     return pb_read(stream, x->bytes, x->size);
@@ -482,7 +551,8 @@ bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, vo
     if (!pb_decode_varint32(stream, &size))
         return false;
     
-    if (size > field->data_size - 1)
+    /* Check length, noting the null terminator */
+    if (size + 1 > field->data_size)
         return false;
     
     status = pb_read(stream, (uint8_t*)dest, size);
@@ -492,6 +562,7 @@ bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, vo
 
 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
+    bool status;
     pb_istream_t substream;
     
     if (!make_string_substream(stream, &substream))
@@ -500,5 +571,7 @@ bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field
     if (field->ptr == NULL)
         return false;
     
-    return pb_decode(&substream, (pb_field_t*)field->ptr, dest);
+    status = pb_decode(&substream, (pb_field_t*)field->ptr, dest);
+    stream->state = substream.state;
+    return status;
 }