X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_decode.c;h=bc6df7b978a138cd8026ba30fb5338bb5d71df63;hb=5442e690f65fd09e7a44437da02fb7e14af6fe8f;hp=28856d37896f36ee9c34351247a4d368abbdfff8;hpb=ead3b734d8f96837ea6564b694df5618134e3cf8;p=apps%2Fagl-service-can-low-level.git

diff --git a/pb_decode.c b/pb_decode.c
index 28856d37..bc6df7b9 100644
--- a/pb_decode.c
+++ b/pb_decode.c
@@ -3,60 +3,100 @@
  * 2011 Petteri Aimonen <jpa@kapsi.fi>
  */
 
+/* The warn_unused_result attribute appeared first in gcc-3.4.0 */
+#if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
+    #define checkreturn
+#else
+    /* Verify that we remember to check all return values for proper error propagation */
+    #define checkreturn __attribute__((warn_unused_result))
+#endif
+
+#define NANOPB_INTERNALS
 #include "pb.h"
 #include "pb_decode.h"
 #include <string.h>
 
-const pb_decoder_t PB_DECODERS[16] = {
-    (pb_decoder_t)&pb_dec_uint32,
-    (pb_decoder_t)&pb_dec_sint32,
-    (pb_decoder_t)&pb_dec_fixed32,
-    (pb_decoder_t)&pb_dec_uint64,
-    (pb_decoder_t)&pb_dec_sint64,
-    (pb_decoder_t)&pb_dec_fixed64,
-    (pb_decoder_t)&pb_dec_bool,
-    (pb_decoder_t)&pb_dec_enum,
-    
-    (pb_decoder_t)&pb_dec_float,
-    (pb_decoder_t)&pb_dec_double,
-    
-    (pb_decoder_t)&pb_dec_bytes,
-    (pb_decoder_t)&pb_dec_string,
-    (pb_decoder_t)&pb_dec_submessage
+typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
+
+/* --- Function pointers to field decoders ---
+ * Order in the array must match pb_action_t LTYPE numbering.
+ */
+static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
+    &pb_dec_varint,
+    &pb_dec_svarint,
+    &pb_dec_fixed32,
+    &pb_dec_fixed64,
+    
+    &pb_dec_bytes,
+    &pb_dec_string,
+    &pb_dec_submessage
 };
 
 /**************
  * pb_istream *
  **************/
 
-bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
+static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
 {
-    bool status;
-    if (stream->bytes_left < count)
-        return false;
+    uint8_t *source = (uint8_t*)stream->state;
+    stream->state = source + count;
     
-    status = stream->callback(stream, buf, count);
-    stream->bytes_left -= count;
-    return status;
+    if (buf != NULL)
+    {
+        while (count--)
+            *buf++ = *source++;
+    }
+    
+    return true;
 }
 
-static bool buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
+bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
 {
-    uint8_t *source = (uint8_t*)stream->state;
+#ifndef PB_BUFFER_ONLY
+	if (buf == NULL && stream->callback != buf_read)
+	{
+		/* Skip input bytes */
+		uint8_t tmp[16];
+		while (count > 16)
+		{
+			if (!pb_read(stream, tmp, 16))
+				return false;
+			
+			count -= 16;
+		}
+		
+		return pb_read(stream, tmp, count);
+	}
+#endif
+
+    if (stream->bytes_left < count)
+        PB_RETURN_ERROR(stream, "end-of-stream");
     
-    if (buf != NULL)
-        memcpy(buf, source, count);
+#ifndef PB_BUFFER_ONLY
+    if (!stream->callback(stream, buf, count))
+        PB_RETURN_ERROR(stream, "io error");
+#else
+    if (!buf_read(stream, buf, count))
+        return false;
+#endif
     
-    stream->state = source + count;
+    stream->bytes_left -= count;
     return true;
 }
 
 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
 {
     pb_istream_t stream;
+#ifdef PB_BUFFER_ONLY
+    stream.callback = NULL;
+#else
     stream.callback = &buf_read;
+#endif
     stream.state = buf;
     stream.bytes_left = bufsize;
+#ifndef PB_NO_ERRMSG
+    stream.errmsg = NULL;
+#endif
     return stream;
 }
 
@@ -64,34 +104,65 @@ pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
  * Helper functions *
  ********************/
 
-bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
+static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
 {
-    uint64_t temp;
-    if (!pb_decode_varint64(stream, &temp))
+    uint8_t byte;
+    uint32_t result;
+    
+    if (!pb_read(stream, &byte, 1))
         return false;
-    *dest = temp;
-    return true;
+    
+    if (!(byte & 0x80))
+    {
+        /* Quick case, 1 byte value */
+        result = byte;
+    }
+    else
+    {
+        /* Multibyte case */
+        uint8_t bitpos = 7;
+        result = byte & 0x7F;
+        
+        do
+        {
+            if (bitpos >= 32)
+                PB_RETURN_ERROR(stream, "varint overflow");
+            
+            if (!pb_read(stream, &byte, 1))
+                return false;
+            
+            result |= (uint32_t)(byte & 0x7F) << bitpos;
+            bitpos = (uint8_t)(bitpos + 7);
+        } while (byte & 0x80);
+   }
+   
+   *dest = result;
+   return true;
 }
 
-bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest)
+bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
 {
     uint8_t byte;
-    int bitpos = 0;
-    *dest = 0;
+    uint8_t bitpos = 0;
+    uint64_t result = 0;
     
-    while (bitpos < 64 && pb_read(stream, &byte, 1))
+    do
     {
-        *dest |= (byte & 0x7F) << bitpos;
-        bitpos += 7;
+        if (bitpos >= 64)
+            PB_RETURN_ERROR(stream, "varint overflow");
         
-        if (!(byte & 0x80))
-            return true;
-    }
+        if (!pb_read(stream, &byte, 1))
+            return false;
+
+        result |= (uint64_t)(byte & 0x7F) << bitpos;
+        bitpos = (uint8_t)(bitpos + 7);
+    } while (byte & 0x80);
     
-    return false;
+    *dest = result;
+    return true;
 }
 
-bool pb_skip_varint(pb_istream_t *stream)
+bool checkreturn pb_skip_varint(pb_istream_t *stream)
 {
     uint8_t byte;
     do
@@ -102,7 +173,7 @@ bool pb_skip_varint(pb_istream_t *stream)
     return true;
 }
 
-bool pb_skip_string(pb_istream_t *stream)
+bool checkreturn pb_skip_string(pb_istream_t *stream)
 {
     uint32_t length;
     if (!pb_decode_varint32(stream, &length))
@@ -111,61 +182,78 @@ bool pb_skip_string(pb_istream_t *stream)
     return pb_read(stream, NULL, length);
 }
 
-/* Currently all 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, uint32_t *tag, bool *eof)
+{
+    uint32_t temp;
+    *eof = false;
+    *wire_type = (pb_wire_type_t) 0;
+    *tag = 0;
+    
+    if (!pb_decode_varint32(stream, &temp))
+    {
+        if (stream->bytes_left == 0)
+            *eof = true;
 
-enum wire_type_t {
-    WT_VARINT = 0,
-    WT_64BIT  = 1,
-    WT_STRING = 2,
-    WT_32BIT  = 5
-};
+        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 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)
     {
-        case WT_VARINT: return pb_skip_varint(stream);
-        case WT_64BIT: return pb_read(stream, NULL, 8);
-        case WT_STRING: return pb_skip_string(stream);
-        case WT_32BIT: return pb_read(stream, NULL, 4);
-        default: return false;
+        case PB_WT_VARINT: return pb_skip_varint(stream);
+        case PB_WT_64BIT: return pb_read(stream, NULL, 8);
+        case PB_WT_STRING: return pb_skip_string(stream);
+        case PB_WT_32BIT: return pb_read(stream, NULL, 4);
+        default: PB_RETURN_ERROR(stream, "invalid wire_type");
     }
 }
 
-/* Read a raw value to buffer, for the purpose of passing it to callback.
- * Size is maximum size on call, and actual size on return. */
-static bool read_raw_value(pb_istream_t *stream, int wire_type, uint8_t *buf, size_t *size)
+/* Read a raw value to buffer, for the purpose of passing it to callback as
+ * a substream. Size is maximum size on call, and actual size on return.
+ */
+static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
 {
     size_t max_size = *size;
     switch (wire_type)
     {
-        case WT_VARINT:
+        case PB_WT_VARINT:
             *size = 0;
             do
             {
                 (*size)++;
                 if (*size > max_size) return false;
-                if (!pb_read(stream, buf++, 1)) return false;
-            } while (*buf & 0x80);
+                if (!pb_read(stream, buf, 1)) return false;
+            } while (*buf++ & 0x80);
             return true;
             
-        case WT_64BIT:
+        case PB_WT_64BIT:
             *size = 8;
             return pb_read(stream, buf, 8);
         
-        case WT_32BIT:
+        case PB_WT_32BIT:
             *size = 4;
             return pb_read(stream, buf, 4);
         
-        default: return false;
+        default: PB_RETURN_ERROR(stream, "invalid wire_type");
     }
 }
 
-/* Decode string length from stream and return a substream with limited length */
-static bool make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
+/* Decode string length from stream and return a substream with limited length.
+ * Remember to close the substream using pb_close_string_substream().
+ */
+bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
 {
     uint32_t size;
     if (!pb_decode_varint32(stream, &size))
@@ -173,259 +261,443 @@ static bool make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
     
     *substream = *stream;
     if (substream->bytes_left < size)
-        return false;
+        PB_RETURN_ERROR(stream, "parent stream too short");
     
     substream->bytes_left = size;
     stream->bytes_left -= size;
     return true;
 }
 
-bool decode_field(pb_istream_t *stream, int wire_type, const pb_field_t *field, void *dest_struct)
+void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
+{
+    stream->state = substream->state;
+
+#ifndef PB_NO_ERRMSG
+    stream->errmsg = substream->errmsg;
+#endif
+}
+
+/* Iterator for pb_field_t list */
+typedef struct {
+    const pb_field_t *start; /* Start of the pb_field_t array */
+    const pb_field_t *current; /* Current position of the iterator */
+    unsigned field_index; /* Zero-based index of the field. */
+    unsigned required_field_index; /* Zero-based index that counts only the required fields */
+    void *dest_struct; /* Pointer to the destination structure to decode to */
+    void *pData; /* Pointer where to store current field value */
+    void *pSize; /* Pointer where to store the size of current array field */
+} pb_field_iterator_t;
+
+static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
+{
+    iter->start = iter->current = fields;
+    iter->field_index = 0;
+    iter->required_field_index = 0;
+    iter->pData = (char*)dest_struct + iter->current->data_offset;
+    iter->pSize = (char*)iter->pData + iter->current->size_offset;
+    iter->dest_struct = dest_struct;
+}
+
+static bool pb_field_next(pb_field_iterator_t *iter)
+{
+    bool notwrapped = true;
+    size_t prev_size = iter->current->data_size;
+    
+    if (PB_ATYPE(iter->current->type) == PB_ATYPE_STATIC &&
+        PB_HTYPE(iter->current->type) == PB_HTYPE_REPEATED)
+    {
+        prev_size *= iter->current->array_size;
+    }
+    
+    if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
+        iter->required_field_index++;
+    
+    iter->current++;
+    iter->field_index++;
+    if (iter->current->tag == 0)
+    {
+        iter->current = iter->start;
+        iter->field_index = 0;
+        iter->required_field_index = 0;
+        iter->pData = iter->dest_struct;
+        prev_size = 0;
+        notwrapped = false;
+    }
+    
+    iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
+    iter->pSize = (char*)iter->pData + iter->current->size_offset;
+    return notwrapped;
+}
+
+static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
 {
-    pb_decoder_t func = PB_DECODERS[PB_LTYPE(field->type)];
-    void *pData = (char*)dest_struct + field->data_offset;
-    void *pSize = (char*)dest_struct + field->size_offset;
+    unsigned start = iter->field_index;
+    
+    do {
+        if (iter->current->tag == tag)
+            return true;
+        pb_field_next(iter);
+    } while (iter->field_index != start);
     
-    switch (PB_HTYPE(field->type))
+    return false;
+}
+
+/*************************
+ * Decode a single field *
+ *************************/
+
+static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
+{
+    pb_type_t type;
+    pb_decoder_t func;
+    
+    type = iter->current->type;
+    func = PB_DECODERS[PB_LTYPE(type)];
+
+    switch (PB_HTYPE(type))
     {
         case PB_HTYPE_REQUIRED:
-            return func(stream, field, pData);
+            return func(stream, iter->current, iter->pData);
             
         case PB_HTYPE_OPTIONAL:
-            *(bool*)pSize = true;
-            return func(stream, field, pData);
-    
-        case PB_HTYPE_ARRAY:
-            if (wire_type == WT_STRING
-                && PB_LTYPE(field->type) != PB_LTYPE_BYTES
-                && PB_LTYPE(field->type) != PB_LTYPE_STRING
-                && PB_LTYPE(field->type) != PB_LTYPE_SUBMESSAGE)
+            *(bool*)iter->pSize = true;
+            return func(stream, iter->current, iter->pData);
+    
+        case PB_HTYPE_REPEATED:
+            if (wire_type == PB_WT_STRING
+                && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
             {
                 /* Packed array */
-                size_t *size = (size_t*)pSize;
+                bool status = true;
+                size_t *size = (size_t*)iter->pSize;
                 pb_istream_t substream;
-                if (!make_string_substream(stream, &substream))
+                if (!pb_make_string_substream(stream, &substream))
                     return false;
                 
-                while (substream.bytes_left && *size < field->array_size)
+                while (substream.bytes_left && *size < iter->current->array_size)
                 {
-                    void *pItem = (uint8_t*)pData + field->data_size * (*size);
-                    if (!func(stream, field, pItem))
-                        return false;
+                    void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
+                    if (!func(&substream, iter->current, pItem))
+                    {
+                        status = false;
+                        break;
+                    }
                     (*size)++;
                 }
-                return (substream.bytes_left == 0);
-            }
-            else
-            {
-                /* Repeated field */
-                size_t *size = (size_t*)pSize;
-                void *pItem = (uint8_t*)pData + field->data_size * (*size);
-                if (*size >= field->array_size)
-                    return false;
-                
-                (*size)++;
-                return func(stream, field, pItem);
-            }
-        
-        case PB_HTYPE_CALLBACK:
-            if (wire_type == WT_STRING)
-            {
-                pb_callback_t *pCallback = (pb_callback_t*)pData;
-                pb_istream_t substream;
+                pb_close_string_substream(stream, &substream);
                 
-                if (!make_string_substream(stream, &substream))
-                    return false;
+                if (substream.bytes_left != 0)
+                    PB_RETURN_ERROR(stream, "array overflow");
                 
-                while (substream.bytes_left)
-                {
-                    if (!pCallback->funcs.decode(&substream, field, pCallback->arg))
-                        return false;
-                }
+                return status;
             }
             else
             {
-                /* Copy the single scalar value to stack.
-                 * This is required so that we can limit the stream length,
-                 * which in turn allows to use same callback for packed and
-                 * not-packed fields. */
-                pb_istream_t substream;
-                pb_callback_t *pCallback = (pb_callback_t*)pData;
-                uint8_t buffer[10];
-                size_t size = sizeof(buffer);
-                
-                if (!read_raw_value(stream, wire_type, buffer, &size))
-                    return false;
-                substream = pb_istream_from_buffer(buffer, size);
+                /* Repeated field */
+                size_t *size = (size_t*)iter->pSize;
+                void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
+                if (*size >= iter->current->array_size)
+                    PB_RETURN_ERROR(stream, "array overflow");
                 
-                return pCallback->funcs.decode(&substream, field, pCallback->arg);
+                (*size)++;
+                return func(stream, iter->current, pItem);
             }
-            
+
         default:
-            return false;
+            PB_RETURN_ERROR(stream, "invalid field type");
     }
 }
 
-bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
+static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
 {
-    /* Used to check for required fields */
-    uint32_t fields_seen = 0;
-    int i;
+    pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
     
-    /* Initialize size/has fields and apply default values */
-    for (i = 0; fields[i].tag != 0; i++)
+    if (pCallback->funcs.decode == NULL)
+        return pb_skip_field(stream, wire_type);
+    
+    if (wire_type == PB_WT_STRING)
     {
-        void *pData = (char*)dest_struct + fields[i].data_offset;
-        void *pSize = (char*)dest_struct + fields[i].size_offset;
-        if (PB_HTYPE(fields[i].type) == PB_HTYPE_OPTIONAL)
-        {
-            *(bool*)pSize = false;
-        }
-        else if (PB_HTYPE(fields[i].type) == PB_HTYPE_ARRAY)
+        pb_istream_t substream;
+        
+        if (!pb_make_string_substream(stream, &substream))
+            return false;
+        
+        while (substream.bytes_left)
         {
-            *(size_t*)pSize = 0;
+            if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
+                PB_RETURN_ERROR(stream, "callback failed");
         }
         
-        if (PB_HTYPE(fields[i].type) != PB_HTYPE_ARRAY &&
-            PB_HTYPE(fields[i].type) != PB_HTYPE_CALLBACK)
+        pb_close_string_substream(stream, &substream);
+        return true;
+    }
+    else
+    {
+        /* Copy the single scalar value to stack.
+         * This is required so that we can limit the stream length,
+         * which in turn allows to use same callback for packed and
+         * not-packed fields. */
+        pb_istream_t substream;
+        uint8_t buffer[10];
+        size_t size = sizeof(buffer);
+        
+        if (!read_raw_value(stream, wire_type, buffer, &size))
+            return false;
+        substream = pb_istream_from_buffer(buffer, size);
+        
+        return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
+    }
+}
+
+static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
+{
+    switch (PB_ATYPE(iter->current->type))
+    {
+        case PB_ATYPE_STATIC:
+            return decode_static_field(stream, wire_type, iter);
+        
+        case PB_ATYPE_CALLBACK:
+            return decode_callback_field(stream, wire_type, iter);
+        
+        default:
+            PB_RETURN_ERROR(stream, "invalid field type");
+    }
+}
+
+/* Initialize message fields to default values, recursively */
+static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
+{
+    pb_field_iterator_t iter;
+    pb_field_init(&iter, fields, dest_struct);
+    
+    /* Initialize size/has fields and apply default values */
+    do
+    {
+        pb_type_t type;
+        type = iter.current->type;
+    
+        if (iter.current->tag == 0)
+            continue;
+        
+        if (PB_ATYPE(type) == PB_ATYPE_STATIC)
         {
-            if (fields[i].ptr != NULL)
+            /* Initialize the size field for optional/repeated fields to 0. */
+            if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
             {
-                memcpy(pData, fields[i].ptr, fields[i].data_size);
+                *(bool*)iter.pSize = false;
+            }
+            else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
+            {
+                *(size_t*)iter.pSize = 0;
+                continue; /* Array is empty, no need to initialize contents */
+            }
+            
+            /* Initialize field contents to default value */
+            if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
+            {
+                pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
+            }
+            else if (iter.current->ptr != NULL)
+            {
+                memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
             }
             else
             {
-                memset(pData, 0, fields[i].data_size);
+                memset(iter.pData, 0, iter.current->data_size);
             }
         }
-    }
+        else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
+        {
+            continue; /* Don't overwrite callback */
+        }
+    } while (pb_field_next(&iter));
+}
+
+/*********************
+ * Decode all fields *
+ *********************/
+
+bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
+{
+    uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
+    pb_field_iterator_t iter;
+    
+    pb_field_init(&iter, fields, dest_struct);
     
     while (stream->bytes_left)
     {
-        uint32_t temp;
-        int tag, wire_type;
-        if (!pb_decode_varint32(stream, &temp))
-            return false;
-        
-        tag = temp >> 3;
-        wire_type = temp & 7;
+        uint32_t tag;
+        pb_wire_type_t wire_type;
+        bool eof;
         
-        i = 0;
-        while (fields[i].tag != 0 && fields[i].tag != tag)
+        if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
         {
-            i++;
+            if (eof)
+                break;
+            else
+                return false;
         }
         
-        if (fields[i].tag == 0) /* No match found, skip data */
+        if (!pb_field_find(&iter, tag))
         {
-            skip(stream, wire_type);
+            /* No match found, skip data */
+            if (!pb_skip_field(stream, wire_type))
+                return false;
             continue;
         }
         
-        fields_seen |= 1 << (i & 31);
+        if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
+            && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
+        {
+            fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
+        }
             
-        if (!decode_field(stream, wire_type, &fields[i], dest_struct))
+        if (!decode_field(stream, wire_type, &iter))
             return false;
     }
     
-    /* Check that all required fields (mod 31) were present. */
-    for (i = 0; fields[i].tag != 0; i++)
+    /* Check that all required fields were present. */
     {
-        if (PB_HTYPE(fields[i].type) == PB_HTYPE_REQUIRED &&
-            !(fields_seen & (1 << (i & 31))))
+        /* First figure out the number of required fields by
+         * seeking to the end of the field array. Usually we
+         * are already close to end after decoding.
+         */
+        unsigned req_field_count;
+        pb_type_t last_type;
+        unsigned i;
+        do {
+            req_field_count = iter.required_field_index;
+            last_type = iter.current->type;
+        } while (pb_field_next(&iter));
+        
+        /* Fixup if last field was also required. */
+        if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED)
+            req_field_count++;
+        
+        /* Check the whole bytes */
+        for (i = 0; i < (req_field_count >> 3); i++)
         {
-            return false;
+            if (fields_seen[i] != 0xFF)
+                PB_RETURN_ERROR(stream, "missing required field");
         }
+        
+        /* Check the remaining bits */
+        if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
+            PB_RETURN_ERROR(stream, "missing required field");
     }
     
     return true;
 }
 
-/* Field decoders */
-
-bool pb_dec_uint32(pb_istream_t *stream, const pb_field_t *field, uint32_t *dest)
+bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
 {
-    return pb_decode_varint32(stream, dest);
+    pb_message_set_to_defaults(fields, dest_struct);
+    return pb_decode_noinit(stream, fields, dest_struct);
 }
 
-bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, int32_t *dest)
-{
-    uint32_t *x = (uint32_t*)dest;
-    bool status = pb_decode_varint32(stream, x);
-    *x = (*x >> 1) ^ -(int32_t)(*x & 1);
-    return status;
-}
+/* Field decoders */
 
-bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, uint32_t *dest)
+bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
 {
-    uint8_t bytes[4] = {0};
-    bool status = pb_read(stream, bytes, 4);
+    uint64_t value;
+    if (!pb_decode_varint(stream, &value))
+        return false;
     
-#ifdef __BIG_ENDIAN__
-    uint8_t lebytes[4] = {bytes[3], bytes[2], bytes[1], bytes[0]};
-    memcpy(dest, lebytes, 4);
-#else
-    memcpy(dest, bytes, 4);
-#endif
-    return status;
-}
-
-bool pb_dec_uint64(pb_istream_t *stream, const pb_field_t *field, uint64_t *dest)
-{
-    return pb_decode_varint64(stream, dest);
+    if (value & 1)
+        *dest = (int64_t)(~(value >> 1));
+    else
+        *dest = (int64_t)(value >> 1);
+    
+    return true;
 }
 
-bool pb_dec_sint64(pb_istream_t *stream, const pb_field_t *field, int64_t *dest)
+bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
 {
-    uint64_t *x = (uint64_t*)dest;
-    bool status = pb_decode_varint64(stream, x);
-    *x = (*x >> 1) ^ -(int64_t)(*x & 1);
-    return status;
+    #ifdef __BIG_ENDIAN__
+    uint8_t *bytes = (uint8_t*)dest;
+    uint8_t lebytes[4];
+    
+    if (!pb_read(stream, lebytes, 4))
+        return false;
+    
+    bytes[0] = lebytes[3];
+    bytes[1] = lebytes[2];
+    bytes[2] = lebytes[1];
+    bytes[3] = lebytes[0];
+    return true;
+    #else
+    return pb_read(stream, (uint8_t*)dest, 4);
+    #endif   
 }
 
-bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, uint64_t *dest)
+bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
 {
-    uint8_t bytes[8] = {0};
-    bool status = pb_read(stream, bytes, 8);
+    #ifdef __BIG_ENDIAN__
+    uint8_t *bytes = (uint8_t*)dest;
+    uint8_t lebytes[8];
     
-#ifdef __BIG_ENDIAN__
-    uint8_t lebytes[8] = {bytes[7], bytes[6], bytes[5], bytes[4], 
-                          bytes[3], bytes[2], bytes[1], bytes[0]};
-    memcpy(dest, lebytes, 4);
-#else
-    memcpy(dest, bytes, 4);
-#endif
-    return status;
+    if (!pb_read(stream, lebytes, 8))
+        return false;
+    
+    bytes[0] = lebytes[7];
+    bytes[1] = lebytes[6];
+    bytes[2] = lebytes[5];
+    bytes[3] = lebytes[4];
+    bytes[4] = lebytes[3];
+    bytes[5] = lebytes[2];
+    bytes[6] = lebytes[1];
+    bytes[7] = lebytes[0];
+    return true;
+    #else
+    return pb_read(stream, (uint8_t*)dest, 8);
+    #endif   
 }
 
-bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, bool *dest)
+bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    uint32_t temp = 0;
-    bool status = pb_decode_varint32(stream, &temp);
-    *(bool*)dest = !!temp;
+    uint64_t value;
+    bool status = pb_decode_varint(stream, &value);
+    
+    switch (field->data_size)
+    {
+        case 1: *(uint8_t*)dest = (uint8_t)value; break;
+        case 2: *(uint16_t*)dest = (uint16_t)value; break;
+        case 4: *(uint32_t*)dest = (uint32_t)value; break;
+        case 8: *(uint64_t*)dest = value; break;
+        default: PB_RETURN_ERROR(stream, "invalid data_size");
+    }
+    
     return status;
 }
 
-bool pb_dec_enum(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    /* Enum sizes can vary, copy only data_size amount of bytes. */
-    uint32_t temp = 0;
-    bool status = pb_decode_varint32(stream, &temp);
-    memcpy(dest, &temp, field->data_size);
+    int64_t value;
+    bool status = pb_decode_svarint(stream, &value);
+    
+    switch (field->data_size)
+    {
+        case 4: *(int32_t*)dest = (int32_t)value; break;
+        case 8: *(int64_t*)dest = value; break;
+        default: PB_RETURN_ERROR(stream, "invalid data_size");
+    }
+    
     return status;
 }
 
-bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, float *dest)
+bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    return pb_read(stream, (uint8_t*)dest, sizeof(float));
+    UNUSED(field);
+    return pb_decode_fixed32(stream, dest);
 }
 
-bool pb_dec_double(pb_istream_t *stream, const pb_field_t *field, double *dest)
+bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    return pb_read(stream, (uint8_t*)dest, sizeof(double));
+    UNUSED(field);
+    return pb_decode_fixed64(stream, dest);
 }
 
-bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, uint8_t *dest)
+bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
     pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
     
@@ -434,38 +706,48 @@ bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, uint8_t *dest)
         return false;
     x->size = temp;
     
-    /* Note: data_size includes the size of the x.size field, too.
-     * Calculate actual size starting from offset. */
+    /* 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;
+        PB_RETURN_ERROR(stream, "bytes overflow");
     
     return pb_read(stream, x->bytes, x->size);
 }
 
-bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, uint8_t *dest)
+bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
     uint32_t size;
     bool status;
     if (!pb_decode_varint32(stream, &size))
         return false;
     
-    if (size > field->data_size - 1)
-        return false;
+    /* Check length, noting the null terminator */
+    if (size + 1 > field->data_size)
+        PB_RETURN_ERROR(stream, "string overflow");
     
     status = pb_read(stream, (uint8_t*)dest, size);
     *((uint8_t*)dest + size) = 0;
     return status;
 }
 
-bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
+    bool status;
     pb_istream_t substream;
+    const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
     
-    if (!make_string_substream(stream, &substream))
+    if (!pb_make_string_substream(stream, &substream))
         return false;
     
     if (field->ptr == NULL)
-        return false;
+        PB_RETURN_ERROR(stream, "invalid field descriptor");
+    
+    /* New array entries need to be initialized, while required and optional
+     * submessages have already been initialized in the top-level pb_decode. */
+    if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
+        status = pb_decode(&substream, submsg_fields, dest);
+    else
+        status = pb_decode_noinit(&substream, submsg_fields, dest);
     
-    return pb_decode(&substream, (pb_field_t*)field->ptr, dest);
+    pb_close_string_substream(stream, &substream);
+    return status;
 }