X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=pb_decode.c;h=4e1872560c63b0509351c480273ad4f7ed054a7c;hb=eaa3c7b157ffd2a308dfc6d35d79309a9aacbcef;hp=acd9b204349c5a20a3a511a8173e1251d5c512d3;hpb=84304b343a4b06a7918bc80ab45f08d1cae0b9cb;p=apps%2Fagl-service-can-low-level.git

diff --git a/pb_decode.c b/pb_decode.c
index acd9b204..4e187256 100644
--- a/pb_decode.c
+++ b/pb_decode.c
@@ -3,77 +3,227 @@
  * 2011 Petteri Aimonen <jpa@kapsi.fi>
  */
 
+/* Use the GCC warn_unused_result attribute to check that all return values
+ * are propagated correctly. On other compilers and gcc before 3.4.0 just
+ * ignore the annotation.
+ */
+#if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
+    #define checkreturn
+#else
+    #define checkreturn __attribute__((warn_unused_result))
+#endif
+
 #include "pb.h"
 #include "pb_decode.h"
-#include <string.h>
 
-const pb_decoder_t PB_DECODERS[16] = {
-    &pb_dec_uint32,
-    &pb_dec_sint32,
+/**************************************
+ * Declarations internal to this file *
+ **************************************/
+
+/* Iterator for pb_field_t list */
+typedef struct {
+    const pb_field_t *start; /* Start of the pb_field_t array */
+    const pb_field_t *pos; /* 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;
+
+typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
+
+static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count);
+static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
+static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size);
+static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct);
+static bool pb_field_next(pb_field_iterator_t *iter);
+static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag);
+static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
+static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t 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);
+static bool checkreturn default_extension_decoder(pb_istream_t *stream, pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type);
+static bool checkreturn decode_extension(pb_istream_t *stream, uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
+static bool checkreturn find_extension_field(pb_field_iterator_t *iter);
+static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct);
+static bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_uvarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest);
+static bool checkreturn pb_skip_varint(pb_istream_t *stream);
+static bool checkreturn pb_skip_string(pb_istream_t *stream);
+
+/* --- 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_uvarint,
+    &pb_dec_svarint,
     &pb_dec_fixed32,
-    &pb_dec_uint64,
-    &pb_dec_sint64,
     &pb_dec_fixed64,
-    &pb_dec_bool,
-    &pb_dec_enum,
-    
-    &pb_dec_float,
-    &pb_dec_double,
     
     &pb_dec_bytes,
     &pb_dec_string,
-    &pb_dec_submessage
+    &pb_dec_submessage,
+    NULL /* extensions */
 };
 
-////////////////////////
-// Helper functions
-////////////////////////
+/*******************************
+ * pb_istream_t implementation *
+ *******************************/
 
-static bool buf_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)
 {
     uint8_t *source = (uint8_t*)stream->state;
+    stream->state = source + count;
     
     if (buf != NULL)
-        memcpy(buf, source, count);
+    {
+        while (count--)
+            *buf++ = *source++;
+    }
     
-    stream->state = source + count;
     return true;
 }
 
+bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
+{
+#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");
+    
+#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->bytes_left -= count;
+    return true;
+}
+
+/* Read a single byte from input stream. buf may not be NULL.
+ * This is an optimization for the varint decoding. */
+static bool checkreturn pb_readbyte(pb_istream_t *stream, uint8_t *buf)
+{
+    if (stream->bytes_left == 0)
+        PB_RETURN_ERROR(stream, "end-of-stream");
+
+#ifndef PB_BUFFER_ONLY
+    if (!stream->callback(stream, buf, 1))
+        PB_RETURN_ERROR(stream, "io error");
+#else
+    *buf = *(uint8_t*)stream->state;
+    stream->state = (uint8_t*)stream->state + 1;
+#endif
+
+    stream->bytes_left--;
+    
+    return true;    
+}
+
 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
 {
-    pb_istream_t stream = {&buf_read, buf, 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;
 }
 
-bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
+/********************
+ * Helper functions *
+ ********************/
+
+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_readbyte(stream, &byte))
         return false;
-    *dest = temp;
-    return true;
+    
+    if ((byte & 0x80) == 0)
+    {
+        /* 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_readbyte(stream, &byte))
+                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_readbyte(stream, &byte))
+            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
@@ -84,7 +234,7 @@ 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))
@@ -93,61 +243,78 @@ 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))
@@ -155,295 +322,873 @@ 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
+}
+
+static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
+{
+    iter->start = iter->pos = fields;
+    iter->field_index = 0;
+    iter->required_field_index = 0;
+    iter->pData = (char*)dest_struct + iter->pos->data_offset;
+    iter->pSize = (char*)iter->pData + iter->pos->size_offset;
+    iter->dest_struct = dest_struct;
+}
+
+static bool pb_field_next(pb_field_iterator_t *iter)
 {
-    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;
+    bool notwrapped = true;
+    size_t prev_size = iter->pos->data_size;
     
-    switch (PB_HTYPE(field->type))
+    if (PB_ATYPE(iter->pos->type) == PB_ATYPE_STATIC &&
+        PB_HTYPE(iter->pos->type) == PB_HTYPE_REPEATED)
+    {
+        prev_size *= iter->pos->array_size;
+    }
+    else if (PB_ATYPE(iter->pos->type) == PB_ATYPE_POINTER)
+    {
+        prev_size = sizeof(void*);
+    }
+    
+    if (iter->pos->tag == 0)
+        return false; /* Only happens with empty message types */
+    
+    if (PB_HTYPE(iter->pos->type) == PB_HTYPE_REQUIRED)
+        iter->required_field_index++;
+    
+    iter->pos++;
+    iter->field_index++;
+    if (iter->pos->tag == 0)
+    {
+        iter->pos = 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->pos->data_offset;
+    iter->pSize = (char*)iter->pData + iter->pos->size_offset;
+    return notwrapped;
+}
+
+static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
+{
+    unsigned start = iter->field_index;
+    
+    do {
+        if (iter->pos->tag == tag &&
+            PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
+        {
+            return true;
+        }
+        (void)pb_field_next(iter);
+    } while (iter->field_index != start);
+    
+    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->pos->type;
+    func = PB_DECODERS[PB_LTYPE(type)];
+
+    switch (PB_HTYPE(type))
     {
         case PB_HTYPE_REQUIRED:
-            return func(stream, field, pData);
+            return func(stream, iter->pos, 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->pos, 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;
+                /* Packed array */
+                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 > 0 && *size < iter->pos->array_size)
                 {
-                    void *pItem = pData + field->data_size * (*size);
-                    if (!func(stream, field, pItem))
-                        return false;
+                    void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
+                    if (!func(&substream, iter->pos, pItem))
+                    {
+                        status = false;
+                        break;
+                    }
                     (*size)++;
                 }
-                return (substream.bytes_left == 0);
+                pb_close_string_substream(stream, &substream);
+                
+                if (substream.bytes_left != 0)
+                    PB_RETURN_ERROR(stream, "array overflow");
+                
+                return status;
             }
             else
             {
-                // Repeated field
-                size_t *size = (size_t*)pSize;
-                if (*size >= field->array_size)
-                    return false;
+                /* Repeated field */
+                size_t *size = (size_t*)iter->pSize;
+                void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
+                if (*size >= iter->pos->array_size)
+                    PB_RETURN_ERROR(stream, "array overflow");
                 
-                void *pItem = pData + field->data_size * (*size);
                 (*size)++;
-                return func(stream, field, pItem);
+                return func(stream, iter->pos, pItem);
             }
-        
-        case PB_HTYPE_CALLBACK:
-            if (wire_type == WT_STRING)
+
+        default:
+            PB_RETURN_ERROR(stream, "invalid field type");
+    }
+}
+
+#ifdef PB_ENABLE_MALLOC
+/* Allocate storage for the field and store the pointer at iter->pData.
+ * array_size is the number of entries to reserve in an array.
+ * Zero size is not allowed, use pb_free() for releasing.
+ */
+static bool checkreturn allocate_field(pb_istream_t *stream, void *pData, size_t data_size, size_t array_size)
+{    
+    void *ptr = *(void**)pData;
+    
+    /* Check for multiplication overflows.
+     * This code avoids the costly division if the sizes are small enough.
+     * Multiplication is safe as long as only half of bits are set
+     * in either multiplicand.
+     */
+    const size_t check_limit = (size_t)1 << (sizeof(size_t) * 4);
+    if (data_size >= check_limit || array_size >= check_limit)
+    {
+        const size_t size_max = (size_t)-1;
+        if (size_max / array_size < data_size)
+        {
+            PB_RETURN_ERROR(stream, "size too large");
+        }
+    }
+    
+    /* Allocate new or expand previous allocation */
+    /* Note: on failure the old pointer will remain in the structure,
+     * the message must be freed by caller also on error return. */
+    ptr = pb_realloc(ptr, array_size * data_size);
+    if (ptr == NULL)
+        PB_RETURN_ERROR(stream, "realloc failed");
+    
+    *(void**)pData = ptr;
+    return true;
+}
+
+/* Clear a newly allocated item in case it contains a pointer, or is a submessage. */
+static void initialize_pointer_field(void *pItem, pb_field_iterator_t *iter)
+{
+    if (PB_LTYPE(iter->pos->type) == PB_LTYPE_STRING ||
+        PB_LTYPE(iter->pos->type) == PB_LTYPE_BYTES)
+    {
+        *(void**)pItem = NULL;
+    }
+    else if (PB_LTYPE(iter->pos->type) == PB_LTYPE_SUBMESSAGE)
+    {
+        pb_message_set_to_defaults((const pb_field_t *) iter->pos->ptr, pItem);
+    }
+}
+#endif
+
+static bool checkreturn decode_pointer_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
+{
+#ifndef PB_ENABLE_MALLOC
+    UNUSED(wire_type);
+    UNUSED(iter);
+    PB_RETURN_ERROR(stream, "no malloc support");
+#else
+    pb_type_t type;
+    pb_decoder_t func;
+    
+    type = iter->pos->type;
+    func = PB_DECODERS[PB_LTYPE(type)];
+    
+    switch (PB_HTYPE(type))
+    {
+        case PB_HTYPE_REQUIRED:
+        case PB_HTYPE_OPTIONAL:
+            if (PB_LTYPE(type) == PB_LTYPE_STRING ||
+                PB_LTYPE(type) == PB_LTYPE_BYTES)
+            {
+                return func(stream, iter->pos, iter->pData);
+            }
+            else
             {
-                pb_callback_t *pCallback = (pb_callback_t*)pData;
+                if (!allocate_field(stream, iter->pData, iter->pos->data_size, 1))
+                    return false;
+                
+                initialize_pointer_field(*(void**)iter->pData, iter);
+                return func(stream, iter->pos, *(void**)iter->pData);
+            }
+    
+        case PB_HTYPE_REPEATED:
+            if (wire_type == PB_WT_STRING
+                && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
+            {
+                /* Packed array, multiple items come in at once. */
+                bool status = true;
+                size_t *size = (size_t*)iter->pSize;
+                size_t allocated_size = *size;
+                void *pItem;
                 pb_istream_t substream;
                 
-                if (!make_string_substream(stream, &substream))
+                if (!pb_make_string_substream(stream, &substream))
                     return false;
                 
                 while (substream.bytes_left)
                 {
-                    if (!pCallback->funcs.decode(&substream, field, pCallback->arg))
-                        return false;
+                    if (*size + 1 > allocated_size)
+                    {
+                        /* Allocate more storage. This tries to guess the
+                         * number of remaining entries. Round the division
+                         * upwards. */
+                        allocated_size += (substream.bytes_left - 1) / iter->pos->data_size + 1;
+                        
+                        if (!allocate_field(&substream, iter->pData, iter->pos->data_size, allocated_size))
+                        {
+                            status = false;
+                            break;
+                        }
+                    }
+
+                    /* Decode the array entry */
+                    pItem = *(uint8_t**)iter->pData + iter->pos->data_size * (*size);
+                    initialize_pointer_field(pItem, iter);
+                    if (!func(&substream, iter->pos, pItem))
+                    {
+                        status = false;
+                        break;
+                    }
+                    (*size)++;
                 }
+                pb_close_string_substream(stream, &substream);
+                
+                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.
-                uint8_t buffer[10];
-                size_t size = sizeof(buffer);
-                if (!read_raw_value(stream, wire_type, buffer, &size))
-                    return false;
-                pb_istream_t substream = pb_istream_from_buffer(buffer, size);
+                /* Normal repeated field, i.e. only one item at a time. */
+                size_t *size = (size_t*)iter->pSize;
+                void *pItem;
                 
-                pb_callback_t *pCallback = (pb_callback_t*)pData;
-                return pCallback->funcs.decode(&substream, field, pCallback->arg);
+                (*size)++;
+                if (!allocate_field(stream, iter->pData, iter->pos->data_size, *size))
+                    return false;
+            
+                pItem = *(uint8_t**)iter->pData + iter->pos->data_size * (*size - 1);
+                initialize_pointer_field(pItem, iter);
+                return func(stream, iter->pos, pItem);
             }
             
         default:
-            return false;
+            PB_RETURN_ERROR(stream, "invalid field type");
     }
+#endif
 }
 
-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;
+    
+#ifdef PB_OLD_CALLBACK_STYLE
+    void *arg = pCallback->arg;
+#else
+    void **arg = &(pCallback->arg);
+#endif
     
-    // 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;
+        
+        do
         {
-            *(size_t*)pSize = 0;
-        }
+            if (!pCallback->funcs.decode(&substream, iter->pos, arg))
+                PB_RETURN_ERROR(stream, "callback failed");
+        } while (substream.bytes_left);
+        
+        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->pos, 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->pos->type))
+    {
+        case PB_ATYPE_STATIC:
+            return decode_static_field(stream, wire_type, iter);
+        
+        case PB_ATYPE_POINTER:
+            return decode_pointer_field(stream, wire_type, iter);
+        
+        case PB_ATYPE_CALLBACK:
+            return decode_callback_field(stream, wire_type, iter);
         
-        if (PB_HTYPE(fields[i].type) != PB_HTYPE_ARRAY &&
-            PB_HTYPE(fields[i].type) != PB_HTYPE_CALLBACK)
+        default:
+            PB_RETURN_ERROR(stream, "invalid field type");
+    }
+}
+
+/* Default handler for extension fields. Expects a pb_field_t structure
+ * in extension->type->arg. */
+static bool checkreturn default_extension_decoder(pb_istream_t *stream,
+    pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type)
+{
+    const pb_field_t *field = (const pb_field_t*)extension->type->arg;
+    pb_field_iterator_t iter;
+    
+    if (field->tag != tag)
+        return true;
+    
+    iter.start = field;
+    iter.pos = field;
+    iter.field_index = 0;
+    iter.required_field_index = 0;
+    iter.dest_struct = extension->dest;
+    iter.pData = extension->dest;
+    iter.pSize = &extension->found;
+    
+    return decode_field(stream, wire_type, &iter);
+}
+
+/* Try to decode an unknown field as an extension field. Tries each extension
+ * decoder in turn, until one of them handles the field or loop ends. */
+static bool checkreturn decode_extension(pb_istream_t *stream,
+    uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
+{
+    pb_extension_t *extension = *(pb_extension_t* const *)iter->pData;
+    size_t pos = stream->bytes_left;
+    
+    while (extension != NULL && pos == stream->bytes_left)
+    {
+        bool status;
+        if (extension->type->decode)
+            status = extension->type->decode(stream, extension, tag, wire_type);
+        else
+            status = default_extension_decoder(stream, extension, tag, wire_type);
+
+        if (!status)
+            return false;
+        
+        extension = extension->next;
+    }
+    
+    return true;
+}
+
+/* Step through the iterator until an extension field is found or until all
+ * entries have been checked. There can be only one extension field per
+ * message. Returns false if no extension field is found. */
+static bool checkreturn find_extension_field(pb_field_iterator_t *iter)
+{
+    unsigned start = iter->field_index;
+    
+    do {
+        if (PB_LTYPE(iter->pos->type) == PB_LTYPE_EXTENSION)
+            return true;
+        (void)pb_field_next(iter);
+    } while (iter->field_index != start);
+    
+    return false;
+}
+
+/* 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);
+    
+    do
+    {
+        pb_type_t type;
+        type = iter.pos->type;
+    
+        /* Avoid crash on empty message types (zero fields) */
+        if (iter.pos->tag == 0)
+            continue;
+        
+        if (PB_ATYPE(type) == PB_ATYPE_STATIC)
         {
-            if (fields[i].ptr != NULL)
+            if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
             {
-                memcpy(pData, fields[i].ptr, fields[i].data_size);
+                /* Set has_field to false. Still initialize the optional field
+                 * itself also. */
+                *(bool*)iter.pSize = false;
+            }
+            else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
+            {
+                /* Set array count to 0, no need to initialize contents. */
+                *(size_t*)iter.pSize = 0;
+                continue;
+            }
+            
+            if (PB_LTYPE(iter.pos->type) == PB_LTYPE_SUBMESSAGE)
+            {
+                /* Initialize submessage to defaults */
+                pb_message_set_to_defaults((const pb_field_t *) iter.pos->ptr, iter.pData);
+            }
+            else if (iter.pos->ptr != NULL)
+            {
+                /* Initialize to default value */
+                memcpy(iter.pData, iter.pos->ptr, iter.pos->data_size);
             }
             else
             {
-                memset(pData, 0, fields[i].data_size);
+                /* Initialize to zeros */
+                memset(iter.pData, 0, iter.pos->data_size);
             }
         }
-    }
+        else if (PB_ATYPE(type) == PB_ATYPE_POINTER)
+        {
+            /* Initialize the pointer to NULL. */
+            *(void**)iter.pData = NULL;
+            
+            /* Initialize array count to 0. */
+            if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
+            {
+                *(size_t*)iter.pSize = 0;
+            }
+        }
+        else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
+        {
+            /* 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, 0, 0, 0, 0, 0, 0, 0};
+    uint32_t extension_range_start = 0;
+    pb_field_iterator_t iter;
+    
+    pb_field_init(&iter, fields, dest_struct);
     
     while (stream->bytes_left)
     {
-        uint32_t temp;
-        if (!pb_decode_varint32(stream, &temp))
-            return false;
+        uint32_t tag;
+        pb_wire_type_t wire_type;
+        bool eof;
         
-        int tag = temp >> 3;
-        int wire_type = temp & 7;
-        
-        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, check if it matches an extension. */
+            if (tag >= extension_range_start)
+            {
+                if (!find_extension_field(&iter))
+                    extension_range_start = (uint32_t)-1;
+                else
+                    extension_range_start = iter.pos->tag;
+                
+                if (tag >= extension_range_start)
+                {
+                    size_t pos = stream->bytes_left;
+                
+                    if (!decode_extension(stream, tag, wire_type, &iter))
+                        return false;
+                    
+                    if (pos != stream->bytes_left)
+                    {
+                        /* The field was handled */
+                        continue;                    
+                    }
+                }
+            }
+        
+            /* No match found, skip data */
+            if (!pb_skip_field(stream, wire_type))
+                return false;
             continue;
         }
         
-        fields_seen |= 1 << (i & 31);
+        if (PB_HTYPE(iter.pos->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.pos->type;
+        } while (pb_field_next(&iter));
+        
+        /* Fixup if last field was also required. */
+        if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED && iter.pos->tag != 0)
+            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, void *dest)
+bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
 {
-    return pb_decode_varint32(stream, (uint32_t*)dest);
+    bool status;
+    pb_message_set_to_defaults(fields, dest_struct);
+    status = pb_decode_noinit(stream, fields, dest_struct);
+    
+#ifdef PB_ENABLE_MALLOC
+    if (!status)
+        pb_release(fields, dest_struct);
+#endif
+    
+    return status;
 }
 
-bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
 {
-    uint32_t *x = (uint32_t*)dest;
-    bool status = pb_decode_varint32(stream, x);
-    *x = (*x >> 1) ^ -(int32_t)(*x & 1);
+    pb_istream_t substream;
+    bool status;
+    
+    if (!pb_make_string_substream(stream, &substream))
+        return false;
+    
+    status = pb_decode(&substream, fields, dest_struct);
+    pb_close_string_substream(stream, &substream);
     return status;
 }
 
-bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
+#ifdef PB_ENABLE_MALLOC
+void pb_release(const pb_field_t fields[], void *dest_struct)
 {
-    uint8_t bytes[4] = {0};
-    bool status = pb_read(stream, bytes, 4);
+    pb_field_iterator_t iter;
+    pb_field_init(&iter, fields, dest_struct);
     
-#ifdef __BIG_ENDIAN__
-    uint8_t lebytes[4] = {bytes[3], bytes[2], bytes[1], bytes[0]};
-    memcpy(dest, lebytes, 4);
-#else
-    memcpy(dest, bytes, 4);
+    do
+    {
+        pb_type_t type;
+        type = iter.pos->type;
+    
+        /* Avoid crash on empty message types (zero fields) */
+        if (iter.pos->tag == 0)
+            continue;
+        
+        if (PB_ATYPE(type) == PB_ATYPE_POINTER)
+        {
+            if (PB_HTYPE(type) == PB_HTYPE_REPEATED &&
+                (PB_LTYPE(type) == PB_LTYPE_STRING ||
+                 PB_LTYPE(type) == PB_LTYPE_BYTES))
+            {
+                /* Release entries in repeated string or bytes array */
+                void **pItem = *(void***)iter.pData;
+                size_t count = *(size_t*)iter.pSize;
+                while (count--)
+                {
+                    pb_free(*pItem);
+                    *pItem++ = NULL;
+                }
+            }
+            else if (PB_LTYPE(type) == PB_LTYPE_SUBMESSAGE)
+            {
+                /* Release fields in submessages */
+                void *pItem = *(void**)iter.pData;
+                size_t count = (pItem ? 1 : 0);
+                
+                if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
+                {
+                    count = *(size_t*)iter.pSize;   
+                }
+                
+                while (count--)
+                {
+                    pb_release((const pb_field_t*)iter.pos->ptr, pItem);
+                    pItem = (uint8_t*)pItem + iter.pos->data_size;
+                }
+            }
+            
+            /* Release main item */
+            pb_free(*(void**)iter.pData);
+            *(void**)iter.pData = NULL;
+        }
+    } while (pb_field_next(&iter));
+}
 #endif
-    return status;
+
+/* Field decoders */
+
+bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
+{
+    uint64_t value;
+    if (!pb_decode_varint(stream, &value))
+        return false;
+    
+    if (value & 1)
+        *dest = (int64_t)(~(value >> 1));
+    else
+        *dest = (int64_t)(value >> 1);
+    
+    return true;
 }
 
-bool pb_dec_uint64(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
 {
-    return pb_decode_varint64(stream, (uint64_t*)dest);
+    #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_sint64(pb_istream_t *stream, const pb_field_t *field, void *dest)
+bool pb_decode_fixed64(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[8];
+    
+    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_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
+static bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    uint8_t bytes[8] = {0};
-    bool status = pb_read(stream, bytes, 8);
+    uint64_t value;
+    if (!pb_decode_varint(stream, &value))
+        return false;
     
-#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;
+    switch (field->data_size)
+    {
+        case 1: *(int8_t*)dest = (int8_t)value; break;
+        case 2: *(int16_t*)dest = (int16_t)value; break;
+        case 4: *(int32_t*)dest = (int32_t)value; break;
+        case 8: *(int64_t*)dest = (int64_t)value; break;
+        default: PB_RETURN_ERROR(stream, "invalid data_size");
+    }
+    
+    return true;
 }
 
-bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, void *dest)
+static bool checkreturn pb_dec_uvarint(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;
-    return status;
+    uint64_t value;
+    if (!pb_decode_varint(stream, &value))
+        return false;
+    
+    switch (field->data_size)
+    {
+        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 true;
 }
 
-bool pb_dec_enum(pb_istream_t *stream, const pb_field_t *field, void *dest)
+static 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);
-    return status;
+    int64_t value;
+    if (!pb_decode_svarint(stream, &value))
+        return false;
+    
+    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 true;
 }
 
-bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, void *dest)
+static 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, void *dest)
+static 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, void *dest)
+static 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;
+    uint32_t size;
+    pb_bytes_array_t *bdest;
     
-    uint32_t temp;
-    if (!pb_decode_varint32(stream, &temp))
+    if (!pb_decode_varint32(stream, &size))
         return false;
-    x->size = temp;
     
-    // Note: data_size includes the size of the x.size field, too.
-    // Calculate actual size starting from offset.
-    if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
-        return false;
+    if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
+    {
+#ifndef PB_ENABLE_MALLOC
+        PB_RETURN_ERROR(stream, "no malloc support");
+#else
+        if (!allocate_field(stream, dest, PB_BYTES_ARRAY_T_ALLOCSIZE(size), 1))
+            return false;
+        bdest = *(pb_bytes_array_t**)dest;
+#endif
+    }
+    else
+    {
+        if (PB_BYTES_ARRAY_T_ALLOCSIZE(size) > field->data_size)
+            PB_RETURN_ERROR(stream, "bytes overflow");
+        bdest = (pb_bytes_array_t*)dest;
+    }
     
-    return pb_read(stream, x->bytes, x->size);
+    bdest->size = size;
+    return pb_read(stream, bdest->bytes, size);
 }
 
-bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
+static bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
     uint32_t size;
+    size_t alloc_size;
+    bool status;
     if (!pb_decode_varint32(stream, &size))
         return false;
     
-    if (size > field->data_size - 1)
-        return false;
+    /* Space for null terminator */
+    alloc_size = size + 1;
     
-    bool status = pb_read(stream, (uint8_t*)dest, size);
+    if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
+    {
+#ifndef PB_ENABLE_MALLOC
+        PB_RETURN_ERROR(stream, "no malloc support");
+#else
+        if (!allocate_field(stream, dest, alloc_size, 1))
+            return false;
+        dest = *(void**)dest;
+#endif
+    }
+    else
+    {
+        if (alloc_size > 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)
+static 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");
     
-    return pb_decode(&substream, (pb_field_t*)field->ptr, dest);
+    /* 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);
+    
+    pb_close_string_substream(stream, &substream);
+    return status;
 }