WSHUB-458: cborparser: Pass CborValue to operation routines.

The `token` parameter is not sufficient since it is effectively shared
by all `CborValue` instances.  Since `tinycbor` often uses a temporary
`CborValue` context to perform some operation, we need to store our
context inside that `CborValue` so that we don't pollute the global
state of the reader.

Author: sjlongland

src/cbor.h

@@ -330,25 +330,21 @@ struct CborParserOperations
      * called before \ref read_bytes and \ref transfer_bytes to ensure it is safe
      * to read the requested number of bytes from the reader.
      *
-     * \param   token   An opaque object passed to \ref cbor_parser_init_reader
-     *                  that may be used to pass context information between the
-     *                  \ref CborParserOperations methods.
+     * \param   value   The CBOR value being parsed.
      *
      * \param   len     The number of bytes sought.
      *
      * \retval  true    \a len bytes may be read from the reader.
      * \retval  false   Insufficient data is available to be read at this time.
      */
-    bool (*can_read_bytes)(void *token, size_t len);
+    bool (*can_read_bytes)(const struct CborValue *value, size_t len);
 
     /**
      * Reads \a len bytes from the reader starting at \a offset bytes from
      * the current read position and copies them to \a dst.  The read pointer
      * is *NOT* modified by this operation.
      *
-     * \param   token   An opaque object passed to \ref cbor_parser_init_reader
-     *                  that may be used to pass context information between the
-     *                  \ref CborParserOperations methods.
+     * \param   value   The CBOR value being parsed.
      *
      * \param   dst     The buffer the read bytes will be copied to.
      *
@@ -357,19 +353,17 @@ struct CborParserOperations
      *
      * \param   len     The number of bytes sought.
      */
-    void *(*read_bytes)(void *token, void *dst, size_t offset, size_t len);
+    void *(*read_bytes)(const struct CborValue *value, void *dst, size_t offset, size_t len);
 
     /**
      * Skips past \a len bytes from the reader without reading them.  The read
      * pointer is advanced in the process.
      *
-     * \param   token   An opaque object passed to \ref cbor_parser_init_reader
-     *                  that may be used to pass context information between the
-     *                  \ref CborParserOperations methods.
+     * \param   value   The CBOR value being parsed.
      *
      * \param   len     The number of bytes skipped.
      */
-    void (*advance_bytes)(void *token, size_t len);
+    void (*advance_bytes)(struct CborValue *value, size_t len);
 
     /**
      * Overwrite the user-supplied pointer \a userptr with the address where the
@@ -379,9 +373,7 @@ struct CborParserOperations
      * This routine is used for accessing strings embedded in CBOR documents
      * (both text and binary strings).
      *
-     * \param   token   An opaque object passed to \ref cbor_parser_init_reader
-     *                  that may be used to pass context information between the
-     *                  \ref CborParserOperations methods.
+     * \param   value   The CBOR value being parsed.
      *
      * \param   userptr The pointer that will be updated to reference the location
      *                  of the data in the buffer.
@@ -391,7 +383,7 @@ struct CborParserOperations
      *
      * \param   len     The number of bytes sought.
      */
-    CborError (*transfer_string)(void *token, const void **userptr, size_t offset, size_t len);
+    CborError (*transfer_string)(struct CborValue *value, const void **userptr, size_t offset, size_t len);
 };
 
 struct CborParser

src/cborinternal_p.h

@@ -176,9 +176,9 @@ static inline bool can_read_bytes(const CborValue *it, size_t n)
     if (CBOR_PARSER_READER_CONTROL >= 0) {
         if (it->parser->flags & CborParserFlag_ExternalSource || CBOR_PARSER_READER_CONTROL != 0) {
 #ifdef CBOR_PARSER_CAN_READ_BYTES_FUNCTION
-            return CBOR_PARSER_CAN_READ_BYTES_FUNCTION(it->source.token, n);
+            return CBOR_PARSER_CAN_READ_BYTES_FUNCTION(it, n);
 #else
-            return it->parser->source.ops->can_read_bytes(it->source.token, n);
+            return it->parser->source.ops->can_read_bytes(it, n);
 #endif
         }
     }
@@ -194,9 +194,9 @@ static inline void advance_bytes(CborValue *it, size_t n)
     if (CBOR_PARSER_READER_CONTROL >= 0) {
         if (it->parser->flags & CborParserFlag_ExternalSource || CBOR_PARSER_READER_CONTROL != 0) {
 #ifdef CBOR_PARSER_ADVANCE_BYTES_FUNCTION
-            CBOR_PARSER_ADVANCE_BYTES_FUNCTION(it->source.token, n);
+            CBOR_PARSER_ADVANCE_BYTES_FUNCTION(it, n);
 #else
-            it->parser->source.ops->advance_bytes(it->source.token, n);
+            it->parser->source.ops->advance_bytes(it, n);
 #endif
             return;
         }
@@ -210,9 +210,9 @@ static inline CborError transfer_string(CborValue *it, const void **ptr, size_t
     if (CBOR_PARSER_READER_CONTROL >= 0) {
         if (it->parser->flags & CborParserFlag_ExternalSource || CBOR_PARSER_READER_CONTROL != 0) {
 #ifdef CBOR_PARSER_TRANSFER_STRING_FUNCTION
-            return CBOR_PARSER_TRANSFER_STRING_FUNCTION(it->source.token, ptr, offset, len);
+            return CBOR_PARSER_TRANSFER_STRING_FUNCTION(it, ptr, offset, len);
 #else
-            return it->parser->source.ops->transfer_string(it->source.token, ptr, offset, len);
+            return it->parser->source.ops->transfer_string(it, ptr, offset, len);
 #endif
         }
     }
@@ -231,9 +231,9 @@ static inline void *read_bytes_unchecked(const CborValue *it, void *dst, size_t
     if (CBOR_PARSER_READER_CONTROL >= 0) {
         if (it->parser->flags & CborParserFlag_ExternalSource || CBOR_PARSER_READER_CONTROL != 0) {
 #ifdef CBOR_PARSER_READ_BYTES_FUNCTION
-            return CBOR_PARSER_READ_BYTES_FUNCTION(it->source.token, dst, offset, n);
+            return CBOR_PARSER_READ_BYTES_FUNCTION(it, dst, offset, n);
 #else
-            return it->parser->source.ops->read_bytes(it->source.token, dst, offset, n);
+            return it->parser->source.ops->read_bytes(it, dst, offset, n);
 #endif
         }
     }

tests/parser/tst_parser.cpp

@@ -763,21 +763,21 @@ struct Input {
 };
 
 static const CborParserOperations byteArrayOps = {
-    /* can_read_bytes = */ [](void *token, size_t len) {
-        auto input = static_cast<Input *>(token);
+    /* can_read_bytes = */ [](const CborValue *value, size_t len) {
+        auto input = static_cast<Input *>(value->source.token);
         return input->data.size() - input->consumed >= int(len);
     },
-    /* read_bytes = */ [](void *token, void *dst, size_t offset, size_t len) {
-        auto input = static_cast<Input *>(token);
+    /* read_bytes = */ [](const CborValue *value, void *dst, size_t offset, size_t len) {
+        auto input = static_cast<Input *>(value->source.token);
         return memcpy(dst, input->data.constData() + input->consumed + offset, len);
     },
-    /* advance_bytes = */ [](void *token, size_t len) {
-        auto input = static_cast<Input *>(token);
+    /* advance_bytes = */ [](CborValue *value, size_t len) {
+        auto input = static_cast<Input *>(value->source.token);
         input->consumed += int(len);
     },
-    /* transfer_string = */ [](void *token, const void **userptr, size_t offset, size_t len) {
+    /* transfer_string = */ [](CborValue *value, const void **userptr, size_t offset, size_t len) {
         // ###
-        auto input = static_cast<Input *>(token);
+        auto input = static_cast<Input *>(value->source.token);
         if (input->data.size() - input->consumed < int(len + offset))
             return CborErrorUnexpectedEOF;
         input->consumed += int(offset);