protobuf/upb/wire/decode.h

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// upb_decode: parsing into a upb_Message using a upb_MiniTable.

#ifndef UPB_WIRE_DECODE_H_
#define UPB_WIRE_DECODE_H_

#include "upb/mem/arena.h"
#include "upb/message/message.h"
#include "upb/mini_table/extension_registry.h"

// Must be last.
#include "upb/port/def.inc"

#ifdef __cplusplus
extern "C" {
#endif

enum {
  /* If set, strings will alias the input buffer instead of copying into the
   * arena. */
  kUpb_DecodeOption_AliasString = 1,

  /* If set, the parse will return failure if any message is missing any
   * required fields when the message data ends.  The parse will still continue,
   * and the failure will only be reported at the end.
   *
   * IMPORTANT CAVEATS:
   *
   * 1. This can throw a false positive failure if an incomplete message is seen
   *    on the wire but is later completed when the sub-message occurs again.
   *    For this reason, a second pass is required to verify a failure, to be
   *    truly robust.
   *
   * 2. This can return a false success if you are decoding into a message that
   *    already has some sub-message fields present.  If the sub-message does
   *    not occur in the binary payload, we will never visit it and discover the
   *    incomplete sub-message.  For this reason, this check is only useful for
   *    implemting ParseFromString() semantics.  For MergeFromString(), a
   *    post-parse validation step will always be necessary. */
  kUpb_DecodeOption_CheckRequired = 2,
};

UPB_INLINE uint32_t upb_DecodeOptions_MaxDepth(uint16_t depth) {
  return (uint32_t)depth << 16;
}

UPB_INLINE uint16_t upb_DecodeOptions_GetMaxDepth(uint32_t options) {
  return options >> 16;
}

// Enforce an upper bound on recursion depth.
UPB_INLINE int upb_Decode_LimitDepth(uint32_t decode_options, uint32_t limit) {
  uint32_t max_depth = upb_DecodeOptions_GetMaxDepth(decode_options);
  if (max_depth > limit) max_depth = limit;
  return upb_DecodeOptions_MaxDepth(max_depth) | (decode_options & 0xffff);
}

typedef enum {
  kUpb_DecodeStatus_Ok = 0,
  kUpb_DecodeStatus_Malformed = 1,    // Wire format was corrupt
  kUpb_DecodeStatus_OutOfMemory = 2,  // Arena alloc failed
  kUpb_DecodeStatus_BadUtf8 = 3,      // String field had bad UTF-8
  kUpb_DecodeStatus_MaxDepthExceeded =
      4,  // Exceeded upb_DecodeOptions_MaxDepth

  // kUpb_DecodeOption_CheckRequired failed (see above), but the parse otherwise
  // succeeded.
  kUpb_DecodeStatus_MissingRequired = 5,
} upb_DecodeStatus;

UPB_API upb_DecodeStatus upb_Decode(const char* buf, size_t size,
                                    upb_Message* msg, const upb_MiniTable* l,
                                    const upb_ExtensionRegistry* extreg,
                                    int options, upb_Arena* arena);

#ifdef __cplusplus
} /* extern "C" */
#endif

#include "upb/port/undef.inc"

#endif /* UPB_WIRE_DECODE_H_ */