| /* |
| ** Internal implementation details of the decoder that are shared between |
| ** decode.c and decode_fast.c. |
| */ |
| |
| #ifndef UPB_DECODE_INT_H_ |
| #define UPB_DECODE_INT_H_ |
| |
| #include <setjmp.h> |
| |
| #include "upb/msg.h" |
| #include "upb/upb.int.h" |
| |
| /* Must be last. */ |
| #include "upb/port_def.inc" |
| |
| #define DECODE_NOGROUP -1 |
| |
| typedef struct upb_decstate { |
| const char *end; /* Can read up to 16 bytes slop beyond this. */ |
| const char *limit_ptr; /* = end + UPB_MIN(limit, 0) */ |
| upb_msg *unknown_msg; /* If non-NULL, add unknown data at buffer flip. */ |
| const char *unknown; /* Start of unknown data. */ |
| int limit; /* Submessage limit relative to end. */ |
| int depth; |
| uint32_t end_group; /* field number of END_GROUP tag, else DECODE_NOGROUP */ |
| bool alias; |
| char patch[32]; |
| upb_arena arena; |
| jmp_buf err; |
| } upb_decstate; |
| |
| /* Error function that will abort decoding with longjmp(). We can't declare this |
| * UPB_NORETURN, even though it is appropriate, because if we do then compilers |
| * will "helpfully" refuse to tailcall to it |
| * (see: https://stackoverflow.com/a/55657013), which will defeat a major goal |
| * of our optimizations. That is also why we must declare it in a separate file, |
| * otherwise the compiler will see that it calls longjmp() and deduce that it is |
| * noreturn. */ |
| const char *fastdecode_err(upb_decstate *d); |
| |
| extern const uint8_t upb_utf8_offsets[]; |
| |
| UPB_INLINE |
| bool decode_verifyutf8_inl(const char *buf, int len) { |
| int i, j; |
| uint8_t offset; |
| |
| i = 0; |
| while (i < len) { |
| offset = upb_utf8_offsets[(uint8_t)buf[i]]; |
| if (offset == 0 || i + offset > len) { |
| return false; |
| } |
| for (j = i + 1; j < i + offset; j++) { |
| if ((buf[j] & 0xc0) != 0x80) { |
| return false; |
| } |
| } |
| i += offset; |
| } |
| return i == len; |
| } |
| |
| /* x86-64 pointers always have the high 16 bits matching. So we can shift |
| * left 8 and right 8 without loss of information. */ |
| UPB_INLINE intptr_t decode_totable(const upb_msglayout *tablep) { |
| return ((intptr_t)tablep << 8) | tablep->table_mask; |
| } |
| |
| UPB_INLINE const upb_msglayout *decode_totablep(intptr_t table) { |
| return (const upb_msglayout*)(table >> 8); |
| } |
| |
| UPB_INLINE |
| const char *decode_isdonefallback_inl(upb_decstate *d, const char *ptr, |
| int overrun) { |
| if (overrun < d->limit) { |
| /* Need to copy remaining data into patch buffer. */ |
| UPB_ASSERT(overrun < 16); |
| if (d->unknown_msg) { |
| if (!_upb_msg_addunknown(d->unknown_msg, d->unknown, ptr - d->unknown, |
| &d->arena)) { |
| return NULL; |
| } |
| d->unknown = &d->patch[0] + overrun; |
| } |
| memset(d->patch + 16, 0, 16); |
| memcpy(d->patch, d->end, 16); |
| ptr = &d->patch[0] + overrun; |
| d->end = &d->patch[16]; |
| d->limit -= 16; |
| d->limit_ptr = d->end + d->limit; |
| d->alias = false; |
| UPB_ASSERT(ptr < d->limit_ptr); |
| return ptr; |
| } else { |
| return NULL; |
| } |
| } |
| |
| const char *decode_isdonefallback(upb_decstate *d, const char *ptr, |
| int overrun); |
| |
| UPB_INLINE |
| bool decode_isdone(upb_decstate *d, const char **ptr) { |
| int overrun = *ptr - d->end; |
| if (UPB_LIKELY(*ptr < d->limit_ptr)) { |
| return false; |
| } else if (UPB_LIKELY(overrun == d->limit)) { |
| return true; |
| } else { |
| *ptr = decode_isdonefallback(d, *ptr, overrun); |
| return false; |
| } |
| } |
| |
| UPB_INLINE |
| const char *fastdecode_tagdispatch(upb_decstate *d, const char *ptr, |
| upb_msg *msg, intptr_t table, |
| uint64_t hasbits, uint32_t tag) { |
| const upb_msglayout *table_p = decode_totablep(table); |
| uint8_t mask = table; |
| uint64_t data; |
| size_t idx = tag & mask; |
| UPB_ASSUME((idx & 7) == 0); |
| idx >>= 3; |
| data = table_p->fasttable[idx].field_data ^ tag; |
| return table_p->fasttable[idx].field_parser(d, ptr, msg, table, hasbits, data); |
| } |
| |
| UPB_INLINE uint32_t fastdecode_loadtag(const char* ptr) { |
| uint16_t tag; |
| memcpy(&tag, ptr, 2); |
| return tag; |
| } |
| |
| UPB_INLINE void decode_checklimit(upb_decstate *d) { |
| UPB_ASSERT(d->limit_ptr == d->end + UPB_MIN(0, d->limit)); |
| } |
| |
| UPB_INLINE int decode_pushlimit(upb_decstate *d, const char *ptr, int size) { |
| int limit = size + (int)(ptr - d->end); |
| int delta = d->limit - limit; |
| decode_checklimit(d); |
| d->limit = limit; |
| d->limit_ptr = d->end + UPB_MIN(0, limit); |
| decode_checklimit(d); |
| return delta; |
| } |
| |
| UPB_INLINE void decode_poplimit(upb_decstate *d, const char *ptr, |
| int saved_delta) { |
| UPB_ASSERT(ptr - d->end == d->limit); |
| decode_checklimit(d); |
| d->limit += saved_delta; |
| d->limit_ptr = d->end + UPB_MIN(0, d->limit); |
| decode_checklimit(d); |
| } |
| |
| #include "upb/port_undef.inc" |
| |
| #endif /* UPB_DECODE_INT_H_ */ |