diff options
author | Joshua Haberman <joshua@reverberate.org> | 2010-01-15 18:12:28 -0800 |
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committer | Joshua Haberman <joshua@reverberate.org> | 2010-01-15 18:12:28 -0800 |
commit | 9116c697f845e7ca215628029800c36f7dfbfaee (patch) | |
tree | f5f416d54f9fb1034abc40022855dbc2fbec61a7 /src/upb_decoder.c | |
parent | 57d6353a3c225cbfa523d7f15cef2691e8806741 (diff) |
upb_parser -> upb_decoder
Diffstat (limited to 'src/upb_decoder.c')
-rw-r--r-- | src/upb_decoder.c | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/src/upb_decoder.c b/src/upb_decoder.c new file mode 100644 index 0000000..ff9753d --- /dev/null +++ b/src/upb_decoder.c @@ -0,0 +1,507 @@ +/* + * upb - a minimalist implementation of protocol buffers. + * + * Copyright (c) 2008-2009 Joshua Haberman. See LICENSE for details. + */ + +#include "upb_decoder.h" + +#include <inttypes.h> +#include <stddef.h> +#include <stdlib.h> +#include "upb_def.h" + +/* Functions to read wire values. *********************************************/ + +// These functions are internal to the decode, but might be moved into an +// internal header file if we at some point in the future opt to do code +// generation, because the generated code would want to inline these functions. +// The same applies to the functions to read .proto values below. + +const uint8_t *upb_get_v_uint64_t_full(const uint8_t *buf, const uint8_t *end, + uint64_t *val, + struct upb_status *status); + +// Gets a varint (wire type: UPB_WIRE_TYPE_VARINT). +INLINE const uint8_t *upb_get_v_uint64_t(const uint8_t *buf, const uint8_t *end, + uint64_t *val, + struct upb_status *status) +{ + // We inline this common case (1-byte varints), if that fails we dispatch to + // the full (non-inlined) version. + if((*buf & 0x80) == 0) { + *val = *buf & 0x7f; + return buf + 1; + } else { + return upb_get_v_uint64_t_full(buf, end, val, status); + } +} + +// Gets a varint -- called when we only need 32 bits of it. Note that a 32-bit +// varint is not a true wire type. +INLINE const uint8_t *upb_get_v_uint32_t(const uint8_t *buf, const uint8_t *end, + uint32_t *val, + struct upb_status *status) +{ + uint64_t val64; + const uint8_t *ret = upb_get_v_uint64_t(buf, end, &val64, status); + *val = (uint32_t)val64; // Discard the high bits. + return ret; +} + +// Gets a fixed-length 32-bit integer (wire type: UPB_WIRE_TYPE_32BIT). +INLINE const uint8_t *upb_get_f_uint32_t(const uint8_t *buf, const uint8_t *end, + uint32_t *val, struct upb_status *status) +{ + const uint8_t *uint32_end = buf + sizeof(uint32_t); + if(uint32_end > end) { + status->code = UPB_STATUS_NEED_MORE_DATA; + return end; + } +#if UPB_UNALIGNED_READS_OK + *val = *(uint32_t*)buf; +#else +#define SHL(val, bits) ((uint32_t)val << bits) + *val = SHL(buf[0], 0) | SHL(buf[1], 8) | SHL(buf[2], 16) | SHL(buf[3], 24); +#undef SHL +#endif + return uint32_end; +} + +// Gets a fixed-length 64-bit integer (wire type: UPB_WIRE_TYPE_64BIT). +INLINE const uint8_t *upb_get_f_uint64_t(const uint8_t *buf, const uint8_t *end, + uint64_t *val, + struct upb_status *status) +{ + const uint8_t *uint64_end = buf + sizeof(uint64_t); + if(uint64_end > end) { + status->code = UPB_STATUS_NEED_MORE_DATA; + return end; + } +#if UPB_UNALIGNED_READS_OK + *val = *(uint64_t*)buf; +#else +#define SHL(val, bits) ((uint64_t)val << bits) + *val = SHL(buf[0], 0) | SHL(buf[1], 8) | SHL(buf[2], 16) | SHL(buf[3], 24) | + SHL(buf[4], 32) | SHL(buf[5], 40) | SHL(buf[6], 48) | SHL(buf[7], 56); +#undef SHL +#endif + return uint64_end; +} + +INLINE const uint8_t *upb_skip_v_uint64_t(const uint8_t *buf, + const uint8_t *end, + struct upb_status *status) +{ + const uint8_t *const maxend = buf + 10; + uint8_t last = 0x80; + for(; buf < (uint8_t*)end && (last & 0x80); buf++) + last = *buf; + + if(buf >= end && buf <= maxend && (last & 0x80)) { + status->code = UPB_STATUS_NEED_MORE_DATA; + buf = end; + } else if(buf > maxend) { + status->code = UPB_ERROR_UNTERMINATED_VARINT; + buf = end; + } + return buf; +} + +INLINE const uint8_t *upb_skip_f_uint32_t(const uint8_t *buf, + const uint8_t *end, + struct upb_status *status) +{ + const uint8_t *uint32_end = buf + sizeof(uint32_t); + if(uint32_end > end) { + status->code = UPB_STATUS_NEED_MORE_DATA; + return end; + } + return uint32_end; +} + +INLINE const uint8_t *upb_skip_f_uint64_t(const uint8_t *buf, + const uint8_t *end, + struct upb_status *status) +{ + const uint8_t *uint64_end = buf + sizeof(uint64_t); + if(uint64_end > end) { + status->code = UPB_STATUS_NEED_MORE_DATA; + return end; + } + return uint64_end; +} + +/* Functions to read .proto values. *******************************************/ + +// Performs zig-zag decoding, which is used by sint32 and sint64. +INLINE int32_t upb_zzdec_32(uint32_t n) { return (n >> 1) ^ -(int32_t)(n & 1); } +INLINE int64_t upb_zzdec_64(uint64_t n) { return (n >> 1) ^ -(int64_t)(n & 1); } + +// Use macros to define a set of two functions for each .proto type: +// +// // Reads and converts a .proto value from buf, placing it in d. +// // "end" indicates the end of the current buffer (if the buffer does +// // not contain the entire value UPB_STATUS_NEED_MORE_DATA is returned). +// // On success, a pointer will be returned to the first byte that was +// // not consumed. +// const uint8_t *upb_get_INT32(const uint8_t *buf, const uint8_t *end, +// int32_t *d, struct upb_status *status); +// +// // Given an already read wire value s (source), convert it to a .proto +// // value and return it. +// int32_t upb_wvtov_INT32(uint32_t s); +// +// These are the most efficient functions to call if you want to decode a value +// for a known type. + +#define WVTOV(type, wire_t, val_t) \ + INLINE val_t upb_wvtov_ ## type(wire_t s) + +#define GET(type, v_or_f, wire_t, val_t, member_name) \ + INLINE const uint8_t *upb_get_ ## type(const uint8_t *buf, const uint8_t *end, \ + val_t *d, struct upb_status *status) { \ + wire_t tmp = 0; \ + const uint8_t *ret = upb_get_ ## v_or_f ## _ ## wire_t(buf, end, &tmp, status); \ + *d = upb_wvtov_ ## type(tmp); \ + return ret; \ + } + +#define T(type, v_or_f, wire_t, val_t, member_name) \ + WVTOV(type, wire_t, val_t); /* prototype for GET below */ \ + GET(type, v_or_f, wire_t, val_t, member_name) \ + WVTOV(type, wire_t, val_t) + +T(INT32, v, uint32_t, int32_t, int32) { return (int32_t)s; } +T(INT64, v, uint64_t, int64_t, int64) { return (int64_t)s; } +T(UINT32, v, uint32_t, uint32_t, uint32) { return s; } +T(UINT64, v, uint64_t, uint64_t, uint64) { return s; } +T(SINT32, v, uint32_t, int32_t, int32) { return upb_zzdec_32(s); } +T(SINT64, v, uint64_t, int64_t, int64) { return upb_zzdec_64(s); } +T(FIXED32, f, uint32_t, uint32_t, uint32) { return s; } +T(FIXED64, f, uint64_t, uint64_t, uint64) { return s; } +T(SFIXED32, f, uint32_t, int32_t, int32) { return (int32_t)s; } +T(SFIXED64, f, uint64_t, int64_t, int64) { return (int64_t)s; } +T(BOOL, v, uint32_t, bool, _bool) { return (bool)s; } +T(ENUM, v, uint32_t, int32_t, int32) { return (int32_t)s; } +T(DOUBLE, f, uint64_t, double, _double) { + union upb_value v; + v.uint64 = s; + return v._double; +} +T(FLOAT, f, uint32_t, float, _float) { + union upb_value v; + v.uint32 = s; + return v._float; +} + +#undef WVTOV +#undef GET +#undef T + +// Parses a tag, places the result in *tag. +INLINE const uint8_t *decode_tag(const uint8_t *buf, const uint8_t *end, + struct upb_tag *tag, struct upb_status *status) +{ + uint32_t tag_int; + const uint8_t *ret = upb_get_v_uint32_t(buf, end, &tag_int, status); + tag->wire_type = (upb_wire_type_t)(tag_int & 0x07); + tag->field_number = tag_int >> 3; + return ret; +} + + +/** + * Parses a 64-bit varint that is known to be >= 2 bytes (the inline version + * handles 1 and 2 byte varints). + */ +const uint8_t *upb_get_v_uint64_t_full(const uint8_t *buf, const uint8_t *end, + uint64_t *val, struct upb_status *status) +{ + const uint8_t *const maxend = buf + 10; + uint8_t last = 0x80; + *val = 0; + int bitpos; + + for(bitpos = 0; buf < (uint8_t*)end && (last & 0x80); buf++, bitpos += 7) + *val |= ((uint64_t)((last = *buf) & 0x7F)) << bitpos; + + if(buf >= end && buf <= maxend && (last & 0x80)) { + upb_seterr(status, UPB_STATUS_NEED_MORE_DATA, + "Provided data ended in the middle of a varint.\n"); + buf = end; + } else if(buf > maxend) { + upb_seterr(status, UPB_ERROR_UNTERMINATED_VARINT, + "Varint was unterminated after 10 bytes.\n"); + buf = end; + } + + return buf; +} + +const uint8_t *upb_decode_wire_value(uint8_t *buf, uint8_t *end, + upb_wire_type_t wt, + union upb_wire_value *wv, + struct upb_status *status) +{ + switch(wt) { + case UPB_WIRE_TYPE_VARINT: + return upb_get_v_uint64_t(buf, end, &wv->varint, status); + case UPB_WIRE_TYPE_64BIT: + return upb_get_f_uint64_t(buf, end, &wv->_64bit, status); + case UPB_WIRE_TYPE_32BIT: + return upb_get_f_uint32_t(buf, end, &wv->_32bit, status); + default: + status->code = UPB_STATUS_ERROR; // Doesn't handle delimited, groups. + return end; + } +} + +/** + * Advances buf past the current wire value (of type wt), saving the result in + * outbuf. + */ +static const uint8_t *skip_wire_value(const uint8_t *buf, const uint8_t *end, + upb_wire_type_t wt, + struct upb_status *status) +{ + switch(wt) { + case UPB_WIRE_TYPE_VARINT: + return upb_skip_v_uint64_t(buf, end, status); + case UPB_WIRE_TYPE_64BIT: + return upb_skip_f_uint64_t(buf, end, status); + case UPB_WIRE_TYPE_32BIT: + return upb_skip_f_uint32_t(buf, end, status); + case UPB_WIRE_TYPE_START_GROUP: + // TODO: skip to matching end group. + case UPB_WIRE_TYPE_END_GROUP: + return buf; + default: + status->code = UPB_STATUS_ERROR; + return end; + } +} + +static const uint8_t *upb_decode_value(const uint8_t *buf, const uint8_t *end, + upb_field_type_t ft, + union upb_value_ptr v, + struct upb_status *status) +{ +#define CASE(t, member_name) \ + case UPB_TYPE(t): return upb_get_ ## t(buf, end, v.member_name, status); + + switch(ft) { + CASE(DOUBLE, _double) + CASE(FLOAT, _float) + CASE(INT32, int32) + CASE(INT64, int64) + CASE(UINT32, uint32) + CASE(UINT64, uint64) + CASE(SINT32, int32) + CASE(SINT64, int64) + CASE(FIXED32, uint32) + CASE(FIXED64, uint64) + CASE(SFIXED32, int32) + CASE(SFIXED64, int64) + CASE(BOOL, _bool) + CASE(ENUM, int32) + default: return end; + } + +#undef CASE +} + +struct upb_decoder_frame { + struct upb_msgdef *msgdef; + struct upb_fielddef *field; + size_t end_offset; // For groups, 0. +}; + +struct upb_decoder { + // Immutable state of the decoder. + struct upb_msgdef *toplevel_msgdef; + upb_sink *sink; + + // State pertaining to a particular decode (resettable). + // Stack entries store the offset where the submsg ends (for groups, 0). + struct upb_decoder_frame stack[UPB_MAX_NESTING], *top, *limit; + size_t completed_offset; + void *udata; +}; + +upb_decoder *upb_decoder_new(struct upb_msgdef *msgdef) +{ + upb_decoder *d = malloc(sizeof(*d)); + d->toplevel_msgdef = msgdef; + d->limit = &d->stack[UPB_MAX_NESTING]; + return d; +} + +void upb_decoder_free(upb_decoder *d) +{ + free(d); +} + +void upb_decoder_reset(upb_decoder *d, upb_sink *sink) +{ + d->top = d->stack; + d->completed_offset = 0; + d->sink = sink; + d->top->msgdef = d->toplevel_msgdef; + // The top-level message is not delimited (we can keep receiving data for it + // indefinitely), so we treat it like a group. + d->top->end_offset = 0; +} + +static const void *get_msgend(upb_decoder *d, const uint8_t *start) +{ + if(d->top->end_offset > 0) + return start + (d->top->end_offset - d->completed_offset); + else + return (void*)UINTPTR_MAX; // group. +} + +static bool isgroup(const void *submsg_end) +{ + return submsg_end == (void*)UINTPTR_MAX; +} + +extern upb_wire_type_t upb_expected_wire_types[]; +// Returns true if wt is the correct on-the-wire type for ft. +INLINE bool upb_check_type(upb_wire_type_t wt, upb_field_type_t ft) { + // This doesn't currently support packed arrays. + return upb_type_info[ft].expected_wire_type == wt; +} + + +/** + * Pushes a new stack frame for a submessage with the given len (which will + * be zero if the submessage is a group). + */ +static const uint8_t *push(upb_decoder *d, const uint8_t *start, + uint32_t submsg_len, struct upb_fielddef *f, + struct upb_status *status) +{ + d->top->field = f; + d->top++; + if(d->top >= d->limit) { + upb_seterr(status, UPB_STATUS_ERROR, + "Nesting exceeded maximum (%d levels)\n", + UPB_MAX_NESTING); + return NULL; + } + struct upb_decoder_frame *frame = d->top; + frame->end_offset = d->completed_offset + submsg_len; + frame->msgdef = upb_downcast_msgdef(f->def); + + upb_sink_onstart(d->sink, f); + return get_msgend(d, start); +} + +/** + * Pops a stack frame, returning a pointer for where the next submsg should + * end (or a pointer that is out of range for a group). + */ +static const void *pop(upb_decoder *d, const uint8_t *start) +{ + d->top--; + upb_sink_onend(d->sink, d->top->field); + return get_msgend(d, start); +} + + +size_t upb_decoder_decode(upb_decoder *d, upb_strptr str, struct upb_status *status) +{ + // buf is our current offset, moves from start to end. + const uint8_t *buf = (uint8_t*)upb_string_getrobuf(str); + const uint8_t *const start = buf; // ptr equivalent of d->completed_offset + const uint8_t *const end = buf + upb_strlen(str); + + // When we have fully decoded a tag/value pair, we advance this. + const uint8_t *completed = buf; + + const uint8_t *submsg_end = get_msgend(d, start); + struct upb_msgdef *msgdef = d->top->msgdef; + upb_sink_status sink_status = UPB_SINK_CONTINUE; + + // We need to check the status of operations that can fail, but we do so as + // late as possible to avoid introducing branches that have to wait on + // (status->code) which must be loaded from memory. We must always check + // before calling a user callback. +#define CHECK_STATUS() do { if(!upb_ok(status)) goto err; } while(0) + + // Main loop: executed once per tag/field pair. + while(sink_status == UPB_SINK_CONTINUE && buf < end) { + // Parse/handle tag. + struct upb_tag tag; + buf = decode_tag(buf, end, &tag, status); + if(tag.wire_type == UPB_WIRE_TYPE_END_GROUP) { + CHECK_STATUS(); + if(!isgroup(submsg_end)) { + upb_seterr(status, UPB_STATUS_ERROR, "End group seen but current " + "message is not a group, byte offset: %zd", + d->completed_offset + (completed - start)); + goto err; + } + submsg_end = pop(d, start); + msgdef = d->top->msgdef; + completed = buf; + continue; + } + + // Look up field by tag number. + struct upb_fielddef *f = upb_msg_itof(msgdef, tag.field_number); + + // Parse/handle field. + if(tag.wire_type == UPB_WIRE_TYPE_DELIMITED) { + int32_t delim_len; + buf = upb_get_INT32(buf, end, &delim_len, status); + CHECK_STATUS(); // Checking decode_tag() and upb_get_INT32(). + const uint8_t *delim_end = buf + delim_len; + if(f && f->type == UPB_TYPE(MESSAGE)) { + submsg_end = push(d, start, delim_end - start, f, status); + msgdef = d->top->msgdef; + } else { + if(f && upb_isstringtype(f->type)) { + int32_t str_start = buf - start; + sink_status = + upb_sink_onstr(d->sink, f, str, str_start, str_start + delim_len); + } // else { TODO: packed arrays } + // If field was not found, it is skipped silently. + buf = delim_end; // Could be >end. + } + } else { + if(!f || !upb_check_type(tag.wire_type, f->type)) { + buf = skip_wire_value(buf, end, tag.wire_type, status); + } else if (f->type == UPB_TYPE(GROUP)) { + submsg_end = push(d, start, 0, f, status); + msgdef = d->top->msgdef; + } else { + union upb_value val; + buf = upb_decode_value(buf, end, f->type, upb_value_addrof(&val), + status); + CHECK_STATUS(); // Checking upb_decode_value(). + sink_status = upb_sink_onvalue(d->sink, f, val); + } + } + CHECK_STATUS(); + + while(buf >= submsg_end) { + if(buf > submsg_end) { + upb_seterr(status, UPB_STATUS_ERROR, "Expected submsg end offset " + "did not lie on a tag/value boundary."); + goto err; + } + submsg_end = pop(d, start); + msgdef = d->top->msgdef; + } + // while(buf < d->packed_end) { TODO: packed arrays } + completed = buf; + } + + size_t read; +err: + read = (char*)completed - (char*)start; + d->completed_offset += read; + return read; +} |