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protobuf/upb/json/parser.rl

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/*
* upb - a minimalist implementation of protocol buffers.
*
* Copyright (c) 2014 Google Inc. See LICENSE for details.
* Author: Josh Haberman <jhaberman@gmail.com>
*
* A parser that uses the Ragel State Machine Compiler to generate
* the finite automata.
*
* Ragel only natively handles regular languages, but we can manually
* program it a bit to handle context-free languages like JSON, by using
* the "fcall" and "fret" constructs.
*
* This parser can handle the basics, but needs several things to be fleshed
* out:
*
* - handling of unicode escape sequences (including high surrogate pairs).
* - properly check and report errors for unknown fields, stack overflow,
* improper array nesting (or lack of nesting).
* - handling of base64 sequences with padding characters.
* - handling of push-back (non-success returns from sink functions).
* - handling of keys/escape-sequences/etc that span input buffers.
*/
#include <stdio.h>
#include <stdint.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include "upb/json/parser.h"
#define UPB_JSON_MAX_DEPTH 64
typedef struct {
upb_sink sink;
/* The current message in which we're parsing, and the field whose value we're
* expecting next. */
const upb_msgdef *m;
const upb_fielddef *f;
/* We are in a repeated-field context, ready to emit mapentries as
* submessages. This flag alters the start-of-object (open-brace) behavior to
* begin a sequence of mapentry messages rather than a single submessage. */
bool is_map;
/* We are in a map-entry message context. This flag is set when parsing the
* value field of a single map entry and indicates to all value-field parsers
* (subobjects, strings, numbers, and bools) that the map-entry submessage
* should end as soon as the value is parsed. */
bool is_mapentry;
/* If |is_map| or |is_mapentry| is true, |mapfield| refers to the parent
* message's map field that we're currently parsing. This differs from |f|
* because |f| is the field in the *current* message (i.e., the map-entry
* message itself), not the parent's field that leads to this map. */
const upb_fielddef *mapfield;
} upb_jsonparser_frame;
struct upb_json_parser {
upb_env *env;
upb_byteshandler input_handler_;
upb_bytessink input_;
/* Stack to track the JSON scopes we are in. */
upb_jsonparser_frame stack[UPB_JSON_MAX_DEPTH];
upb_jsonparser_frame *top;
upb_jsonparser_frame *limit;
upb_status *status;
/* Ragel's internal parsing stack for the parsing state machine. */
int current_state;
int parser_stack[UPB_JSON_MAX_DEPTH];
int parser_top;
/* The handle for the current buffer. */
const upb_bufhandle *handle;
/* Accumulate buffer. See details in parser.rl. */
const char *accumulated;
size_t accumulated_len;
char *accumulate_buf;
size_t accumulate_buf_size;
/* Multi-part text data. See details in parser.rl. */
int multipart_state;
upb_selector_t string_selector;
/* Input capture. See details in parser.rl. */
const char *capture;
/* Intermediate result of parsing a unicode escape sequence. */
uint32_t digit;
};
#define PARSER_CHECK_RETURN(x) if (!(x)) return false
/* Used to signal that a capture has been suspended. */
static char suspend_capture;
static upb_selector_t getsel_for_handlertype(upb_json_parser *p,
upb_handlertype_t type) {
upb_selector_t sel;
bool ok = upb_handlers_getselector(p->top->f, type, &sel);
UPB_ASSERT_VAR(ok, ok);
return sel;
}
static upb_selector_t parser_getsel(upb_json_parser *p) {
return getsel_for_handlertype(
p, upb_handlers_getprimitivehandlertype(p->top->f));
}
static bool check_stack(upb_json_parser *p) {
if ((p->top + 1) == p->limit) {
upb_status_seterrmsg(p->status, "Nesting too deep");
return false;
}
return true;
}
/* There are GCC/Clang built-ins for overflow checking which we could start
* using if there was any performance benefit to it. */
static bool checked_add(size_t a, size_t b, size_t *c) {
if (SIZE_MAX - a < b) return false;
*c = a + b;
return true;
}
static size_t saturating_multiply(size_t a, size_t b) {
/* size_t is unsigned, so this is defined behavior even on overflow. */
size_t ret = a * b;
if (b != 0 && ret / b != a) {
ret = SIZE_MAX;
}
return ret;
}
/* Base64 decoding ************************************************************/
/* TODO(haberman): make this streaming. */
static const signed char b64table[] = {
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, 62/*+*/, -1, -1, -1, 63/*/ */,
52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/,
60/*8*/, 61/*9*/, -1, -1, -1, -1, -1, -1,
-1, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/,
07/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/,
15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/,
23/*X*/, 24/*Y*/, 25/*Z*/, -1, -1, -1, -1, -1,
-1, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/,
33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/,
41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/,
49/*x*/, 50/*y*/, 51/*z*/, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1
};
/* Returns the table value sign-extended to 32 bits. Knowing that the upper
* bits will be 1 for unrecognized characters makes it easier to check for
* this error condition later (see below). */
int32_t b64lookup(unsigned char ch) { return b64table[ch]; }
/* Returns true if the given character is not a valid base64 character or
* padding. */
bool nonbase64(unsigned char ch) { return b64lookup(ch) == -1 && ch != '='; }
static bool base64_push(upb_json_parser *p, upb_selector_t sel, const char *ptr,
size_t len) {
const char *limit = ptr + len;
for (; ptr < limit; ptr += 4) {
uint32_t val;
char output[3];
if (limit - ptr < 4) {
upb_status_seterrf(p->status,
"Base64 input for bytes field not a multiple of 4: %s",
upb_fielddef_name(p->top->f));
return false;
}
val = b64lookup(ptr[0]) << 18 |
b64lookup(ptr[1]) << 12 |
b64lookup(ptr[2]) << 6 |
b64lookup(ptr[3]);
/* Test the upper bit; returns true if any of the characters returned -1. */
if (val & 0x80000000) {
goto otherchar;
}
output[0] = val >> 16;
output[1] = (val >> 8) & 0xff;
output[2] = val & 0xff;
upb_sink_putstring(&p->top->sink, sel, output, 3, NULL);
}
return true;
otherchar:
if (nonbase64(ptr[0]) || nonbase64(ptr[1]) || nonbase64(ptr[2]) ||
nonbase64(ptr[3]) ) {
upb_status_seterrf(p->status,
"Non-base64 characters in bytes field: %s",
upb_fielddef_name(p->top->f));
return false;
} if (ptr[2] == '=') {
uint32_t val;
char output;
/* Last group contains only two input bytes, one output byte. */
if (ptr[0] == '=' || ptr[1] == '=' || ptr[3] != '=') {
goto badpadding;
}
val = b64lookup(ptr[0]) << 18 |
b64lookup(ptr[1]) << 12;
assert(!(val & 0x80000000));
output = val >> 16;
upb_sink_putstring(&p->top->sink, sel, &output, 1, NULL);
return true;
} else {
uint32_t val;
char output[2];
/* Last group contains only three input bytes, two output bytes. */
if (ptr[0] == '=' || ptr[1] == '=' || ptr[2] == '=') {
goto badpadding;
}
val = b64lookup(ptr[0]) << 18 |
b64lookup(ptr[1]) << 12 |
b64lookup(ptr[2]) << 6;
output[0] = val >> 16;
output[1] = (val >> 8) & 0xff;
upb_sink_putstring(&p->top->sink, sel, output, 2, NULL);
return true;
}
badpadding:
upb_status_seterrf(p->status,
"Incorrect base64 padding for field: %s (%.*s)",
upb_fielddef_name(p->top->f),
4, ptr);
return false;
}
/* Accumulate buffer **********************************************************/
/* Functionality for accumulating a buffer.
*
* Some parts of the parser need an entire value as a contiguous string. For
* example, to look up a member name in a hash table, or to turn a string into
* a number, the relevant library routines need the input string to be in
* contiguous memory, even if the value spanned two or more buffers in the
* input. These routines handle that.
*
* In the common case we can just point to the input buffer to get this
* contiguous string and avoid any actual copy. So we optimistically begin
* this way. But there are a few cases where we must instead copy into a
* separate buffer:
*
* 1. The string was not contiguous in the input (it spanned buffers).
*
* 2. The string included escape sequences that need to be interpreted to get
* the true value in a contiguous buffer. */
static void assert_accumulate_empty(upb_json_parser *p) {
UPB_UNUSED(p);
assert(p->accumulated == NULL);
assert(p->accumulated_len == 0);
}
static void accumulate_clear(upb_json_parser *p) {
p->accumulated = NULL;
p->accumulated_len = 0;
}
/* Used internally by accumulate_append(). */
static bool accumulate_realloc(upb_json_parser *p, size_t need) {
void *mem;
size_t old_size = p->accumulate_buf_size;
size_t new_size = UPB_MAX(old_size, 128);
while (new_size < need) {
new_size = saturating_multiply(new_size, 2);
}
mem = upb_env_realloc(p->env, p->accumulate_buf, old_size, new_size);
if (!mem) {
upb_status_seterrmsg(p->status, "Out of memory allocating buffer.");
return false;
}
p->accumulate_buf = mem;
p->accumulate_buf_size = new_size;
return true;
}
/* Logically appends the given data to the append buffer.
* If "can_alias" is true, we will try to avoid actually copying, but the buffer
* must be valid until the next accumulate_append() call (if any). */
static bool accumulate_append(upb_json_parser *p, const char *buf, size_t len,
bool can_alias) {
size_t need;
if (!p->accumulated && can_alias) {
p->accumulated = buf;
p->accumulated_len = len;
return true;
}
if (!checked_add(p->accumulated_len, len, &need)) {
upb_status_seterrmsg(p->status, "Integer overflow.");
return false;
}
if (need > p->accumulate_buf_size && !accumulate_realloc(p, need)) {
return false;
}
if (p->accumulated != p->accumulate_buf) {
memcpy(p->accumulate_buf, p->accumulated, p->accumulated_len);
p->accumulated = p->accumulate_buf;
}
memcpy(p->accumulate_buf + p->accumulated_len, buf, len);
p->accumulated_len += len;
return true;
}
/* Returns a pointer to the data accumulated since the last accumulate_clear()
* call, and writes the length to *len. This with point either to the input
* buffer or a temporary accumulate buffer. */
static const char *accumulate_getptr(upb_json_parser *p, size_t *len) {
assert(p->accumulated);
*len = p->accumulated_len;
return p->accumulated;
}
/* Mult-part text data ********************************************************/
/* When we have text data in the input, it can often come in multiple segments.
* For example, there may be some raw string data followed by an escape
* sequence. The two segments are processed with different logic. Also buffer
* seams in the input can cause multiple segments.
*
* As we see segments, there are two main cases for how we want to process them:
*
* 1. we want to push the captured input directly to string handlers.
*
* 2. we need to accumulate all the parts into a contiguous buffer for further
* processing (field name lookup, string->number conversion, etc). */
/* This is the set of states for p->multipart_state. */
enum {
/* We are not currently processing multipart data. */
MULTIPART_INACTIVE = 0,
/* We are processing multipart data by accumulating it into a contiguous
* buffer. */
MULTIPART_ACCUMULATE = 1,
/* We are processing multipart data by pushing each part directly to the
* current string handlers. */
MULTIPART_PUSHEAGERLY = 2
};
/* Start a multi-part text value where we accumulate the data for processing at
* the end. */
static void multipart_startaccum(upb_json_parser *p) {
assert_accumulate_empty(p);
assert(p->multipart_state == MULTIPART_INACTIVE);
p->multipart_state = MULTIPART_ACCUMULATE;
}
/* Start a multi-part text value where we immediately push text data to a string
* value with the given selector. */
static void multipart_start(upb_json_parser *p, upb_selector_t sel) {
assert_accumulate_empty(p);
assert(p->multipart_state == MULTIPART_INACTIVE);
p->multipart_state = MULTIPART_PUSHEAGERLY;
p->string_selector = sel;
}
static bool multipart_text(upb_json_parser *p, const char *buf, size_t len,
bool can_alias) {
switch (p->multipart_state) {
case MULTIPART_INACTIVE:
upb_status_seterrmsg(
p->status, "Internal error: unexpected state MULTIPART_INACTIVE");
return false;
case MULTIPART_ACCUMULATE:
if (!accumulate_append(p, buf, len, can_alias)) {
return false;
}
break;
case MULTIPART_PUSHEAGERLY: {
const upb_bufhandle *handle = can_alias ? p->handle : NULL;
upb_sink_putstring(&p->top->sink, p->string_selector, buf, len, handle);
break;
}
}
return true;
}
/* Note: this invalidates the accumulate buffer! Call only after reading its
* contents. */
static void multipart_end(upb_json_parser *p) {
assert(p->multipart_state != MULTIPART_INACTIVE);
p->multipart_state = MULTIPART_INACTIVE;
accumulate_clear(p);
}
/* Input capture **************************************************************/
/* Functionality for capturing a region of the input as text. Gracefully
* handles the case where a buffer seam occurs in the middle of the captured
* region. */
static void capture_begin(upb_json_parser *p, const char *ptr) {
assert(p->multipart_state != MULTIPART_INACTIVE);
assert(p->capture == NULL);
p->capture = ptr;
}
static bool capture_end(upb_json_parser *p, const char *ptr) {
assert(p->capture);
if (multipart_text(p, p->capture, ptr - p->capture, true)) {
p->capture = NULL;
return true;
} else {
return false;
}
}
/* This is called at the end of each input buffer (ie. when we have hit a
* buffer seam). If we are in the middle of capturing the input, this
* processes the unprocessed capture region. */
static void capture_suspend(upb_json_parser *p, const char **ptr) {
if (!p->capture) return;
if (multipart_text(p, p->capture, *ptr - p->capture, false)) {
/* We use this as a signal that we were in the middle of capturing, and
* that capturing should resume at the beginning of the next buffer.
*
* We can't use *ptr here, because we have no guarantee that this pointer
* will be valid when we resume (if the underlying memory is freed, then
* using the pointer at all, even to compare to NULL, is likely undefined
* behavior). */
p->capture = &suspend_capture;
} else {
/* Need to back up the pointer to the beginning of the capture, since
* we were not able to actually preserve it. */
*ptr = p->capture;
}
}
static void capture_resume(upb_json_parser *p, const char *ptr) {
if (p->capture) {
assert(p->capture == &suspend_capture);
p->capture = ptr;
}
}
/* Callbacks from the parser **************************************************/
/* These are the functions called directly from the parser itself.
* We define these in the same order as their declarations in the parser. */
static char escape_char(char in) {
switch (in) {
case 'r': return '\r';
case 't': return '\t';
case 'n': return '\n';
case 'f': return '\f';
case 'b': return '\b';
case '/': return '/';
case '"': return '"';
case '\\': return '\\';
default:
assert(0);
return 'x';
}
}
static bool escape(upb_json_parser *p, const char *ptr) {
char ch = escape_char(*ptr);
return multipart_text(p, &ch, 1, false);
}
static void start_hex(upb_json_parser *p) {
p->digit = 0;
}
static void hexdigit(upb_json_parser *p, const char *ptr) {
char ch = *ptr;
p->digit <<= 4;
if (ch >= '0' && ch <= '9') {
p->digit += (ch - '0');
} else if (ch >= 'a' && ch <= 'f') {
p->digit += ((ch - 'a') + 10);
} else {
assert(ch >= 'A' && ch <= 'F');
p->digit += ((ch - 'A') + 10);
}
}
static bool end_hex(upb_json_parser *p) {
uint32_t codepoint = p->digit;
/* emit the codepoint as UTF-8. */
char utf8[3]; /* support \u0000 -- \uFFFF -- need only three bytes. */
int length = 0;
if (codepoint <= 0x7F) {
utf8[0] = codepoint;
length = 1;
} else if (codepoint <= 0x07FF) {
utf8[1] = (codepoint & 0x3F) | 0x80;
codepoint >>= 6;
utf8[0] = (codepoint & 0x1F) | 0xC0;
length = 2;
} else /* codepoint <= 0xFFFF */ {
utf8[2] = (codepoint & 0x3F) | 0x80;
codepoint >>= 6;
utf8[1] = (codepoint & 0x3F) | 0x80;
codepoint >>= 6;
utf8[0] = (codepoint & 0x0F) | 0xE0;
length = 3;
}
/* TODO(haberman): Handle high surrogates: if codepoint is a high surrogate
* we have to wait for the next escape to get the full code point). */
return multipart_text(p, utf8, length, false);
}
static void start_text(upb_json_parser *p, const char *ptr) {
capture_begin(p, ptr);
}
static bool end_text(upb_json_parser *p, const char *ptr) {
return capture_end(p, ptr);
}
static void start_number(upb_json_parser *p, const char *ptr) {
multipart_startaccum(p);
capture_begin(p, ptr);
}
static bool parse_number(upb_json_parser *p);
static bool end_number(upb_json_parser *p, const char *ptr) {
if (!capture_end(p, ptr)) {
return false;
}
return parse_number(p);
}
static bool parse_number(upb_json_parser *p) {
size_t len;
const char *buf;
const char *myend;
char *end;
/* strtol() and friends unfortunately do not support specifying the length of
* the input string, so we need to force a copy into a NULL-terminated buffer. */
if (!multipart_text(p, "\0", 1, false)) {
return false;
}
buf = accumulate_getptr(p, &len);
myend = buf + len - 1; /* One for NULL. */
/* XXX: We are using strtol to parse integers, but this is wrong as even
* integers can be represented as 1e6 (for example), which strtol can't
* handle correctly.
*
* XXX: Also, we can't handle large integers properly because strto[u]ll
* isn't in C89.
*
* XXX: Also, we don't properly check floats for overflow, since strtof
* isn't in C89. */
switch (upb_fielddef_type(p->top->f)) {
case UPB_TYPE_ENUM:
case UPB_TYPE_INT32: {
long val = strtol(p->accumulated, &end, 0);
if (val > INT32_MAX || val < INT32_MIN || errno == ERANGE || end != myend)
goto err;
else
upb_sink_putint32(&p->top->sink, parser_getsel(p), val);
break;
}
case UPB_TYPE_INT64: {
long long val = strtol(p->accumulated, &end, 0);
if (val > INT64_MAX || val < INT64_MIN || errno == ERANGE || end != myend)
goto err;
else
upb_sink_putint64(&p->top->sink, parser_getsel(p), val);
break;
}
case UPB_TYPE_UINT32: {
unsigned long val = strtoul(p->accumulated, &end, 0);
if (val > UINT32_MAX || errno == ERANGE || end != myend)
goto err;
else
upb_sink_putuint32(&p->top->sink, parser_getsel(p), val);
break;
}
case UPB_TYPE_UINT64: {
unsigned long long val = strtoul(p->accumulated, &end, 0);
if (val > UINT64_MAX || errno == ERANGE || end != myend)
goto err;
else
upb_sink_putuint64(&p->top->sink, parser_getsel(p), val);
break;
}
case UPB_TYPE_DOUBLE: {
double val = strtod(p->accumulated, &end);
if (errno == ERANGE || end != myend)
goto err;
else
upb_sink_putdouble(&p->top->sink, parser_getsel(p), val);
break;
}
case UPB_TYPE_FLOAT: {
float val = strtod(p->accumulated, &end);
if (errno == ERANGE || end != myend)
goto err;
else
upb_sink_putfloat(&p->top->sink, parser_getsel(p), val);
break;
}
default:
assert(false);
}
multipart_end(p);
return true;
err:
upb_status_seterrf(p->status, "error parsing number: %s", buf);
multipart_end(p);
return false;
}
static bool parser_putbool(upb_json_parser *p, bool val) {
bool ok;
if (upb_fielddef_type(p->top->f) != UPB_TYPE_BOOL) {
upb_status_seterrf(p->status,
"Boolean value specified for non-bool field: %s",
upb_fielddef_name(p->top->f));
return false;
}
ok = upb_sink_putbool(&p->top->sink, parser_getsel(p), val);
UPB_ASSERT_VAR(ok, ok);
return true;
}
static bool start_stringval(upb_json_parser *p) {
assert(p->top->f);
if (upb_fielddef_isstring(p->top->f)) {
upb_jsonparser_frame *inner;
upb_selector_t sel;
if (!check_stack(p)) return false;
/* Start a new parser frame: parser frames correspond one-to-one with
* handler frames, and string events occur in a sub-frame. */
inner = p->top + 1;
sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
upb_sink_startstr(&p->top->sink, sel, 0, &inner->sink);
inner->m = p->top->m;
inner->f = p->top->f;
inner->is_map = false;
inner->is_mapentry = false;
p->top = inner;
if (upb_fielddef_type(p->top->f) == UPB_TYPE_STRING) {
/* For STRING fields we push data directly to the handlers as it is
* parsed. We don't do this yet for BYTES fields, because our base64
* decoder is not streaming.
*
* TODO(haberman): make base64 decoding streaming also. */
multipart_start(p, getsel_for_handlertype(p, UPB_HANDLER_STRING));
return true;
} else {
multipart_startaccum(p);
return true;
}
} else if (upb_fielddef_type(p->top->f) == UPB_TYPE_ENUM) {
/* No need to push a frame -- symbolic enum names in quotes remain in the
* current parser frame.
*
* Enum string values must accumulate so we can look up the value in a table
* once it is complete. */
multipart_startaccum(p);
return true;
} else {
upb_status_seterrf(p->status,
"String specified for non-string/non-enum field: %s",
upb_fielddef_name(p->top->f));
return false;
}
}
static bool end_stringval(upb_json_parser *p) {
bool ok = true;
switch (upb_fielddef_type(p->top->f)) {
case UPB_TYPE_BYTES:
if (!base64_push(p, getsel_for_handlertype(p, UPB_HANDLER_STRING),
p->accumulated, p->accumulated_len)) {
return false;
}
/* Fall through. */
case UPB_TYPE_STRING: {
upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
upb_sink_endstr(&p->top->sink, sel);
p->top--;
break;
}
case UPB_TYPE_ENUM: {
/* Resolve enum symbolic name to integer value. */
const upb_enumdef *enumdef =
(const upb_enumdef*)upb_fielddef_subdef(p->top->f);
size_t len;
const char *buf = accumulate_getptr(p, &len);
int32_t int_val = 0;
ok = upb_enumdef_ntoi(enumdef, buf, len, &int_val);
if (ok) {
upb_selector_t sel = parser_getsel(p);
upb_sink_putint32(&p->top->sink, sel, int_val);
} else {
upb_status_seterrf(p->status, "Enum value unknown: '%.*s'", len, buf);
}
break;
}
default:
assert(false);
upb_status_seterrmsg(p->status, "Internal error in JSON decoder");
ok = false;
break;
}
multipart_end(p);
return ok;
}
static void start_member(upb_json_parser *p) {
assert(!p->top->f);
multipart_startaccum(p);
}
/* Helper: invoked during parse_mapentry() to emit the mapentry message's key
* field based on the current contents of the accumulate buffer. */
static bool parse_mapentry_key(upb_json_parser *p) {
size_t len;
const char *buf = accumulate_getptr(p, &len);
/* Emit the key field. We do a bit of ad-hoc parsing here because the
* parser state machine has already decided that this is a string field
* name, and we are reinterpreting it as some arbitrary key type. In
* particular, integer and bool keys are quoted, so we need to parse the
* quoted string contents here. */
p->top->f = upb_msgdef_itof(p->top->m, UPB_MAPENTRY_KEY);
if (p->top->f == NULL) {
upb_status_seterrmsg(p->status, "mapentry message has no key");
return false;
}
switch (upb_fielddef_type(p->top->f)) {
case UPB_TYPE_INT32:
case UPB_TYPE_INT64:
case UPB_TYPE_UINT32:
case UPB_TYPE_UINT64:
/* Invoke end_number. The accum buffer has the number's text already. */
if (!parse_number(p)) {
return false;
}
break;
case UPB_TYPE_BOOL:
if (len == 4 && !strncmp(buf, "true", 4)) {
if (!parser_putbool(p, true)) {
return false;
}
} else if (len == 5 && !strncmp(buf, "false", 5)) {
if (!parser_putbool(p, false)) {
return false;
}
} else {
upb_status_seterrmsg(p->status,
"Map bool key not 'true' or 'false'");
return false;
}
multipart_end(p);
break;
case UPB_TYPE_STRING:
case UPB_TYPE_BYTES: {
upb_sink subsink;
upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
upb_sink_startstr(&p->top->sink, sel, len, &subsink);
sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
upb_sink_putstring(&subsink, sel, buf, len, NULL);
sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
upb_sink_endstr(&subsink, sel);
multipart_end(p);
break;
}
default:
upb_status_seterrmsg(p->status, "Invalid field type for map key");
return false;
}
return true;
}
/* Helper: emit one map entry (as a submessage in the map field sequence). This
* is invoked from end_membername(), at the end of the map entry's key string,
* with the map key in the accumulate buffer. It parses the key from that
* buffer, emits the handler calls to start the mapentry submessage (setting up
* its subframe in the process), and sets up state in the subframe so that the
* value parser (invoked next) will emit the mapentry's value field and then
* end the mapentry message. */
static bool handle_mapentry(upb_json_parser *p) {
const upb_fielddef *mapfield;
const upb_msgdef *mapentrymsg;
upb_jsonparser_frame *inner;
upb_selector_t sel;
/* Map entry: p->top->sink is the seq frame, so we need to start a frame
* for the mapentry itself, and then set |f| in that frame so that the map
* value field is parsed, and also set a flag to end the frame after the
* map-entry value is parsed. */
if (!check_stack(p)) return false;
mapfield = p->top->mapfield;
mapentrymsg = upb_fielddef_msgsubdef(mapfield);
inner = p->top + 1;
p->top->f = mapfield;
sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSUBMSG);
upb_sink_startsubmsg(&p->top->sink, sel, &inner->sink);
inner->m = mapentrymsg;
inner->mapfield = mapfield;
inner->is_map = false;
/* Don't set this to true *yet* -- we reuse parsing handlers below to push
* the key field value to the sink, and these handlers will pop the frame
* if they see is_mapentry (when invoked by the parser state machine, they
* would have just seen the map-entry value, not key). */
inner->is_mapentry = false;
p->top = inner;
/* send STARTMSG in submsg frame. */
upb_sink_startmsg(&p->top->sink);
parse_mapentry_key(p);
/* Set up the value field to receive the map-entry value. */
p->top->f = upb_msgdef_itof(p->top->m, UPB_MAPENTRY_VALUE);
p->top->is_mapentry = true; /* set up to pop frame after value is parsed. */
p->top->mapfield = mapfield;
if (p->top->f == NULL) {
upb_status_seterrmsg(p->status, "mapentry message has no value");
return false;
}
return true;
}
static bool end_membername(upb_json_parser *p) {
assert(!p->top->f);
if (p->top->is_map) {
return handle_mapentry(p);
} else {
size_t len;
const char *buf = accumulate_getptr(p, &len);
const upb_fielddef *f = upb_msgdef_ntof(p->top->m, buf, len);
if (!f) {
/* TODO(haberman): Ignore unknown fields if requested/configured to do
* so. */
upb_status_seterrf(p->status, "No such field: %.*s\n", (int)len, buf);
return false;
}
p->top->f = f;
multipart_end(p);
return true;
}
}
static void end_member(upb_json_parser *p) {
/* If we just parsed a map-entry value, end that frame too. */
if (p->top->is_mapentry) {
upb_status s = UPB_STATUS_INIT;
upb_selector_t sel;
bool ok;
const upb_fielddef *mapfield;
assert(p->top > p->stack);
/* send ENDMSG on submsg. */
upb_sink_endmsg(&p->top->sink, &s);
mapfield = p->top->mapfield;
/* send ENDSUBMSG in repeated-field-of-mapentries frame. */
p->top--;
ok = upb_handlers_getselector(mapfield, UPB_HANDLER_ENDSUBMSG, &sel);
UPB_ASSERT_VAR(ok, ok);
upb_sink_endsubmsg(&p->top->sink, sel);
}
p->top->f = NULL;
}
static bool start_subobject(upb_json_parser *p) {
assert(p->top->f);
if (upb_fielddef_ismap(p->top->f)) {
upb_jsonparser_frame *inner;
upb_selector_t sel;
/* Beginning of a map. Start a new parser frame in a repeated-field
* context. */
if (!check_stack(p)) return false;
inner = p->top + 1;
sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSEQ);
upb_sink_startseq(&p->top->sink, sel, &inner->sink);
inner->m = upb_fielddef_msgsubdef(p->top->f);
inner->mapfield = p->top->f;
inner->f = NULL;
inner->is_map = true;
inner->is_mapentry = false;
p->top = inner;
return true;
} else if (upb_fielddef_issubmsg(p->top->f)) {
upb_jsonparser_frame *inner;
upb_selector_t sel;
/* Beginning of a subobject. Start a new parser frame in the submsg
* context. */
if (!check_stack(p)) return false;
inner = p->top + 1;
sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSUBMSG);
upb_sink_startsubmsg(&p->top->sink, sel, &inner->sink);
inner->m = upb_fielddef_msgsubdef(p->top->f);
inner->f = NULL;
inner->is_map = false;
inner->is_mapentry = false;
p->top = inner;
return true;
} else {
upb_status_seterrf(p->status,
"Object specified for non-message/group field: %s",
upb_fielddef_name(p->top->f));
return false;
}
}
static void end_subobject(upb_json_parser *p) {
if (p->top->is_map) {
upb_selector_t sel;
p->top--;
sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSEQ);
upb_sink_endseq(&p->top->sink, sel);
} else {
upb_selector_t sel;
p->top--;
sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSUBMSG);
upb_sink_endsubmsg(&p->top->sink, sel);
}
}
static bool start_array(upb_json_parser *p) {
upb_jsonparser_frame *inner;
upb_selector_t sel;
assert(p->top->f);
if (!upb_fielddef_isseq(p->top->f)) {
upb_status_seterrf(p->status,
"Array specified for non-repeated field: %s",
upb_fielddef_name(p->top->f));
return false;
}
if (!check_stack(p)) return false;
inner = p->top + 1;
sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSEQ);
upb_sink_startseq(&p->top->sink, sel, &inner->sink);
inner->m = p->top->m;
inner->f = p->top->f;
inner->is_map = false;
inner->is_mapentry = false;
p->top = inner;
return true;
}
static void end_array(upb_json_parser *p) {
upb_selector_t sel;
assert(p->top > p->stack);
p->top--;
sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSEQ);
upb_sink_endseq(&p->top->sink, sel);
}
static void start_object(upb_json_parser *p) {
if (!p->top->is_map) {
upb_sink_startmsg(&p->top->sink);
}
}
static void end_object(upb_json_parser *p) {
if (!p->top->is_map) {
upb_status status;
upb_sink_endmsg(&p->top->sink, &status);
}
}
#define CHECK_RETURN_TOP(x) if (!(x)) goto error
/* The actual parser **********************************************************/
/* What follows is the Ragel parser itself. The language is specified in Ragel
* and the actions call our C functions above.
*
* Ragel has an extensive set of functionality, and we use only a small part of
* it. There are many action types but we only use a few:
*
* ">" -- transition into a machine
* "%" -- transition out of a machine
* "@" -- transition into a final state of a machine.
*
* "@" transitions are tricky because a machine can transition into a final
* state repeatedly. But in some cases we know this can't happen, for example
* a string which is delimited by a final '"' can only transition into its
* final state once, when the closing '"' is seen. */
%%{
machine json;
ws = space*;
integer = "0" | /[1-9]/ /[0-9]/*;
decimal = "." /[0-9]/+;
exponent = /[eE]/ /[+\-]/? /[0-9]/+;
number_machine :=
("-"? integer decimal? exponent?)
<: any >{ fhold; fret; };
number = /[0-9\-]/ >{ fhold; fcall number_machine; };
text =
/[^\\"]/+
>{ start_text(parser, p); }
%{ CHECK_RETURN_TOP(end_text(parser, p)); }
;
unicode_char =
"\\u"
/[0-9A-Fa-f]/{4}
>{ start_hex(parser); }
${ hexdigit(parser, p); }
%{ CHECK_RETURN_TOP(end_hex(parser)); }
;
escape_char =
"\\"
/[rtbfn"\/\\]/
>{ CHECK_RETURN_TOP(escape(parser, p)); }
;
string_machine :=
(text | unicode_char | escape_char)**
'"'
@{ fhold; fret; }
;
string = '"' @{ fcall string_machine; } '"';
value2 = ^(space | "]" | "}") >{ fhold; fcall value_machine; } ;
member =
ws
string
>{ start_member(parser); }
@{ CHECK_RETURN_TOP(end_membername(parser)); }
ws ":" ws
value2
%{ end_member(parser); }
ws;
object =
"{"
ws
>{ start_object(parser); }
(member ("," member)*)?
"}"
>{ end_object(parser); }
;
element = ws value2 ws;
array =
"["
>{ CHECK_RETURN_TOP(start_array(parser)); }
ws
(element ("," element)*)?
"]"
>{ end_array(parser); }
;
value =
number
>{ start_number(parser, p); }
%{ CHECK_RETURN_TOP(end_number(parser, p)); }
| string
>{ CHECK_RETURN_TOP(start_stringval(parser)); }
@{ CHECK_RETURN_TOP(end_stringval(parser)); }
| "true"
%{ CHECK_RETURN_TOP(parser_putbool(parser, true)); }
| "false"
%{ CHECK_RETURN_TOP(parser_putbool(parser, false)); }
| "null"
%{ /* null value */ }
| object
>{ CHECK_RETURN_TOP(start_subobject(parser)); }
%{ end_subobject(parser); }
| array;
value_machine :=
value
<: any >{ fhold; fret; } ;
main := ws object ws;
}%%
%% write data noerror nofinal;
size_t parse(void *closure, const void *hd, const char *buf, size_t size,
const upb_bufhandle *handle) {
upb_json_parser *parser = closure;
/* Variables used by Ragel's generated code. */
int cs = parser->current_state;
int *stack = parser->parser_stack;
int top = parser->parser_top;
const char *p = buf;
const char *pe = buf + size;
parser->handle = handle;
UPB_UNUSED(hd);
UPB_UNUSED(handle);
capture_resume(parser, buf);
%% write exec;
if (p != pe) {
upb_status_seterrf(parser->status, "Parse error at %s\n", p);
} else {
capture_suspend(parser, &p);
}
error:
/* Save parsing state back to parser. */
parser->current_state = cs;
parser->parser_top = top;
return p - buf;
}
bool end(void *closure, const void *hd) {
UPB_UNUSED(closure);
UPB_UNUSED(hd);
/* Prevent compile warning on unused static constants. */
UPB_UNUSED(json_start);
UPB_UNUSED(json_en_number_machine);
UPB_UNUSED(json_en_string_machine);
UPB_UNUSED(json_en_value_machine);
UPB_UNUSED(json_en_main);
return true;
}
static void json_parser_reset(upb_json_parser *p) {
int cs;
int top;
p->top = p->stack;
p->top->f = NULL;
p->top->is_map = false;
p->top->is_mapentry = false;
/* Emit Ragel initialization of the parser. */
%% write init;
p->current_state = cs;
p->parser_top = top;
accumulate_clear(p);
p->multipart_state = MULTIPART_INACTIVE;
p->capture = NULL;
p->accumulated = NULL;
}
/* Public API *****************************************************************/
upb_json_parser *upb_json_parser_create(upb_env *env, upb_sink *output) {
#ifndef NDEBUG
const size_t size_before = upb_env_bytesallocated(env);
#endif
upb_json_parser *p = upb_env_malloc(env, sizeof(upb_json_parser));
if (!p) return false;
p->env = env;
p->limit = p->stack + UPB_JSON_MAX_DEPTH;
p->accumulate_buf = NULL;
p->accumulate_buf_size = 0;
upb_byteshandler_init(&p->input_handler_);
upb_byteshandler_setstring(&p->input_handler_, parse, NULL);
upb_byteshandler_setendstr(&p->input_handler_, end, NULL);
upb_bytessink_reset(&p->input_, &p->input_handler_, p);
json_parser_reset(p);
upb_sink_reset(&p->top->sink, output->handlers, output->closure);
p->top->m = upb_handlers_msgdef(output->handlers);
/* If this fails, uncomment and increase the value in parser.h.
* fprintf(stderr, "%zd\n", upb_env_bytesallocated(env) - size_before); */
assert(upb_env_bytesallocated(env) - size_before <= UPB_JSON_PARSER_SIZE);
return p;
}
upb_bytessink *upb_json_parser_input(upb_json_parser *p) {
return &p->input_;
}