Sync from Google-internal development.

Most notably, a JSON parser is now provided.

1 files changed, 623 insertions, 0 deletions

diff --git a/upb/json/parser.rl b/upb/json/parser.rl
new file mode 100644
index 0000000..75860e5
--- /dev/null
+++ b/upb/json/parser.rl
@@ -0,0 +1,623 @@
+/*
+ * 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 CHECK_RETURN(x) if (!(x)) return false
+
+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 getsel(upb_json_parser *p) {
+  return getsel_for_handlertype(
+      p, upb_handlers_getprimitivehandlertype(p->top->f));
+}
+
+static void start_member(upb_json_parser *p) {
+  assert(!p->top->f);
+  assert(!p->accumulated);
+  p->accumulated_len = 0;
+}
+
+static bool end_member(upb_json_parser *p) {
+  // TODO(haberman): support keys that span buffers or have escape sequences.
+  assert(!p->top->f);
+  assert(p->accumulated);
+  const upb_fielddef *f =
+      upb_msgdef_ntof(p->top->m, p->accumulated, p->accumulated_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)p->accumulated_len, p->accumulated);
+    return false;
+  }
+
+  p->top->f = f;
+  p->accumulated = NULL;
+
+  return true;
+}
+
+static void start_object(upb_json_parser *p) {
+  upb_sink_startmsg(&p->top->sink);
+}
+
+static void end_object(upb_json_parser *p) {
+  upb_status status;
+  upb_sink_endmsg(&p->top->sink, &status);
+}
+
+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;
+}
+
+static bool start_subobject(upb_json_parser *p) {
+  assert(p->top->f);
+
+  if (!upb_fielddef_issubmsg(p->top->f)) {
+    upb_status_seterrf(p->status,
+                       "Object specified for non-message/group field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
+  }
+
+  if (!check_stack(p)) return false;
+
+  upb_jsonparser_frame *inner = p->top + 1;
+
+  upb_selector_t 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;
+  p->top = inner;
+
+  return true;
+}
+
+static void end_subobject(upb_json_parser *p) {
+  p->top--;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSUBMSG);
+  upb_sink_endsubmsg(&p->top->sink, sel);
+}
+
+static bool start_array(upb_json_parser *p) {
+  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;
+
+  upb_jsonparser_frame *inner = p->top + 1;
+  upb_selector_t 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;
+  p->top = inner;
+
+  return true;
+}
+
+static void end_array(upb_json_parser *p) {
+  assert(p->top > p->stack);
+
+  p->top--;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSEQ);
+  upb_sink_endseq(&p->top->sink, sel);
+}
+
+static void clear_member(upb_json_parser *p) { p->top->f = NULL; }
+
+static bool putbool(upb_json_parser *p, bool val) {
+  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;
+  }
+
+  bool ok = upb_sink_putbool(&p->top->sink, getsel(p), val);
+  UPB_ASSERT_VAR(ok, ok);
+  return true;
+}
+
+static void start_text(upb_json_parser *p, const char *ptr) {
+  p->text_begin = ptr;
+}
+
+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) {
+    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;
+    }
+
+    uint32_t 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;
+    }
+
+    char output[3];
+    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] == '=') {
+    // Last group contains only two input bytes, one output byte.
+    if (ptr[0] == '=' || ptr[1] == '=' || ptr[3] != '=') {
+      goto badpadding;
+    }
+
+    uint32_t val = b64lookup(ptr[0]) << 18 |
+                   b64lookup(ptr[1]) << 12;
+
+    assert(!(val & 0x80000000));
+    char output = val >> 16;
+    upb_sink_putstring(&p->top->sink, sel, &output, 1, NULL);
+    return true;
+  } else {
+    // Last group contains only three input bytes, two output bytes.
+    if (ptr[0] == '=' || ptr[1] == '=' || ptr[2] == '=') {
+      goto badpadding;
+    }
+
+    uint32_t val = b64lookup(ptr[0]) << 18 |
+                   b64lookup(ptr[1]) << 12 |
+                   b64lookup(ptr[2]) << 6;
+
+    char output[2];
+    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;
+}
+
+static bool end_text(upb_json_parser *p, const char *ptr) {
+  assert(!p->accumulated);  // TODO: handle this case.
+  p->accumulated = p->text_begin;
+  p->accumulated_len = ptr - p->text_begin;
+
+  if (p->top->f && upb_fielddef_isstring(p->top->f)) {
+    // This is a string field (as opposed to a member name).
+    upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
+    if (upb_fielddef_type(p->top->f) == UPB_TYPE_BYTES) {
+      CHECK_RETURN(base64_push(p, sel, p->accumulated, p->accumulated_len));
+    } else {
+      upb_sink_putstring(&p->top->sink, sel, p->accumulated, p->accumulated_len, NULL);
+    }
+    p->accumulated = NULL;
+  }
+
+  return true;
+}
+
+static bool start_stringval(upb_json_parser *p) {
+  assert(p->top->f);
+
+  if (!upb_fielddef_isstring(p->top->f)) {
+    upb_status_seterrf(p->status,
+                       "String specified for non-string field: %s",
+                       upb_fielddef_name(p->top->f));
+    return false;
+  }
+
+  if (!check_stack(p)) return false;
+
+  upb_jsonparser_frame *inner = p->top + 1;  // TODO: check for overflow.
+  upb_selector_t 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;
+  p->top = inner;
+
+  return true;
+}
+
+static void end_stringval(upb_json_parser *p) {
+  p->top--;
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+  upb_sink_endstr(&p->top->sink, sel);
+}
+
+static void start_number(upb_json_parser *p, const char *ptr) {
+  start_text(p, ptr);
+  assert(p->accumulated == NULL);
+}
+
+static void end_number(upb_json_parser *p, const char *ptr) {
+  end_text(p, ptr);
+  const char *myend = p->accumulated + p->accumulated_len;
+  char *end;
+
+  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)
+        assert(false);
+      else
+        upb_sink_putint32(&p->top->sink, getsel(p), val);
+      break;
+    }
+    case UPB_TYPE_INT64: {
+      long long val = strtoll(p->accumulated, &end, 0);
+      if (val > INT64_MAX || val < INT64_MIN || errno == ERANGE || end != myend)
+        assert(false);
+      else
+        upb_sink_putint64(&p->top->sink, getsel(p), val);
+      break;
+    }
+    case UPB_TYPE_UINT32: {
+      unsigned long val = strtoul(p->accumulated, &end, 0);
+      if (val > UINT32_MAX || errno == ERANGE || end != myend)
+        assert(false);
+      else
+        upb_sink_putuint32(&p->top->sink, getsel(p), val);
+      break;
+    }
+    case UPB_TYPE_UINT64: {
+      unsigned long long val = strtoull(p->accumulated, &end, 0);
+      if (val > UINT64_MAX || errno == ERANGE || end != myend)
+        assert(false);
+      else
+        upb_sink_putuint64(&p->top->sink, getsel(p), val);
+      break;
+    }
+    case UPB_TYPE_DOUBLE: {
+      double val = strtod(p->accumulated, &end);
+      if (errno == ERANGE || end != myend)
+        assert(false);
+      else
+        upb_sink_putdouble(&p->top->sink, getsel(p), val);
+      break;
+    }
+    case UPB_TYPE_FLOAT: {
+      float val = strtof(p->accumulated, &end);
+      if (errno == ERANGE || end != myend)
+        assert(false);
+      else
+        upb_sink_putfloat(&p->top->sink, getsel(p), val);
+      break;
+    }
+    default:
+      assert(false);
+  }
+
+  p->accumulated = NULL;
+}
+
+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 void escape(upb_json_parser *p, const char *ptr) {
+  char ch = escape_char(*ptr);
+  upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
+  upb_sink_putstring(&p->top->sink, sel, &ch, 1, NULL);
+}
+
+static uint8_t hexdigit(char ch) {
+  if (ch >= '0' && ch <= '9') {
+    return ch - '0';
+  } else if (ch >= 'a' && ch <= 'f') {
+    return ch - 'a' + 10;
+  } else {
+    assert(ch >= 'A' && ch <= 'F');
+    return ch - 'A' + 10;
+  }
+}
+
+static void start_hex(upb_json_parser *p, const char *ptr) {
+  start_text(p, ptr);
+}
+
+static void hex(upb_json_parser *p, const char *end) {
+  UPB_UNUSED(end);
+  const char *start = p->text_begin;
+  assert(end - start == 4);
+  uint16_t codepoint =
+      (hexdigit(start[0]) << 12) |
+      (hexdigit(start[1]) << 8) |
+      (hexdigit(start[2]) << 4) |
+      hexdigit(start[3]);
+  // TODO(haberman): convert to UTF-8 and emit (though if it is a high surrogate
+  // we have to wait for the next escape to get the full code point).
+  UPB_UNUSED(codepoint);
+}
+
+#define CHECK_RETURN_TOP(x) if (!(x)) goto error
+
+// What follows is the Ragel parser itself.  The language is specified in Ragel
+// and the actions call our C functions above.
+%%{
+  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, p); }
+      %{ hex(parser, p); }
+    ;
+
+  escape_char  =
+    "\\"
+    /[rtbfn"\/\\]/
+      >{ escape(parser, p); }
+    ;
+
+  string_machine := (text | unicode_char | escape_char)** '"' @{ fret; } ;
+  string       = '"' @{ fcall string_machine; };
+
+  value2 = ^(space | "]" | "}") >{ fhold; fcall value_machine; } ;
+
+  member =
+    ws
+    string
+      >{ start_member(parser); }
+      %{ CHECK_RETURN_TOP(end_member(parser)); }
+    ws ":" ws
+    value2
+      %{ clear_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); }
+      %{ end_number(parser, p); }
+    | string
+      >{ CHECK_RETURN_TOP(start_stringval(parser)); }
+      %{ end_stringval(parser); }
+    | "true"
+      %{ CHECK_RETURN_TOP(putbool(parser, true)); }
+    | "false"
+      %{ CHECK_RETURN_TOP(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;
+
+size_t parse(void *closure, const void *hd, const char *buf, size_t size,
+             const upb_bufhandle *handle) {
+  UPB_UNUSED(hd);
+  UPB_UNUSED(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;
+
+  %% write exec;
+
+  if (p != pe) {
+    upb_status_seterrf(parser->status, "Parse error at %s\n", 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);
+  return true;
+}
+
+void upb_json_parser_init(upb_json_parser *p, upb_status *status) {
+  p->limit = p->stack + UPB_JSON_MAX_DEPTH;
+  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);
+  p->status = status;
+}
+
+void upb_json_parser_uninit(upb_json_parser *p) {
+  upb_byteshandler_uninit(&p->input_handler_);
+}
+
+void upb_json_parser_reset(upb_json_parser *p) {
+  p->top = p->stack;
+  p->top->f = NULL;
+
+  int cs;
+  int top;
+  // Emit Ragel initialization of the parser.
+  %% write init;
+  p->current_state = cs;
+  p->parser_top = top;
+  p->text_begin = NULL;
+  p->accumulated = NULL;
+  p->accumulated_len = 0;
+}
+
+void upb_json_parser_resetoutput(upb_json_parser *p, upb_sink *sink) {
+  upb_json_parser_reset(p);
+  upb_sink_reset(&p->top->sink, sink->handlers, sink->closure);
+  p->top->m = upb_handlers_msgdef(sink->handlers);
+  p->accumulated = NULL;
+}
+
+upb_bytessink *upb_json_parser_input(upb_json_parser *p) {
+  return &p->input_;
+}