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// Copyright (C) 2015 the Massachusetts Institute of Technology
// Copyright (C) 2015 Benjamin Barenblat
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include "src/regex__FFI.h"
#include <cstdio>
#include <cstring>
#include <regex> // NOLINT(build/c++11)
#include <boost/numeric/conversion/cast.hpp> // NOLINT(build/include_order)
extern "C" {
#include <urweb/urweb_cpp.h> // NOLINT(build/include_order)
}
#include "./config.h"
namespace {
// Asserts a condition without crashing or releasing information about where the
// error occurred. This function is essential for web programming, where an
// attacker should not be able to bring down the app by causing an assertion
// failure.
void Assert(uw_context* const context, const bool condition,
const failure_kind action, const char* const message) {
if (!condition) {
uw_error(context, action, message);
}
}
void Assert(uw_context* const context, const bool condition,
const char* const message) {
Assert(context, condition, FATAL, message);
}
void DeleteMatchResults(void* match_result,
[[gnu::unused]] const int _will_retry) {
delete reinterpret_cast<std::cmatch*>(match_result);
}
// Bounds-checked numeric type conversion
template <typename Target, typename Source>
Target Number(uw_context* const context, Source arg) {
try {
return boost::numeric_cast<Target>(arg);
} catch (const boost::numeric::bad_numeric_cast& e) {
uw_error(context, FATAL, "regex: %s", e.what());
}
}
} // namespace
uw_Basis_bool uw_Regex__FFI_succeeded([[gnu::unused]] uw_context* const context,
const uw_Regex__FFI_match match) {
if (reinterpret_cast<std::cmatch*>(match.result)->empty()) {
return uw_Basis_False;
} else {
return uw_Basis_True;
}
}
uw_Basis_int uw_Regex__FFI_n_subexpression_matches(
uw_context* const context, const uw_Regex__FFI_match match) {
const std::cmatch::size_type n_matches =
reinterpret_cast<std::cmatch*>(match.result)->size();
if (n_matches == 0) {
// Nothing got matched.
return 0;
} else {
// At least one match occurred. Compute the number of parenthesized
// subexpressions that got matched, and return it.
return Number<uw_Basis_int>(context, n_matches) - 1;
}
}
uw_Basis_string uw_Regex__FFI_subexpression_match(
uw_context* const context, const uw_Regex__FFI_match match,
const uw_Basis_int match_index_signed) {
const std::cmatch* const match_result =
reinterpret_cast<std::cmatch*>(match.result);
const std::size_t match_index =
Number<std::size_t>(context, match_index_signed);
Assert(context, match_index < match_result->size(),
"regex: match does not exist");
const auto matched_substring = (*match_result)[match_index + 1];
// Save the matched substring.
const std::size_t result_length =
Number<std::size_t>(context, matched_substring.length());
uw_Basis_string result =
reinterpret_cast<uw_Basis_string>(uw_malloc(context, result_length + 1));
Assert(context, std::snprintf(result, result_length + 1, "%s",
matched_substring.str().c_str()) >= 0,
"regex: snprintf failed during match");
return result;
}
uw_Regex__FFI_match uw_Regex__FFI_do_match(uw_context* const context,
const uw_Basis_string needle_string,
const uw_Basis_string haystack) {
std::regex needle;
try {
needle.assign(needle_string, std::regex_constants::ECMAScript);
} catch (const std::regex_error& e) {
switch (e.code()) {
case std::regex_constants::error_space:
case std::regex_constants::error_stack:
// We ran out of memory.
uw_error(context, BOUNDED_RETRY, "regex: compilation failed: %s",
e.what());
default:
uw_error(context, FATAL, "regex: compilation failed: %s", e.what());
}
}
uw_Regex__FFI_match result;
// Make a duplicate of the string to match against, so if it goes out of
// scope in the calling Ur code, we still have it.
const auto haystack_length = std::strlen(haystack);
result.haystack =
reinterpret_cast<char*>(uw_malloc(context, haystack_length + 1));
Assert(context, std::snprintf(result.haystack, haystack_length + 1, "%s",
haystack) >= 0,
"regex: snprintf failed during match");
// Allocate to store the match information.
auto* match_results = new std::cmatch;
Assert(context, uw_register_transactional(context, match_results, nullptr,
nullptr, DeleteMatchResults) == 0,
"regex: could not register DeleteMatchResults finalizer");
result.result = match_results;
// Execute the regex on the saved haystack, not the original one.
std::regex_search(result.haystack, *match_results, needle);
return result;
}
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