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// Copyright (C) 2015 the Massachusetts Institute of Technology
//
// 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 "regex__FFI.h"
#include <regex.h>
#include <cstring>
#include <limits>
#include <regex>
extern "C" {
#include <urweb/urweb_cpp.h>
}
#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 DeleteRegex(void* regex, [[gnu::unused]] const int _will_retry) {
delete reinterpret_cast<std::regex*>(regex);
}
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 T, typename U>
U Number(uw_context* const context, const T input) {
Assert(context, input <= std::numeric_limits<U>::max(),
"regex: detected overflow during numeric conversion");
if (std::numeric_limits<T>::is_signed == std::numeric_limits<U>::is_signed) {
Assert(context, std::numeric_limits<U>::lowest() <= input,
"regex: detected underflow during numeric conversion");
} else if (std::numeric_limits<T>::is_signed) {
Assert(context, 0 <= input,
"regex: detected underflow during numeric conversion");
}
return static_cast<U>(input);
}
} // 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<std::cmatch::size_type, 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<uw_Basis_int, 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::csub_match::difference_type, std::size_t>(
context,
matched_substring.length());
uw_Basis_string result =
reinterpret_cast<uw_Basis_string>(
uw_malloc(context, result_length + 1));
std::strcpy(result, matched_substring.str().c_str());
return result;
}
uw_Regex__FFI_regex uw_Regex__FFI_compile(uw_context* const context,
const uw_Basis_bool case_sensitive,
const uw_Basis_string input) {
// We'd like to stack-allocate the result--or, at least, to allocate it with
// uw_malloc. Unfortunately, neither of those will work, because we need to
// run a finalizer on it, and Ur finalizers can only reference addresses that
// are not managed by Ur.
auto* result = new std::regex;
Assert(context,
uw_register_transactional(context, result,
nullptr, nullptr, DeleteRegex) == 0,
"regex: could not register DeleteRegex finalizer");
auto flags = std::regex_constants::extended;
if (!case_sensitive) {
flags |= std::regex_constants::icase;
}
try {
result->assign(input, flags);
} 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());
}
}
return result;
}
uw_Regex__FFI_match uw_Regex__FFI_do_match(uw_context* const context,
const uw_Regex__FFI_regex needle,
const uw_Basis_string haystack) {
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.
result.haystack =
reinterpret_cast<char*>(uw_malloc(context, std::strlen(haystack)));
std::strcpy(result.haystack, haystack);
// 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,
*reinterpret_cast<std::regex*>(needle));
return result;
}
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