add manually allocated jit stack for pcre expressions to avoid PCRE_E…

…RROR_JIT_STACKLIMIT when calling pcre_exec()

hphp/runtime/base/preg.cpp

@@ -71,7 +71,12 @@ void PCREglobals::onSessionExit() {
   smart::vector<const pcre_cache_entry*>().swap(m_overflow);
 }
 
+PCREglobals::PCREglobals() {
+  m_jit_stack = pcre_jit_stack_alloc(32768, 524288);
+}
+
 PCREglobals::~PCREglobals() {
+  pcre_jit_stack_free(m_jit_stack);
   onSessionExit();
 }
 
@@ -196,6 +201,10 @@ static __thread pcre_extra t_extra_data;
 // The last pcre error code is available for the whole thread.
 static __thread int t_last_error_code;
 
+static pcre_jit_stack *alloc_jit_stack(void* data) {
+  return s_pcre_globals->m_jit_stack;
+}
+
 namespace {
 
 template<bool useSmartFree = false>
@@ -443,6 +452,7 @@ pcre_get_compiled_regex_cache(const String& regex) {
     if (extra) {
       extra->flags |= PCRE_EXTRA_MATCH_LIMIT |
         PCRE_EXTRA_MATCH_LIMIT_RECURSION;
+      pcre_assign_jit_stack(extra, alloc_jit_stack, nullptr);
     }
     if (error != nullptr) {
       try {

hphp/runtime/base/preg.h

@@ -69,13 +69,14 @@ class pcre_cache_entry {
 
 class PCREglobals {
 public:
-  PCREglobals() { }
+  PCREglobals();
   ~PCREglobals();
   void cleanupOnRequestEnd(const pcre_cache_entry* ent);
   void onSessionExit();
   // pcre ini_settings
   int64_t m_preg_backtrace_limit;
   int64_t m_preg_recursion_limit;
+  pcre_jit_stack *m_jit_stack;
 private:
   smart::vector<const pcre_cache_entry*> m_overflow;
 };