Use req::vector in pcntl_exec

Summary:
std::vector<String> is unsound in general. We get away with it
here because the GC never runs while the argv/envp vectors are
alive. But its worth fixing anyway.

Reviewed By: alexeyt, kodafb

Differential Revision: D5089155

fbshipit-source-id: bcb7002c1fd0c5ca6ec447fc9206e46c304bdc46

hphp/runtime/ext/process/ext_process.cpp

@@ -61,24 +61,21 @@ namespace HPHP {
 ///////////////////////////////////////////////////////////////////////////////
 
 // build environment pair list
-static char **build_envp(const Array& envs, std::vector<String> &senvs) {
-  char **envp = NULL;
-  int size = envs.size();
-  if (size) {
-    envp = (char **)malloc((size + 1) * sizeof(char *));
-    int i = 0;
-    for (ArrayIter iter(envs); iter; ++iter, ++i) {
-      StringBuffer nvpair;
-      nvpair.append(iter.first().toString());
-      nvpair.append('=');
-      nvpair.append(iter.second().toString());
-
-      String env = nvpair.detach();
-      senvs.push_back(env);
-      *(envp + i) = (char *)env.data();
-    }
-    *(envp + i) = NULL;
+static char** build_envp(const Array& envs, req::vector<String> &senvs) {
+  auto const size = envs.size();
+  if (!size) return nullptr;
+  auto envp = req::make_raw_array<char*>(size + 1);
+  size_t i = 0;
+  for (ArrayIter iter(envs); iter; ++iter, ++i) {
+    StringBuffer nvpair;
+    nvpair.append(iter.first().toString());
+    nvpair.append('=');
+    nvpair.append(iter.second().toString());
+    String env = nvpair.detach();
+    senvs.push_back(env);
+    envp[i] = (char*)env.data();
   }
+  envp[i] = nullptr;
   return envp;
 }
 
@@ -89,7 +86,7 @@ static bool check_cmd(const char *cmd) {
     bool allow = false;
     while (isblank(*cmd_tmp)) cmd_tmp++;
     const char *space = strchr(cmd_tmp, ' ');
-    unsigned int cmd_len = strlen(cmd_tmp);
+    auto cmd_len = strlen(cmd_tmp);
     if (space) {
       cmd_len = space - cmd_tmp;
     }
@@ -213,25 +210,25 @@ void HHVM_FUNCTION(pcntl_exec,
     return;
   }
 
-  // build argumnent list
-  std::vector<String> sargs; // holding those char *
-  int size = args.size();
-  char **argv = (char **)malloc((size + 2) * sizeof(char *));
-  *argv = (char *)path.data();
+  // build argument list
+  req::vector<String> sargs; // holding those char *
+  auto const size = args.size();
+  auto argv = req::make_raw_array<char*>(size + 2);
+  argv[0] = (char*)path.data();
   int i = 1;
   if (size) {
     sargs.reserve(size);
     for (ArrayIter iter(args); iter; ++iter, ++i) {
       String arg = iter.second().toString();
       sargs.push_back(arg);
-      *(argv + i) = (char *)arg.data();
+      argv[i] = (char*)arg.data();
     }
   }
-  *(argv + i) = NULL;
+  argv[i] = nullptr;
 
   // build environment pair list
-  std::vector<String> senvs; // holding those char *
-  char **envp = build_envp(envs, senvs);
+  req::vector<String> senvs; // holding those char *
+  auto envp = build_envp(envs, senvs);
   if (execve(path.c_str(), argv, envp) == -1) {
     raise_warning("Error has occurred: (errno %d) %s",
                     errno, folly::errnoStr(errno).c_str());