Create jiterator cache dirs recursively (reland) (pytorch#74592)

Summary:
Reland of pytorch#74425 with internal compilation error fixed

The change expects the base directories (`HOME/TEMP`, `XDG_CACHE_HOME`, or the user-defined `PYTORCH_KERNEL_CACHE_PATH`) to exist to avoid potentially exploiting the recursive folder creation.

Pull Request resolved: pytorch#74592

Reviewed By: mruberry

Differential Revision: D35066710

Pulled By: malfet

fbshipit-source-id: c26aff826b0a3d6ca99286b031711698a515fbbb

aten/src/ATen/native/cuda/jit_utils.cpp

@@ -808,6 +808,65 @@ std::string generate_code(
   return code;
 }
 
+// Creates directories recursively
+bool _r_mkdir(const std::string& dir) {
+  // Check if current dir exists
+  const char* p_dir = dir.c_str();
+  const bool dir_exists = (access(p_dir, F_OK) == 0);
+  if (dir_exists) {
+    return true;
+  }
+
+  // Try to create current directory
+#ifdef _WIN32
+  int ret = _mkdir(dir.c_str());
+#else
+  int ret = mkdir(dir.c_str(), S_IRWXU | S_IRWXG | S_IRWXO);
+#endif
+  // Success
+  if (ret == 0) {
+    return true;
+  }
+
+  // Find folder separator and check if we are at the top
+  auto  pos = dir.find_last_of("/\\");
+  if (pos == std::string::npos) {
+    return false;
+  }
+
+  // Try to create parent directory
+  if (!(_r_mkdir(dir.substr(0, pos)))) {
+    return false;
+  }
+
+  // Try to create complete path again
+#ifdef _WIN32
+  ret = _mkdir(dir.c_str());
+#else
+  ret = mkdir(dir.c_str(), S_IRWXU | S_IRWXG | S_IRWXO);
+#endif
+  return ret == 0;
+}
+
+// Creates directories recursively assuming that base exists
+bool r_mkdir_with_base(std::string& base, std::string& dir){
+  const char* p_base = base.c_str();
+  const bool base_exists = (access(p_base, F_OK) == 0);
+  if (!base_exists) {
+    return false;
+  }
+
+  // remove trailing '/' or '\\'
+  if ((base[base.size()-1]=='/') || base[base.size()-1]=='\\') {
+    base.pop_back();
+  }
+  if ((dir[dir.size()-1]=='/') || dir[dir.size()-1]=='\\') {
+    dir.pop_back();
+  }
+
+  return _r_mkdir(base+dir);
+}
+
 
 // Acquires (possibly creating) the kernel cache directory
 c10::optional<std::string> get_cache_dir() {
@@ -822,6 +881,8 @@ c10::optional<std::string> get_cache_dir() {
   // Cache path comes from PYTORCH_KERNEL_CACHE_PATH, then TEMP (Windows) or XDG_CACHE_HOME (Linux), then HOME environment variables
   std::string cache_dir;
   char* ptkcp = std::getenv("PYTORCH_KERNEL_CACHE_PATH");
+  // Create kernel_cache_dir if needed as we do not want to create the base directory passed by the user
+  std::string kernels_cache_dir = "";
   if (ptkcp != nullptr) {
     cache_dir = std::string(ptkcp);
   } else {
@@ -832,7 +893,8 @@ c10::optional<std::string> get_cache_dir() {
     ptkcp = std::getenv("XDG_CACHE_HOME");
 #endif
     if (ptkcp != nullptr) {
-      cache_dir = std::string(ptkcp) + "/torch/kernels";
+      kernels_cache_dir = "/torch/kernels";
+      cache_dir = std::string(ptkcp) + kernels_cache_dir;
     } else {
       // Falls back to HOME/.cache
       ptkcp = std::getenv("HOME");
@@ -841,7 +903,8 @@ c10::optional<std::string> get_cache_dir() {
                         " This disables kernel caching.");
         return {};
       } else {
-        cache_dir = std::string(ptkcp) + "/.cache/torch/kernels";
+        kernels_cache_dir = "/.cache/torch/kernels";
+        cache_dir = std::string(ptkcp) + kernels_cache_dir;
       }
     }
   }
@@ -850,11 +913,8 @@ c10::optional<std::string> get_cache_dir() {
   const char* p_cache_dir = cache_dir.c_str();
   const bool cache_dir_exists = (access(p_cache_dir, F_OK) == 0);
   if (!cache_dir_exists) {
-#ifdef _WIN32
-    if (_mkdir(p_cache_dir) != 0) {
-#else
-    if (mkdir(p_cache_dir, S_IRWXU | S_IRWXG | S_IRWXO) != 0) {
-#endif
+    std::string s_ptkcp = std::string(ptkcp);
+    if (!r_mkdir_with_base(s_ptkcp, kernels_cache_dir)) {
       TORCH_WARN_ONCE("Specified kernel cache directory could not be created! This disables kernel caching.",
                       " Specified directory is ", cache_dir, ".",
                       " This warning will appear only once per process.");