common: add new class OpenPilotPrefix (#26753)

* new class OpenPilotPrefix

* move random_string to util

* rename file

* style

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
old-commit-hash: 0d8254e95935f27d7c371ecc4c2d6c9ff8c204d0

common/prefix.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <cassert>
+#include <string>
+
+#include "common/params.h"
+#include "common/util.h"
+
+class OpenpilotPrefix {
+public:
+  OpenpilotPrefix(std::string prefix = {}) {
+    if (prefix.empty()) {
+      prefix = util::random_string(15);
+    }
+    msgq_path = "/dev/shm/" + prefix;
+    bool ret = util::create_directories(msgq_path, 0777);
+    assert(ret);
+    setenv("OPENPILOT_PREFIX", prefix.c_str(), 1);
+  }
+
+  ~OpenpilotPrefix() {
+    auto param_path = Params().getParamPath();
+    if (util::file_exists(param_path)) {
+      std::string real_path = util::readlink(param_path);
+      system(util::string_format("rm %s -rf", real_path.c_str()).c_str());
+      unlink(param_path.c_str());
+    }
+    system(util::string_format("rm %s -rf", msgq_path.c_str()).c_str());
+    unsetenv("OPENPILOT_PREFIX");
+  }
+
+private:
+  std::string msgq_path;
+};

common/util.cc

@@ -10,6 +10,7 @@
 #include <dirent.h>
 #include <fstream>
 #include <iomanip>
+#include <random>
 #include <sstream>
 
 #ifdef __linux__
@@ -228,6 +229,18 @@ std::string hexdump(const uint8_t* in, const size_t size) {
   return ss.str();
 }
 
+std::string random_string(std::string::size_type length) {
+  const char* chrs = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+  std::mt19937 rg{std::random_device{}()};
+  std::uniform_int_distribution<std::string::size_type> pick(0, sizeof(chrs) - 2);
+  std::string s;
+  s.reserve(length);
+  while (length--) {
+    s += chrs[pick(rg)];
+  }
+  return s;
+}
+
 std::string dir_name(std::string const &path) {
   size_t pos = path.find_last_of("/");
   if (pos == std::string::npos) return "";

common/util.h

@@ -75,6 +75,7 @@ int getenv(const char* key, int default_val);
 float getenv(const char* key, float default_val);
 
 std::string hexdump(const uint8_t* in, const size_t size);
+std::string random_string(std::string::size_type length);
 std::string dir_name(std::string const& path);
 
 // **** file fhelpers *****

release/files_common

@@ -146,6 +146,7 @@ selfdrive/debug/vw_mqb_config.py
 common/SConscript
 common/version.h
 
+common/prefix.h
 common/swaglog.h
 common/swaglog.cc
 common/statlog.h

tools/cabana/cabana.cc

@@ -1,8 +1,7 @@
 #include <QApplication>
-#include <QDir>
 #include <QCommandLineParser>
-#include <QUuid>
 
+#include "common/prefix.h"
 #include "selfdrive/ui/qt/util.h"
 #include "tools/cabana/mainwin.h"
 
@@ -23,12 +22,6 @@ int main(int argc, char *argv[]) {
     cmd_parser.showHelp();
   }
 
-  QString uuid =  QUuid::createUuid().toString(QUuid::WithoutBraces);
-  QString msgq_path = "/dev/shm/" + uuid;
-
-  QDir dir;
-  dir.mkdir(msgq_path);
-  setenv("OPENPILOT_PREFIX", qPrintable(uuid), 1);
 
   const QString route = args.empty() ? DEMO_ROUTE : args.first();
   uint32_t replay_flags = REPLAY_FLAG_NONE;
@@ -38,6 +31,7 @@ int main(int argc, char *argv[]) {
     replay_flags |= REPLAY_FLAG_QCAMERA;
   }
 
+  OpenpilotPrefix op_prefix;
   CANMessages p(&app);
   int ret = 0;
   if (p.loadRoute(route, cmd_parser.value("data_dir"), replay_flags)) {
@@ -45,7 +39,5 @@ int main(int argc, char *argv[]) {
     w.showMaximized();
     ret = app.exec();
   }
-
-  dir.rmdir(msgq_path);
   return ret;
 }