util.cc: reduce two read_file functions into one (#20655)

* no need to malloc one extra byte

* combine two read_file into a faster one

* cleanup #include

* use resize

* apply suggestions from review

* space

* rebase master
old-commit-hash: fe2f63849a

selfdrive/common/framebuffer.cc

@@ -40,7 +40,7 @@ void FrameBuffer::swap() {
 bool set_brightness(int brightness) {
   char bright[64];
   snprintf(bright, sizeof(bright), "%d", brightness);
-  return 0 == write_file("/sys/class/leds/lcd-backlight/brightness", bright, strlen(bright));
+  return 0 == util::write_file("/sys/class/leds/lcd-backlight/brightness", bright, strlen(bright));
 }
 
 void FrameBuffer::set_power(int mode) {

selfdrive/common/gpio.cc

@@ -15,7 +15,7 @@ int gpio_init(int pin_nr, bool output){
     return -1;
   }
   const char *value = output ? "out" : "in";
-  return write_file(pin_dir_path, (void*)value, strlen(value));
+  return util::write_file(pin_dir_path, (void*)value, strlen(value));
 }
 
 int gpio_set(int pin_nr, bool high){
@@ -25,5 +25,5 @@ int gpio_set(int pin_nr, bool high){
   if(pin_val_path_len <= 0){
     return -1;
   }
-  return write_file(pin_val_path, (void*)(high ? "1" : "0"), 1);
+  return util::write_file(pin_val_path, (void*)(high ? "1" : "0"), 1);
 }

selfdrive/common/util.cc

@@ -11,46 +11,6 @@
 #include <sched.h>
 #endif // __linux__
 
-void* read_file(const char* path, size_t* out_len) {
-  FILE* f = fopen(path, "r");
-  if (!f) {
-    return NULL;
-  }
-  fseek(f, 0, SEEK_END);
-  long f_len = ftell(f);
-  rewind(f);
-
-  // malloc one extra byte so the file will always be NULL terminated
-  // cl_cached_program_from_file relies on this
-  char* buf = (char*)malloc(f_len+1);
-  assert(buf);
-
-  size_t num_read = fread(buf, f_len, 1, f);
-  fclose(f);
-
-  if (num_read != 1) {
-    free(buf);
-    return NULL;
-  }
-
-  buf[f_len] = '\0';
-  if (out_len) {
-    *out_len = f_len;
-  }
-
-  return buf;
-}
-
-int write_file(const char* path, const void* data, size_t size, int flags, mode_t mode) {
-  int fd = open(path, flags, mode);
-  if (fd == -1) {
-    return -1;
-  }
-  ssize_t n = write(fd, data, size);
-  close(fd);
-  return (n >= 0 && (size_t)n == size) ? 0 : -1;
-}
-
 void set_thread_name(const char* name) {
 #ifdef __linux__
   // pthread_setname_np is dumb (fails instead of truncates)
@@ -84,3 +44,30 @@ int set_core_affinity(int core) {
   return -1;
 #endif
 }
+
+namespace util {
+
+std::string read_file(const std::string& fn) {
+  std::ifstream ifs(fn, std::ios::binary | std::ios::ate);
+  if (ifs) {
+    std::ifstream::pos_type pos = ifs.tellg();
+    std::string result;
+    result.resize(pos);
+    ifs.seekg(0, std::ios::beg);
+    ifs.read(result.data(), pos);
+    if (ifs) return result;
+  }
+  return "";
+}
+
+int write_file(const char* path, const void* data, size_t size, int flags, mode_t mode) {
+  int fd = open(path, flags, mode);
+  if (fd == -1) {
+    return -1;
+  }
+  ssize_t n = write(fd, data, size);
+  close(fd);
+  return (n >= 0 && (size_t)n == size) ? 0 : -1;
+}
+
+}  // namespace util

selfdrive/common/util.h

@@ -10,7 +10,6 @@
 #include <string>
 #include <memory>
 #include <atomic>
-#include <sstream>
 #include <fstream>
 #include <thread>
 #include <chrono>
@@ -20,13 +19,6 @@
 typedef void (*sighandler_t)(int sig);
 #endif
 
-// Reads a file into a newly allocated buffer.
-//
-// Returns NULL on failure, otherwise the NULL-terminated file contents.
-// The result must be freed by the caller.
-void* read_file(const char* path, size_t* out_len);
-int write_file(const char* path, const void* data, size_t size, int flags=O_WRONLY, mode_t mode=0777);
-
 void set_thread_name(const char* name);
 
 int set_realtime_priority(int level);
@@ -59,12 +51,9 @@ inline std::string string_format(const std::string& format, Args... args) {
   return std::string(buf.get(), buf.get() + size - 1);
 }
 
-inline std::string read_file(const std::string &fn) {
-  std::ifstream t(fn);
-  std::stringstream buffer;
-  buffer << t.rdbuf();
-  return buffer.str();
-}
+std::string read_file(const std::string &fn);
+
+int write_file(const char* path, const void* data, size_t size, int flags = O_WRONLY, mode_t mode = 0777);
 
 inline std::string tohex(const uint8_t* buf, size_t buf_size) {
   std::unique_ptr<char[]> hexbuf(new char[buf_size*2+1]);

selfdrive/common/watchdog.cc

@@ -12,6 +12,6 @@ bool watchdog_kick(){
   std::string fn = watchdog_fn_prefix + std::to_string(getpid());
   std::string cur_t = std::to_string(nanos_since_boot());
 
-  int r = write_file(fn.c_str(), cur_t.data(), cur_t.length(), O_WRONLY | O_CREAT);
+  int r = util::write_file(fn.c_str(), cur_t.data(), cur_t.length(), O_WRONLY | O_CREAT);
   return r == 0;
 }

selfdrive/modeld/runners/snpemodel.cc

@@ -24,14 +24,13 @@ SNPEModel::SNPEModel(const char *path, float *loutput, size_t loutput_size, int
   }
   assert(zdl::SNPE::SNPEFactory::isRuntimeAvailable(Runtime));
 #endif
-  size_t model_size;
-  model_data = (uint8_t *)read_file(path, &model_size);
-  assert(model_data);
+  model_data = util::read_file(path);
+  assert(model_data.size() > 0);
 
   // load model
-  std::unique_ptr<zdl::DlContainer::IDlContainer> container = zdl::DlContainer::IDlContainer::open(model_data, model_size);
+  std::unique_ptr<zdl::DlContainer::IDlContainer> container = zdl::DlContainer::IDlContainer::open((uint8_t*)model_data.data(), model_data.size());
   if (!container) { PrintErrorStringAndExit(); }
-  printf("loaded model with size: %lu\n", model_size);
+  printf("loaded model with size: %lu\n", model_data.size());
 
   // create model runner
   zdl::SNPE::SNPEBuilder snpeBuilder(container.get());

selfdrive/modeld/runners/snpemodel.h

@@ -24,9 +24,6 @@
 class SNPEModel : public RunModel {
 public:
   SNPEModel(const char *path, float *loutput, size_t loutput_size, int runtime);
-  ~SNPEModel() {
-    if (model_data) free(model_data);
-  }
   void addRecurrent(float *state, int state_size);
   void addTrafficConvention(float *state, int state_size);
   void addDesire(float *state, int state_size);
@@ -37,7 +34,7 @@ public:
 #endif
 
 private:
-  uint8_t *model_data = NULL;
+  std::string model_data;
 
 #if defined(QCOM) || defined(QCOM2)
   zdl::DlSystem::Runtime_t Runtime;

selfdrive/proclogd/SConscript

@@ -1,2 +1,2 @@
-Import('env', 'cereal', 'messaging')
-env.Program('proclogd.cc', LIBS=[cereal, messaging, 'pthread', 'zmq', 'capnp', 'kj'])
+Import('env', 'cereal', 'messaging', 'common')
+env.Program('proclogd.cc', LIBS=[cereal, messaging, 'pthread', 'zmq', 'capnp', 'kj', 'common'])