watch mapped file for changes

imgui.ini

@@ -8,9 +8,9 @@ Size=1152,1414
 
 [Window][main]
 Pos=0,0
-Size=1115,1414
+Size=1115,470
 
 [Window][Hex View]
 Pos=91,62
-Size=1002,681
+Size=986,681
 

src/app_state.h

@@ -49,6 +49,9 @@ struct App_State {
   Window_Data win_data;
   User_Input user_input;
 
-  u8 *inspected_file;
+  FILE *inspected_file;
+  u8   *inspected_fmem;
   u64   inspected_file_size;
+	// @Platform: inotify file descriptor
+	int inot;
 };

src/mainloop.cpp

@@ -1,3 +1,12 @@
+internal
+size_t file_size(FILE *f)
+{
+  fseek(f, 0, SEEK_END);
+  size_t res = ftell(f);
+  fseek(f, 0, SEEK_SET);
+  return res;  
+}
+
 internal
 void monitor_key(GLFWwindow *window, u16 *key_state, i32 glfw_key, Input_Key haru_key) {
 	u16& state = key_state[haru_key];
@@ -53,6 +62,14 @@ void run_main_loop(GLFWwindow *window, Arena *arena, App_State &app)
 		ImGui_ImplGlfw_NewFrame();
 		ImGui::NewFrame();
 
+		// Check if the inspected file changed
+		{
+			char buf[sizeof(inotify_event) + NAME_MAX + 1];
+			ssize_t nbytes = read(app.inot, buf, sizeof(buf));
+			if (nbytes)
+				app.inspected_file_size = file_size(app.inspected_file);
+		}
+
 		if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS ||
 				glfwWindowShouldClose(window))
 		{

src/mem.cpp

@@ -12,18 +12,21 @@
 #define asan_unpoison_memory_region(mem, cmt)
 #endif
 
+// @Platform
 internal 
 void *os_reserve(u64 size)
 {
   return mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 }
 
+// @Platform
 internal 
 void os_release(void *mem, u64 size)
 {
   munmap(mem, size);
 }
 
+// @Platform
 internal 
 b32x os_commit(void *addr, u64 size)
 {

src/render.cpp

@@ -20,7 +20,7 @@ void update_and_render(Arena *arena, App_State &app, f32 delta_time)
   char *text_buf = arena_push_array_no_zero<char>(scratch.arena, text_buf_size + 1);
   // TODO: convert file content to human readable
   for (u64 i = 0; i < text_buf_size / 2; ++i)
-    sprintf(&text_buf[2 * i], "%02X", app.inspected_file[i]);
+    sprintf(&text_buf[2 * i], "%02X", app.inspected_fmem[i]);
   text_buf[text_buf_size] = 0;
   
   if (ImGui::Begin("main")) {
@@ -28,7 +28,7 @@ void update_and_render(Arena *arena, App_State &app, f32 delta_time)
     // ImGui::SetCursorX(30);
     // ImGui::TextWrapped("%s", text_buf);
     static MemoryEditor mem_edit = make_memory_editor();
-    mem_edit.DrawWindow("Hex View", app.inspected_file, app.inspected_file_size);
+    mem_edit.DrawWindow("Hex View", app.inspected_fmem, app.inspected_file_size);
     ImGui::End();
   }
 }

src/rntviewer.cpp

@@ -6,8 +6,11 @@
 #include <cstdint>
 #include <chrono>
 
+// @Platform
 #include <sys/mman.h>
+#include <sys/inotify.h>
 #include <unistd.h>
+#include <limits.h> // for NAME_MAX
 
 #ifdef DEBUG
 #include <sanitizer/asan_interface.h>
@@ -34,15 +37,6 @@ namespace chr = std::chrono;
 
 using namespace ROOT::Experimental;
 
-internal
-size_t file_size(FILE *f)
-{
-  fseek(f, 0, SEEK_END);
-  size_t res = ftell(f);
-  fseek(f, 0, SEEK_SET);
-  return res;  
-}
-
 internal 
 b8 init_imgui(GLFWwindow* window) {
 	IMGUI_CHECKVERSION();
@@ -124,12 +118,13 @@ int main(int argc, char **argv)
     return 1;
   }
 
-  // Open and map the file
+  // Open and map te file
   FILE *file = fopen(fname, "rb");
   defer { fclose(file); };
 
-  const int fd = fileno(file);
-  const size_t fsize = file_size(file);
+  int fd = fileno(file);
+  size_t fsize = file_size(file);
+  // @Platform
   void *fmem = mmap(0, fsize, PROT_READ, MAP_SHARED_VALIDATE, fd, 0);
   if (!fmem) {
     fprintf(stderr, "Failed to open file %s\n", fname);
@@ -137,7 +132,21 @@ int main(int argc, char **argv)
   }
   defer { munmap(fmem, fsize); };
 
+  // @Platform: watch file for changes (to adapt the displayed file size - otherwise
+  // we may try to access invalid memory when the file gets shrunk)
+  int inot = inotify_init1(IN_NONBLOCK);
+  if (inot == -1) {
+    fprintf(stderr, "Failed to init inotify: %s (%d)\n", strerror(errno), errno);
+    return 1;
+  }
+  if (inotify_add_watch(inot, fname, IN_MODIFY) == -1) {
+    fprintf(stderr, "Failed to add inotify watch: %s (%d)\n", strerror(errno), errno);
+    return 1;
+  }
+  defer { close(inot); };
+
   // Open the TFile
+#if 0
   TFile *tfile = TFile::Open(fname, "READ");
   if (!tfile) {
     fprintf(stderr, "Failed to open TFile.\n");
@@ -151,11 +160,14 @@ int main(int argc, char **argv)
     fprintf(stderr, "RNTuple '%s' not found in %s.\n", ntpl_name, fname);
     return 1;
   }
+#endif
 
   // Start main loop
   App_State app {};
-  app.inspected_file = (u8*)fmem;
+  app.inspected_file = file;
+  app.inspected_fmem = (u8*)fmem;
   app.inspected_file_size = fsize;
+  app.inot = inot;
   
   run_main_loop(window, arena, app);