Implement directory monitoring using septag/dmon

Use a notification based directory monitoring based on the
septag/dmon lirbary instead of periodically rescan the whole
project's tree.

src/api/system.c

@@ -6,6 +6,7 @@
 #include <errno.h>
 #include <sys/stat.h>
 #include "api.h"
+#include "dirmonitor.h"
 #include "rencache.h"
 #ifdef _WIN32
   #include <direct.h>
@@ -236,6 +237,14 @@ top:
       lua_pushnumber(L, e.wheel.y);
       return 2;
 
+    case SDL_USEREVENT:
+      lua_pushstring(L, "dirchange");
+      lua_pushnumber(L, e.user.code >> 16);
+      lua_pushstring(L, (e.user.code & 0xffff) == DMON_ACTION_DELETE ? "delete" : "create");
+      lua_pushstring(L, e.user.data1);
+      free(e.user.data1);
+      return 4;
+
     default:
       goto top;
   }
@@ -651,6 +660,91 @@ static int f_set_window_opacity(lua_State *L) {
   return 1;
 }
 
+static int f_watch_dir(lua_State *L) {
+  const char *path = luaL_checkstring(L, 1);
+  const int recursive = lua_toboolean(L, 2);
+  uint32_t dmon_flags = (recursive ? DMON_WATCHFLAGS_RECURSIVE : 0);
+  dmon_watch_id watch_id = dmon_watch(path, dirmonitor_watch_callback, dmon_flags, NULL);
+  if (watch_id.id == 0) { luaL_error(L, "directory monitoring watch failed"); }
+  lua_pushnumber(L, watch_id.id);
+  return 1;
+}
+
+#if __linux__
+static int f_watch_dir_add(lua_State *L) {
+  dmon_watch_id watch_id;
+  watch_id.id = luaL_checkinteger(L, 1);
+  const char *subdir = luaL_checkstring(L, 2);
+  lua_pushboolean(L, dmon_watch_add(watch_id, subdir));
+  return 1;
+}
+
+static int f_watch_dir_rm(lua_State *L) {
+  dmon_watch_id watch_id;
+  watch_id.id = luaL_checkinteger(L, 1);
+  const char *subdir = luaL_checkstring(L, 2);
+  lua_pushboolean(L, dmon_watch_rm(watch_id, subdir));
+  return 1;
+}
+#endif
+
+#ifdef _WIN32
+#define PATHSEP '\\'
+#else
+#define PATHSEP '/'
+#endif
+
+/* Special purpose filepath compare function. Corresponds to the
+   order used in the TreeView view of the project's files. Returns true iff
+   path1 < path2 in the TreeView order. */
+static int f_path_compare(lua_State *L) {
+  const char *path1 = luaL_checkstring(L, 1);
+  const char *type1_s = luaL_checkstring(L, 2);
+  const char *path2 = luaL_checkstring(L, 3);
+  const char *type2_s = luaL_checkstring(L, 4);
+  const int len1 = strlen(path1), len2 = strlen(path2);
+  int type1 = strcmp(type1_s, "dir") != 0;
+  int type2 = strcmp(type2_s, "dir") != 0;
+  /* Find the index of the common part of the path. */
+  int offset = 0, i;
+  for (i = 0; i < len1 && i < len2; i++) {
+    if (path1[i] != path2[i]) break;
+    if (path1[i] == PATHSEP) {
+      offset = i + 1;
+    }
+  }
+  /* If a path separator is present in the name after the common part we consider
+     the entry like a directory. */
+  if (strchr(path1 + offset, PATHSEP)) {
+    type1 = 0;
+  }
+  if (strchr(path2 + offset, PATHSEP)) {
+    type2 = 0;
+  }
+  /* If types are different "dir" types comes before "file" types. */
+  if (type1 != type2) {
+    lua_pushboolean(L, type1 < type2);
+    return 1;
+  }
+  /* If types are the same compare the files' path alphabetically. */
+  int cfr = 0;
+  int len_min = (len1 < len2 ? len1 : len2);
+  for (int j = offset; j <= len_min; j++) {
+    if (path1[j] == path2[j]) continue;
+    if (path1[j] == 0 || path2[j] == 0) {
+      cfr = (path1[j] == 0);
+    } else if (path1[j] == PATHSEP || path2[j] == PATHSEP) {
+      /* For comparison we treat PATHSEP as if it was the string terminator. */
+      cfr = (path1[j] == PATHSEP);
+    } else {
+      cfr = (path1[j] < path2[j]);
+    }
+    break;
+  }
+  lua_pushboolean(L, cfr);
+  return 1;
+}
+
 
 static const luaL_Reg lib[] = {
   { "poll_event",          f_poll_event          },
@@ -678,6 +772,12 @@ static const luaL_Reg lib[] = {
   { "exec",                f_exec                },
   { "fuzzy_match",         f_fuzzy_match         },
   { "set_window_opacity",  f_set_window_opacity  },
+  { "watch_dir",           f_watch_dir           },
+  { "path_compare",        f_path_compare        },
+#if __linux__
+  { "watch_dir_add",       f_watch_dir_add       },
+  { "watch_dir_rm",        f_watch_dir_rm        },
+#endif
   { NULL, NULL }
 };
 

src/dirmonitor.c

@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <string.h>
+
+#include <SDL.h>
+
+#define DMON_IMPL
+#include "dmon.h"
+
+#include "dirmonitor.h"
+
+static void send_sdl_event(dmon_watch_id watch_id, dmon_action action, const char *filepath) {
+  SDL_Event ev;
+  const int size = strlen(filepath) + 1;
+  /* The string allocated below should be deallocated as soon as the event is
+     treated in the SDL main loop. */
+  char *new_filepath = malloc(size);
+  if (!new_filepath) return;
+  memcpy(new_filepath, filepath, size);
+#ifdef _WIN32
+  for (int i = 0; i < size; i++) {
+    if (new_filepath[i] == '/') {
+      new_filepath[i] = '\\';
+    }
+  }
+#endif
+  SDL_zero(ev);
+  ev.type = SDL_USEREVENT;
+  ev.user.code = ((watch_id.id & 0xffff) << 16) | (action & 0xffff);
+  ev.user.data1 = new_filepath;
+  SDL_PushEvent(&ev);
+}
+
+void dirmonitor_init() {
+  dmon_init();
+  /* In theory we should register our user event but since we
+     have just one type of user event this is not really needed. */
+  /* sdl_dmon_event_type = SDL_RegisterEvents(1); */
+}
+
+void dirmonitor_deinit() {
+  dmon_deinit();
+}
+
+void dirmonitor_watch_callback(dmon_watch_id watch_id, dmon_action action, const char *rootdir,
+  const char *filepath, const char *oldfilepath, void *user)
+{
+  (void) rootdir;
+  (void) user;
+  switch (action) {
+  case DMON_ACTION_MOVE:
+    send_sdl_event(watch_id, DMON_ACTION_DELETE, oldfilepath);
+    send_sdl_event(watch_id, DMON_ACTION_CREATE, filepath);
+    break;
+  case DMON_ACTION_MODIFY:
+    break;
+  default:
+    send_sdl_event(watch_id, action, filepath);
+  }
+}
+

src/dirmonitor.h

@@ -0,0 +1,14 @@
+#ifndef DIRMONITOR_H
+#define DIRMONITOR_H
+
+#include <stdint.h>
+
+#include "dmon.h"
+
+void dirmonitor_init();
+void dirmonitor_deinit();
+void dirmonitor_watch_callback(dmon_watch_id watch_id, dmon_action action, const char *rootdir,
+  const char *filepath, const char *oldfilepath, void *user);
+
+#endif
+

src/main.c

@@ -14,6 +14,8 @@
   #include <mach-o/dyld.h>
 #endif
 
+#include "dirmonitor.h"
+
 
 SDL_Window *window;
 
@@ -107,6 +109,8 @@ int main(int argc, char **argv) {
   SDL_DisplayMode dm;
   SDL_GetCurrentDisplayMode(0, &dm);
 
+  dirmonitor_init();
+
   window = SDL_CreateWindow(
     "", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, dm.w * 0.8, dm.h * 0.8,
     SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_HIDDEN);
@@ -189,6 +193,7 @@ init_lua:
 
   lua_close(L);
   ren_free_window_resources();
+  dirmonitor_deinit();
 
   return EXIT_SUCCESS;
 }

src/meson.build

@@ -6,6 +6,7 @@ lite_sources = [
     'api/regex.c',
     'api/system.c',
     'api/process.c',
+    'dirmonitor.c',
     'renderer.c',
     'renwindow.c',
     'fontdesc.c',