implement POSIX polling dirmonitor

lite-xl · Nov 14, 2024 · 530908e · 530908e
1 parent 5530d8a
commit 530908e
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Showing 3 changed files with 147 additions and 1 deletion.
diff --git a/meson_options.txt b/meson_options.txt
@@ -2,6 +2,6 @@ option('bundle', type : 'boolean', value : false, description: 'Build a macOS bu
 option('source-only', type : 'boolean', value : false, description: 'Configure source files only, doesn\'t checks for dependencies')
 option('portable', type : 'boolean', value : false, description: 'Portable install')
 option('renderer', type : 'boolean', value : false, description: 'Use SDL renderer')
-option('dirmonitor_backend', type : 'combo', value : '', choices : ['', 'inotify', 'fsevents', 'kqueue', 'win32', 'dummy'], description: 'define what dirmonitor backend to use')
+option('dirmonitor_backend', type : 'combo', value : '', choices : ['', 'inotify', 'fsevents', 'kqueue', 'win32', 'posix_polling', 'dummy'], description: 'define what dirmonitor backend to use')
 option('arch_tuple', type : 'string', value : '', description: 'Specify a custom architecture tuple')
 option('use_system_lua', type : 'boolean', value : false, description: 'Prefer System Lua over a the meson wrap')
diff --git a/src/api/dirmonitor/posix_polling.c b/src/api/dirmonitor/posix_polling.c
@@ -0,0 +1,142 @@
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <SDL.h>
+
+#define EVENT_MODIFIED (1 << 0)
+
+#if _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE > 700 || _POSIX_C_SOURCE >= 200809L
+#define STAT_HAS_TIM
+#endif
+
+struct file_info {
+  int fd;
+  dev_t dev;
+  ino_t ino;
+  struct timespec mtim;
+  int events;
+};
+
+struct dirmonitor_internal {
+  struct file_info* fds;
+  size_t fd_count;
+};
+
+
+struct dirmonitor_internal* init_dirmonitor() {
+  struct dirmonitor_internal* monitor = calloc(1, sizeof(struct dirmonitor_internal));
+
+  monitor->fd_count = 0;
+  monitor->fds = NULL;
+  return monitor;
+}
+
+void deinit_dirmonitor(struct dirmonitor_internal* monitor) {
+  for (size_t i = 0; i < monitor->fd_count; ++i)
+    close(monitor->fds[i].fd);
+  free(monitor->fds);
+}
+
+int get_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int len)
+{
+  struct stat new_stat;
+  int c = 0;
+
+  for (size_t i = 0; i < monitor->fd_count; ++i) {
+    if (monitor->fds[i].fd < 0)
+      continue;
+
+    fstat(monitor->fds[i].fd, &new_stat);
+
+    if (
+      new_stat.st_mtime > monitor->fds[i].mtim.tv_sec ||
+#ifdef STAT_HAS_TIM
+      (new_stat.st_mtim.tv_sec == monitor->fds[i].mtim.tv_sec && new_stat.st_mtim.tv_nsec > monitor->fds[i].mtim.tv_nsec) ||
+#endif
+      new_stat.st_dev != monitor->fds[i].dev || // device changed
+      new_stat.st_ino != monitor->fds[i].ino || // inode changed
+      0
+    ) {
+      monitor->fds[i].mtim.tv_sec = new_stat.st_mtime;
+#ifdef STAT_HAS_TIM
+      monitor->fds[i].mtim.tv_nsec = new_stat.st_mtim.tv_nsec;
+#endif
+      monitor->fds[i].dev = new_stat.st_dev;
+      monitor->fds[i].ino = new_stat.st_ino;
+      monitor->fds[i].events |= EVENT_MODIFIED;
+      c += 1;
+    }
+  }
+
+  if (!c)
+    SDL_Delay(100);
+
+  return c;
+}
+
+int translate_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int count, int (*change_callback)(int, const char*, void*), void* data) {
+  for (size_t i = 0; i < monitor->fd_count; ++i) {
+    if (monitor->fds[i].events & EVENT_MODIFIED) {
+      --count;
+      monitor->fds[i].events = monitor->fds[i].events & ~ EVENT_MODIFIED;
+      change_callback(monitor->fds[i].fd, NULL, data);
+    }
+  }
+
+  return 0;
+}
+
+int add_dirmonitor(struct dirmonitor_internal* monitor, const char* path)
+{
+  int fd = open(path, O_RDONLY | O_NOFOLLOW);
+  if (fd == -1)
+    return -1;
+
+  // Check if there is any space we can reuse
+  for (size_t i = 0; i < monitor->fd_count; ++i) {
+    if (monitor->fds[i].fd == -1) {
+      monitor->fds[i].fd = fd;
+      monitor->fds[i].mtim.tv_sec = 0;
+      return fd;
+    }
+  }
+
+  // There is no empty space, add a new entry;
+  // Prepare a new list before switching it to prevent race conditions
+  struct file_info* old_fds = monitor->fds;
+  struct file_info* new_fds;
+  new_fds = malloc(sizeof(*new_fds) * (monitor->fd_count + 1));
+  if (old_fds)
+    memcpy(new_fds, old_fds, sizeof(*new_fds) * (monitor->fd_count));
+
+  new_fds[monitor->fd_count].fd = fd;
+  new_fds[monitor->fd_count].mtim.tv_sec = 0;
+
+  monitor->fds = new_fds;
+  free(old_fds);
+
+  monitor->fd_count++;
+
+  return fd;
+}
+
+void remove_dirmonitor(struct dirmonitor_internal* monitor, int fd)
+{
+  for (size_t i = 0; i < monitor->fd_count; ++i) {
+    if (monitor->fds[i].fd == fd) {
+      int fd = monitor->fds[i].fd;
+
+      monitor->fds[i].fd = -1;
+      monitor->fds[i].events = 0;
+      close(fd);
+      return;
+    }
+  }
+}
+
+int get_mode_dirmonitor() {
+  return 2;
+}
diff --git a/src/meson.build b/src/meson.build
@@ -28,6 +28,8 @@ if get_option('dirmonitor_backend') == ''
         dirmonitor_backend = 'kqueue'
     elif host_machine.system() == 'windows'
         dirmonitor_backend = 'win32'
+    elif cc.has_header('sys/stat.h')
+        dirmonitor_backend = 'posix_polling'
     else
         dirmonitor_backend = 'dummy'
         warning('no suitable backend found, defaulting to dummy backend')
@@ -51,6 +53,8 @@ elif dirmonitor_backend == 'inodewatcher'
     lite_sources += 'api/dirmonitor/inodewatcher.cpp'
 elif dirmonitor_backend == 'win32'
     lite_sources += 'api/dirmonitor/win32.c'
+elif dirmonitor_backend == 'posix_polling'
+    lite_sources += 'api/dirmonitor/posix_polling.c'
 else
     lite_sources += 'api/dirmonitor/dummy.c'
 endif