添加解析 .Xresources 文件配置功能

src/include/xcb.h

@@ -32,3 +32,7 @@ window_list_t *scan_window_list(void);
 void free_window_list(window_list_t *window_list);
 void start_xcb_event_loop(void);
 void clean_xcb(void);
+
+bool get_xresource_uint32(const char *name, uint32_t *value);
+void get_xresource_string(const char *name, char **value, const char *fallback);
+void clean_xresource(void);

src/xcb/CMakeLists.txt

@@ -1,7 +1,7 @@
 set(LIB_XCB "zswm-xcb")
 set(LIB_XCB_NAME ${LIB_XCB} PARENT_SCOPE)
 
-add_library(${LIB_XCB} STATIC xcb.c window.c)
+add_library(${LIB_XCB} STATIC xcb.c window.c res.c)
 
 target_include_directories(${LIB_XCB} SYSTEM
     PRIVATE ${XCB_INCLUDE_DIRS}

src/xcb/res.c

@@ -0,0 +1,54 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <xcb/xcb_xrm.h>
+
+#include "utils.h"
+#include "xcb-private.h"
+#include "xcb.h"
+
+static xcb_xrm_database_t *db = NULL;
+
+static xcb_xrm_database_t *get_xrm_db(void) {
+  if (!db) {
+    db = xcb_xrm_database_from_default(conn);
+  }
+  return db;
+}
+
+bool get_xresource_uint32(const char *name, uint32_t *value) {
+  xcb_xrm_database_t *db = get_xrm_db();
+  if (!db) return false;
+
+  long temp_value = *value;
+  bool success = xcb_xrm_resource_get_long(db, name, NULL, &temp_value) == 0;
+  if (success) *value = (uint32_t)temp_value;
+  return success;
+}
+
+/**
+ * @brief 读取 Xresources 文件中的字符串配置
+ * @param name Xresources 文件中的配置名
+ * @param value 存放读取到的字符串存储的指针的指针，使用完后记得使用
+ * free(*value) 释放字符串对应的内存
+ * @param fallback 若 Xresources 解析失败，则使用这个默认值
+ */
+void get_xresource_string(const char *name, char **value,
+                          const char *fallback) {
+  xcb_xrm_database_t *db = get_xrm_db();
+  if (!db) return;
+
+  if (!xcb_xrm_resource_get_string(db, name, NULL, value)) return;
+
+  size_t len = strlen(fallback) + 1;
+  *value = ecalloc(len, sizeof(char));
+  strncpy(*value, fallback, len);
+}
+
+void clean_xresource(void) {
+  if (!db) return;
+
+  xcb_xrm_database_free(db);
+  db = NULL;
+}