try to make file io more portable

c/src/include/utils.h

@@ -1,38 +1,72 @@
 #pragma once
 #include <stdlib.h>
 #include <string.h>
+#ifdef _WIN32
+#include <direct.h>
+#include <windows.h>
+#define PATH_SEPARATOR "\\"
+#else
 #include <libgen.h>
-
+#include <unistd.h>
+#define PATH_SEPARATOR "/"
+#endif
 
 char* get_parent_directory(char* path, const unsigned int levels) {
+#ifdef _WIN32
+    static char drive[_MAX_DRIVE];
+    static char dir[_MAX_DIR];
+    _splitpath(path, drive, dir, NULL, NULL);
+    for (unsigned int i = 0; i < levels; ++i) {
+        size_t len = strlen(dir);
+        if (len > 1 && (dir[len - 1] == '\\' || dir[len - 1] == '/')) {
+            dir[len - 1] = '\0';
+        }
+        char* last_slash = strrchr(dir, '\\');
+        if (!last_slash) last_slash = strrchr(dir, '/');
+        if (last_slash) *last_slash = '\0';
+    }
+    static char parent_dir[_MAX_PATH];
+    snprintf(parent_dir, sizeof(parent_dir), "%s%s", drive, dir);
+    return parent_dir;
+#else
     char* dir = dirname(path);
     for (unsigned int i = 0; i < levels; ++i) {
         dir = dirname(dir);
         if (strcmp(dir, "/") == 0 || strcmp(dir, ".") == 0) {
             break;
         }
     }
-
     return dir;
+#endif
 }
 
-
 char *get_data_file(const char *name) {
     const char* start = __FILE__;
-    char* absolute_path = realpath(start, NULL);
+#ifdef _WIN32
+    char absolute_path[MAX_PATH];
+    if (!_fullpath(absolute_path, start, MAX_PATH)) {
+        perror("_fullpath");
+        return NULL;
+    }
+#else
+   char* absolute_path = realpath(start, NULL);
     if (!absolute_path) {
         perror("realpath");
+        return NULL;
     }
+#endif
     char* parents_dir = get_parent_directory(absolute_path, 3);
     const size_t p_len = strlen(parents_dir),
     name_len = strlen(name);
     char *file_path = (char *)malloc(p_len + name_len + 8);
     memcpy(file_path, parents_dir, p_len);
-    memcpy(file_path + p_len, "/_data/", 7);
+    memcpy(file_path + p_len, PATH_SEPARATOR "_data" PATH_SEPARATOR, 7);
     memcpy(file_path + p_len + 7, name, name_len);
     file_path[p_len + name_len + 7] = 0;
     FILE* file = fopen(file_path, "r");
+#ifndef _WIN32
     free(absolute_path);
+#endif
 //    free(parents_dir);
     free(file_path);
     if (!file) {