added macro RESULT_ERROR_FMT and some filesystem functions

src/filesystem/dir.c

@@ -35,7 +35,7 @@ Result(void) dir_create(cstr path){
     if(mkdir(path, 0777) == -1)
 #endif
     {
-        return RESULT_ERROR(sprintf_malloc(512, "can't create dicectory '%s'", path), true);
+        return RESULT_ERROR_FMT("Can't create dicectory '%s': %s", path, strerror(errno));
     }
 
     return RESULT_VOID;

src/filesystem/file.c

@@ -26,9 +26,24 @@ bool file_exists(cstr path){
 Result(FILE*) file_open(cstr file_name, cstr fopen_mode){
     FILE* f = fopen(file_name, fopen_mode);
     if(f == NULL){
-        char* errmsg = sprintf_malloc(256, "can't open (%s) file '%s': %s",
+        return RESULT_ERROR_FMT("Can't open (%s) file '%s': %s",
                 fopen_mode, file_name, strerror(errno));
-        return RESULT_ERROR(errmsg, true);
     }
     return RESULT_VALUE(p, f);
 }
+
+Result(i64) file_getSize(FILE* f){
+    i64 r = IFWIN(_ftelli64, ftello64)(f);
+    if(r < 0){
+        return RESULT_ERROR(strerror(errno), false);
+    }
+    return RESULT_VALUE(i, r);
+}
+
+Result(void) file_seek(FILE* f, i64 offset, SeekOrigin origin){
+    if(IFWIN(_fseeki64, fseeko64)(f, offset, (int)origin) != 0){
+        return RESULT_ERROR_FMT(
+            "Can't seek (offset: " IFWIN("%lli", "%li") ", origin: %i) in file: %s",
+            offset, origin, strerror(errno));
+    }
+}