diff --git a/include/tlibc/errors.h b/include/tlibc/errors.h
index 29dbd4c..1e42296 100755
--- a/include/tlibc/errors.h
+++ b/include/tlibc/errors.h
@@ -41,6 +41,7 @@ typedef struct Result_ {
 
 
 #define RESULT_ERROR(MSG, IS_MSG_ON_HEAP) (Result_){ .error = Error_create(MSG, IS_MSG_ON_HEAP, ErrorCallPos_here()) }
+#define RESULT_ERROR_FMT(FORMAT, ARGS...) RESULT_ERROR(sprintf_malloc(4096, FORMAT, ARGS), true)
 #define RESULT_VOID (Result_){ .error = NULL }
 #define RESULT_VALUE(FIELD, V) (Result_){ .error = NULL, .FIELD = V }
 
diff --git a/include/tlibc/filesystem.h b/include/tlibc/filesystem.h
index fc3a1f5..3996000 100644
--- a/include/tlibc/filesystem.h
+++ b/include/tlibc/filesystem.h
@@ -47,6 +47,15 @@ Result(FILE*) file_open(cstr file_name, cstr fopen_mode);
 
 bool file_exists(cstr path);
 
+Result(i64) file_getSize(FILE* f);
+
+typedef enum SeekOrigin {
+    SeekOrigin_Start = SEEK_SET,
+    SeekOrigin_Current = SEEK_CUR,
+    SeekOrigin_End = SEEK_END,
+} SeekOrigin;
+
+Result(void) file_seek(FILE* f, i64 offset, SeekOrigin origin);
 
 
 bool dir_exists(cstr path);
diff --git a/src/filesystem/dir.c b/src/filesystem/dir.c
index 6e8c97d..5b5a0e8 100644
--- a/src/filesystem/dir.c
+++ b/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;
diff --git a/src/filesystem/file.c b/src/filesystem/file.c
index f340cc8..1c62e2c 100644
--- a/src/filesystem/file.c
+++ b/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));
+    }
+}
\ No newline at end of file