use a shared fs_normslice() function to handle offsets

1 files changed, 13 insertions, 0 deletions

diff --git a/src/shared/include/camellia/fsutil.h b/src/shared/include/camellia/fsutil.h
new file mode 100644
index 0000000..eb2b23e
--- /dev/null
+++ b/src/shared/include/camellia/fsutil.h
@@ -0,0 +1,13 @@
+#pragma once
+#include <stdbool.h>
+#include <stddef.h>
+
+/** Normalizes the offset and length passed to a fs into safe values.
+ * If returns *length == 0, *offset is meaningless.
+ *
+ * @param expand Can this operation expand the target file?
+ *                true  if writing to a file with an adjustable size
+ *                false if reading any sort of file
+ *                      or writing to a file with static size
+ */
+void fs_normslice(long *restrict offset, size_t *restrict length, size_t max, bool expand);