Cleanup libsquashfs invalid argument error codes

 - Add an explicit "you're holding it wrong" error code.
 - Consistently return error codes and not have some special places
   where -1 is returned.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/sqfs/compressor.h b/include/sqfs/compressor.h
index a53fbc1..4f22b0d 100644
--- a/include/sqfs/compressor.h
+++ b/include/sqfs/compressor.h
@@ -386,7 +386,8 @@ SQFS_API const char *sqfs_compressor_name_from_id(E_SQFS_COMPRESSOR id);
  * @param name The name of the compressor backend.
  * @param out Returns the coresponding @ref E_SQFS_COMPRESSOR identifier.
  *
- * @return Zero on success, -1 if the backend is unknown.
+ * @return Zero on success, @ref SQFS_ERROR_UNSUPPORTED if the backend
+ *         is unknown.
  */
 SQFS_API
 int sqfs_compressor_id_from_name(const char *name, E_SQFS_COMPRESSOR *out);