bfstd: New {error,errno}_is_like() functions

We used to have is_nonexistence_error() to consistently treat ENOENT and
ENOTDIR the same.  Recently, we started considering EFAULT the same as
ENAMETOOLONG on DragonFly BSD to work around a kernel bug.  Unify both
of these behind a more generic interface.

1 files changed, 16 insertions, 2 deletions

diff --git a/src/bfstd.h b/src/bfstd.h
index 0fcb892..8953b9b 100644
--- a/src/bfstd.h
+++ b/src/bfstd.h
@@ -45,9 +45,23 @@
 // #include <errno.h>
 
 /**
- * Return whether an error code is due to a path not existing.
+ * Check if an error code is "like" another one.  For example, ENOTDIR is
+ * like ENOENT because they can both be triggered by non-existent paths.
+ *
+ * @param error
+ *         The error code to check.
+ * @param category
+ *         The category to test for.  Known categories include ENOENT and
+ *         ENAMETOOLONG.
+ * @return
+ *         Whether the error belongs to the given category.
+ */
+bool error_is_like(int error, int category);
+
+/**
+ * Equivalent to error_is_like(errno, category).
  */
-bool is_nonexistence_error(int error);
+bool errno_is_like(int category);
 
 #include <fcntl.h>