Change default errno value to 0 (no error) and add prototypes in lvm.h

Since we are using errno values, we should use '0' as a default value
which indicates a non-error, rather than defining some made-up default
value that is not defined in errno.  If we need to deviate from errno
values, this will most likely indicate a flaw in our design.

Add prototypes for lvm_errno and lvm_errmsg inside lvm.h and provide
a basic description of their function.  This fixes a couple compile
warnings.


Author: Dave Wysochanski <dwysocha@redhat.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/liblvm/lvm.h b/liblvm/lvm.h
index 19ab5dd7..e179d872 100644
--- a/liblvm/lvm.h
+++ b/liblvm/lvm.h
@@ -72,6 +72,30 @@ void lvm_destroy(lvm_t libh);
 int lvm_reload_config(lvm_t libh);
 
 /**
+ * Return stored error no describing last LVM API error.
+ *
+ * Users of liblvm should use lvm_errno to determine success or failure
+ * of the last call, unless the API indicates another method of determining
+ * success or failure.
+ *
+ * \param   libh
+ *          Handle obtained from lvm_create.
+ *
+ * \return  An errno value describing the last LVM error.
+ */
+int lvm_errno(lvm_t libh);
+
+/**
+ * Return stored error message describing last LVM error.
+ *
+ * \param   libh
+ *          Handle obtained from lvm_create.
+ *
+ * \return  An error string describing the last LVM error.
+ */
+const char *lvm_errmsg(lvm_t libh);
+
+/**
  * Create a VG with default parameters.
  *
  * This API requires calling lvm_vg_write to commit the change to disk.