errors: Add glnx_throw() and tests

Following up to the previous commit, also shorten our use of
`g_set_error (..., G_IO_ERROR_FAILED, ...)`. There's a lot of
this in libostree at least.

See also https://bugzilla.gnome.org/show_bug.cgi?id=774061

1 files changed, 25 insertions, 0 deletions

diff --git a/glnx-errors.h b/glnx-errors.h
index 7bf53d3..8f9cad8 100644
--- a/glnx-errors.h
+++ b/glnx-errors.h
@@ -25,6 +25,31 @@
 
 G_BEGIN_DECLS
 
+/* Set @error with G_IO_ERROR/G_IO_ERROR_FAILED.
+ *
+ * This function returns %FALSE so it can be used conveniently in a single
+ * statement:
+ *
+ * ``
+ *   if (strcmp (foo, "somevalue") != 0)
+ *     return glnx_throw (error, "key must be somevalue, not '%s'", foo);
+ * ```
+ */
+static inline gboolean G_GNUC_PRINTF (2,3)
+glnx_throw (GError **error, const char *fmt, ...)
+{
+  if (error == NULL)
+    return FALSE;
+
+  va_list args;
+  va_start (args, fmt);
+  GError *new = g_error_new_valist (G_IO_ERROR, G_IO_ERROR_FAILED, fmt, args);
+  va_end (args);
+  g_propagate_error (error, g_steal_pointer (&new));
+  return FALSE;
+}
+
+
 /* Set @error using the value of `g_strerror (errno)`.
  *
  * This function returns %FALSE so it can be used conveniently in a single