device_tree: qemu_fdt_getprop converted to use the error API

Current qemu_fdt_getprop exits if the property is not found. It is
sometimes needed to read an optional property, in which case we do
not wish to exit but simply returns a null value.

This patch converts qemu_fdt_getprop to accept an Error **, and existing
users are converted to pass &error_fatal. This preserves the existing
behaviour. Then to use the API with your optional semantic a null
parameter can be conveyed.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index 552df21..48bf3b5 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -54,8 +54,19 @@ int qemu_fdt_setprop_string(void *fdt, const char *node_path,
 int qemu_fdt_setprop_phandle(void *fdt, const char *node_path,
                              const char *property,
                              const char *target_node_path);
+/**
+ * qemu_fdt_getprop: retrieve the value of a given property
+ * @fdt: pointer to the device tree blob
+ * @node_path: node path
+ * @property: name of the property to find
+ * @lenp: fdt error if any or length of the property on success
+ * @errp: handle to an error object
+ *
+ * returns a pointer to the property on success and NULL on failure
+ */
 const void *qemu_fdt_getprop(void *fdt, const char *node_path,
-                             const char *property, int *lenp);
+                             const char *property, int *lenp,
+                             Error **errp);
 uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path,
                                const char *property);
 uint32_t qemu_fdt_get_phandle(void *fdt, const char *path);