introduce pevent_read_number_field()

This helper function allows reading a number from a
variable size field, e.g. to account for architecture
differences of pointer lengths.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

2 files changed, 17 insertions, 0 deletions

diff --git a/parse-events.c b/parse-events.c
index 4acb56f..48f29d3 100644
--- a/parse-events.c
+++ b/parse-events.c
@@ -2092,6 +2092,21 @@ unsigned long long pevent_read_number(void *ptr, int size)
         }
 }
 
+int pevent_read_number_field(struct format_field *field, const void *data,
+                             unsigned long long *value)
+{
+        switch (field->size) {
+        case 1:
+        case 2:
+        case 4:
+        case 8:
+                *value = pevent_read_number(data + field->offset, field->size);
+                return 0;
+        default:
+                return -1;
+        }
+}
+
 static int get_common_info(const char *type, int *offset, int *size)
 {
         struct event *event;
diff --git a/parse-events.h b/parse-events.h
index 55621e4..c0dbc60 100644
--- a/parse-events.h
+++ b/parse-events.h
@@ -302,6 +302,8 @@ int pevent_register_event_handler(int id, char *sys_name, char *event_name,
 struct format_field *pevent_find_field(struct event *event, const char *name);
 const char *pevent_find_function(unsigned long long addr);
 unsigned long long pevent_read_number(void *ptr, int size);
+int pevent_read_number_field(struct format_field *field, const void *data,
+                             unsigned long long *value);
 
 
 /* for debugging */