update(userspace/plugin): Update ss_plugin_field_extract_input

Remove field_offsets from ss_plugin_field_extract_input. We can just
check to see if field_offsets is set. Update some comments.

Signed-off-by: Gerald Combs <[email protected]>

Author: geraldcombs

userspace/libsinsp/plugin.cpp

@@ -1003,11 +1003,6 @@ bool sinsp_plugin::extract_fields_and_offsets(sinsp_evt* evt,
 	in.get_owner_last_error = sinsp_plugin::get_owner_last_error;
 	in.table_reader_ext = &table_reader_ext;
 	in.field_offsets = field_offsets;
-	if(in.field_offsets) {
-		in.request_offsets = true;
-	} else {
-		in.request_offsets = false;
-	}
 	sinsp_plugin::table_read_api(in.table_reader, table_reader_ext);
 	auto res = m_handle->api.extract_fields(m_state, &ev, &in) == SS_PLUGIN_SUCCESS;
 

userspace/plugin/plugin_api.h

@@ -371,12 +371,8 @@ typedef struct ss_plugin_field_extract_input {
 	// Vtable for controlling a state table for read operations.
 	ss_plugin_table_reader_vtable_ext* table_reader_ext;
 
-	// If true, signal that the framework wants offsets to be computed.
-	ss_plugin_bool request_offsets;
-
-	// An array of ss_plugin_extract_field_offsets structs. Optional.
-	// The array should be allocated only if `request_offsets` is true.
-	// Indexed as `fields`.
+	// An array of ss_plugin_extract_field_offsets structs. This member
+	// is optional, and might be ignored by extractors.
 	ss_plugin_extract_field_offsets* field_offsets;
 } ss_plugin_field_extract_input;
 

userspace/plugin/plugin_types.h

@@ -130,10 +130,12 @@ typedef struct ss_plugin_byte_buffer {
 
 // Used in extract_fields_and_offsets to receive field offsets along
 // with field data.
-// Extraction functions should be set these to the zero-indexed start
-// and end offsets of the field in the event or log data. 0..0 can be
-// used to indicate that there are no valid offsets, e.g. if the field
-// was generated or computed from other data.
+// Extraction functions might not support offsets. In order to detect
+// this, callers can initialize this to an invalid pair, such as 1..0.
+// Extraction functions that support offsets should be set these to the
+// zero-indexed start and end offsets of the field in the event or log
+// data. 0..0 can be used to indicate that there are no valid offsets,
+// e.g. if the field was generated or computed from other data.
 typedef struct ss_plugin_extract_field_offsets {
 	uint32_t start_offset;
 	uint32_t end_offset;