New config $g_bug_revision_view_threshold

Access level required to view bug history revisions. Note that users
can always see the revisions for issues and bugnotes they reported,
regardless of the new config's value.

Two new Access API functions, access_can_view_bug_revisions() and
access_can_view_bugnote_revisions(), can be used to check whether user
has required access level.

Fixes #20690

config_defaults_inc.php

@@ -2698,7 +2698,14 @@
 $g_bug_reminder_threshold = DEVELOPER;
 
 /**
- * Access lever required to drop bug history revisions
+ * Access level required to view bug history revisions.
+ * Users can always see revisions for the issues and bugnote they reported.
+ * @global integer $g_bug_revision_view_threshold
+ */
+$g_bug_revision_view_threshold = DEVELOPER;
+
+/**
+ * Access level required to drop bug history revisions.
  * @global integer $g_bug_revision_drop_threshold
  */
 $g_bug_revision_drop_threshold = MANAGER;
@@ -4379,6 +4386,7 @@
 	'bug_resolution_fixed_threshold',
 	'bug_resolution_not_fixed_threshold',
 	'bug_resolved_status_threshold',
+	'bug_revision_view_threshold',
 	'bug_revision_drop_threshold',
 	'bug_submit_status',
 	'bug_update_page_fields',

core/access_api.php

@@ -936,3 +936,57 @@ function access_has_limited_view( $p_project_id = null, $p_user_id = null ) {
 	$t_project_level = access_get_project_level( $p_project_id, $p_user_id );
 	return !access_compare_level( $t_project_level, $t_threshold_can_view );
 }
+
+/**
+ * Return true if user is allowed to view bug revisions.
+ *
+ * User must have $g_bug_revision_view_threshold or be the bug's reporter.
+ *
+ * @param int $p_bug_id
+ * @param int $p_user_id
+ *
+ * @return bool
+ */
+function access_can_view_bug_revisions( $p_bug_id, $p_user_id = null ) {
+	if( !bug_exists( $p_bug_id ) ) {
+		return false;
+	}
+	$t_project_id = bug_get_field( $p_bug_id, 'project_id' );
+	$t_user_id = null === $p_user_id ? auth_get_current_user_id() : $p_user_id;
+
+	$t_has_access = access_has_bug_level(
+		config_get( 'bug_revision_view_threshold', null, $t_user_id, $t_project_id ),
+		$p_bug_id,
+		$t_user_id
+	);
+
+	return $t_has_access || bug_is_user_reporter( $p_bug_id, $t_user_id );
+}
+
+/**
+ * Return true if user is allowed to view bugnote revisions.
+ *
+ * User must have $g_bug_revision_view_threshold or be the bugnote's reporter.
+ *
+ * @param int $p_bugnote_id
+ * @param int $p_user_id
+ *
+ * @return bool
+ */
+function access_can_view_bugnote_revisions( $p_bugnote_id, $p_user_id = null ) {
+	if( !bugnote_exists( $p_bugnote_id ) ) {
+		return false;
+	}
+	$t_bug_id = bugnote_get_field( $p_bugnote_id, 'bug_id' );
+	$t_project_id = bug_get_field( $t_bug_id, 'project_id' );
+	$t_user_id = null === $p_user_id ? auth_get_current_user_id() : $p_user_id;
+
+	$t_has_access = access_has_bugnote_level(
+		config_get( 'bug_revision_view_threshold', null, $t_user_id, $t_project_id ),
+		$p_bugnote_id,
+		$t_user_id
+	);
+
+
+	return $t_has_access || bugnote_is_user_reporter( $p_bugnote_id, $t_user_id );
+}