+(define (sexp->system-provenance sexp)
+ "Parse SEXP, an s-expression read from /run/current-system/provenance or
+similar, and return two values: the list of channels listed therein, and the
+OS configuration file or #f."
+ (match sexp
+ (('provenance ('version 0)
+ ('channels channels ...)
+ ('configuration-file config-file))
+ (values (map sexp->channel channels)
+ config-file))
+ (_
+ (values '() #f))))
+
+(define (system-provenance system)
+ "Given SYSTEM, the file name of a system generation, return two values: the
+list of channels SYSTEM is built from, and its configuration file. If that
+information is missing, return the empty list (for channels) and possibly
+#false (for the configuration file)."
+ (catch 'system-error
+ (lambda ()
+ (sexp->system-provenance
+ (call-with-input-file (string-append system "/provenance")
+ read)))
+ (lambda _
+ (values '() #f))))