scripts: support GNU make 4.4 in jobserver-exec

Starting with GNU make 4.4, --jobserver-auth newly uses named
pipe (fifo) instead of part of opened file descriptors:
https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html

Support also the new format.

Signed-off-by: Martin Liska <mliska@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/scripts/jobserver-exec b/scripts/jobserver-exec
index 4192855..7eca035 100755 (executable)
--- a/scripts/jobserver-exec
+++ b/scripts/jobserver-exec
@@ -26,11 +26,20 @@ try:
        # If the MAKEFLAGS variable contains multiple instances of the
        # --jobserver-auth= option, the last one is relevant.
        fds = opts[-1].split("=", 1)[1]
-       reader, writer = [int(x) for x in fds.split(",", 1)]
-       # Open a private copy of reader to avoid setting nonblocking
-       # on an unexpecting process with the same reader fd.
-       reader = os.open("/proc/self/fd/%d" % (reader),
-                        os.O_RDONLY | os.O_NONBLOCK)
+
+       # Starting with GNU Make 4.4, named pipes are used for reader and writer.
+       # Example argument: --jobserver-auth=fifo:/tmp/GMfifo8134
+       _, _, path = fds.partition('fifo:')
+
+       if path:
+               reader = os.open(path, os.O_RDONLY | os.O_NONBLOCK)
+               writer = os.open(path, os.O_WRONLY)
+       else:
+               reader, writer = [int(x) for x in fds.split(",", 1)]
+               # Open a private copy of reader to avoid setting nonblocking
+               # on an unexpecting process with the same reader fd.
+               reader = os.open("/proc/self/fd/%d" % (reader),
+                                os.O_RDONLY | os.O_NONBLOCK)
 
        # Read out as many jobserver slots as possible.
        while True: