From 86fa8679f981c2a02a6eddeb50b619787691d5fd Mon Sep 17 00:00:00 2001
From: Anton Lundin <glance@ac2.se>
Date: Mon, 20 Oct 2025 14:46:44 +0200
Subject: [PATCH] Teach jobclient.h about fifo jobservers

In make 4.4 a new jobserver communication format over a fifo appeared.

This teaches the jobclient.h "library" about that format.
---
 jobclient.h | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/jobclient.h b/jobclient.h
index 5d6eee4..8f02a5f 100644
--- a/jobclient.h
+++ b/jobclient.h
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 // https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver
 
@@ -22,15 +23,35 @@ static int parse_makeflags(int *fds) {
     }
     p += sizeof(flagname) - 1;
 
-    const char *c = strchr(p, ',');
-    if (!c) {
-        fprintf(stderr, "job: error: Incorrect --jobserver-auth format\n");
-        return 0;
-    }
-    c++;
+    if (strncmp(p, "fifo:", strlen("fifo:")) == 0) {
+        const char *fifo_name = strchr(p, ':');
+        if (!fifo_name) {
+            fprintf(stderr, "X_job: error: Incorrect --jobserver-auth format\n");
+            return 0;
+        }
+        fifo_name++;
+        fds[0] = open(fifo_name, O_RDONLY);
+        if (fds[0] < 0) {
+            fprintf(stderr, "job: cannot open jobserver %s: %s", fifo_name, strerror (errno));
+            return 0;
+        }
+        fds[1] = open(fifo_name, O_WRONLY);
+        if (fds[1] < 0) {
+            close(fds[0]);
+            fprintf(stderr, "job: cannot open jobserver %s: %s", fifo_name, strerror (errno));
+            return 0;
+        }
+    } else {
+        const char *c = strchr(p, ',');
+        if (!c) {
+            fprintf(stderr, "Y_job: error: Incorrect --jobserver-auth format\n");
+            return 0;
+        }
+        c++;
 
-    fds[0] = atoi(p);
-    fds[1] = atoi(c);
+        fds[0] = atoi(p);
+        fds[1] = atoi(c);
+    }
 
     return 1;
 }