feat: add streq and printErr

user/fifowriter.c

@@ -0,0 +1,43 @@
+#include "ulib.h"
+
+/*
+ * Only ever spawned by fifomaster.c, with the shared pipe's handle number
+ * as argv[1] (decToString'd -- see fifomaster.c). Sleeps well past when
+ * fiforeader.c (spawned moments earlier) will already be parked in a
+ * blocking read() on the still-empty pipe, so the write below has to
+ * actually wake it back up (schedWakeChannel, pipeWrite in pipe.c) instead
+ * of the reader simply finding data already waiting for it -- proof that
+ * the block was real, not a lucky race.
+ */
+
+#define fifoWriterDelayMs 200
+
+static const char* payload = "shared pipe payload";
+
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        print("fifowriter: FAIL expected one argv (pipe handle)\n");
+        return 1;
+    }
+
+    long handle = parseDec(argv[1]);
+    long fd = userPipeAttach(handle, 1);
+    if (fd < 0) {
+        print("fifowriter: FAIL attach\n");
+        return 1;
+    }
+
+    print("fifowriter: attached, sleeping before write\n");
+    userSleep(fifoWriterDelayMs);
+
+    long written = userWrite((int)fd, payload, stringLength(payload));
+    if (written != (long)stringLength(payload)) {
+        print("fifowriter: FAIL short/failed write\n");
+        return 1;
+    }
+    print("fifowriter: wrote payload\n");
+
+    userClose((int)fd);
+    return 0;
+}