feat: add onUsr1, streq and printOut

user/stderrreader.c

@@ -0,0 +1,53 @@
+#include "ulib.h"
+
+/*
+ * Companion to stderrwriter.c -- reads fd 0 (redirected by the shell to a
+ * REAL file via `<`, jobctlApplyRedirects) in a loop until a real EOF,
+ * exactly like redirreader.c does, then compares byte-for-byte against two
+ * back-to-back copies of stderrwriter.c's own payload -- proof that `2>`
+ * (create/truncate) followed by `2>>` (append) on the SAME path produced
+ * exactly that file, not a truncated/duplicated/reordered one.
+ *
+ * This process's own fd 1 (stdout) is NOT redirected -- print() (ulib.h)
+ * reaches the real console exactly like any unredirected demo, so the
+ * needle below is exactly as observable to ci-test.sh as every other one.
+ */
+
+static int streq(const char* a, const char* b)
+{
+    while (*a && *a == *b) {
+        a++;
+        b++;
+    }
+    return *a == *b;
+}
+
+int main(void)
+{
+    print("stderrreader: reading redirected stdin\n");
+
+    char buffer[80];
+    unsigned long total = 0;
+    for (;;) {
+        long got = userRead(0, buffer + total, sizeof(buffer) - 1 - total);
+        if (got < 0) {
+            print("stderrreader: FAIL read\n");
+            return 1;
+        }
+        if (got == 0)
+            break;
+        total += (unsigned long)got;
+        if (total >= sizeof(buffer) - 1)
+            break;
+    }
+    buffer[total] = 0;
+
+    print("stderrreader: got: ");
+    print(buffer);
+    print("\n");
+
+    int ok = streq(buffer, "stderr-payload-okstderr-payload-ok");
+    print(ok ? "stderrreader: payload-ok\n" : "stderrreader: payload-FAIL\n");
+
+    return ok ? 0 : 1;
+}