From 0f4437ed804f3348639076c39a2444da73b78fb3 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Wed, 9 Sep 2026 13:20:57 +0200
Subject: [PATCH] feat: add onUsr1 and printErr

---
 user/pgroupbg.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++
 user/pgroupfg.c | 57 +++++++++++++++++++++++++++++++
 user/pipecat.c  | 56 ++++++++++++++++++++++++++++++
 3 files changed, 203 insertions(+)
 create mode 100644 user/pgroupbg.c
 create mode 100644 user/pgroupfg.c
 create mode 100644 user/pipecat.c

diff --git a/user/pgroupbg.c b/user/pgroupbg.c
new file mode 100644
index 0000000..2374bc3
--- /dev/null
+++ b/user/pgroupbg.c
@@ -0,0 +1,90 @@
+#include "ulib.h"
+
+/*
+ * Spawned directly by kmain.c at boot, alongside pgroupfg.c. Deliberately
+ * NEVER told to keyboardSetForegroundPgid -- every boot-time spawnUser call
+ * becomes its own new process group leader by default (sched.c's
+ * initialPgid), so this process's pgid already differs from pgroupfg's
+ * without any extra call, the same way two independently-launched
+ * background jobs in a real shell would each get their own group. This is
+ * the CONTROL side of the pgroupfg/pgroupbg pair: pgroupfg proves the
+ * injected Ctrl-C reaches the foreground group and kills it; this file
+ * proves that exact same event does NOT reach a DIFFERENT group at all --
+ * if keyboard.c's scoping were ever broken to deliver sigInt/sigTstp to
+ * every live thread (the bug this whole subsystem exists to prevent), this
+ * process would already be Dead by the time kmain.c's injector later tries
+ * to prove it alive, and every needle below would simply never appear.
+ *
+ * Along the way, exercises the actual syscall boundary (sysSetpgid/
+ * sysGetpgid, syscall.c) that sched.c's own KTEST coverage cannot reach on
+ * its own (ktestRunAll runs before schedStart(), with no int 0x80 path at
+ * all -- see schedTest.c's file comment): userGetpgid(0) must already
+ * equal this process's own pid (new-group-leader default), and an
+ * explicit, real setpgid(0, 0) self-affirmation (the same defensive call a
+ * real shell places a background job's own PID with, even when it is
+ * already its own leader) must be a harmless no-op.
+ */
+
+static volatile int handlerFired = 0;
+
+static void onUsr1(int signum)
+{
+    (void)signum;
+    handlerFired = 1;
+    print("pgroupbg: still-alive-after-ctrlc-ok\n");
+}
+
+int main(void)
+{
+    long myPid = userGetpid();
+    print("pgroupbg: start, pid=");
+    printDec(myPid);
+    print("\n");
+
+    long pgid = userGetpgid(0);
+    if (pgid != myPid) {
+        print("pgroupbg: FAIL expected to be its own group leader\n");
+        return 1;
+    }
+    if (userSetpgid(0, 0) != 0) {
+        print("pgroupbg: FAIL self setpgid(0,0) rejected\n");
+        return 1;
+    }
+    if (userGetpgid(0) != myPid) {
+        print("pgroupbg: FAIL pgid changed after self-affirming setpgid\n");
+        return 1;
+    }
+    print("pgroupbg: own-process-group-ok\n");
+
+    if (userSigAction(sigUsr1, onUsr1, 0, 0) == (long)sigSetFailed) {
+        print("pgroupbg: FAIL install handler\n");
+        return 1;
+    }
+
+    long victimHandle = userPipeCreate();
+    if (victimHandle < 0) {
+        print("pgroupbg: FAIL create victim pipe\n");
+        return 1;
+    }
+    long victimFd = userPipeAttach(victimHandle, 0);
+    if (victimFd < 0) {
+        print("pgroupbg: FAIL attach victim pipe\n");
+        return 1;
+    }
+
+    print("pgroupbg: ready, blocking on go pipe\n");
+    char buffer[4];
+    userRead((int)victimFd, buffer, sizeof(buffer));
+
+    if (!handlerFired) {
+        print("pgroupbg: FAIL read returned without being signaled\n");
+        return 1;
+    }
+
+    /* Reached only if the read was genuinely interrupted (errInterrupted,
+       no sigFlagRestart) by onUsr1 above, itself only ever sent by
+       kmain.c's own injector thread well AFTER the Ctrl-C event -- proving
+       this process was never touched by it at all. */
+    print("pgroupbg: resumed-after-signal-ok\n");
+    return 0;
+}
diff --git a/user/pgroupfg.c b/user/pgroupfg.c
new file mode 100644
index 0000000..2d07769
--- /dev/null
+++ b/user/pgroupfg.c
@@ -0,0 +1,57 @@
+#include "ulib.h"
+
+/*
+ * Spawned directly by kmain.c at boot, alongside pgroupbg.c -- the live
+ * ring-3 proof that sched.h's new Thread.pgid and keyboard.c's new real
+ * Ctrl-C actually scope a terminal-generated signal to the FOREGROUND
+ * process group, not to "every process reading a keyboard" or "one single
+ * hardcoded target". kmain.c makes this process's own pgid (its default,
+ * unchanged: every boot-time spawnUser call becomes its own new group
+ * leader, sched.c's initialPgid) the foreground via
+ * keyboardSetForegroundPgid right after spawning it.
+ *
+ * Installs NO handler for sigInt at all -- the real-world default
+ * disposition (signal.c's sigDefaultIsIgnore does not list sigInt) is
+ * Terminate, exactly like a real un-caught Ctrl-C killing a foreground
+ * program with no signal handling of its own. The read below blocks on a
+ * pipe no writer will ever attach to (the same "blocked forever" setup
+ * eintrtarget.c/killvictim.c/alarmdefault.c already use), so the only way
+ * this process ever leaves it is the kernel-injected Ctrl-C's early-wake
+ * (signal.c's sigWouldDeliver/sched.c's threadWakeForSignal, the same
+ * mechanism eintrtarget.c's own sigTerm already proves) actually reaching
+ * a genuinely Blocked thread and terminating it. If keyboard.c's group
+ * scoping were ever broken such that this process were somehow excluded
+ * from its own foreground group, this process would simply never return
+ * from the read below, hanging the whole boot gate to its 25s QEMU timeout
+ * instead of merely failing a check -- the same fault-injection-visible
+ * shape eintrtest.c's own file comment already establishes.
+ */
+
+int main(void)
+{
+    print("pgroupfg: start, pid=");
+    printDec(userGetpid());
+    print("\n");
+
+    long victimHandle = userPipeCreate();
+    if (victimHandle < 0) {
+        print("pgroupfg: FAIL create victim pipe\n");
+        return 1;
+    }
+    long victimFd = userPipeAttach(victimHandle, 0);
+    if (victimFd < 0) {
+        print("pgroupfg: FAIL attach victim pipe\n");
+        return 1;
+    }
+
+    print("pgroupfg: ready, blocking on go pipe\n");
+    char buffer[4];
+    userRead((int)victimFd, buffer, sizeof(buffer));
+
+    /* Only reached if userRead somehow returned on its own -- nothing ever
+       writes to the victim pipe, so the foreground Ctrl-C never arriving
+       (or arriving but not actually terminating this process) is the only
+       way to get here. */
+    print("pgroupfg: FAIL read returned without being interrupted\n");
+    return 1;
+}
diff --git a/user/pipecat.c b/user/pipecat.c
new file mode 100644
index 0000000..b8339e6
--- /dev/null
+++ b/user/pipecat.c
@@ -0,0 +1,56 @@
+#include "ulib.h"
+
+/*
+ * Middle stage of shell.c's new N-stage pipeline live demo
+ * (`pipesrc | pipecat | pipesink`) -- the first process in this kernel with
+ * BOTH ends of two DIFFERENT real inter-process pipes baked into its fds at
+ * once (fd 0 from jobctlSpawnPiped's stdinHandle, fd 1 from its
+ * stdoutHandle). user/hcat.c already proved a piped stdout alongside a
+ * piped stdin, but that stdin was always a shell-fed here-string
+ * (jobctlSpawnPipedHereString), never a second real process-to-process
+ * pipe the way this one's is -- this program is the actual proof that
+ * shell.c's runPipelineStages can wire a genuine middle pipeline stage
+ * where NEITHER end is the console. From this program's own point of view
+ * there is nothing special about either fd: it is simply "cat" -- read
+ * stdin to real EOF, then write exactly those bytes to stdout -- with no
+ * idea either end is a pipe rather than a real file or console, the same
+ * shape as hcat.c's/pipesink.c's own read loops.
+ *
+ * Diagnostics go to fd 2 (never fd 1), same reason as every other filter in
+ * this pipeline family: fd 1 here is the real payload pipesink.c compares
+ * byte-for-byte, and print()/printDec() (ulib.h) are both hardcoded to fd 1.
+ */
+
+static void printErr(const char* text)
+{
+    userWrite(2, text, stringLength(text));
+}
+
+int main(void)
+{
+    printErr("pipecat: reading piped stdin\n");
+
+    char buffer[64];
+    unsigned long total = 0;
+    for (;;) {
+        long got = userRead(0, buffer + total, sizeof(buffer) - 1 - total);
+        if (got < 0) {
+            printErr("pipecat: FAIL read\n");
+            return 1;
+        }
+        if (got == 0)
+            break;
+        total += (unsigned long)got;
+        if (total >= sizeof(buffer) - 1)
+            break;
+    }
+
+    long written = userWrite(1, buffer, total);
+    if (written != (long)total) {
+        printErr("pipecat: FAIL short/failed write\n");
+        return 1;
+    }
+
+    printErr("pipecat: forwarded payload\n");
+    return 0;
+}