From: Marco Schlumpp <marco@unikraft.io>
Date: Wed, 30 Apr 2025 13:33:50 +0000 (+0200)
Subject: lib/posix-process: Make rt_sitgimedwait stub block
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=417554a35ef8ec6487b8f7f8a78fe67a67813d2b;p=unikraft%2Funikraft.git

lib/posix-process: Make rt_sitgimedwait stub block

According to rt_sigtimedwait(2) the syscall should return a signal
number on success (> 0) or -1 on failure, so the zero value currently
returned by the stubbed implementation can be misinterpreted by
applications that check against failure. Update the stub to return
implementation to block and never return a signal.

Co-authored-by: Michalis Pappas <michalis@unikraft.io>
Signed-off-by: Marco Schlumpp <marco@unikraft.io>
Signed-off-by: Michalis Pappas <michalis@unikraft.io>
Reviewed-by: Sergiu Moga <sergiu@unikraft.io>
Reviewed-by: Andrei Tatar <andrei@unikraft.io>
Approved-by: Sergiu Moga <sergiu@unikraft.io>
GitHub-Closes: #1639
---

diff --git a/lib/posix-process/signal/rt_sigtimedwait.c b/lib/posix-process/signal/rt_sigtimedwait.c
index bd7fbda47..4fe54762b 100644
--- a/lib/posix-process/signal/rt_sigtimedwait.c
+++ b/lib/posix-process/signal/rt_sigtimedwait.c
@@ -12,6 +12,11 @@
 #include <uk/syscall.h>
 #include <uk/timeutil.h>
 
+#if !CONFIG_LIBPOSIX_PROCESS_SIGNAL
+#include <uk/plat/time.h>
+#include <uk/sched.h>
+#endif /* !CONFIG_LIBPOSIX_PROCESS_SIGNAL */
+
 #include "process.h"
 #include "signal.h"
 
@@ -64,9 +69,31 @@ UK_LLSYSCALL_R_DEFINE(int, rt_sigtimedwait,
 		      const struct timespec *, timeout,
 		      size_t, sigsetsize)
 {
-	UK_WARN_STUBBED();
+	struct uk_thread *current = uk_thread_current();
+	__nsec timeout_ns;
+	int rc;
+
+	if (timeout) {
+		if (unlikely(!(uk_time_spec_canonical(timeout) &&
+			       uk_time_spec_positive(timeout))))
+			return -EINVAL;
+		timeout_ns = ukplat_monotonic_clock() +
+			ukarch_time_sec_to_nsec(timeout->tv_sec) +
+			timeout->tv_nsec;
+		uk_thread_block_until(current, (__snsec)timeout_ns);
+		uk_sched_yield();
+		rc = -EAGAIN;
+	} else {
+		uk_thread_block(current);
+		uk_sched_yield();
+		/* If this ever returns then just return an EINTR to not
+		 * confuse the application
+		 */
+		rc = -EINTR;
+	}
+
+	/* We currently never return a signal */
 	*info = (siginfo_t){0};
-	info->si_signo = SIGINT;
-	return 0;
+	return rc;
 }
 #endif /* !CONFIG_LIBPOSIX_PROCESS_SIGNAL */