lib/posix-process/signal: Add rt_sigaction()

rt_sigaction() allows examining and changing a signal action.
For more info see sigaction(2)

Signed-off-by: Michalis Pappas <michalis@unikraft.io>
Reviewed-by: Ioan-Teodor Teugea <ioan_teodor.teugea@stud.acs.upb.ro>
Reviewed-by: Sergiu Moga <sergiu@unikraft.io>
Reviewed-by: Andrei Tatar <andrei@unikraft.io>
Approved-by: Andrei Tatar <andrei@unikraft.io>
GitHub-Closes: #1248

diff --git a/lib/posix-process/Makefile.uk b/lib/posix-process/Makefile.uk
index 532d15feaaa0bd69dba2387b4c75ac89064ab3a0..977e42f66f47f778eb40ec7310c7f9769647b484 100644 (file)
--- a/lib/posix-process/Makefile.uk
+++ b/lib/posix-process/Makefile.uk
@@ -21,6 +21,7 @@ LIBPOSIX_PROCESS_SRCS-y += $(LIBPOSIX_PROCESS_BASE)/signals.c
 
 LIBPOSIX_PROCESS_SRCS-$(CONFIG_LIBPOSIX_PROCESS_SIGNAL) += $(LIBPOSIX_PROCESS_BASE)/signal/signal.c
 LIBPOSIX_PROCESS_SRCS-y += $(LIBPOSIX_PROCESS_BASE)/signal/rt_sigprocmask.c
+LIBPOSIX_PROCESS_SRCS-y += $(LIBPOSIX_PROCESS_BASE)/signal/rt_sigaction.c
 
 LIBPOSIX_PROCESS_SRCS-$(CONFIG_LIBPOSIX_PROCESS_CLONE) += $(LIBPOSIX_PROCESS_BASE)/clone.c
 LIBPOSIX_PROCESS_SRCS-$(CONFIG_LIBPOSIX_PROCESS_CLONE) += $(LIBPOSIX_PROCESS_BASE)/clonetab.ld
@@ -35,6 +36,7 @@ LIBPOSIX_PROCESS_CXXINCLUDES-y += -I$(UK_PLAT_COMMON_BASE)/include
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS_CLONE) += clone-5e
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS_EXECVE) += execve-3e
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS) += rt_sigprocmask-4
+UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS) += rt_sigaction-4
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS_VFORK) += vfork-2e
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS) += wait4-4 waitid-4
 UK_PROVIDED_SYSCALLS-$(CONFIG_LIBPOSIX_PROCESS) += getpgid-1

diff --git a/lib/posix-process/signal/rt_sigaction.c b/lib/posix-process/signal/rt_sigaction.c
new file mode 100644 (file)
index 0000000..51be917
--- /dev/null
+++ b/lib/posix-process/signal/rt_sigaction.c
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* Copyright (c) 2023, Unikraft GmbH and The Unikraft Authors.
+ * Licensed under the BSD-3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+
+#include <uk/essentials.h>
+#include <uk/process.h>
+#include <uk/syscall.h>
+
+#include "process.h"
+#include "signal.h"
+#include "sigset.h"
+
+#if CONFIG_LIBPOSIX_PROCESS_SIGNAL
+UK_LLSYSCALL_R_DEFINE(int, rt_sigaction, int, signum,
+                     const struct kern_sigaction *, act,
+                     struct kern_sigaction *, oldact,
+                     size_t, sigsetsize)
+{
+       struct posix_process *proc;
+
+       if (unlikely(!IS_VALID(signum)))
+               return -EINVAL;
+
+       if (unlikely(signum == SIGKILL || signum == SIGSTOP))
+               return -EINVAL;
+
+       if (unlikely(sigsetsize != sizeof(uk_sigset_t)))
+               return -EINVAL;
+
+       proc = uk_pprocess_current();
+       UK_ASSERT(proc);
+
+       if (oldact)
+               memcpy(oldact, KERN_SIGACTION(proc, signum),
+                      sizeof(struct kern_sigaction));
+
+       if (!act)
+               return 0;
+
+       if (act->ks_flags & SA_NOCLDSTOP)
+               uk_pr_warn("ks_flags: SA_NOCLDSTOP not supported, ignoring\n");
+
+       if (act->ks_flags & SA_RESTART)
+               uk_pr_warn("ks_flags: SA_RESTART not supported, ignoring\n");
+
+       /* TODO Don't update sigaction while executing a signal handler */
+
+       memcpy(KERN_SIGACTION(proc, signum), act,
+              sizeof(struct kern_sigaction));
+
+       /* Clear pending signals if the action has been changed to SIG_IGN */
+       if (IS_IGNORED(proc, signum))
+               pprocess_signal_clear_pending(proc, signum);
+
+       return 0;
+}
+#else /* !CONFIG_LIBPOSIX_PROCESS_SIGNAL */
+UK_LLSYSCALL_R_DEFINE(int, rt_sigaction, int, signum,
+                     const struct kern_sigaction *, act,
+                     struct kern_sigaction *, oldact,
+                     size_t, sigsetsize)
+{
+       UK_WARN_STUBBED();
+       if (oldact)
+               *oldact = (struct kern_sigaction){0};
+
+       return 0;
+}
+#endif /* !CONFIG_LIBPOSIX_PROCESS_SIGNAL */