kern: Add initial signals work

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/src/sys/compat/unix/os/os_signal.c b/src/sys/compat/unix/os/os_signal.c
new file mode 100644
index 0000000..4093c98
--- /dev/null
+++ b/src/sys/compat/unix/os/os_signal.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/errno.h>
+#include <sys/signal.h>
+#include <sys/cdefs.h>
+#include <sys/proc.h>
+#include <os/signal.h>
+
+/*
+ * Handle a POSIX sigaction
+ */
+static int
+do_sigaction(int sig, const struct sigaction *act, struct sigaction *oact)
+{
+    struct proc *self;
+
+    if (act == NULL || oact == NULL) {
+        return -EINVAL;
+    }
+
+    if ((self = proc_self()) == NULL) {
+        return -ESRCH;
+    }
+
+    /* Don't overflow the signal table */
+    if (sig >= NELEM(self->sigtab) || sig < 0) {
+        return -EINVAL;
+    }
+
+    if (oact != NULL) {
+        *oact = self->sigtab[sig];
+    }
+
+    if (act != NULL) {
+        self->sigtab[sig] = *act;
+    }
+
+    return 0;
+}
+
+/*
+ * ARG0: Signal number
+ * ARG1: Action to set (act)
+ * ARG2: Old action (old sigaction written here)
+ */
+scret_t
+sys_sigaction(struct syscall_args *scargs)
+{
+    struct proc *self = proc_self();
+    int sig;
+    struct sigaction *sap, *sap_old;
+    int error;
+
+    sig = SCARG(scargs, int, 0);
+    sap = SCARG(scargs, struct sigaction *, 1);
+    sap_old = SCARG(scargs, struct sigaction *, 2);
+
+    /* Sigactions at a valid address? */
+    error = proc_check_addr(self, (uintptr_t)sap, sizeof(*sap));
+    if (error < 0) {
+        return error;
+    }
+
+    /* Old sigactions at a valid address? */
+    error = proc_check_addr(self, (uintptr_t)sap_old, sizeof(sap_old));
+    if (error < 0) {
+        return error;
+    }
+
+    return do_sigaction(sig, sap, sap_old);
+
+}