From caacc16f356d6d5e1c9580ceb2b0f17459192b70 Mon Sep 17 00:00:00 2001
From: antifallobst <antifallobst@systemausfall.org>
Date: Sun, 7 May 2023 01:16:33 +0200
Subject: [PATCH] feature (processes): implemented signals and the 'nx_psignal'
 syscall

---
 inc/proc/process.h     |  9 +++++++++
 src/boot/kmain.c       |  3 ++-
 src/platform/syscall.c | 22 ++++++++++++++++++++++
 src/proc/process.c     | 27 +++++++++++++++++++++++++++
 4 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/inc/proc/process.h b/inc/proc/process.h
index 2ffbcd6..127a189 100644
--- a/inc/proc/process.h
+++ b/inc/proc/process.h
@@ -28,6 +28,13 @@ typedef enum {
     PROCESS_BLOCK_ENUM_SIZE
 } process_blockers_E;
 
+typedef enum {
+    PROCESS_SIGNAL_START,   // SIGSTART
+    PROCESS_SIGNAL_PAUSE,   // SIGPAUSE
+    PROCESS_SIGNAL_KILL,    // SIGKILL
+    PROCESS_SIGNAL_PFAULT,  // SIGPFAULT
+} process_signals_E;
+
 typedef struct process_T process_T;
 struct process_T {
     char                        name        [128];
@@ -57,6 +64,8 @@ struct process_T {
 
 void        process_kernel_spawn    (elf_executable_T* executable);
 pid_t       process_spawn           (pid_t parent, string_t name, elf_executable_T* executable, void* buffer);
+void        process_signal          (process_T* process, process_signals_E signal);
+bool        process_is_child_of     (process_T* process, process_T* parent);
 int32_t     process_get_thread_id   (process_T* process);
 void        process_clear_thread_id (process_T* process, uint32_t id);
 void        process_pause_pid       (pid_t pid);
diff --git a/src/boot/kmain.c b/src/boot/kmain.c
index fe56624..1ed065e 100644
--- a/src/boot/kmain.c
+++ b/src/boot/kmain.c
@@ -69,12 +69,13 @@ void kmain(boot_info_T boot_info) {
     syscall_perform(SYSCALL_PROCESS_CREATE, (uint64_t)"/initrd/shell.elf", 0, (uint64_t)&pid, 0);
 
     process_T* process = scheduler_get_process(pid);
-    thread_start(process->threads);
 
     scheduler_dump_info(scheduler_get_process(PROCESS_KERNEL), 0);
 
     g_tty->output   = &process->stdin;
     process->stdout = &g_tty->input;
 
+    syscall_perform(SYSCALL_PROCESS_SIGNAL, pid, PROCESS_SIGNAL_START, 0, 0);
+
     CORE_HALT_FOREVER
 }
diff --git a/src/platform/syscall.c b/src/platform/syscall.c
index 48fc890..5161426 100644
--- a/src/platform/syscall.c
+++ b/src/platform/syscall.c
@@ -245,6 +245,24 @@ void syscall_handle_nx_pcreate(cpu_state_T* state) {
     state->rax = STATUS_SUCCESS;
 }
 
+void syscall_handle_nx_psignal(cpu_state_T* state) {
+    pid_t    pid    = (pid_t)state->rdi; // arg1
+    uint64_t signal = state->rsi;        // arg2
+
+    if (pid == PROCESS_NONE) {
+        state->rax = STATUS_RESOURCE_NOT_AVAILABLE;
+        return;
+    }
+
+    process_T* process = scheduler_get_process(pid);
+    if (!process_is_child_of(process, scheduler_get_current_process())) {
+        state->rax = STATUS_PERMISSION_DENIED;
+        return;
+    }
+
+    process_signal(scheduler_get_process(pid), signal);
+    state->rax = STATUS_SUCCESS;
+}
 
 cpu_state_T* syscall_handle(cpu_state_T* state) {
     cpu_state_T*    return_state = state;
@@ -303,6 +321,10 @@ cpu_state_T* syscall_handle(cpu_state_T* state) {
                     syscall_handle_nx_pcreate(state);
                     break;
                 }
+                case SYSCALL_PROCESS_SIGNAL: {
+                    syscall_handle_nx_psignal(state);
+                    break;
+                }
             }
             break;
         }
diff --git a/src/proc/process.c b/src/proc/process.c
index e40363b..302fb45 100644
--- a/src/proc/process.c
+++ b/src/proc/process.c
@@ -52,6 +52,33 @@ pid_t process_spawn(pid_t parent, string_t name, elf_executable_T* executable, v
     return scheduler_register_process(process);
 }
 
+void process_signal(process_T* process, process_signals_E signal) {
+    switch (signal) {
+        case PROCESS_SIGNAL_START: {
+            process_start(process);
+            break;
+        }
+        case PROCESS_SIGNAL_PAUSE: {
+            process_pause(process);
+            break;
+        }
+        case PROCESS_SIGNAL_KILL: {
+            process_kill(process);
+            break;
+        }
+        default: break;
+    }
+}
+
+bool process_is_child_of(process_T* process, process_T* parent) {
+    process_T* tmp = process->parent;
+    while (tmp != NULL) {
+        if (tmp == parent) return true;
+        tmp = tmp->parent;
+    }
+    return false;
+}
+
 int32_t process_get_thread_id(process_T* process) {
     for (int i = 0; i < MAX_THREADS_PER_PROCESS; i++) {
         if (!bitmap_get(&process->thread_ids, i)) {