Add write_file () syscall, CE implement redirections, libarena arena_realloc ()

kernel/syscall/syscall.c

@@ -483,6 +483,38 @@ DEFINE_SYSCALL (sys_create_file) {
   return SYSRESULT (ret);
 }
 
+/* int write_file (char* path, size_t off, uint8_t* buffer, size_t size) */
+DEFINE_SYSCALL (sys_write_file) {
+  uintptr_t uvaddr_path = a1;
+  size_t off = (size_t)a2;
+  uintptr_t uvaddr_buffer = a3;
+  size_t size = (size_t)a4;
+
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+
+  uintptr_t out_paddr;
+
+  spin_lock (&proc->procgroup->lock);
+  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
+  spin_unlock (&proc->procgroup->lock);
+
+  if (out_paddr == 0)
+    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);
+
+  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);
+
+  uint8_t* buffer = sys_get_user_buffer (proc, uvaddr_buffer, size);
+
+  if (buffer == NULL)
+    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);
+
+  spin_lock (&proc->lock);
+  int ret = vfs_write_file (proc, proc->cwv, path, buffer, off, size);
+  spin_unlock (&proc->lock);
+
+  return SYSRESULT (ret);
+}
+
 /* int get_exec_pid (void) */
 DEFINE_SYSCALL (sys_get_exec_pid) { return SYSRESULT (proc->exec_pid); }
 
@@ -510,6 +542,7 @@ static syscall_handler_func_t handler_table[] = {
     [SYS_GET_EXEC_PID] = &sys_get_exec_pid,
     [SYS_READ_DIR_ENTRY] = &sys_read_dir_entry,
     [SYS_CREATE_FILE] = &sys_create_file,
+    [SYS_WRITE_FILE] = &sys_write_file,
 };
 
 syscall_handler_func_t syscall_find_handler (int syscall_num) {