granicus.if.org Git - strace/blob - fetch_indirect_syscall_args.c

   1 /*
   2  * Copyright (c) 2018 The strace developers.
   3  * All rights reserved.
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-or-later
   6  */
   7
   8 #include "defs.h"
   9
  10 /*
  11  * Fetch indirect syscall arguments that are provided as an array.
  12  * Return a pointer to a static array of kernel_ulong_t elements,
  13  * or NULL in case of fetch failure.
  14  */
  15 kernel_ulong_t *
  16 fetch_indirect_syscall_args(struct tcb *const tcp,
  17                             const kernel_ulong_t addr,
  18                             const unsigned int n_args)
  19 {
  20         static kernel_ulong_t u_arg[MAX_ARGS];
  21
  22         if (current_wordsize == sizeof(*u_arg)) {
  23                 if (umoven(tcp, addr, sizeof(*u_arg) * n_args, u_arg))
  24                         return NULL;
  25         } else {
  26                 uint32_t narrow_arg[ARRAY_SIZE(u_arg)];
  27
  28                 if (umoven(tcp, addr, sizeof(*narrow_arg) * n_args, narrow_arg))
  29                         return NULL;
  30                 for (unsigned int i = 0; i < n_args; ++i)
  31                         u_arg[i] = narrow_arg[i];
  32         }
  33
  34         return u_arg;
  35 }