libc/src/signal/linux/sigaltstack.cpp

   1 //===-- Linux implementation of sigaltstack -------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/signal/sigaltstack.h"
  10 #include "hdr/types/stack_t.h"
  11 #include "src/__support/macros/config.h"
  12 #include "src/errno/libc_errno.h"
  13 #include "src/signal/linux/signal_utils.h"
  14
  15 #include "src/__support/common.h"
  16
  17 #include <sys/syscall.h>
  18
  19 namespace LIBC_NAMESPACE_DECL {
  20
  21 LLVM_LIBC_FUNCTION(int, sigaltstack,
  22                    (const stack_t *__restrict ss, stack_t *__restrict oss)) {
  23   if (ss != nullptr) {
  24     unsigned not_ss_disable = ~unsigned(SS_DISABLE);
  25     if ((unsigned(ss->ss_flags) & not_ss_disable) != 0) {
  26       // Flags cannot have anything other than SS_DISABLE set.
  27       // We do the type-casting to unsigned because the |ss_flags|
  28       // field of stack_t is of type "int".
  29       libc_errno = EINVAL;
  30       return -1;
  31     }
  32     if (ss->ss_size < MINSIGSTKSZ) {
  33       libc_errno = ENOMEM;
  34       return -1;
  35     }
  36   }
  37
  38   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_sigaltstack, ss, oss);
  39   if (ret < 0) {
  40     libc_errno = -ret;
  41     return -1;
  42   }
  43   return 0;
  44 }
  45
  46 } // namespace LIBC_NAMESPACE_DECL