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 "src/errno/libc_errno.h"
  11 #include "src/signal/linux/signal_utils.h"
  12
  13 #include "src/__support/common.h"
  14
  15 #include <signal.h>
  16 #include <sys/syscall.h>
  17
  18 namespace __llvm_libc {
  19
  20 LLVM_LIBC_FUNCTION(int, sigaltstack,
  21                    (const stack_t *__restrict ss, stack_t *__restrict oss)) {
  22   if (ss != nullptr) {
  23     unsigned not_ss_disable = ~unsigned(SS_DISABLE);
  24     if ((unsigned(ss->ss_flags) & not_ss_disable) != 0) {
  25       // Flags cannot have anything other than SS_DISABLE set.
  26       // We do the type-casting to unsigned because the |ss_flags|
  27       // field of stack_t is of type "int".
  28       libc_errno = EINVAL;
  29       return -1;
  30     }
  31     if (ss->ss_size < MINSIGSTKSZ) {
  32       libc_errno = ENOMEM;
  33       return -1;
  34     }
  35   }
  36
  37   int ret = __llvm_libc::syscall_impl(SYS_sigaltstack, ss, oss);
  38   if (ret < 0) {
  39     libc_errno = -ret;
  40     return -1;
  41   }
  42   return 0;
  43 }
  44
  45 } // namespace __llvm_libc