1 /* Temporarily install an alternate signal stack 2 3 Copyright (C) 2019-2020 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #ifndef GDBSUPPORT_ALT_STACK_H 21 #define GDBSUPPORT_ALT_STACK_H 22 23 #include <signal.h> 24 25 namespace gdb 26 { 27 28 /* Try to set up an alternate signal stack for SIGSEGV handlers. 29 This allows us to handle SIGSEGV signals generated when the 30 normal process stack is exhausted. If this stack is not set 31 up (sigaltstack is unavailable or fails) and a SIGSEGV is 32 generated when the normal stack is exhausted then the program 33 will behave as though no SIGSEGV handler was installed. */ 34 class alternate_signal_stack 35 { 36 public: 37 alternate_signal_stack () 38 { 39 #ifdef HAVE_SIGALTSTACK 40 m_stack.reset ((char *) xmalloc (SIGSTKSZ)); 41 42 stack_t stack; 43 stack.ss_sp = m_stack.get (); 44 stack.ss_size = SIGSTKSZ; 45 stack.ss_flags = 0; 46 47 sigaltstack (&stack, &m_old_stack); 48 #endif 49 } 50 51 ~alternate_signal_stack () 52 { 53 #ifdef HAVE_SIGALTSTACK 54 sigaltstack (&m_old_stack, nullptr); 55 #endif 56 } 57 58 DISABLE_COPY_AND_ASSIGN (alternate_signal_stack); 59 60 private: 61 62 #ifdef HAVE_SIGALTSTACK 63 gdb::unique_xmalloc_ptr<char> m_stack; 64 stack_t m_old_stack; 65 #endif 66 }; 67 68 } 69 70 #endif /* GDBSUPPORT_ALT_STACK_H */ 71