1 /*
   2  * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "runtime/os.hpp"
  26 
  27 #ifndef OS_POSIX_VM_OS_POSIX_HPP
  28 #define OS_POSIX_VM_OS_POSIX_HPP
  29 
  30 // File conventions
  31 static const char* file_separator() { return "/"; }
  32 static const char* line_separator() { return "\n"; }
  33 static const char* path_separator() { return ":"; }
  34 
  35 class Posix {
  36   friend class os;
  37 
  38 protected:
  39   static void print_distro_info(outputStream* st);
  40   static void print_rlimit_info(outputStream* st);
  41   static void print_uname_info(outputStream* st);
  42   static void print_libversion_info(outputStream* st);
  43   static void print_load_average(outputStream* st);
  44 
  45   // Minimum stack size a thread can be created with (allowing
  46   // the VM to completely create the thread and enter user code)
  47   static size_t _compiler_thread_min_stack_allowed;
  48   static size_t _java_thread_min_stack_allowed;
  49   static size_t _vm_internal_thread_min_stack_allowed;
  50 
  51 public:
  52   // Return default stack size for the specified thread type
  53   static size_t default_stack_size(os::ThreadType thr_type);
  54   // Check and sets minimum stack sizes
  55   static jint set_minimum_stack_sizes();
  56   static size_t get_initial_stack_size(ThreadType thr_type, size_t req_stack_size);
  57 
  58   // Returns true if signal is valid.
  59   static bool is_valid_signal(int sig);
  60 
  61   // Helper function, returns a string (e.g. "SIGILL") for a signal.
  62   // Returned string is a constant. For unknown signals "UNKNOWN" is returned.
  63   static const char* get_signal_name(int sig, char* out, size_t outlen);
  64 
  65   // Helper function, returns a signal number for a given signal name, e.g. 11
  66   // for "SIGSEGV". Name can be given with or without "SIG" prefix, so both
  67   // "SEGV" or "SIGSEGV" work. Name must be uppercase.
  68   // Returns -1 for an unknown signal name.
  69   static int get_signal_number(const char* signal_name);
  70 
  71   // Returns one-line short description of a signal set in a user provided buffer.
  72   static const char* describe_signal_set_short(const sigset_t* set, char* buffer, size_t size);
  73 
  74   // Prints a short one-line description of a signal set.
  75   static void print_signal_set_short(outputStream* st, const sigset_t* set);
  76 
  77   // unblocks the signal masks for current thread
  78   static int unblock_thread_signal_mask(const sigset_t *set);
  79 
  80   // Writes a one-line description of a combination of sigaction.sa_flags
  81   // into a user provided buffer. Returns that buffer.
  82   static const char* describe_sa_flags(int flags, char* buffer, size_t size);
  83 
  84   // Prints a one-line description of a combination of sigaction.sa_flags.
  85   static void print_sa_flags(outputStream* st, int flags);
  86 
  87   static address ucontext_get_pc(const ucontext_t* ctx);
  88   // Set PC into context. Needed for continuation after signal.
  89   static void ucontext_set_pc(ucontext_t* ctx, address pc);
  90 
  91   // Helper function; describes pthread attributes as short string. String is written
  92   // to buf with len buflen; buf is returned.
  93   static char* describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr);
  94 
  95 };
  96 
  97 /*
  98  * Crash protection for the watcher thread. Wrap the callback
  99  * with a sigsetjmp and in case of a SIGSEGV/SIGBUS we siglongjmp
 100  * back.
 101  * To be able to use this - don't take locks, don't rely on destructors,
 102  * don't make OS library calls, don't allocate memory, don't print,
 103  * don't call code that could leave the heap / memory in an inconsistent state,
 104  * or anything else where we are not in control if we suddenly jump out.
 105  */
 106 class WatcherThreadCrashProtection : public StackObj {
 107 public:
 108   WatcherThreadCrashProtection();
 109   bool call(os::CrashProtectionCallback& cb);
 110 
 111   static void check_crash_protection(int signal, Thread* thread);
 112 private:
 113   void restore();
 114   sigjmp_buf _jmpbuf;
 115 };
 116 
 117 #endif // OS_POSIX_VM_OS_POSIX_HPP