gdbsupport/ptid.h

   1 /* The ptid_t type and common functions operating on it.
   2
   3    Copyright (C) 1986-2022 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 COMMON_PTID_H
  21 #define COMMON_PTID_H
  22
  23 /* The ptid struct is a collection of the various "ids" necessary for
  24    identifying the inferior process/thread being debugged.  This
  25    consists of the process id (pid), lightweight process id (lwp) and
  26    thread id (tid).  When manipulating ptids, the constructors,
  27    accessors, and predicates declared in this file should be used.  Do
  28    NOT access the struct ptid members directly.
  29
  30    process_stratum targets that handle threading themselves should
  31    prefer using the ptid.lwp field, leaving the ptid.tid field for any
  32    thread_stratum target that might want to sit on top.
  33 */
  34
  35 #include <functional>
  36 #include <string>
  37 #include "gdbsupport/common-types.h"
  38
  39 class ptid_t
  40 {
  41 public:
  42   /* Must have a trivial defaulted default constructor so that the
  43      type remains POD.  */
  44   ptid_t () noexcept = default;
  45
  46   /* Make a ptid given the necessary PID, LWP, and TID components.
  47
  48      A ptid with only a PID (LWP and TID equal to zero) is usually used to
  49      represent a whole process, including all its lwps/threads.  */
  50
  51   explicit constexpr ptid_t (int pid, long lwp = 0, ULONGEST tid = 0)
  52     : m_pid (pid), m_lwp (lwp), m_tid (tid)
  53   {}
  54
  55   /* Fetch the pid (process id) component from the ptid.  */
  56
  57   constexpr int pid () const
  58   { return m_pid; }
  59
  60   /* Return true if the ptid's lwp member is non-zero.  */
  61
  62   constexpr bool lwp_p () const
  63   { return m_lwp != 0; }
  64
  65   /* Fetch the lwp (lightweight process) component from the ptid.  */
  66
  67   constexpr long lwp () const
  68   { return m_lwp; }
  69
  70   /* Return true if the ptid's tid member is non-zero.  */
  71
  72   constexpr bool tid_p () const
  73   { return m_tid != 0; }
  74
  75   /* Fetch the tid (thread id) component from a ptid.  */
  76
  77   constexpr ULONGEST tid () const
  78   { return m_tid; }
  79
  80   /* Return true if the ptid represents a whole process, including all its
  81      lwps/threads.  Such ptids have the form of (pid, 0, 0), with
  82      pid != -1.  */
  83
  84   constexpr bool is_pid () const
  85   {
  86     return (*this != make_null ()
  87             && *this != make_minus_one ()
  88             && m_lwp == 0
  89             && m_tid == 0);
  90   }
  91
  92   /* Compare two ptids to see if they are equal.  */
  93
  94   constexpr bool operator== (const ptid_t &other) const
  95   {
  96     return (m_pid == other.m_pid
  97             && m_lwp == other.m_lwp
  98             && m_tid == other.m_tid);
  99   }
 100
 101   /* Compare two ptids to see if they are different.  */
 102
 103   constexpr bool operator!= (const ptid_t &other) const
 104   {
 105     return !(*this == other);
 106   }
 107
 108   /* Return true if the ptid matches FILTER.  FILTER can be the wild
 109      card MINUS_ONE_PTID (all ptids match it); can be a ptid representing
 110      a process (ptid.is_pid () returns true), in which case, all lwps and
 111      threads of that given process match, lwps and threads of other
 112      processes do not; or, it can represent a specific thread, in which
 113      case, only that thread will match true.  The ptid must represent a
 114      specific LWP or THREAD, it can never be a wild card.  */
 115
 116   constexpr bool matches (const ptid_t &filter) const
 117   {
 118     return (/* If filter represents any ptid, it's always a match.  */
 119             filter == make_minus_one ()
 120             /* If filter is only a pid, any ptid with that pid
 121                matches.  */
 122             || (filter.is_pid () && m_pid == filter.pid ())
 123
 124             /* Otherwise, this ptid only matches if it's exactly equal
 125                to filter.  */
 126             || *this == filter);
 127   }
 128
 129   /* Return a string representation of the ptid.
 130
 131      This is only meant to be used in debug messages.  */
 132
 133   std::string to_string () const;
 134
 135   /* Make a null ptid.  */
 136
 137   static constexpr ptid_t make_null ()
 138   { return ptid_t (0, 0, 0); }
 139
 140   /* Make a minus one ptid.  */
 141
 142   static constexpr ptid_t make_minus_one ()
 143   { return ptid_t (-1, 0, 0); }
 144
 145 private:
 146   /* Process id.  */
 147   int m_pid;
 148
 149   /* Lightweight process id.  */
 150   long m_lwp;
 151
 152   /* Thread id.  */
 153   ULONGEST m_tid;
 154 };
 155
 156 /* Functor to hash a ptid.  */
 157
 158 struct hash_ptid
 159 {
 160   size_t operator() (const ptid_t &ptid) const
 161   {
 162     std::hash<long> long_hash;
 163
 164     return (long_hash (ptid.pid ())
 165             + long_hash (ptid.lwp ())
 166             + long_hash (ptid.tid ()));
 167   }
 168 };
 169
 170 /* The null or zero ptid, often used to indicate no process. */
 171
 172 extern const ptid_t null_ptid;
 173
 174 /* The (-1,0,0) ptid, often used to indicate either an error condition
 175    or a "don't care" condition, i.e, "run all threads."  */
 176
 177 extern const ptid_t minus_one_ptid;
 178
 179 #endif /* COMMON_PTID_H */