gdb/common/environ.c

   1 /* environ.c -- library for manipulating environments for GNU.
   2
   3    Copyright (C) 1986-2017 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include "common-defs.h"
  19 #include "environ.h"
  20 #include <algorithm>
  21 #include <utility>
  22
  23 /* See common/environ.h.  */
  24
  25 gdb_environ &
  26 gdb_environ::operator= (gdb_environ &&e)
  27 {
  28   /* Are we self-moving?  */
  29   if (&e == this)
  30     return *this;
  31
  32   m_environ_vector = std::move (e.m_environ_vector);
  33   e.m_environ_vector.clear ();
  34   e.m_environ_vector.push_back (NULL);
  35   return *this;
  36 }
  37
  38 /* See common/environ.h.  */
  39
  40 gdb_environ gdb_environ::from_host_environ ()
  41 {
  42   extern char **environ;
  43   gdb_environ e;
  44
  45   if (environ == NULL)
  46     return e;
  47
  48   for (int i = 0; environ[i] != NULL; ++i)
  49     {
  50       /* Make sure we add the element before the last (NULL).  */
  51       e.m_environ_vector.insert (e.m_environ_vector.end () - 1,
  52                                  xstrdup (environ[i]));
  53     }
  54
  55   return e;
  56 }
  57
  58 /* See common/environ.h.  */
  59
  60 void
  61 gdb_environ::clear ()
  62 {
  63   for (char *v : m_environ_vector)
  64     xfree (v);
  65   m_environ_vector.clear ();
  66   /* Always add the NULL element.  */
  67   m_environ_vector.push_back (NULL);
  68 }
  69
  70 /* Helper function to check if STRING contains an environment variable
  71    assignment of VAR, i.e., if STRING starts with 'VAR='.  Return true
  72    if it contains, false otherwise.  */
  73
  74 static bool
  75 match_var_in_string (char *string, const char *var, size_t var_len)
  76 {
  77   if (strncmp (string, var, var_len) == 0 && string[var_len] == '=')
  78     return true;
  79
  80   return false;
  81 }
  82
  83 /* See common/environ.h.  */
  84
  85 const char *
  86 gdb_environ::get (const char *var) const
  87 {
  88   size_t len = strlen (var);
  89
  90   for (char *el : m_environ_vector)
  91     if (el != NULL && match_var_in_string (el, var, len))
  92       return &el[len + 1];
  93
  94   return NULL;
  95 }
  96
  97 /* See common/environ.h.  */
  98
  99 void
 100 gdb_environ::set (const char *var, const char *value)
 101 {
 102   /* We have to unset the variable in the vector if it exists.  */
 103   unset (var);
 104
 105   /* Insert the element before the last one, which is always NULL.  */
 106   m_environ_vector.insert (m_environ_vector.end () - 1,
 107                            concat (var, "=", value, NULL));
 108 }
 109
 110 /* See common/environ.h.  */
 111
 112 void
 113 gdb_environ::unset (const char *var)
 114 {
 115   size_t len = strlen (var);
 116
 117   /* We iterate until '.cend () - 1' because the last element is
 118      always NULL.  */
 119   for (std::vector<char *>::iterator el = m_environ_vector.begin ();
 120        el != m_environ_vector.end () - 1;
 121        ++el)
 122     if (match_var_in_string (*el, var, len))
 123       {
 124         xfree (*el);
 125         m_environ_vector.erase (el);
 126         break;
 127       }
 128 }
 129
 130 /* See common/environ.h.  */
 131
 132 char **
 133 gdb_environ::envp () const
 134 {
 135   return const_cast<char **> (&m_environ_vector[0]);
 136 }