mono/eglib/gmisc-unix.c

   1 /*
   2  * gmisc.c: Misc functions with no place to go (right now)
   3  *
   4  * Author:
   5  *   Aaron Bockover (abockover@novell.com)
   6  *
   7  * (C) 2006 Novell, Inc.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining
  10  * a copy of this software and associated documentation files (the
  11  * "Software"), to deal in the Software without restriction, including
  12  * without limitation the rights to use, copy, modify, merge, publish,
  13  * distribute, sublicense, and/or sell copies of the Software, and to
  14  * permit persons to whom the Software is furnished to do so, subject to
  15  * the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be
  18  * included in all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27  */
  28
  29 #include <config.h>
  30 #include <stdlib.h>
  31 #include <glib.h>
  32 #include <pthread.h>
  33
  34 #ifdef HAVE_PWD_H
  35 #include <pwd.h>
  36 #endif
  37
  38 #ifdef HAVE_UNISTD_H
  39 #include <unistd.h>
  40 #endif
  41
  42 static pthread_mutex_t env_lock = PTHREAD_MUTEX_INITIALIZER;
  43
  44 /* MONO Comment
  45  *
  46  * As per the UNIX spec,
  47  * "The return value from getenv() may point to static data which may be overwritten by subsequent calls to getenv(), setenv(), or unsetenv()."
  48  * Source: Unix Manual Pages for getenv, IEEE Std 1003.1
  49  *
  50  * This means that using pointers returned from getenv may (and does) lead to many
  51  * pointers which refer to the same piece of memory. When one is freed, all will be freed.
  52  *
  53  * This is unsafe and an ergonomics risk to fix in the callers. While the caller could lock,
  54  * this introduces the risk for looping or exiting while inside of a lock. For this reason,
  55  * g_getenv does not mimic the behavior of POSIX getenv anymore.
  56  *
  57  * The memory address returned will be unique to the invocaton, and must be freed.
  58  * */
  59 gchar *
  60 g_getenv (const gchar *variable)
  61 {
  62         gchar *ret = NULL;
  63         pthread_mutex_lock (&env_lock);
  64         gchar *res = getenv(variable);
  65         if (res)
  66                 ret = g_strdup(res);
  67         pthread_mutex_unlock (&env_lock);
  68
  69         return ret;
  70 }
  71
  72 /*
  73  * This function checks if the given variable is non-NULL
  74  * in the environment. It's useful because it removes memory
  75  * freeing requirements.
  76  *
  77  */
  78 gboolean
  79 g_hasenv (const gchar *variable)
  80 {
  81         pthread_mutex_lock (&env_lock);
  82         gchar *res = getenv(variable);
  83         gboolean not_null = (res != NULL);
  84         pthread_mutex_unlock (&env_lock);
  85
  86         return not_null;
  87 }
  88
  89 gboolean
  90 g_setenv(const gchar *variable, const gchar *value, gboolean overwrite)
  91 {
  92         gboolean res;
  93         pthread_mutex_lock (&env_lock);
  94         res = (setenv(variable, value, overwrite) == 0);
  95         pthread_mutex_unlock (&env_lock);
  96         return res;
  97 }
  98
  99 void
 100 g_unsetenv(const gchar *variable)
 101 {
 102         pthread_mutex_lock (&env_lock);
 103         unsetenv(variable);
 104         pthread_mutex_unlock (&env_lock);
 105 }
 106
 107 gchar*
 108 g_win32_getlocale(void)
 109 {
 110         return NULL;
 111 }
 112
 113 gboolean
 114 g_path_is_absolute (const char *filename)
 115 {
 116         g_return_val_if_fail (filename != NULL, FALSE);
 117
 118         return (*filename == '/');
 119 }
 120
 121 static pthread_mutex_t pw_lock = PTHREAD_MUTEX_INITIALIZER;
 122 static const gchar *home_dir;
 123 static const gchar *user_name;
 124
 125 static void
 126 get_pw_data (void)
 127 {
 128 #ifdef HAVE_GETPWUID_R
 129         struct passwd pw;
 130         struct passwd *result = NULL;
 131         char buf [4096];
 132 #endif
 133
 134         if (user_name != NULL)
 135                 return;
 136
 137         pthread_mutex_lock (&pw_lock);
 138         if (user_name != NULL) {
 139                 pthread_mutex_unlock (&pw_lock);
 140                 return;
 141         }
 142
 143         home_dir = g_getenv ("HOME");
 144         user_name = g_getenv ("USER");
 145
 146 #ifdef HAVE_GETPWUID_R
 147         if (home_dir == NULL || user_name == NULL) {
 148                 if (getpwuid_r (getuid (), &pw, buf, 4096, &result) == 0 && result) {
 149                         if (home_dir == NULL)
 150                                 home_dir = g_strdup (pw.pw_dir);
 151                         if (user_name == NULL)
 152                                 user_name = g_strdup (pw.pw_name);
 153                 }
 154         }
 155 #endif
 156
 157         if (user_name == NULL)
 158                 user_name = "somebody";
 159         if (home_dir == NULL)
 160                 home_dir = "/";
 161
 162         pthread_mutex_unlock (&pw_lock);
 163 }
 164
 165 const gchar *
 166 g_get_home_dir (void)
 167 {
 168         get_pw_data ();
 169         return home_dir;
 170 }
 171
 172 const gchar *
 173 g_get_user_name (void)
 174 {
 175         get_pw_data ();
 176         return user_name;
 177 }
 178
 179 static const char *tmp_dir;
 180
 181 static pthread_mutex_t tmp_lock = PTHREAD_MUTEX_INITIALIZER;
 182
 183 const gchar *
 184 g_get_tmp_dir (void)
 185 {
 186         if (tmp_dir == NULL){
 187                 pthread_mutex_lock (&tmp_lock);
 188                 if (tmp_dir == NULL){
 189                         tmp_dir = g_getenv ("TMPDIR");
 190                         if (tmp_dir == NULL){
 191                                 tmp_dir = g_getenv ("TMP");
 192                                 if (tmp_dir == NULL){
 193                                         tmp_dir = g_getenv ("TEMP");
 194                                         if (tmp_dir == NULL)
 195                                                 tmp_dir = "/tmp";
 196                                 }
 197                         }
 198                 }
 199                 pthread_mutex_unlock (&tmp_lock);
 200         }
 201         return tmp_dir;
 202 }
 203