src/condition.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdlib.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #ifdef HAVE_SELINUX
  28 #include <selinux/selinux.h>
  29 #endif
  30
  31 #include "util.h"
  32 #include "condition.h"
  33
  34 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  35         Condition *c;
  36
  37         if (!(c = new0(Condition, 1)))
  38                 return NULL;
  39
  40         c->type = type;
  41         c->trigger = trigger;
  42         c->negate = negate;
  43
  44         if (parameter)
  45                 if (!(c->parameter = strdup(parameter))) {
  46                         free(c);
  47                         return NULL;
  48                 }
  49
  50         return c;
  51 }
  52
  53 void condition_free(Condition *c) {
  54         assert(c);
  55
  56         free(c->parameter);
  57         free(c);
  58 }
  59
  60 void condition_free_list(Condition *first) {
  61         Condition *c, *n;
  62
  63         LIST_FOREACH_SAFE(conditions, c, n, first)
  64                 condition_free(c);
  65 }
  66
  67 static bool test_kernel_command_line(const char *parameter) {
  68         char *line, *w, *state, *word = NULL;
  69         bool equal;
  70         int r;
  71         size_t l, pl;
  72         bool found = false;
  73
  74         assert(parameter);
  75
  76         if (detect_virtualization(NULL) > 0)
  77                 return false;
  78
  79         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  80                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  81                 return false;
  82         }
  83
  84         equal = !!strchr(parameter, '=');
  85         pl = strlen(parameter);
  86
  87         FOREACH_WORD_QUOTED(w, l, line, state) {
  88
  89                 free(word);
  90                 if (!(word = strndup(w, l)))
  91                         break;
  92
  93                 if (equal) {
  94                         if (streq(word, parameter)) {
  95                                 found = true;
  96                                 break;
  97                         }
  98                 } else {
  99                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
 100                                 found = true;
 101                                 break;
 102                         }
 103                 }
 104
 105         }
 106
 107         free(word);
 108         free(line);
 109
 110         return found;
 111 }
 112
 113 static bool test_virtualization(const char *parameter) {
 114         int r, b;
 115         const char *id;
 116
 117         assert(parameter);
 118
 119         if ((r = detect_virtualization(&id)) < 0) {
 120                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 121                 return false;
 122         }
 123
 124         b = parse_boolean(parameter);
 125
 126         if (r > 0 && b > 0)
 127                 return true;
 128
 129         if (r == 0 && b == 0)
 130                 return true;
 131
 132         return streq(parameter, id);
 133 }
 134
 135 static bool test_security(const char *parameter) {
 136 #ifdef HAVE_SELINUX
 137         if (streq(parameter, "selinux"))
 138                 return is_selinux_enabled() > 0;
 139 #endif
 140         return false;
 141 }
 142
 143 bool condition_test(Condition *c) {
 144         assert(c);
 145
 146         switch(c->type) {
 147
 148         case CONDITION_PATH_EXISTS:
 149                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 150
 151         case CONDITION_PATH_IS_DIRECTORY: {
 152                 struct stat st;
 153
 154                 if (lstat(c->parameter, &st) < 0)
 155                         return !c->negate;
 156                 return S_ISDIR(st.st_mode) == !c->negate;
 157         }
 158
 159         case CONDITION_DIRECTORY_NOT_EMPTY: {
 160                 int k;
 161
 162                 k = dir_is_empty(c->parameter);
 163                 return !(k == -ENOENT || k > 0) == !c->negate;
 164         }
 165
 166         case CONDITION_KERNEL_COMMAND_LINE:
 167                 return test_kernel_command_line(c->parameter) == !c->negate;
 168
 169         case CONDITION_VIRTUALIZATION:
 170                 return test_virtualization(c->parameter) == !c->negate;
 171
 172         case CONDITION_SECURITY:
 173                 return test_security(c->parameter) == !c->negate;
 174
 175         case CONDITION_NULL:
 176                 return !c->negate;
 177
 178         default:
 179                 assert_not_reached("Invalid condition type.");
 180         }
 181 }
 182
 183 bool condition_test_list(Condition *first) {
 184         Condition *c;
 185         int triggered = -1;
 186
 187         /* If the condition list is empty, then it is true */
 188         if (!first)
 189                 return true;
 190
 191         /* Otherwise, if all of the non-trigger conditions apply and
 192          * if any of the trigger conditions apply (unless there are
 193          * none) we return true */
 194         LIST_FOREACH(conditions, c, first) {
 195                 bool b;
 196
 197                 b = condition_test(c);
 198
 199                 if (!c->trigger && !b)
 200                         return false;
 201
 202                 if (c->trigger && triggered <= 0)
 203                         triggered = b;
 204         }
 205
 206         return triggered != 0;
 207 }
 208
 209 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 210         assert(c);
 211         assert(f);
 212
 213         if (!prefix)
 214                 prefix = "";
 215
 216         fprintf(f,
 217                 "%s\t%s: %s%s%s\n",
 218                 prefix,
 219                 condition_type_to_string(c->type),
 220                 c->trigger ? "|" : "",
 221                 c->negate ? "!" : "",
 222                 c->parameter);
 223 }
 224
 225 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 226         Condition *c;
 227
 228         LIST_FOREACH(conditions, c, first)
 229                 condition_dump(c, f, prefix);
 230 }
 231
 232 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 233         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 234         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 235         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 236         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 237         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 238         [CONDITION_SECURITY] = "ConditionSecurity",
 239         [CONDITION_NULL] = "ConditionNull"
 240 };
 241
 242 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);