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 #include "util.h"
  28 #include "condition.h"
  29
  30 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  31         Condition *c;
  32
  33         c = new0(Condition, 1);
  34         c->type = type;
  35         c->trigger = trigger;
  36         c->negate = negate;
  37
  38         if (parameter)
  39                 if (!(c->parameter = strdup(parameter))) {
  40                         free(c);
  41                         return NULL;
  42                 }
  43
  44         return c;
  45 }
  46
  47 void condition_free(Condition *c) {
  48         assert(c);
  49
  50         free(c->parameter);
  51         free(c);
  52 }
  53
  54 void condition_free_list(Condition *first) {
  55         Condition *c, *n;
  56
  57         LIST_FOREACH_SAFE(conditions, c, n, first)
  58                 condition_free(c);
  59 }
  60
  61 static bool test_kernel_command_line(const char *parameter) {
  62         char *line, *w, *state, *word = NULL;
  63         bool equal;
  64         int r;
  65         size_t l, pl;
  66         bool found = false;
  67
  68         assert(parameter);
  69
  70         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  71                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  72                 return false;
  73         }
  74
  75         equal = !!strchr(parameter, '=');
  76         pl = strlen(parameter);
  77
  78         FOREACH_WORD_QUOTED(w, l, line, state) {
  79
  80                 free(word);
  81                 if (!(word = strndup(w, l)))
  82                         break;
  83
  84                 if (equal) {
  85                         if (streq(word, parameter)) {
  86                                 found = true;
  87                                 break;
  88                         }
  89                 } else {
  90                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
  91                                 found = true;
  92                                 break;
  93                         }
  94                 }
  95
  96         }
  97
  98         free(word);
  99         free(line);
 100
 101         return found;
 102 }
 103
 104 static bool test_virtualization(const char *parameter) {
 105         int r, b;
 106         const char *id;
 107
 108         assert(parameter);
 109
 110         if ((r = detect_virtualization(&id)) < 0) {
 111                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 112                 return false;
 113         }
 114
 115         b = parse_boolean(parameter);
 116
 117         if (r > 0 && b > 0)
 118                 return true;
 119
 120         if (r == 0 && b == 0)
 121                 return true;
 122
 123         return streq(parameter, id);
 124 }
 125
 126 bool condition_test(Condition *c) {
 127         assert(c);
 128
 129         switch(c->type) {
 130
 131         case CONDITION_PATH_EXISTS:
 132                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 133
 134         case CONDITION_DIRECTORY_NOT_EMPTY: {
 135                 int k;
 136
 137                 k = dir_is_empty(c->parameter);
 138                 return !(k == -ENOENT || k > 0) == !c->negate;
 139         }
 140
 141         case CONDITION_KERNEL_COMMAND_LINE:
 142                 return test_kernel_command_line(c->parameter) == !c->negate;
 143
 144         case CONDITION_VIRTUALIZATION:
 145                 return test_virtualization(c->parameter) == !c->negate;
 146
 147         case CONDITION_NULL:
 148                 return !c->negate;
 149
 150         default:
 151                 assert_not_reached("Invalid condition type.");
 152         }
 153 }
 154
 155 bool condition_test_list(Condition *first) {
 156         Condition *c;
 157         int triggered = -1;
 158
 159         /* If the condition list is empty, then it is true */
 160         if (!first)
 161                 return true;
 162
 163         /* Otherwise, if all of the non-trigger conditions apply and
 164          * if any of the trigger conditions apply (unless there are
 165          * none) we return true */
 166         LIST_FOREACH(conditions, c, first) {
 167                 bool b;
 168
 169                 b = condition_test(c);
 170
 171                 if (!c->trigger && !b)
 172                         return false;
 173
 174                 if (c->trigger && triggered <= 0)
 175                         triggered = b;
 176         }
 177
 178         return triggered != 0;
 179 }
 180
 181 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 182         assert(c);
 183         assert(f);
 184
 185         if (!prefix)
 186                 prefix = "";
 187
 188         fprintf(f,
 189                 "%s%s: %s%s%s\n",
 190                 prefix,
 191                 condition_type_to_string(c->type),
 192                 c->trigger ? "|" : "",
 193                 c->negate ? "!" : "",
 194                 c->parameter);
 195 }
 196
 197 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 198         Condition *c;
 199
 200         LIST_FOREACH(conditions, c, first)
 201                 condition_dump(c, f, prefix);
 202 }
 203
 204 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 205         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 206         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 207         [CONDITION_NULL] = "ConditionNull"
 208 };
 209
 210 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);