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         if (!(c = new0(Condition, 1)))
  34                 return NULL;
  35
  36         c->type = type;
  37         c->trigger = trigger;
  38         c->negate = negate;
  39
  40         if (parameter)
  41                 if (!(c->parameter = strdup(parameter))) {
  42                         free(c);
  43                         return NULL;
  44                 }
  45
  46         return c;
  47 }
  48
  49 void condition_free(Condition *c) {
  50         assert(c);
  51
  52         free(c->parameter);
  53         free(c);
  54 }
  55
  56 void condition_free_list(Condition *first) {
  57         Condition *c, *n;
  58
  59         LIST_FOREACH_SAFE(conditions, c, n, first)
  60                 condition_free(c);
  61 }
  62
  63 static bool test_kernel_command_line(const char *parameter) {
  64         char *line, *w, *state, *word = NULL;
  65         bool equal;
  66         int r;
  67         size_t l, pl;
  68         bool found = false;
  69
  70         assert(parameter);
  71
  72         if (detect_virtualization(NULL) > 0)
  73                 return false;
  74
  75         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  76                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  77                 return false;
  78         }
  79
  80         equal = !!strchr(parameter, '=');
  81         pl = strlen(parameter);
  82
  83         FOREACH_WORD_QUOTED(w, l, line, state) {
  84
  85                 free(word);
  86                 if (!(word = strndup(w, l)))
  87                         break;
  88
  89                 if (equal) {
  90                         if (streq(word, parameter)) {
  91                                 found = true;
  92                                 break;
  93                         }
  94                 } else {
  95                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
  96                                 found = true;
  97                                 break;
  98                         }
  99                 }
 100
 101         }
 102
 103         free(word);
 104         free(line);
 105
 106         return found;
 107 }
 108
 109 static bool test_virtualization(const char *parameter) {
 110         int r, b;
 111         const char *id;
 112
 113         assert(parameter);
 114
 115         if ((r = detect_virtualization(&id)) < 0) {
 116                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 117                 return false;
 118         }
 119
 120         b = parse_boolean(parameter);
 121
 122         if (r > 0 && b > 0)
 123                 return true;
 124
 125         if (r == 0 && b == 0)
 126                 return true;
 127
 128         return streq(parameter, id);
 129 }
 130
 131 bool condition_test(Condition *c) {
 132         assert(c);
 133
 134         switch(c->type) {
 135
 136         case CONDITION_PATH_EXISTS:
 137                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 138
 139         case CONDITION_PATH_IS_DIRECTORY: {
 140                 struct stat st;
 141
 142                 if (lstat(c->parameter, &st) < 0)
 143                         return !c->negate;
 144                 return S_ISDIR(st.st_mode) == !c->negate;
 145         }
 146
 147         case CONDITION_DIRECTORY_NOT_EMPTY: {
 148                 int k;
 149
 150                 k = dir_is_empty(c->parameter);
 151                 return !(k == -ENOENT || k > 0) == !c->negate;
 152         }
 153
 154         case CONDITION_KERNEL_COMMAND_LINE:
 155                 return test_kernel_command_line(c->parameter) == !c->negate;
 156
 157         case CONDITION_VIRTUALIZATION:
 158                 return test_virtualization(c->parameter) == !c->negate;
 159
 160         case CONDITION_NULL:
 161                 return !c->negate;
 162
 163         default:
 164                 assert_not_reached("Invalid condition type.");
 165         }
 166 }
 167
 168 bool condition_test_list(Condition *first) {
 169         Condition *c;
 170         int triggered = -1;
 171
 172         /* If the condition list is empty, then it is true */
 173         if (!first)
 174                 return true;
 175
 176         /* Otherwise, if all of the non-trigger conditions apply and
 177          * if any of the trigger conditions apply (unless there are
 178          * none) we return true */
 179         LIST_FOREACH(conditions, c, first) {
 180                 bool b;
 181
 182                 b = condition_test(c);
 183
 184                 if (!c->trigger && !b)
 185                         return false;
 186
 187                 if (c->trigger && triggered <= 0)
 188                         triggered = b;
 189         }
 190
 191         return triggered != 0;
 192 }
 193
 194 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 195         assert(c);
 196         assert(f);
 197
 198         if (!prefix)
 199                 prefix = "";
 200
 201         fprintf(f,
 202                 "%s\t%s: %s%s%s\n",
 203                 prefix,
 204                 condition_type_to_string(c->type),
 205                 c->trigger ? "|" : "",
 206                 c->negate ? "!" : "",
 207                 c->parameter);
 208 }
 209
 210 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 211         Condition *c;
 212
 213         LIST_FOREACH(conditions, c, first)
 214                 condition_dump(c, f, prefix);
 215 }
 216
 217 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 218         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 219         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 220         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 221         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 222         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 223         [CONDITION_NULL] = "ConditionNull"
 224 };
 225
 226 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);