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 negate) {
  31         Condition *c;
  32
  33         c = new0(Condition, 1);
  34         c->type = type;
  35         c->negate = negate;
  36
  37         if (parameter)
  38                 if (!(c->parameter = strdup(parameter))) {
  39                         free(c);
  40                         return NULL;
  41                 }
  42
  43         return c;
  44 }
  45
  46 void condition_free(Condition *c) {
  47         assert(c);
  48
  49         free(c->parameter);
  50         free(c);
  51 }
  52
  53 void condition_free_list(Condition *first) {
  54         Condition *c, *n;
  55
  56         LIST_FOREACH_SAFE(conditions, c, n, first)
  57                 condition_free(c);
  58 }
  59
  60 static bool test_kernel_command_line(const char *parameter) {
  61         char *line, *w, *state, *word = NULL;
  62         bool equal;
  63         int r;
  64         size_t l, pl;
  65         bool found = false;
  66
  67         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  68                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  69                 return false;
  70         }
  71
  72         equal = !!strchr(parameter, '=');
  73         pl = strlen(parameter);
  74
  75         FOREACH_WORD_QUOTED(w, l, line, state) {
  76
  77                 free(word);
  78                 if (!(word = strndup(w, l)))
  79                         break;
  80
  81                 if (equal) {
  82                         if (streq(word, parameter)) {
  83                                 found = true;
  84                                 break;
  85                         }
  86                 } else {
  87                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
  88                                 found = true;
  89                                 break;
  90                         }
  91                 }
  92
  93         }
  94
  95         free(word);
  96         free(line);
  97
  98         return found;
  99 }
 100
 101 bool condition_test(Condition *c) {
 102         assert(c);
 103
 104         switch(c->type) {
 105
 106         case CONDITION_PATH_EXISTS:
 107                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 108
 109         case CONDITION_DIRECTORY_NOT_EMPTY: {
 110                 int k;
 111
 112                 k = dir_is_empty(c->parameter);
 113                 return !(k == -ENOENT || k > 0) == !c->negate;
 114         }
 115
 116         case CONDITION_KERNEL_COMMAND_LINE:
 117                 return !!test_kernel_command_line(c->parameter) == !c->negate;
 118
 119         case CONDITION_NULL:
 120                 return !c->negate;
 121
 122         default:
 123                 assert_not_reached("Invalid condition type.");
 124         }
 125 }
 126
 127 bool condition_test_list(Condition *first) {
 128         Condition *c;
 129
 130         /* If the condition list is empty, then it is true */
 131         if (!first)
 132                 return true;
 133
 134         /* Otherwise, if any of the conditions apply we return true */
 135         LIST_FOREACH(conditions, c, first)
 136                 if (condition_test(c))
 137                         return true;
 138
 139         return false;
 140 }
 141
 142 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 143         assert(c);
 144         assert(f);
 145
 146         if (!prefix)
 147                 prefix = "";
 148
 149         fprintf(f,
 150                 "%s%s: %s%s\n",
 151                 prefix,
 152                 condition_type_to_string(c->type),
 153                 c->negate ? "!" : "",
 154                 c->parameter);
 155 }
 156
 157 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 158         Condition *c;
 159
 160         LIST_FOREACH(conditions, c, first)
 161                 condition_dump(c, f, prefix);
 162 }
 163
 164 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 165         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 166         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 167         [CONDITION_NULL] = "ConditionNull"
 168 };
 169
 170 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);