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