common/common.c

   1 /*
   2  * Babeltrace common functions
   3  *
   4  * Copyright 2016 Philippe Proulx <pproulx@efficios.com>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #include <string.h>
  26 #include <sys/types.h>
  27 #include <pwd.h>
  28 #include <unistd.h>
  29 #include <assert.h>
  30 #include <glib.h>
  31 #include <babeltrace/babeltrace-internal.h>
  32
  33 #define SYSTEM_PLUGIN_PATH      INSTALL_LIBDIR "/babeltrace/plugins"
  34 #define HOME_ENV_VAR            "HOME"
  35 #define HOME_PLUGIN_SUBPATH     "/.local/lib/babeltrace/plugins"
  36
  37 BT_HIDDEN
  38 const char *bt_common_get_system_plugin_path(void)
  39 {
  40         return SYSTEM_PLUGIN_PATH;
  41 }
  42
  43 BT_HIDDEN
  44 bool bt_common_is_setuid_setgid(void)
  45 {
  46         return (geteuid() != getuid() || getegid() != getgid());
  47 }
  48
  49 static char *bt_secure_getenv(const char *name)
  50 {
  51         if (bt_common_is_setuid_setgid()) {
  52                 printf_error("Disregarding %s environment variable for setuid/setgid binary",
  53                         name);
  54                 return NULL;
  55         }
  56         return getenv(name);
  57 }
  58
  59 static const char *get_home_dir(void)
  60 {
  61         char *val = NULL;
  62         struct passwd *pwd;
  63
  64         val = bt_secure_getenv(HOME_ENV_VAR);
  65         if (val) {
  66                 goto end;
  67         }
  68         /* Fallback on password file. */
  69         pwd = getpwuid(getuid());
  70         if (!pwd) {
  71                 goto end;
  72         }
  73         val = pwd->pw_dir;
  74 end:
  75         return val;
  76 }
  77
  78 BT_HIDDEN
  79 char *bt_common_get_home_plugin_path(void)
  80 {
  81         char *path = NULL;
  82         const char *home_dir;
  83
  84         home_dir = get_home_dir();
  85         if (!home_dir) {
  86                 goto end;
  87         }
  88
  89         if (strlen(home_dir) + strlen(HOME_PLUGIN_SUBPATH) + 1 >= PATH_MAX) {
  90                 printf_error("Home directory path is too long: `%s`\n",
  91                         home_dir);
  92                 goto end;
  93         }
  94
  95         path = malloc(PATH_MAX);
  96         if (!path) {
  97                 goto end;
  98         }
  99
 100         strcpy(path, home_dir);
 101         strcat(path, HOME_PLUGIN_SUBPATH);
 102
 103 end:
 104         return path;
 105 }
 106
 107 BT_HIDDEN
 108 int bt_common_append_plugin_path_dirs(const char *paths, GPtrArray *dirs)
 109 {
 110         int ret = 0;
 111         const char *at;
 112         const char *end;
 113         size_t init_dirs_len;
 114
 115         assert(dirs);
 116         init_dirs_len = dirs->len;
 117
 118         if (!paths) {
 119                 /* Nothing to append */
 120                 goto end;
 121         }
 122
 123         at = paths;
 124         end = paths + strlen(paths);
 125
 126         while (at < end) {
 127                 GString *path;
 128                 const char *next_colon;
 129
 130                 next_colon = strchr(at, ':');
 131                 if (next_colon == at) {
 132                         /*
 133                          * Empty path: try next character (supported
 134                          * to conform to the typical parsing of $PATH).
 135                          */
 136                         at++;
 137                         continue;
 138                 } else if (!next_colon) {
 139                         /* No more colon: use the remaining */
 140                         next_colon = paths + strlen(paths);
 141                 }
 142
 143                 path = g_string_new(NULL);
 144                 if (!path) {
 145                         goto error;
 146                 }
 147
 148                 g_string_append_len(path, at, next_colon - at);
 149                 at = next_colon + 1;
 150                 g_ptr_array_add(dirs, path);
 151         }
 152
 153         goto end;
 154
 155 error:
 156         ret = -1;
 157
 158         /* Remove the new entries in dirs */
 159         while (dirs->len > init_dirs_len) {
 160                 g_ptr_array_remove_index(dirs, init_dirs_len);
 161         }
 162
 163 end:
 164         return ret;
 165 }