src/bin/lttng/conf.c

   1 /*
   2  * Copyright (c)  2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <limits.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <sys/stat.h>
  24 #include <sys/types.h>
  25 #include <unistd.h>
  26
  27 #include <common/error.h>
  28
  29 #include "conf.h"
  30
  31 /*
  32  * Returns the path with '/CONFIG_FILENAME' added to it;
  33  * path will be NULL if an error occurs.
  34  */
  35 char *config_get_file_path(char *path)
  36 {
  37         int ret;
  38         char *file_path;
  39
  40         ret = asprintf(&file_path, "%s/%s", path, CONFIG_FILENAME);
  41         if (ret < 0) {
  42                 ERR("Fail allocating config file path");
  43                 file_path = NULL;
  44         }
  45
  46         return file_path;
  47 }
  48
  49 /*
  50  * Returns an open FILE pointer to the config file;
  51  * on error, NULL is returned.
  52  */
  53 static FILE *open_config(char *path, const char *mode)
  54 {
  55         FILE *fp = NULL;
  56         char *file_path;
  57
  58         file_path = config_get_file_path(path);
  59         if (file_path == NULL) {
  60                 goto error;
  61         }
  62
  63         fp = fopen(file_path, mode);
  64         if (fp == NULL) {
  65                 goto error;
  66         }
  67
  68 error:
  69         if (file_path) {
  70                 free(file_path);
  71         }
  72         return fp;
  73 }
  74
  75 /*
  76  * Creates the empty config file at the path.
  77  * On success, returns 0;
  78  * on error, returns -1.
  79  */
  80 static int create_config_file(char *path)
  81 {
  82         int ret;
  83         FILE *fp;
  84
  85         fp = open_config(path, "w+");
  86         if (fp == NULL) {
  87                 ERR("Unable to create config file");
  88                 ret = -1;
  89                 goto error;
  90         }
  91
  92         ret = fclose(fp);
  93
  94 error:
  95         return ret;
  96 }
  97
  98 /*
  99  * Append data to the config file in file_path
 100  * On success, returns 0;
 101  * on error, returns -1.
 102  */
 103 static int write_config(char *file_path, size_t size, char *data)
 104 {
 105         FILE *fp;
 106         size_t len;
 107         int ret = 0;
 108
 109         fp = open_config(file_path, "a");
 110         if (fp == NULL) {
 111                 ret = -1;
 112                 goto end;
 113         }
 114
 115         /* Write session name into config file */
 116         len = fwrite(data, size, 1, fp);
 117         if (len != 1) {
 118                 ret = -1;
 119         }
 120         if (fclose(fp)) {
 121                 PERROR("close write_config");
 122         }
 123 end:
 124         return ret;
 125 }
 126
 127 /*
 128  * Returns the HOME directory path. Caller MUST NOT free(3) the return pointer.
 129  */
 130 char *config_get_default_path(void)
 131 {
 132         return getenv("HOME");
 133 }
 134
 135 /*
 136  * Destroys directory config and file config.
 137  */
 138 void config_destroy(char *path)
 139 {
 140         int ret;
 141         char *config_path;
 142
 143         config_path = config_get_file_path(path);
 144         if (config_path == NULL) {
 145                 return;
 146         }
 147
 148         if (!config_exists(config_path)) {
 149                 goto end;
 150         }
 151
 152         DBG("Removing %s\n", config_path);
 153         ret = remove(config_path);
 154         if (ret < 0) {
 155                 perror("remove config file");
 156         }
 157 end:
 158         free(config_path);
 159 }
 160
 161 /*
 162  * Destroys the default config
 163  */
 164 void config_destroy_default(void)
 165 {
 166         char *path = config_get_default_path();
 167         if (path == NULL) {
 168                 return;
 169         }
 170         config_destroy(path);
 171 }
 172
 173 /*
 174  * Returns 1 if config exists, 0 otherwise
 175  */
 176 int config_exists(const char *path)
 177 {
 178         int ret;
 179         struct stat info;
 180
 181         ret = stat(path, &info);
 182         if (ret < 0) {
 183                 return 0;
 184         }
 185         return S_ISREG(info.st_mode) || S_ISDIR(info.st_mode);
 186 }
 187
 188 /*
 189  * Returns the session name from the config file.
 190  * The caller is responsible for freeing the returned string.
 191  * On error, NULL is returned.
 192  */
 193 char *config_read_session_name(char *path)
 194 {
 195         int ret;
 196         FILE *fp;
 197         char var[NAME_MAX], *session_name;
 198
 199         session_name = malloc(NAME_MAX);
 200         if (session_name == NULL) {
 201                 ERR("Out of memory");
 202                 goto error;
 203         }
 204
 205         fp = open_config(path, "r");
 206         if (fp == NULL) {
 207                 ERR("Can't find valid lttng config %s/.lttngrc", path);
 208                 MSG("Did you create a session? (lttng create <my_session>)");
 209                 goto error;
 210         }
 211
 212         while (!feof(fp)) {
 213                 if ((ret = fscanf(fp, "%[^'=']=%s\n", var, session_name)) != 2) {
 214                         if (ret == -1) {
 215                                 ERR("Missing session=NAME in config file.");
 216                                 goto error_close;
 217                         }
 218                         continue;
 219                 }
 220
 221                 if (strcmp(var, "session") == 0) {
 222                         goto found;
 223                 }
 224         }
 225
 226 error_close:
 227         ret = fclose(fp);
 228         if (ret < 0) {
 229                 PERROR("close config read session name");
 230         }
 231
 232 error:
 233         return NULL;
 234
 235 found:
 236         ret = fclose(fp);
 237         if (ret < 0) {
 238                 PERROR("close config read session name found");
 239         }
 240         return session_name;
 241
 242 }
 243
 244 /*
 245  * Write session name option to the config file.
 246  * On success, returns 0;
 247  * on error, returns -1.
 248  */
 249 int config_add_session_name(char *path, char *name)
 250 {
 251         int ret;
 252         char *attr = "session=";
 253         /* Max name len accepted plus attribute's len and the NULL byte. */
 254         char session_name[NAME_MAX + strlen(attr) + 1];
 255
 256         /*
 257          * With GNU C <  2.1, snprintf returns -1 if the target buffer is too small;
 258          * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
 259          */
 260         ret = snprintf(session_name, sizeof(session_name), "%s%s\n", attr, name);
 261         if (ret < 0) {
 262                 ret = -1;
 263                 goto error;
 264         }
 265         ret = write_config(path, ret, session_name);
 266 error:
 267         return ret;
 268 }
 269
 270 /*
 271  * Init configuration directory and file.
 272  * On success, returns 0;
 273  * on error, returns -1.
 274  */
 275 int config_init(char *session_name)
 276 {
 277         int ret;
 278         char *path;
 279
 280         path = config_get_default_path();
 281         if (path == NULL) {
 282                 ret = -1;
 283                 goto error;
 284         }
 285
 286         /* Create default config file */
 287         ret = create_config_file(path);
 288         if (ret < 0) {
 289                 goto error;
 290         }
 291
 292         ret = config_add_session_name(path, session_name);
 293         if (ret < 0) {
 294                 goto error;
 295         }
 296
 297         DBG("Init config session in %s", path);
 298
 299 error:
 300         return ret;
 301 }