lttng-view: make babeltrace2 the default viewer
[lttng-tools.git] / 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 _LGPL_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 #include <errno.h>
27
28 #include <common/common.h>
29 #include <common/utils.h>
30
31 #include "conf.h"
32
33 /*
34 * Returns the path with '/CONFIG_FILENAME' added to it;
35 * path will be NULL if an error occurs.
36 */
37 char *config_get_file_path(const char *path)
38 {
39 int ret;
40 char *file_path;
41
42 ret = asprintf(&file_path, "%s/%s", path, CONFIG_FILENAME);
43 if (ret < 0) {
44 ERR("Fail allocating config file path");
45 file_path = NULL;
46 }
47
48 return file_path;
49 }
50
51 /*
52 * Returns an open FILE pointer to the config file;
53 * on error, NULL is returned.
54 */
55 static FILE *open_config(const char *path, const char *mode)
56 {
57 FILE *fp = NULL;
58 char *file_path;
59
60 file_path = config_get_file_path(path);
61 if (file_path == NULL) {
62 goto error;
63 }
64
65 fp = fopen(file_path, mode);
66 if (fp == NULL) {
67 goto error;
68 }
69
70 error:
71 free(file_path);
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(const 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(const 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 * Destroys directory config and file config.
129 */
130 void config_destroy(const char *path)
131 {
132 int ret;
133 char *config_path;
134
135 config_path = config_get_file_path(path);
136 if (config_path == NULL) {
137 return;
138 }
139
140 if (!config_exists(config_path)) {
141 goto end;
142 }
143
144 DBG("Removing %s\n", config_path);
145 ret = remove(config_path);
146 if (ret < 0) {
147 PERROR("remove config file");
148 }
149 end:
150 free(config_path);
151 }
152
153 /*
154 * Destroys the default config
155 */
156 void config_destroy_default(void)
157 {
158 const char *path = utils_get_home_dir();
159 if (path == NULL) {
160 return;
161 }
162 config_destroy(path);
163 }
164
165 /*
166 * Returns 1 if config exists, 0 otherwise
167 */
168 int config_exists(const char *path)
169 {
170 int ret;
171 struct stat info;
172
173 ret = stat(path, &info);
174 if (ret < 0) {
175 return 0;
176 }
177 return S_ISREG(info.st_mode) || S_ISDIR(info.st_mode);
178 }
179
180 static
181 int _config_read_session_name(const char *path, char **name)
182 {
183 int ret = 0;
184 FILE *fp;
185 char var[NAME_MAX], *session_name;
186
187 #if (NAME_MAX == 255)
188 #define NAME_MAX_SCANF_IS_A_BROKEN_API "254"
189 #endif
190
191 session_name = zmalloc(NAME_MAX);
192 if (session_name == NULL) {
193 ret = -ENOMEM;
194 ERR("Out of memory");
195 goto error;
196 }
197
198 fp = open_config(path, "r");
199 if (fp == NULL) {
200 ret = -ENOENT;
201 goto error;
202 }
203
204 while (!feof(fp)) {
205 if ((ret = fscanf(fp, "%" NAME_MAX_SCANF_IS_A_BROKEN_API
206 "[^'=']=%" NAME_MAX_SCANF_IS_A_BROKEN_API "s\n",
207 var, session_name)) != 2) {
208 if (ret == -1) {
209 ERR("Missing session=NAME in config file.");
210 goto error_close;
211 }
212 continue;
213 }
214
215 if (strcmp(var, "session") == 0) {
216 goto found;
217 }
218 }
219
220 error_close:
221 if (fclose(fp) < 0) {
222 PERROR("close config read session name");
223 }
224 error:
225 free(session_name);
226 return ret;
227 found:
228 *name = session_name;
229 if (fclose(fp) < 0) {
230 PERROR("close config read session name found");
231 }
232 return ret;
233 }
234
235 /*
236 * Returns the session name from the config file.
237 *
238 * The caller is responsible for freeing the returned string.
239 * On error, NULL is returned.
240 */
241 char *config_read_session_name(const char *path)
242 {
243 int ret;
244 char *name = NULL;
245
246 ret = _config_read_session_name(path, &name);
247 if (ret == -ENOENT) {
248 const char *home_dir = utils_get_home_dir();
249
250 ERR("Can't find valid lttng config %s/.lttngrc", home_dir);
251 MSG("Did you create a session? (lttng create <my_session>)");
252 }
253
254 return name;
255 }
256
257 /*
258 * Returns the session name from the config file. (no warnings/errors emitted)
259 *
260 * The caller is responsible for freeing the returned string.
261 * On error, NULL is returned.
262 */
263 char *config_read_session_name_quiet(const char *path)
264 {
265 char *name = NULL;
266
267 (void) _config_read_session_name(path, &name);
268 return name;
269 }
270
271 /*
272 * Write session name option to the config file.
273 * On success, returns 0;
274 * on error, returns -1.
275 */
276 int config_add_session_name(const char *path, const char *name)
277 {
278 int ret;
279 char *attr = "session=";
280 /* Max name len accepted plus attribute's len and the NULL byte. */
281 char session_name[NAME_MAX + strlen(attr) + 1];
282
283 /*
284 * With GNU C < 2.1, snprintf returns -1 if the target buffer is too small;
285 * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
286 */
287 ret = snprintf(session_name, sizeof(session_name), "%s%s\n", attr, name);
288 if (ret < 0) {
289 ret = -1;
290 goto error;
291 }
292 ret = write_config(path, ret, session_name);
293 error:
294 return ret;
295 }
296
297 /*
298 * Init configuration directory and file.
299 * On success, returns 0;
300 * on error, returns -1.
301 */
302 int config_init(const char *session_name)
303 {
304 int ret;
305 const char *path;
306
307 path = utils_get_home_dir();
308 if (path == NULL) {
309 ret = -1;
310 goto error;
311 }
312
313 /* Create default config file */
314 ret = create_config_file(path);
315 if (ret < 0) {
316 goto error;
317 }
318
319 ret = config_add_session_name(path, session_name);
320 if (ret < 0) {
321 goto error;
322 }
323
324 DBG("Init config session in %s", path);
325
326 error:
327 return ret;
328 }
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