1
2
3#define _GNU_SOURCE
4
5#include <errno.h>
6#include <fcntl.h>
7#include <linux/limits.h>
8#include <signal.h>
9#include <stdio.h>
10#include <stdlib.h>
11#include <string.h>
12#include <sys/stat.h>
13#include <sys/types.h>
14#include <sys/wait.h>
15#include <unistd.h>
16
17#include "cgroup_util.h"
18
19static ssize_t read_text(const char *path, char *buf, size_t max_len)
20{
21 ssize_t len;
22 int fd;
23
24 fd = open(path, O_RDONLY);
25 if (fd < 0)
26 return fd;
27
28 len = read(fd, buf, max_len - 1);
29 if (len < 0)
30 goto out;
31
32 buf[len] = 0;
33out:
34 close(fd);
35 return len;
36}
37
38static ssize_t write_text(const char *path, char *buf, ssize_t len)
39{
40 int fd;
41
42 fd = open(path, O_WRONLY | O_APPEND);
43 if (fd < 0)
44 return fd;
45
46 len = write(fd, buf, len);
47 if (len < 0) {
48 close(fd);
49 return len;
50 }
51
52 close(fd);
53
54 return len;
55}
56
57char *cg_name(const char *root, const char *name)
58{
59 size_t len = strlen(root) + strlen(name) + 2;
60 char *ret = malloc(len);
61
62 snprintf(ret, len, "%s/%s", root, name);
63
64 return ret;
65}
66
67char *cg_name_indexed(const char *root, const char *name, int index)
68{
69 size_t len = strlen(root) + strlen(name) + 10;
70 char *ret = malloc(len);
71
72 snprintf(ret, len, "%s/%s_%d", root, name, index);
73
74 return ret;
75}
76
77char *cg_control(const char *cgroup, const char *control)
78{
79 size_t len = strlen(cgroup) + strlen(control) + 2;
80 char *ret = malloc(len);
81
82 snprintf(ret, len, "%s/%s", cgroup, control);
83
84 return ret;
85}
86
87int cg_read(const char *cgroup, const char *control, char *buf, size_t len)
88{
89 char path[PATH_MAX];
90
91 snprintf(path, sizeof(path), "%s/%s", cgroup, control);
92
93 if (read_text(path, buf, len) >= 0)
94 return 0;
95
96 return -1;
97}
98
99int cg_read_strcmp(const char *cgroup, const char *control,
100 const char *expected)
101{
102 size_t size;
103 char *buf;
104 int ret;
105
106
107 if (!expected)
108 size = 32;
109 else
110 size = strlen(expected) + 1;
111
112 buf = malloc(size);
113 if (!buf)
114 return -1;
115
116 if (cg_read(cgroup, control, buf, size)) {
117 free(buf);
118 return -1;
119 }
120
121 ret = strcmp(expected, buf);
122 free(buf);
123 return ret;
124}
125
126int cg_read_strstr(const char *cgroup, const char *control, const char *needle)
127{
128 char buf[PAGE_SIZE];
129
130 if (cg_read(cgroup, control, buf, sizeof(buf)))
131 return -1;
132
133 return strstr(buf, needle) ? 0 : -1;
134}
135
136long cg_read_long(const char *cgroup, const char *control)
137{
138 char buf[128];
139
140 if (cg_read(cgroup, control, buf, sizeof(buf)))
141 return -1;
142
143 return atol(buf);
144}
145
146long cg_read_key_long(const char *cgroup, const char *control, const char *key)
147{
148 char buf[PAGE_SIZE];
149 char *ptr;
150
151 if (cg_read(cgroup, control, buf, sizeof(buf)))
152 return -1;
153
154 ptr = strstr(buf, key);
155 if (!ptr)
156 return -1;
157
158 return atol(ptr + strlen(key));
159}
160
161int cg_write(const char *cgroup, const char *control, char *buf)
162{
163 char path[PATH_MAX];
164 ssize_t len = strlen(buf);
165
166 snprintf(path, sizeof(path), "%s/%s", cgroup, control);
167
168 if (write_text(path, buf, len) == len)
169 return 0;
170
171 return -1;
172}
173
174int cg_find_unified_root(char *root, size_t len)
175{
176 char buf[10 * PAGE_SIZE];
177 char *fs, *mount, *type;
178 const char delim[] = "\n\t ";
179
180 if (read_text("/proc/self/mounts", buf, sizeof(buf)) <= 0)
181 return -1;
182
183
184
185
186
187 for (fs = strtok(buf, delim); fs; fs = strtok(NULL, delim)) {
188 mount = strtok(NULL, delim);
189 type = strtok(NULL, delim);
190 strtok(NULL, delim);
191 strtok(NULL, delim);
192 strtok(NULL, delim);
193
194 if (strcmp(type, "cgroup2") == 0) {
195 strncpy(root, mount, len);
196 return 0;
197 }
198 }
199
200 return -1;
201}
202
203int cg_create(const char *cgroup)
204{
205 return mkdir(cgroup, 0644);
206}
207
208int cg_wait_for_proc_count(const char *cgroup, int count)
209{
210 char buf[10 * PAGE_SIZE] = {0};
211 int attempts;
212 char *ptr;
213
214 for (attempts = 10; attempts >= 0; attempts--) {
215 int nr = 0;
216
217 if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf)))
218 break;
219
220 for (ptr = buf; *ptr; ptr++)
221 if (*ptr == '\n')
222 nr++;
223
224 if (nr >= count)
225 return 0;
226
227 usleep(100000);
228 }
229
230 return -1;
231}
232
233int cg_killall(const char *cgroup)
234{
235 char buf[PAGE_SIZE];
236 char *ptr = buf;
237
238 if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf)))
239 return -1;
240
241 while (ptr < buf + sizeof(buf)) {
242 int pid = strtol(ptr, &ptr, 10);
243
244 if (pid == 0)
245 break;
246 if (*ptr)
247 ptr++;
248 else
249 break;
250 if (kill(pid, SIGKILL))
251 return -1;
252 }
253
254 return 0;
255}
256
257int cg_destroy(const char *cgroup)
258{
259 int ret;
260
261retry:
262 ret = rmdir(cgroup);
263 if (ret && errno == EBUSY) {
264 cg_killall(cgroup);
265 usleep(100);
266 goto retry;
267 }
268
269 if (ret && errno == ENOENT)
270 ret = 0;
271
272 return ret;
273}
274
275int cg_enter(const char *cgroup, int pid)
276{
277 char pidbuf[64];
278
279 snprintf(pidbuf, sizeof(pidbuf), "%d", pid);
280 return cg_write(cgroup, "cgroup.procs", pidbuf);
281}
282
283int cg_enter_current(const char *cgroup)
284{
285 char pidbuf[64];
286
287 snprintf(pidbuf, sizeof(pidbuf), "%d", getpid());
288 return cg_write(cgroup, "cgroup.procs", pidbuf);
289}
290
291int cg_run(const char *cgroup,
292 int (*fn)(const char *cgroup, void *arg),
293 void *arg)
294{
295 int pid, retcode;
296
297 pid = fork();
298 if (pid < 0) {
299 return pid;
300 } else if (pid == 0) {
301 char buf[64];
302
303 snprintf(buf, sizeof(buf), "%d", getpid());
304 if (cg_write(cgroup, "cgroup.procs", buf))
305 exit(EXIT_FAILURE);
306 exit(fn(cgroup, arg));
307 } else {
308 waitpid(pid, &retcode, 0);
309 if (WIFEXITED(retcode))
310 return WEXITSTATUS(retcode);
311 else
312 return -1;
313 }
314}
315
316int cg_run_nowait(const char *cgroup,
317 int (*fn)(const char *cgroup, void *arg),
318 void *arg)
319{
320 int pid;
321
322 pid = fork();
323 if (pid == 0) {
324 char buf[64];
325
326 snprintf(buf, sizeof(buf), "%d", getpid());
327 if (cg_write(cgroup, "cgroup.procs", buf))
328 exit(EXIT_FAILURE);
329 exit(fn(cgroup, arg));
330 }
331
332 return pid;
333}
334
335int get_temp_fd(void)
336{
337 return open(".", O_TMPFILE | O_RDWR | O_EXCL);
338}
339
340int alloc_pagecache(int fd, size_t size)
341{
342 char buf[PAGE_SIZE];
343 struct stat st;
344 int i;
345
346 if (fstat(fd, &st))
347 goto cleanup;
348
349 size += st.st_size;
350
351 if (ftruncate(fd, size))
352 goto cleanup;
353
354 for (i = 0; i < size; i += sizeof(buf))
355 read(fd, buf, sizeof(buf));
356
357 return 0;
358
359cleanup:
360 return -1;
361}
362
363int alloc_anon(const char *cgroup, void *arg)
364{
365 size_t size = (unsigned long)arg;
366 char *buf, *ptr;
367
368 buf = malloc(size);
369 for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
370 *ptr = 0;
371
372 free(buf);
373 return 0;
374}
375
376int is_swap_enabled(void)
377{
378 char buf[PAGE_SIZE];
379 const char delim[] = "\n";
380 int cnt = 0;
381 char *line;
382
383 if (read_text("/proc/swaps", buf, sizeof(buf)) <= 0)
384 return -1;
385
386 for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
387 cnt++;
388
389 return cnt > 1;
390}
391
392int set_oom_adj_score(int pid, int score)
393{
394 char path[PATH_MAX];
395 int fd, len;
396
397 sprintf(path, "/proc/%d/oom_score_adj", pid);
398
399 fd = open(path, O_WRONLY | O_APPEND);
400 if (fd < 0)
401 return fd;
402
403 len = dprintf(fd, "%d", score);
404 if (len < 0) {
405 close(fd);
406 return len;
407 }
408
409 close(fd);
410 return 0;
411}
412
413char proc_read_text(int pid, const char *item, char *buf, size_t size)
414{
415 char path[PATH_MAX];
416
417 snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);
418
419 return read_text(path, buf, size);
420}
421
