Bug Summary

File:build-scan/../src/shared/machine-pool.c
Warning:line 314, column 17
Value stored to 'loop' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-unknown-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name machine-pool.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -menable-no-infs -menable-no-nans -menable-unsafe-fp-math -fno-signed-zeros -mreassociate -freciprocal-math -fdenormal-fp-math=preserve-sign,preserve-sign -ffp-contract=fast -fno-rounding-math -ffast-math -ffinite-math-only -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -resource-dir /usr/lib64/clang/12.0.0 -include config.h -I src/shared/libsystemd-shared-239.a.p -I src/shared -I ../src/shared -I src/basic -I ../src/basic -I src/systemd -I ../src/systemd -I src/journal -I ../src/journal -I src/journal-remote -I ../src/journal-remote -I src/nspawn -I ../src/nspawn -I src/resolve -I ../src/resolve -I src/timesync -I ../src/timesync -I ../src/time-wait-sync -I src/login -I ../src/login -I src/udev -I ../src/udev -I src/libudev -I ../src/libudev -I src/core -I ../src/core -I ../src/libsystemd/sd-bus -I ../src/libsystemd/sd-device -I ../src/libsystemd/sd-hwdb -I ../src/libsystemd/sd-id128 -I ../src/libsystemd/sd-netlink -I ../src/libsystemd/sd-network -I src/libsystemd-network -I ../src/libsystemd-network -I . -I .. -I /usr/include/blkid -D _FILE_OFFSET_BITS=64 -internal-isystem /usr/local/include -internal-isystem /usr/lib64/clang/12.0.0/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wwrite-strings -Wno-unused-parameter -Wno-missing-field-initializers -Wno-unused-result -Wno-format-signedness -Wno-error=nonnull -std=gnu99 -fconst-strings -fdebug-compilation-dir /home/mrc0mmand/repos/@redhat-plumbers/systemd-rhel8/build-scan -ferror-limit 19 -fvisibility default -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -analyzer-output=html -faddrsig -o /tmp/scan-build-2021-07-16-221226-1465241-1 -x c ../src/shared/machine-pool.c
1/* SPDX-License-Identifier: LGPL-2.1+ */
2
3#include <errno(*__errno_location ()).h>
4#include <fcntl.h>
5#include <linux1/loop.h>
6#include <signal.h>
7#include <stdbool.h>
8#include <stdio.h>
9#include <stdlib.h>
10#include <sys/file.h>
11#include <sys/ioctl.h>
12#include <sys/mount.h>
13#include <sys/prctl.h>
14#include <sys/stat.h>
15#include <sys/statfs.h>
16#include <sys/statvfs.h>
17#include <unistd.h>
18
19#include "sd-bus-protocol.h"
20#include "sd-bus.h"
21
22#include "alloc-util.h"
23#include "btrfs-util.h"
24#include "fd-util.h"
25#include "fileio.h"
26#include "fs-util.h"
27#include "label.h"
28#include "lockfile-util.h"
29#include "log.h"
30#include "machine-pool.h"
31#include "macro.h"
32#include "missing.h"
33#include "mkdir.h"
34#include "mount-util.h"
35#include "parse-util.h"
36#include "path-util.h"
37#include "process-util.h"
38#include "signal-util.h"
39#include "stat-util.h"
40#include "string-util.h"
41
42#define VAR_LIB_MACHINES_SIZE_START(1024UL*1024UL*500UL) (1024UL*1024UL*500UL)
43#define VAR_LIB_MACHINES_FREE_MIN(1024UL*1024UL*750UL) (1024UL*1024UL*750UL)
44
45static int check_btrfs(void) {
46 struct statfs sfs;
47
48 if (statfs("/var/lib/machines", &sfs) < 0) {
49 if (errno(*__errno_location ()) != ENOENT2)
50 return -errno(*__errno_location ());
51
52 if (statfs("/var/lib", &sfs) < 0)
53 return -errno(*__errno_location ());
54 }
55
56 return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)(sfs.f_type == (typeof(sfs.f_type)) 0x9123683E);
57}
58
59static int setup_machine_raw(uint64_t size, sd_bus_error *error) {
60 _cleanup_free___attribute__((cleanup(freep))) char *tmp = NULL((void*)0);
61 _cleanup_close___attribute__((cleanup(closep))) int fd = -1;
62 struct statvfs ss;
63 pid_t pid = 0;
64 int r;
65
66 /* We want to be able to make use of btrfs-specific file
67 * system features, in particular subvolumes, reflinks and
68 * quota. Hence, if we detect that /var/lib/machines.raw is
69 * not located on btrfs, let's create a loopback file, place a
70 * btrfs file system into it, and mount it to
71 * /var/lib/machines. */
72
73 fd = open("/var/lib/machines.raw", O_RDWR02|O_CLOEXEC02000000|O_NONBLOCK04000|O_NOCTTY0400);
74 if (fd >= 0)
75 return TAKE_FD(fd)({ int _fd_ = (fd); (fd) = -1; _fd_; });
76
77 if (errno(*__errno_location ()) != ENOENT2)
78 return sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to open /var/lib/machines.raw: %m");
79
80 r = tempfn_xxxxxx("/var/lib/machines.raw", NULL((void*)0), &tmp);
81 if (r < 0)
82 return r;
83
84 (void) mkdir_p_label("/var/lib", 0755);
85 fd = open(tmp, O_RDWR02|O_CREAT0100|O_EXCL0200|O_NOCTTY0400|O_CLOEXEC02000000, 0600);
86 if (fd < 0)
87 return sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to create /var/lib/machines.raw: %m");
88
89 if (fstatvfs(fd, &ss) < 0) {
90 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to determine free space on /var/lib/machines.raw: %m");
91 goto fail;
92 }
93
94 if (ss.f_bsize * ss.f_bavail < VAR_LIB_MACHINES_FREE_MIN(1024UL*1024UL*750UL)) {
95 r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED"org.freedesktop.DBus.Error.Failed", "Not enough free disk space to set up /var/lib/machines.");
96 goto fail;
97 }
98
99 if (ftruncate(fd, size) < 0) {
100 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to enlarge /var/lib/machines.raw: %m");
101 goto fail;
102 }
103
104 r = safe_fork("(mkfs)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &pid);
105 if (r < 0) {
106 sd_bus_error_set_errnof(error, r, "Failed to fork mkfs.btrfs: %m");
107 goto fail;
108 }
109 if (r == 0) {
110
111 /* Child */
112
113 fd = safe_close(fd);
114
115 execlp("mkfs.btrfs", "-Lvar-lib-machines", tmp, NULL((void*)0));
116 if (errno(*__errno_location ()) == ENOENT2)
117 _exit(99);
118
119 _exit(EXIT_FAILURE1);
120 }
121
122 r = wait_for_terminate_and_check("mkfs", pid, 0);
123 pid = 0;
124
125 if (r < 0) {
126 sd_bus_error_set_errnof(error, r, "Failed to wait for mkfs.btrfs: %m");
127 goto fail;
128 }
129 if (r == 99) {
130 r = sd_bus_error_set_errnof(error, ENOENT2, "Cannot set up /var/lib/machines, mkfs.btrfs is missing");
131 goto fail;
132 }
133 if (r != EXIT_SUCCESS0) {
134 r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED"org.freedesktop.DBus.Error.Failed", "mkfs.btrfs failed with error code %i", r);
135 goto fail;
136 }
137
138 r = rename_noreplace(AT_FDCWD-100, tmp, AT_FDCWD-100, "/var/lib/machines.raw");
139 if (r < 0) {
140 sd_bus_error_set_errnof(error, r, "Failed to move /var/lib/machines.raw into place: %m");
141 goto fail;
142 }
143
144 return TAKE_FD(fd)({ int _fd_ = (fd); (fd) = -1; _fd_; });
145
146fail:
147 unlink_noerrno(tmp);
148
149 if (pid > 1)
150 kill_and_sigcont(pid, SIGKILL9);
151
152 return r;
153}
154
155int setup_machine_directory(uint64_t size, sd_bus_error *error) {
156 _cleanup_(release_lock_file)__attribute__((cleanup(release_lock_file))) LockFile lock_file = LOCK_FILE_INIT{ .fd = -1, .path = ((void*)0) };
157 struct loop_info64 info = {
158 .lo_flags = LO_FLAGS_AUTOCLEAR,
159 };
160 _cleanup_close___attribute__((cleanup(closep))) int fd = -1, control = -1, loop = -1;
161 _cleanup_free___attribute__((cleanup(freep))) char* loopdev = NULL((void*)0);
162 char tmpdir[] = "/tmp/machine-pool.XXXXXX", *mntdir = NULL((void*)0);
163 bool_Bool tmpdir_made = false0, mntdir_made = false0, mntdir_mounted = false0;
164 char buf[FORMAT_BYTES_MAX8];
165 int r, nr = -1;
166
167 /* btrfs cannot handle file systems < 16M, hence use this as minimum */
168 if (size == (uint64_t) -1)
169 size = VAR_LIB_MACHINES_SIZE_START(1024UL*1024UL*500UL);
170 else if (size < 16*1024*1024)
171 size = 16*1024*1024;
172
173 /* Make sure we only set the directory up once at a time */
174 r = make_lock_file("/run/systemd/machines.lock", LOCK_EX2, &lock_file);
175 if (r < 0)
176 return r;
177
178 r = check_btrfs();
179 if (r < 0)
180 return sd_bus_error_set_errnof(error, r, "Failed to determine whether /var/lib/machines is located on btrfs: %m");
181 if (r > 0) {
182 (void) btrfs_subvol_make_label("/var/lib/machines");
183
184 r = btrfs_quota_enable("/var/lib/machines", true1);
185 if (r < 0)
186 log_warning_errno(r, "Failed to enable quota for /var/lib/machines, ignoring: %m")({ int _level = ((4)), _e = ((r)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 186, __func__, "Failed to enable quota for /var/lib/machines, ignoring: %m"
) : -abs(_e); });
187
188 r = btrfs_subvol_auto_qgroup("/var/lib/machines", 0, true1);
189 if (r < 0)
190 log_warning_errno(r, "Failed to set up default quota hierarchy for /var/lib/machines, ignoring: %m")({ int _level = ((4)), _e = ((r)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 190, __func__, "Failed to set up default quota hierarchy for /var/lib/machines, ignoring: %m"
) : -abs(_e); });
191
192 return 1;
193 }
194
195 if (path_is_mount_point("/var/lib/machines", NULL((void*)0), AT_SYMLINK_FOLLOW0x400) > 0) {
196 log_debug("/var/lib/machines is already a mount point, not creating loopback file for it.")({ int _level = (((7))), _e = ((0)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 196, __func__, "/var/lib/machines is already a mount point, not creating loopback file for it."
) : -abs(_e); });
197 return 0;
198 }
199
200 r = dir_is_populated("/var/lib/machines");
201 if (r < 0 && r != -ENOENT2)
202 return r;
203 if (r > 0) {
204 log_debug("/var/log/machines is already populated, not creating loopback file for it.")({ int _level = (((7))), _e = ((0)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 204, __func__, "/var/log/machines is already populated, not creating loopback file for it."
) : -abs(_e); });
205 return 0;
206 }
207
208 r = mkfs_exists("btrfs");
209 if (r == 0)
210 return sd_bus_error_set_errnof(error, ENOENT2, "Cannot set up /var/lib/machines, mkfs.btrfs is missing");
211 if (r < 0)
212 return r;
213
214 fd = setup_machine_raw(size, error);
215 if (fd < 0)
216 return fd;
217
218 control = open("/dev/loop-control", O_RDWR02|O_CLOEXEC02000000|O_NOCTTY0400|O_NONBLOCK04000);
219 if (control < 0)
220 return sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to open /dev/loop-control: %m");
221
222 nr = ioctl(control, LOOP_CTL_GET_FREE0x4C82);
223 if (nr < 0)
224 return sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to allocate loop device: %m");
225
226 if (asprintf(&loopdev, "/dev/loop%i", nr) < 0) {
227 r = -ENOMEM12;
228 goto fail;
229 }
230
231 loop = open(loopdev, O_CLOEXEC02000000|O_RDWR02|O_NOCTTY0400|O_NONBLOCK04000);
232 if (loop < 0) {
233 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to open loopback device: %m");
234 goto fail;
235 }
236
237 if (ioctl(loop, LOOP_SET_FD0x4C00, fd) < 0) {
238 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to bind loopback device: %m");
239 goto fail;
240 }
241
242 if (ioctl(loop, LOOP_SET_STATUS640x4C04, &info) < 0) {
243 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to enable auto-clear for loopback device: %m");
244 goto fail;
245 }
246
247 /* We need to make sure the new /var/lib/machines directory
248 * has an access mode of 0700 at the time it is first made
249 * available. mkfs will create it with 0755 however. Hence,
250 * let's mount the directory into an inaccessible directory
251 * below /tmp first, fix the access mode, and move it to the
252 * public place then. */
253
254 if (!mkdtemp(tmpdir)) {
255 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to create temporary mount parent directory: %m");
256 goto fail;
257 }
258 tmpdir_made = true1;
259
260 mntdir = strjoina(tmpdir, "/mnt")({ const char *_appendees_[] = { tmpdir, "/mnt" }; char *_d_,
*_p_; size_t _len_ = 0; size_t _i_; for (_i_ = 0; _i_ < __extension__
(__builtin_choose_expr( !__builtin_types_compatible_p(typeof
(_appendees_), typeof(&*(_appendees_))), sizeof(_appendees_
)/sizeof((_appendees_)[0]), ((void)0))) && _appendees_
[_i_]; _i_++) _len_ += strlen(_appendees_[_i_]); _p_ = _d_ = __builtin_alloca
(_len_ + 1); for (_i_ = 0; _i_ < __extension__ (__builtin_choose_expr
( !__builtin_types_compatible_p(typeof(_appendees_), typeof(&
*(_appendees_))), sizeof(_appendees_)/sizeof((_appendees_)[0]
), ((void)0))) && _appendees_[_i_]; _i_++) _p_ = stpcpy
(_p_, _appendees_[_i_]); *_p_ = 0; _d_; });
261 if (mkdir(mntdir, 0700) < 0) {
262 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to create temporary mount directory: %m");
263 goto fail;
264 }
265 mntdir_made = true1;
266
267 if (mount(loopdev, mntdir, "btrfs", 0, NULL((void*)0)) < 0) {
268 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to mount loopback device: %m");
269 goto fail;
270 }
271 mntdir_mounted = true1;
272
273 r = btrfs_quota_enable(mntdir, true1);
274 if (r < 0)
275 log_warning_errno(r, "Failed to enable quota, ignoring: %m")({ int _level = ((4)), _e = ((r)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 275, __func__, "Failed to enable quota, ignoring: %m"
) : -abs(_e); });
276
277 r = btrfs_subvol_auto_qgroup(mntdir, 0, true1);
278 if (r < 0)
279 log_warning_errno(r, "Failed to set up default quota hierarchy, ignoring: %m")({ int _level = ((4)), _e = ((r)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 279, __func__, "Failed to set up default quota hierarchy, ignoring: %m"
) : -abs(_e); });
280
281 if (chmod(mntdir, 0700) < 0) {
282 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to fix owner: %m");
283 goto fail;
284 }
285
286 (void) mkdir_p_label("/var/lib/machines", 0700);
287
288 if (mount(mntdir, "/var/lib/machines", NULL((void*)0), MS_BINDMS_BIND, NULL((void*)0)) < 0) {
289 r = sd_bus_error_set_errnof(error, errno(*__errno_location ()), "Failed to mount directory into right place: %m");
290 goto fail;
291 }
292
293 (void) syncfs(fd);
294
295 log_info("Set up /var/lib/machines as btrfs loopback file system of size %s mounted on /var/lib/machines.raw.", format_bytes(buf, sizeof(buf), size))({ int _level = (((6))), _e = ((0)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 295, __func__, "Set up /var/lib/machines as btrfs loopback file system of size %s mounted on /var/lib/machines.raw."
, format_bytes(buf, sizeof(buf), size)) : -abs(_e); });
296
297 (void) umount2(mntdir, MNT_DETACHMNT_DETACH);
298 (void) rmdir(mntdir);
299 (void) rmdir(tmpdir);
300
301 return 1;
302
303fail:
304 if (mntdir_mounted)
305 (void) umount2(mntdir, MNT_DETACHMNT_DETACH);
306
307 if (mntdir_made)
308 (void) rmdir(mntdir);
309 if (tmpdir_made)
310 (void) rmdir(tmpdir);
311
312 if (loop >= 0) {
313 (void) ioctl(loop, LOOP_CLR_FD0x4C01);
314 loop = safe_close(loop);
Value stored to 'loop' is never read
315 }
316
317 if (control >= 0 && nr >= 0)
318 (void) ioctl(control, LOOP_CTL_REMOVE0x4C81, nr);
319
320 return r;
321}
322
323static int sync_path(const char *p) {
324 _cleanup_close___attribute__((cleanup(closep))) int fd = -1;
325
326 fd = open(p, O_RDONLY00|O_CLOEXEC02000000|O_NOCTTY0400);
327 if (fd < 0)
328 return -errno(*__errno_location ());
329
330 if (syncfs(fd) < 0)
331 return -errno(*__errno_location ());
332
333 return 0;
334}
335
336int grow_machine_directory(void) {
337 char buf[FORMAT_BYTES_MAX8];
338 struct statvfs a, b;
339 uint64_t old_size, new_size, max_add;
340 int r;
341
342 /* Ensure the disk space data is accurate */
343 sync_path("/var/lib/machines");
344 sync_path("/var/lib/machines.raw");
345
346 if (statvfs("/var/lib/machines.raw", &a) < 0)
347 return -errno(*__errno_location ());
348
349 if (statvfs("/var/lib/machines", &b) < 0)
350 return -errno(*__errno_location ());
351
352 /* Don't grow if not enough disk space is available on the host */
353 if (((uint64_t) a.f_bavail * (uint64_t) a.f_bsize) <= VAR_LIB_MACHINES_FREE_MIN(1024UL*1024UL*750UL))
354 return 0;
355
356 /* Don't grow if at least 1/3th of the fs is still free */
357 if (b.f_bavail > b.f_blocks / 3)
358 return 0;
359
360 /* Calculate how much we are willing to add at most */
361 max_add = ((uint64_t) a.f_bavail * (uint64_t) a.f_bsize) - VAR_LIB_MACHINES_FREE_MIN(1024UL*1024UL*750UL);
362
363 /* Calculate the old size */
364 old_size = (uint64_t) b.f_blocks * (uint64_t) b.f_bsize;
365
366 /* Calculate the new size as three times the size of what is used right now */
367 new_size = ((uint64_t) b.f_blocks - (uint64_t) b.f_bavail) * (uint64_t) b.f_bsize * 3;
368
369 /* Always, grow at least to the start size */
370 if (new_size < VAR_LIB_MACHINES_SIZE_START(1024UL*1024UL*500UL))
371 new_size = VAR_LIB_MACHINES_SIZE_START(1024UL*1024UL*500UL);
372
373 /* If the new size is smaller than the old size, don't grow */
374 if (new_size < old_size)
375 return 0;
376
377 /* Ensure we never add more than the maximum */
378 if (new_size > old_size + max_add)
379 new_size = old_size + max_add;
380
381 r = btrfs_resize_loopback("/var/lib/machines", new_size, true1);
382 if (r <= 0)
383 return r;
384
385 /* Also bump the quota, of both the subvolume leaf qgroup, as
386 * well as of any subtree quota group by the same id but a
387 * higher level, if it exists. */
388 (void) btrfs_qgroup_set_limit("/var/lib/machines", 0, new_size);
389 (void) btrfs_subvol_set_subtree_quota_limit("/var/lib/machines", 0, new_size);
390
391 log_info("Grew /var/lib/machines btrfs loopback file system to %s.", format_bytes(buf, sizeof(buf), new_size))({ int _level = (((6))), _e = ((0)), _realm = (LOG_REALM_SYSTEMD
); (log_get_max_level_realm(_realm) >= ((_level) & 0x07
)) ? log_internal_realm(((_realm) << 10 | (_level)), _e
, "../src/shared/machine-pool.c", 391, __func__, "Grew /var/lib/machines btrfs loopback file system to %s."
, format_bytes(buf, sizeof(buf), new_size)) : -abs(_e); });
392 return 1;
393}