13688105616

Committed 05 Mar 2025 11:59PM UTC coverage: 71.788% (-0.07%) from 71.855%

Build # 13688105616

Build Type

push

github

Committed by

yuwata

Commit Message

mkosi: update debian commit reference

* dfdab6b205 Install new files
* e00bee5b4a Install new files

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294781 of 410628 relevant lines covered (71.79%)

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54.84

/src/shared/async.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <errno.h>
#include <stddef.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <unistd.h>

#include "async.h"
#include "errno-util.h"
#include "fd-util.h"
#include "log.h"
#include "macro.h"
#include "process-util.h"
#include "signal-util.h"

int asynchronous_sync(PidRef *ret_pid) {
        int r;

        /* This forks off an invocation of fork() as a child process, in order to initiate synchronization to
         * disk. Note that we implement this as helper process rather than thread as we don't want the sync() to hang our
         * original process ever, and a thread would do that as the process can't exit with threads hanging in blocking
         * syscalls. */

        r = pidref_safe_fork("(sd-sync)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|(ret_pid ? 0 : FORK_DETACH), ret_pid);
        if (r < 0)
                return r;
        if (r == 0) {
                /* Child process */
                sync();
                _exit(EXIT_SUCCESS);
        }

        return 0;
}

int asynchronous_fsync(int fd, PidRef *ret_pid) {
        int r;

        assert(fd >= 0);
        /* Same as asynchronous_sync() above, but calls fsync() on a specific fd */

        r = pidref_safe_fork_full(
                        "(sd-fsync)",
                        /* stdio_fds= */ NULL,
                        /* except_fds= */ &fd,
                        /* n_except_fds= */ 1,
                        FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|(ret_pid ? 0 : FORK_DETACH),
                        ret_pid);
        if (r < 0)
                return r;
        if (r == 0) {
                /* Child process */
                (void) fsync(fd);
                _exit(EXIT_SUCCESS);
        }

        return 0;
}

/* We encode the fd to close in the userdata pointer as an unsigned value. The highest bit indicates whether
 * we need to fork again */
#define NEED_DOUBLE_FORK (1U << (sizeof(unsigned) * 8 - 1))

static int close_func(void *p) {
        unsigned v = PTR_TO_UINT(p);

        (void) prctl(PR_SET_NAME, (unsigned long*) "(sd-close)");

        /* Note: 💣 This function is invoked in a child process created via glibc's clone() wrapper. In such
         *       children memory allocation is not allowed, since glibc does not release malloc mutexes in
         *       clone() 💣 */

        if (v & NEED_DOUBLE_FORK) {
                pid_t pid;

                v &= ~NEED_DOUBLE_FORK;

                /* This inner child will be reparented to the subreaper/PID 1. Here we turn on SIGCHLD, so
                 * that the reaper knows when it's time to reap. */
                pid = clone_with_nested_stack(close_func, SIGCHLD|CLONE_FILES, UINT_TO_PTR(v));
                if (pid >= 0)
                        return 0;
        }

        close((int) v); /* no assert() here, we are in the child and the result would be eaten up anyway */
        return 0;
}

int asynchronous_close(int fd) {
        unsigned v;
        pid_t pid;
        int r;

        /* This is supposed to behave similar to safe_close(), but actually invoke close() asynchronously, so
         * that it will never block. Ideally the kernel would have an API for this, but it doesn't, so we
         * work around it, and hide this as a far away as we can.
         *
         * It is important to us that we don't use threads (via glibc pthread) in PID 1, hence we'll do a
         * minimal subprocess instead which shares our fd table via CLONE_FILES. */

        if (fd < 0)
                return -EBADF; /* already invalid */

        PROTECT_ERRNO;

        v = (unsigned) fd;

        /* We want to fork off a process that is automatically reaped. For that we'd usually double-fork. But
         * we can optimize this a bit: if we are PID 1 or a subreaper anyway (the systemd service manager
         * process qualifies as this), we can avoid the double forking, since the double forked process would
         * be reparented back to us anyway. */
        r = is_reaper_process();
        if (r < 0)
                log_debug_errno(r, "Cannot determine if we are a reaper process, assuming we are not: %m");
        if (r <= 0)
                v |= NEED_DOUBLE_FORK;

        pid = clone_with_nested_stack(close_func, CLONE_FILES | ((v & NEED_DOUBLE_FORK) ? 0 : SIGCHLD), UINT_TO_PTR(v));
        if (pid < 0)
                safe_close(fd); /* local fallback */
        else if (v & NEED_DOUBLE_FORK) {

                /* Reap the intermediate child. Key here is that we specify __WCLONE, since we didn't ask for
                 * any signal to be sent to us on process exit, and otherwise waitid() would refuse waiting
                 * then.
                 *
                 * We usually prefer calling waitid(), but before kernel 4.7 it didn't support __WCLONE while
                 * waitpid() did. Hence let's use waitpid() here, it's good enough for our purposes here. */
                for (;;)
                        if (waitpid(pid, NULL, __WCLONE) >= 0 || errno != EINTR)
                                break;
        }

        return -EBADF; /* return an invalidated fd */
}

void asynchronous_close_many(const int fds[], size_t n_fds) {
        assert(fds || n_fds == 0);

        FOREACH_ARRAY(i, fds, n_fds)
                asynchronous_close(*i);
}

int asynchronous_rm_rf(const char *p, RemoveFlags flags) {
        int r;

        assert(p);

        /* Forks off a child that destroys the specified path. This will be best effort only, i.e. the child
         * will attempt to do its thing, but we won't wait for it or check its success. */

        r = safe_fork("(sd-rmrf)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DETACH, NULL);
        if (r != 0)
                return r;

        /* Child */

        /* Let's block SIGTERM here, to grant the operation more time on e.g. final killing spree
         * during shutdown. If this gets stalled pid1 would eventually send SIGKILL to us. */
        BLOCK_SIGNALS(SIGTERM);

        r = rm_rf(p, flags);
        if (r < 0) {
                log_debug_errno(r, "Failed to rm -rf '%s', ignoring: %m", p);
                _exit(EXIT_FAILURE); /* This is a detached process, hence no one really cares, but who knows
                                      * maybe it's good for debugging/tracing to return an exit code
                                      * indicative of our failure here. */
        }

        _exit(EXIT_SUCCESS);
}

1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3	#include <errno.h>
4	#include <stddef.h>
5	#include <sys/prctl.h>
6	#include <sys/wait.h>
7	#include <unistd.h>
8
9	#include "async.h"
10	#include "errno-util.h"
11	#include "fd-util.h"
12	#include "log.h"
13	#include "macro.h"
14	#include "process-util.h"
15	#include "signal-util.h"
16
17	int asynchronous_sync(PidRef *ret_pid) {	4✔
18	int r;	4✔
19
20	/* This forks off an invocation of fork() as a child process, in order to initiate synchronization to
21	* disk. Note that we implement this as helper process rather than thread as we don't want the sync() to hang our
22	* original process ever, and a thread would do that as the process can't exit with threads hanging in blocking
23	* syscalls. */
24
25	r = pidref_safe_fork("(sd-sync)", FORK_RESET_SIGNALS\|FORK_CLOSE_ALL_FDS\|(ret_pid ? 0 : FORK_DETACH), ret_pid);	4✔
26	if (r < 0)	69✔
27	return r;
28	if (r == 0) {	69✔
29	/* Child process */
30	sync();	65✔
31	_exit(EXIT_SUCCESS);	65✔
32	}
33
34	return 0;
35	}
36
37	int asynchronous_fsync(int fd, PidRef *ret_pid) {	×
38	int r;	×
39
40	assert(fd >= 0);	×
41	/* Same as asynchronous_sync() above, but calls fsync() on a specific fd */
42
43	r = pidref_safe_fork_full(	×
44	"(sd-fsync)",
45	/* stdio_fds= */ NULL,
46	/* except_fds= */ &fd,
47	/* n_except_fds= */ 1,
48	FORK_RESET_SIGNALS\|FORK_CLOSE_ALL_FDS\|(ret_pid ? 0 : FORK_DETACH),
49	ret_pid);
50	if (r < 0)	×
51	return r;
52	if (r == 0) {	×
53	/* Child process */
54	(void) fsync(fd);	×
55	_exit(EXIT_SUCCESS);	×
56	}
57
58	return 0;
59	}
60
61	/* We encode the fd to close in the userdata pointer as an unsigned value. The highest bit indicates whether
62	* we need to fork again */
63	#define NEED_DOUBLE_FORK (1U << (sizeof(unsigned) * 8 - 1))
64
65	static int close_func(void *p) {	×
66	unsigned v = PTR_TO_UINT(p);	×
67
68	(void) prctl(PR_SET_NAME, (unsigned long*) "(sd-close)");	×
69
70	/* Note: 💣 This function is invoked in a child process created via glibc's clone() wrapper. In such
71	* children memory allocation is not allowed, since glibc does not release malloc mutexes in
72	* clone() 💣 */
73
74	if (v & NEED_DOUBLE_FORK) {	×
75	pid_t pid;	×
76
77	v &= ~NEED_DOUBLE_FORK;	×
78
79	/* This inner child will be reparented to the subreaper/PID 1. Here we turn on SIGCHLD, so
80	* that the reaper knows when it's time to reap. */
81	pid = clone_with_nested_stack(close_func, SIGCHLD\|CLONE_FILES, UINT_TO_PTR(v));	×
82	if (pid >= 0)	×
83	return 0;
84	}
85
86	close((int) v); /* no assert() here, we are in the child and the result would be eaten up anyway */	×
87	return 0;	×
88	}
89
90	int asynchronous_close(int fd) {	9,292✔
91	unsigned v;	9,292✔
92	pid_t pid;	9,292✔
93	int r;	9,292✔
94
95	/* This is supposed to behave similar to safe_close(), but actually invoke close() asynchronously, so
96	* that it will never block. Ideally the kernel would have an API for this, but it doesn't, so we
97	* work around it, and hide this as a far away as we can.
98	*
99	* It is important to us that we don't use threads (via glibc pthread) in PID 1, hence we'll do a
100	* minimal subprocess instead which shares our fd table via CLONE_FILES. */
101
102	if (fd < 0)	9,292✔
103	return -EBADF; /* already invalid */	9,292✔
104
105	PROTECT_ERRNO;	×
106
107	v = (unsigned) fd;	4,502✔
108
109	/* We want to fork off a process that is automatically reaped. For that we'd usually double-fork. But
110	* we can optimize this a bit: if we are PID 1 or a subreaper anyway (the systemd service manager
111	* process qualifies as this), we can avoid the double forking, since the double forked process would
112	* be reparented back to us anyway. */
113	r = is_reaper_process();	4,502✔
114	if (r < 0)	4,502✔
115	log_debug_errno(r, "Cannot determine if we are a reaper process, assuming we are not: %m");	×
116	if (r <= 0)	4,502✔
117	v \|= NEED_DOUBLE_FORK;	152✔
118
119	pid = clone_with_nested_stack(close_func, CLONE_FILES \| ((v & NEED_DOUBLE_FORK) ? 0 : SIGCHLD), UINT_TO_PTR(v));	4,502✔
120	if (pid < 0)	4,502✔
121	safe_close(fd); /* local fallback */	×
122	else if (v & NEED_DOUBLE_FORK) {	4,502✔
123
124	/* Reap the intermediate child. Key here is that we specify __WCLONE, since we didn't ask for
125	* any signal to be sent to us on process exit, and otherwise waitid() would refuse waiting
126	* then.
127	*
128	* We usually prefer calling waitid(), but before kernel 4.7 it didn't support __WCLONE while
129	* waitpid() did. Hence let's use waitpid() here, it's good enough for our purposes here. */
130	for (;;)	152✔
131	if (waitpid(pid, NULL, __WCLONE) >= 0 \|\| errno != EINTR)	152✔
132	break;
133	}
134
135	return -EBADF; /* return an invalidated fd */	4,502✔
136	}
137
138	void asynchronous_close_many(const int fds[], size_t n_fds) {	×
139	assert(fds \|\| n_fds == 0);	×
140
141	FOREACH_ARRAY(i, fds, n_fds)	×
142	asynchronous_close(*i);	×
143	}	×
144
145	int asynchronous_rm_rf(const char *p, RemoveFlags flags) {	188✔
146	int r;	188✔
147
148	assert(p);	188✔
149
150	/* Forks off a child that destroys the specified path. This will be best effort only, i.e. the child
151	* will attempt to do its thing, but we won't wait for it or check its success. */
152
153	r = safe_fork("(sd-rmrf)", FORK_RESET_SIGNALS\|FORK_CLOSE_ALL_FDS\|FORK_DETACH, NULL);	188✔
154	if (r != 0)	1,415✔
155	return r;	188✔
156
157	/* Child */
158
159	/* Let's block SIGTERM here, to grant the operation more time on e.g. final killing spree
160	* during shutdown. If this gets stalled pid1 would eventually send SIGKILL to us. */
161	BLOCK_SIGNALS(SIGTERM);	1,227✔
162
163	r = rm_rf(p, flags);	1,227✔
164	if (r < 0) {	1,227✔
165	log_debug_errno(r, "Failed to rm -rf '%s', ignoring: %m", p);	×
166	_exit(EXIT_FAILURE); /* This is a detached process, hence no one really cares, but who knows	×
167	* maybe it's good for debugging/tracing to return an exit code
168	* indicative of our failure here. */
169	}
170
171	_exit(EXIT_SUCCESS);	1,227✔
172	}

systemd / systemd / 13688105616

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