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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <mntent.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include "env-util.h"
#include "exit-status.h"
#include "fstab-util.h"
#include "log.h"
#include "main-func.h"
#include "mount-setup.h"
#include "mount-util.h"
#include "path-util.h"
#include "process-util.h"
#include "signal-util.h"
#include "strv.h"
/* Goes through /etc/fstab and remounts all API file systems, applying options that are in /etc/fstab that systemd
* might not have respected */
static int track_pid(Hashmap **h, const char *path, pid_t pid) {
_cleanup_free_ char *c = NULL;
int r;
assert(h);
assert(path);
assert(pid_is_valid(pid));
c = strdup(path);
if (!c)
return log_oom();
r = hashmap_ensure_put(h, NULL, PID_TO_PTR(pid), c);
if (r == -ENOMEM)
return log_oom();
if (r < 0)
return log_error_errno(r, "Failed to store pid " PID_FMT, pid);
TAKE_PTR(c);
return 0;
}
static int do_remount(const char *path, bool force_rw, Hashmap **pids) {
pid_t pid;
int r;
log_debug("Remounting %s...", path);
r = safe_fork(force_rw ? "(remount-rw)" : "(remount)",
FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
if (r < 0)
return r;
if (r == 0) {
/* Child */
execv(MOUNT_PATH,
STRV_MAKE(MOUNT_PATH,
path,
"-o",
force_rw ? "remount,rw" : "remount"));
log_error_errno(errno, "Failed to execute " MOUNT_PATH ": %m");
_exit(EXIT_FAILURE);
}
/* Parent */
return track_pid(pids, path, pid);
}
static int remount_by_fstab(Hashmap **ret_pids) {
_cleanup_hashmap_free_free_ Hashmap *pids = NULL;
_cleanup_endmntent_ FILE *f = NULL;
bool has_root = false;
struct mntent* me;
int r;
assert(ret_pids);
if (!fstab_enabled())
return 0;
f = setmntent(fstab_path(), "re");
if (!f) {
if (errno != ENOENT)
return log_error_errno(errno, "Failed to open %s: %m", fstab_path());
return 0;
}
while ((me = getmntent(f))) {
/* Remount the root fs, /usr, and all API VFSs */
if (!mount_point_is_api(me->mnt_dir) &&
!PATH_IN_SET(me->mnt_dir, "/", "/usr"))
continue;
if (path_equal(me->mnt_dir, "/"))
has_root = true;
r = do_remount(me->mnt_dir, false, &pids);
if (r < 0)
return r;
}
*ret_pids = TAKE_PTR(pids);
return has_root;
}
static int run(int argc, char *argv[]) {
_cleanup_hashmap_free_free_ Hashmap *pids = NULL;
int r;
log_setup();
if (argc > 1)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"This program takes no arguments.");
umask(0022);
r = remount_by_fstab(&pids);
if (r < 0)
return r;
if (r == 0) {
/* The $SYSTEMD_REMOUNT_ROOT_RW environment variable is set by systemd-gpt-auto-generator to tell us
* whether to remount things. We honour it only if there's no explicit line in /etc/fstab configured
* which takes precedence. */
r = getenv_bool("SYSTEMD_REMOUNT_ROOT_RW");
if (r < 0 && r != -ENXIO)
log_warning_errno(r, "Failed to parse $SYSTEMD_REMOUNT_ROOT_RW, ignoring: %m");
if (r > 0) {
r = do_remount("/", true, &pids);
if (r < 0)
return r;
}
}
r = 0;
while (!hashmap_isempty(pids)) {
_cleanup_free_ char *s = NULL;
siginfo_t si = {};
if (waitid(P_ALL, 0, &si, WEXITED) < 0) {
if (errno == EINTR)
continue;
return log_error_errno(errno, "waitid() failed: %m");
}
s = hashmap_remove(pids, PID_TO_PTR(si.si_pid));
if (s &&
!is_clean_exit(si.si_code, si.si_status, EXIT_CLEAN_COMMAND, NULL)) {
if (si.si_code == CLD_EXITED)
log_error(MOUNT_PATH " for %s exited with exit status %i.", s, si.si_status);
else
log_error(MOUNT_PATH " for %s terminated by signal %s.", s, signal_to_string(si.si_status));
r = -ENOEXEC;
}
}
return r;
}
DEFINE_MAIN_FUNCTION(run);
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