1 files changed, 306 insertions, 0 deletions
diff --git a/src/udev/udevadm-lock.c b/src/udev/udevadm-lock.c
new file mode 100644
index 0000000..bc2d5e7
--- /dev/null
+++ b/src/udev/udevadm-lock.c
@@ -0,0 +1,306 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <getopt.h>
+#include <stdlib.h>
+#include <sys/file.h>
+#include <unistd.h>
+
+#include "blockdev-util.h"
+#include "btrfs-util.h"
+#include "device-util.h"
+#include "fd-util.h"
+#include "fdset.h"
+#include "lock-util.h"
+#include "main-func.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "pretty-print.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "sort-util.h"
+#include "strv.h"
+#include "time-util.h"
+#include "udevadm.h"
+
+static usec_t arg_timeout_usec = USEC_INFINITY;
+static char **arg_devices = NULL;
+static char **arg_backing = NULL;
+static char **arg_cmdline = NULL;
+static bool arg_print = false;
+
+STATIC_DESTRUCTOR_REGISTER(arg_devices, strv_freep);
+STATIC_DESTRUCTOR_REGISTER(arg_backing, strv_freep);
+STATIC_DESTRUCTOR_REGISTER(arg_cmdline, strv_freep);
+
+static int help(void) {
+        _cleanup_free_ char *link = NULL;
+        int r;
+
+        r = terminal_urlify_man("udevadm", "8", &link);
+        if (r < 0)
+                return log_oom();
+
+        printf("%s [OPTIONS...] COMMAND\n"
+               "%s [OPTIONS...] --print\n"
+               "\n%sLock a block device and run a command.%s\n\n"
+               "  -h --help            Print this message\n"
+               "  -V --version         Print version of the program\n"
+               "  -d --device=DEVICE   Block device to lock\n"
+               "  -b --backing=FILE    File whose backing block device to lock\n"
+               "  -t --timeout=SECS    Block at most the specified time waiting for lock\n"
+               "  -p --print           Only show which block device the lock would be taken on\n"
+               "\nSee the %s for details.\n",
+               program_invocation_short_name,
+               program_invocation_short_name,
+               ansi_highlight(),
+               ansi_normal(),
+               link);
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        static const struct option options[] = {
+                { "help",    no_argument,       NULL, 'h'      },
+                { "version", no_argument,       NULL, 'V'      },
+                { "device",  required_argument, NULL, 'd'      },
+                { "backing", required_argument, NULL, 'b'      },
+                { "timeout", required_argument, NULL, 't'      },
+                { "print",   no_argument,       NULL, 'p'      },
+                {}
+        };
+
+        int c, r;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        /* Resetting to 0 forces the invocation of an internal initialization routine of getopt_long()
+         * that checks for GNU extensions in optstring ('-' or '+' at the beginning). */
+        optind = 0;
+        while ((c = getopt_long(argc, argv, arg_print ? "hVd:b:t:p" : "+hVd:b:t:p", options, NULL)) >= 0)
+
+                switch (c) {
+
+                case 'h':
+                        return help();
+
+                case 'V':
+                        return print_version();
+
+                case 'd':
+                case 'b': {
+                        _cleanup_free_ char *s = NULL;
+                        char ***l = c == 'd' ? &arg_devices : &arg_backing;
+
+                        r = path_make_absolute_cwd(optarg, &s);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to make path '%s' absolute: %m", optarg);
+
+                        path_simplify(s);
+
+                        if (strv_consume(l, TAKE_PTR(s)) < 0)
+                                return log_oom();
+
+                        strv_uniq(*l);
+                        break;
+                }
+
+                case 't':
+                        r = parse_sec(optarg, &arg_timeout_usec);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse --timeout= parameter: %s", optarg);
+                        break;
+
+                case 'p':
+                        arg_print = true;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached();
+                }
+
+        if (arg_print) {
+                if (optind != argc)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No arguments expected");
+        } else {
+                if (optind + 1 > argc)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Too few arguments, command to execute.");
+
+                arg_cmdline = strv_copy(argv + optind);
+                if (!arg_cmdline)
+                        return log_oom();
+        }
+
+        if (strv_isempty(arg_devices) && strv_isempty(arg_backing))
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No devices to lock specified, refusing.");
+
+        return 1;
+}
+
+static int find_devno(
+                dev_t **devnos,
+                size_t *n_devnos,
+                const char *device,
+                bool backing) {
+
+        dev_t devt;
+        int r;
+
+        assert(devnos);
+        assert(n_devnos);
+        assert(*devnos || *n_devnos == 0);
+        assert(device);
+
+        r = path_get_whole_disk(device, backing, &devt);
+        if (r < 0)
+                return log_error_errno(r, "Failed to find whole block device for '%s': %m", device);
+
+        if (typesafe_bsearch(&devt, *devnos, *n_devnos, devt_compare_func)) {
+                log_debug("Device %u:%u already listed for locking, ignoring.", major(devt), minor(devt));
+                return 0;
+        }
+
+        if (!GREEDY_REALLOC(*devnos, *n_devnos + 1))
+                return log_oom();
+
+        (*devnos)[(*n_devnos)++] = devt;
+
+        /* Immediately sort again, to ensure the binary search above will work for the next device we add */
+        typesafe_qsort(*devnos, *n_devnos, devt_compare_func);
+        return 1;
+}
+
+static int lock_device(
+                const char *path,
+                dev_t devno,
+                usec_t deadline) {
+
+        _cleanup_close_ int fd = -EBADF;
+        struct stat st;
+        int r;
+
+        fd = open(path, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+        if (fd < 0)
+                return log_error_errno(errno, "Failed to open '%s': %m", path);
+
+        if (fstat(fd, &st) < 0)
+                return log_error_errno(errno, "Failed to stat '%s': %m", path);
+
+        /* Extra safety: check that the device still refers to what we think it refers to */
+        if (!S_ISBLK(st.st_mode) || st.st_rdev != devno)
+                return log_error_errno(SYNTHETIC_ERRNO(ENXIO), "Path '%s' no longer refers to specified block device %u:%u: %m", path, major(devno), minor(devno));
+
+        r = lock_generic(fd, LOCK_BSD, LOCK_EX|LOCK_NB);
+        if (r < 0) {
+                if (r != -EAGAIN)
+                        return log_error_errno(r, "Failed to lock device '%s': %m", path);
+
+                if (deadline == 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(EBUSY), "Device '%s' is currently locked.", path);
+
+                if (deadline == USEC_INFINITY)  {
+                        log_info("Device '%s' is currently locked, waiting%s", path, special_glyph(SPECIAL_GLYPH_ELLIPSIS));
+
+                        r = lock_generic(fd, LOCK_BSD, LOCK_EX);
+                } else {
+                        usec_t left = usec_sub_unsigned(deadline, now(CLOCK_MONOTONIC));
+
+                        log_info("Device '%s' is currently locked, waiting %s%s",
+                                 path, FORMAT_TIMESPAN(left, 0),
+                                 special_glyph(SPECIAL_GLYPH_ELLIPSIS));
+
+                        r = lock_generic_with_timeout(fd, LOCK_BSD, LOCK_EX, left);
+                        if (r == -ETIMEDOUT)
+                                return log_error_errno(r, "Timeout reached.");
+                }
+                if (r < 0)
+                        return log_error_errno(r, "Failed to lock device '%s': %m", path);
+        }
+
+        log_debug("Successfully locked %s (%u:%u)%s", path, major(devno), minor(devno), special_glyph(SPECIAL_GLYPH_ELLIPSIS));
+
+        return TAKE_FD(fd);
+}
+
+int lock_main(int argc, char *argv[], void *userdata) {
+        _cleanup_fdset_free_ FDSet *fds = NULL;
+        _cleanup_free_ dev_t *devnos = NULL;
+        size_t n_devnos = 0;
+        usec_t deadline;
+        pid_t pid;
+        int r;
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r;
+
+        STRV_FOREACH(i, arg_devices) {
+                r = find_devno(&devnos, &n_devnos, *i, /* backing= */ false);
+                if (r < 0)
+                        return r;
+        }
+
+        STRV_FOREACH(i, arg_backing) {
+                r = find_devno(&devnos, &n_devnos, *i, /* backing= */ true);
+                if (r < 0)
+                        return r;
+        }
+
+        assert(n_devnos > 0);
+
+        fds = fdset_new();
+        if (!fds)
+                return log_oom();
+
+        if (!timestamp_is_set(arg_timeout_usec))
+                deadline = arg_timeout_usec;
+        else
+                deadline = usec_add(now(CLOCK_MONOTONIC), arg_timeout_usec);
+
+        for (size_t i = 0; i < n_devnos; i++) {
+                _cleanup_free_ char *node = NULL;
+
+                r = devname_from_devnum(S_IFBLK, devnos[i], &node);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to format block device path: %m");
+
+                if (arg_print)
+                        printf("%s\n", node);
+                else {
+                        _cleanup_close_ int fd = -EBADF;
+
+                        fd = lock_device(node, devnos[i], deadline);
+                        if (fd < 0)
+                                return fd;
+
+                        r = fdset_consume(fds, TAKE_FD(fd));
+                        if (r < 0)
+                                return log_oom();
+                }
+        }
+
+        if (arg_print)
+                return EXIT_SUCCESS;
+
+        /* Ignore SIGINT and allow the forked process to receive it */
+        (void) ignore_signals(SIGINT);
+
+        r = safe_fork("(lock)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_CLOSE_ALL_FDS|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                /* Child */
+
+                execvp(arg_cmdline[0], arg_cmdline);
+                log_open();
+                log_error_errno(errno, "Failed to execute %s: %m", arg_cmdline[0]);
+                _exit(EXIT_FAILURE);
+        }
+
+        return wait_for_terminate_and_check(arg_cmdline[0], pid, 0);
+}