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

#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <stdarg.h>
#include <stddef.h>
#include <sys/signalfd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <unistd.h>

#include "sd-messages.h"

#include "alloc-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "format-util.h"
#include "io-util.h"
#include "log.h"
#include "macro.h"
#include "missing_syscall.h"
#include "parse-util.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "ratelimit.h"
#include "signal-util.h"
#include "socket-util.h"
#include "stdio-util.h"
#include "string-table.h"
#include "string-util.h"
#include "syslog-util.h"
#include "terminal-util.h"
#include "time-util.h"
#include "utf8.h"

#define SNDBUF_SIZE (8*1024*1024)

static log_syntax_callback_t log_syntax_callback = NULL;
static void *log_syntax_callback_userdata = NULL;

static LogTarget log_target = LOG_TARGET_CONSOLE;
static int log_max_level = LOG_INFO;
static int log_facility = LOG_DAEMON;

static int console_fd = STDERR_FILENO;
static int syslog_fd = -1;
static int kmsg_fd = -1;
static int journal_fd = -1;

static bool syslog_is_stream = false;

static int show_color = -1; /* tristate */
static bool show_location = false;
static bool show_time = false;
static bool show_tid = false;

static bool upgrade_syslog_to_journal = false;
static bool always_reopen_console = false;
static bool open_when_needed = false;
static bool prohibit_ipc = false;

/* Akin to glibc's __abort_msg; which is private and we hence cannot
 * use here. */
static char *log_abort_msg = NULL;

/* An assert to use in logging functions that does not call recursively
 * into our logging functions (since that might lead to a loop). */
#define assert_raw(expr)                                                \
        do {                                                            \
                if (_unlikely_(!(expr))) {                              \
                        fputs(#expr "\n", stderr);                      \
                        abort();                                        \
                }                                                       \
        } while (false)

static void log_close_console(void) {
        console_fd = safe_close_above_stdio(console_fd);
}

static int log_open_console(void) {

        if (!always_reopen_console) {
                console_fd = STDERR_FILENO;
                return 0;
        }

        if (console_fd < 3) {
                int fd;

                fd = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
                if (fd < 0)
                        return fd;

                console_fd = fd_move_above_stdio(fd);
        }

        return 0;
}

static void log_close_kmsg(void) {
        kmsg_fd = safe_close(kmsg_fd);
}

static int log_open_kmsg(void) {

        if (kmsg_fd >= 0)
                return 0;

        kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC);
        if (kmsg_fd < 0)
                return -errno;

        kmsg_fd = fd_move_above_stdio(kmsg_fd);
        return 0;
}

static void log_close_syslog(void) {
        syslog_fd = safe_close(syslog_fd);
}

static int create_log_socket(int type) {
        struct timeval tv;
        int fd;

        fd = socket(AF_UNIX, type|SOCK_CLOEXEC, 0);
        if (fd < 0)
                return -errno;

        fd = fd_move_above_stdio(fd);
        (void) fd_inc_sndbuf(fd, SNDBUF_SIZE);

        /* We need a blocking fd here since we'd otherwise lose messages way too early. However, let's not hang forever
         * in the unlikely case of a deadlock. */
        if (getpid_cached() == 1)
                timeval_store(&tv, 10 * USEC_PER_MSEC);
        else
                timeval_store(&tv, 10 * USEC_PER_SEC);
        (void) setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));

        return fd;
}

static int log_open_syslog(void) {

        static const union sockaddr_union sa = {
                .un.sun_family = AF_UNIX,
                .un.sun_path = "/dev/log",
        };

        int r;

        if (syslog_fd >= 0)
                return 0;

        syslog_fd = create_log_socket(SOCK_DGRAM);
        if (syslog_fd < 0) {
                r = syslog_fd;
                goto fail;
        }

        if (connect(syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
                safe_close(syslog_fd);

                /* Some legacy syslog systems still use stream
                 * sockets. They really shouldn't. But what can we
                 * do... */
                syslog_fd = create_log_socket(SOCK_STREAM);
                if (syslog_fd < 0) {
                        r = syslog_fd;
                        goto fail;
                }

                if (connect(syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
                        r = -errno;
                        goto fail;
                }

                syslog_is_stream = true;
        } else
                syslog_is_stream = false;

        return 0;

fail:
        log_close_syslog();
        return r;
}

static void log_close_journal(void) {
        journal_fd = safe_close(journal_fd);
}

static int log_open_journal(void) {

        static const union sockaddr_union sa = {
                .un.sun_family = AF_UNIX,
                .un.sun_path = "/run/systemd/journal/socket",
        };

        int r;

        if (journal_fd >= 0)
                return 0;

        journal_fd = create_log_socket(SOCK_DGRAM);
        if (journal_fd < 0) {
                r = journal_fd;
                goto fail;
        }

        if (connect(journal_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
                r = -errno;
                goto fail;
        }

        return 0;

fail:
        log_close_journal();
        return r;
}

static bool stderr_is_journal(void) {
        _cleanup_free_ char *w = NULL;
        const char *e;
        uint64_t dev, ino;
        struct stat st;

        e = getenv("JOURNAL_STREAM");
        if (!e)
                return false;

        if (extract_first_word(&e, &w, ":", EXTRACT_DONT_COALESCE_SEPARATORS) <= 0)
                return false;
        if (!e)
                return false;

        if (safe_atou64(w, &dev) < 0)
                return false;
        if (safe_atou64(e, &ino) < 0)
                return false;

        if (fstat(STDERR_FILENO, &st) < 0)
                return false;

        return st.st_dev == dev && st.st_ino == ino;
}

int log_open(void) {
        int r;

        /* Do not call from library code. */

        /* This function is often called in preparation for logging. Let's make sure we don't clobber errno,
         * so that a call to a logging function immediately following a log_open() call can still easily
         * reference an error that happened immediately before the log_open() call. */
        PROTECT_ERRNO;

        /* If we don't use the console, we close it here to not get killed by SAK. If we don't use syslog, we
         * close it here too, so that we are not confused by somebody deleting the socket in the fs, and to
         * make sure we don't use it if prohibit_ipc is set. If we don't use /dev/kmsg we still keep it open,
         * because there is no reason to close it. */

        if (log_target == LOG_TARGET_NULL) {
                log_close_journal();
                log_close_syslog();
                log_close_console();
                return 0;
        }

        if (getpid_cached() == 1 ||
            stderr_is_journal() ||
            IN_SET(log_target,
                   LOG_TARGET_KMSG,
                   LOG_TARGET_JOURNAL,
                   LOG_TARGET_JOURNAL_OR_KMSG,
                   LOG_TARGET_SYSLOG,
                   LOG_TARGET_SYSLOG_OR_KMSG)) {

                if (!prohibit_ipc) {
                        if (IN_SET(log_target,
                                   LOG_TARGET_AUTO,
                                   LOG_TARGET_JOURNAL_OR_KMSG,
                                   LOG_TARGET_JOURNAL)) {

                                r = log_open_journal();
                                if (r >= 0) {
                                        log_close_syslog();
                                        log_close_console();
                                        return r;
                                }
                        }

                        if (IN_SET(log_target,
                                   LOG_TARGET_SYSLOG_OR_KMSG,
                                   LOG_TARGET_SYSLOG)) {

                                r = log_open_syslog();
                                if (r >= 0) {
                                        log_close_journal();
                                        log_close_console();
                                        return r;
                                }
                        }
                }

                if (IN_SET(log_target, LOG_TARGET_AUTO,
                                       LOG_TARGET_JOURNAL_OR_KMSG,
                                       LOG_TARGET_SYSLOG_OR_KMSG,
                                       LOG_TARGET_KMSG)) {
                        r = log_open_kmsg();
                        if (r >= 0) {
                                log_close_journal();
                                log_close_syslog();
                                log_close_console();
                                return r;
                        }
                }
        }

        log_close_journal();
        log_close_syslog();

        return log_open_console();
}

void log_set_target(LogTarget target) {
        assert(target >= 0);
        assert(target < _LOG_TARGET_MAX);

        if (upgrade_syslog_to_journal) {
                if (target == LOG_TARGET_SYSLOG)
                        target = LOG_TARGET_JOURNAL;
                else if (target == LOG_TARGET_SYSLOG_OR_KMSG)
                        target = LOG_TARGET_JOURNAL_OR_KMSG;
        }

        log_target = target;
}

void log_close(void) {
        /* Do not call from library code. */

        log_close_journal();
        log_close_syslog();
        log_close_kmsg();
        log_close_console();
}

void log_forget_fds(void) {
        /* Do not call from library code. */

        console_fd = kmsg_fd = syslog_fd = journal_fd = -1;
}

void log_set_max_level(int level) {
        assert(level == LOG_NULL || (level & LOG_PRIMASK) == level);

        log_max_level = level;
}

void log_set_facility(int facility) {
        log_facility = facility;
}

static int write_to_console(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *buffer) {

        char location[256],
             header_time[FORMAT_TIMESTAMP_MAX],
             prefix[1 + DECIMAL_STR_MAX(int) + 2],
             tid_string[3 + DECIMAL_STR_MAX(pid_t) + 1];
        struct iovec iovec[9];
        const char *on = NULL, *off = NULL;
        size_t n = 0;

        if (console_fd < 0)
                return 0;

        if (log_target == LOG_TARGET_CONSOLE_PREFIXED) {
                xsprintf(prefix, "<%i>", level);
                iovec[n++] = IOVEC_MAKE_STRING(prefix);
        }

        if (show_time &&
            format_timestamp(header_time, sizeof(header_time), now(CLOCK_REALTIME))) {
                iovec[n++] = IOVEC_MAKE_STRING(header_time);
                iovec[n++] = IOVEC_MAKE_STRING(" ");
        }

        if (show_tid) {
                xsprintf(tid_string, "(" PID_FMT ") ", gettid());
                iovec[n++] = IOVEC_MAKE_STRING(tid_string);
        }

        if (log_get_show_color())
                get_log_colors(LOG_PRI(level), &on, &off, NULL);

        if (show_location) {
                const char *lon = "", *loff = "";
                if (log_get_show_color()) {
                        lon = ansi_highlight_yellow4();
                        loff = ansi_normal();
                }

                (void) snprintf(location, sizeof location, "%s%s:%i%s: ", lon, file, line, loff);
                iovec[n++] = IOVEC_MAKE_STRING(location);
        }

        if (on)
                iovec[n++] = IOVEC_MAKE_STRING(on);
        iovec[n++] = IOVEC_MAKE_STRING(buffer);
        if (off)
                iovec[n++] = IOVEC_MAKE_STRING(off);
        iovec[n++] = IOVEC_MAKE_STRING("\n");

        if (writev(console_fd, iovec, n) < 0) {

                if (errno == EIO && getpid_cached() == 1) {

                        /* If somebody tried to kick us from our console tty (via vhangup() or suchlike), try
                         * to reconnect. */

                        log_close_console();
                        (void) log_open_console();
                        if (console_fd < 0)
                                return 0;

                        if (writev(console_fd, iovec, n) < 0)
                                return -errno;
                } else
                        return -errno;
        }

        return 1;
}

static int write_to_syslog(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *buffer) {

        char header_priority[2 + DECIMAL_STR_MAX(int) + 1],
             header_time[64],
             header_pid[4 + DECIMAL_STR_MAX(pid_t) + 1];
        time_t t;
        struct tm tm;

        if (syslog_fd < 0)
                return 0;

        xsprintf(header_priority, "<%i>", level);

        t = (time_t) (now(CLOCK_REALTIME) / USEC_PER_SEC);
        if (!localtime_r(&t, &tm))
                return -EINVAL;

        if (strftime(header_time, sizeof(header_time), "%h %e %T ", &tm) <= 0)
                return -EINVAL;

        xsprintf(header_pid, "["PID_FMT"]: ", getpid_cached());

        struct iovec iovec[] = {
                IOVEC_MAKE_STRING(header_priority),
                IOVEC_MAKE_STRING(header_time),
                IOVEC_MAKE_STRING(program_invocation_short_name),
                IOVEC_MAKE_STRING(header_pid),
                IOVEC_MAKE_STRING(buffer),
        };
        const struct msghdr msghdr = {
                .msg_iov = iovec,
                .msg_iovlen = ELEMENTSOF(iovec),
        };

        /* When using syslog via SOCK_STREAM separate the messages by NUL chars */
        if (syslog_is_stream)
                iovec[ELEMENTSOF(iovec) - 1].iov_len++;

        for (;;) {
                ssize_t n;

                n = sendmsg(syslog_fd, &msghdr, MSG_NOSIGNAL);
                if (n < 0)
                        return -errno;

                if (!syslog_is_stream)
                        break;

                if (IOVEC_INCREMENT(iovec, ELEMENTSOF(iovec), n))
                        break;
        }

        return 1;
}

static int write_to_kmsg(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *buffer) {

        /* Set a ratelimit on the amount of messages logged to /dev/kmsg. This is mostly supposed to be a
         * safety catch for the case where start indiscriminately logging in a loop. It will not catch cases
         * where we log excessively, but not in a tight loop.
         *
         * Note that this ratelimit is per-emitter, so we might still overwhelm /dev/kmsg with multiple
         * loggers.
         */
        static thread_local RateLimit ratelimit = { 5 * USEC_PER_SEC, 200 };

        char header_priority[2 + DECIMAL_STR_MAX(int) + 1],
             header_pid[4 + DECIMAL_STR_MAX(pid_t) + 1];

        if (kmsg_fd < 0)
                return 0;

        if (!ratelimit_below(&ratelimit))
                return 0;

        xsprintf(header_priority, "<%i>", level);
        xsprintf(header_pid, "["PID_FMT"]: ", getpid_cached());

        const struct iovec iovec[] = {
                IOVEC_MAKE_STRING(header_priority),
                IOVEC_MAKE_STRING(program_invocation_short_name),
                IOVEC_MAKE_STRING(header_pid),
                IOVEC_MAKE_STRING(buffer),
                IOVEC_MAKE_STRING("\n"),
        };

        if (writev(kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
                return -errno;

        return 1;
}

static int log_do_header(
                char *header,
                size_t size,
                int level,
                int error,
                const char *file, int line, const char *func,
                const char *object_field, const char *object,
                const char *extra_field, const char *extra) {
        int r;

        error = IS_SYNTHETIC_ERRNO(error) ? 0 : ERRNO_VALUE(error);

        r = snprintf(header, size,
                     "PRIORITY=%i\n"
                     "SYSLOG_FACILITY=%i\n"
                     "TID=" PID_FMT "\n"
                     "%s%.256s%s"        /* CODE_FILE */
                     "%s%.*i%s"          /* CODE_LINE */
                     "%s%.256s%s"        /* CODE_FUNC */
                     "%s%.*i%s"          /* ERRNO */
                     "%s%.256s%s"        /* object */
                     "%s%.256s%s"        /* extra */
                     "SYSLOG_IDENTIFIER=%.256s\n",
                     LOG_PRI(level),
                     LOG_FAC(level),
                     gettid(),
                     isempty(file) ? "" : "CODE_FILE=",
                     isempty(file) ? "" : file,
                     isempty(file) ? "" : "\n",
                     line ? "CODE_LINE=" : "",
                     line ? 1 : 0, line, /* %.0d means no output too, special case for 0 */
                     line ? "\n" : "",
                     isempty(func) ? "" : "CODE_FUNC=",
                     isempty(func) ? "" : func,
                     isempty(func) ? "" : "\n",
                     error ? "ERRNO=" : "",
                     error ? 1 : 0, error,
                     error ? "\n" : "",
                     isempty(object) ? "" : object_field,
                     isempty(object) ? "" : object,
                     isempty(object) ? "" : "\n",
                     isempty(extra) ? "" : extra_field,
                     isempty(extra) ? "" : extra,
                     isempty(extra) ? "" : "\n",
                     program_invocation_short_name);
        assert_raw((size_t) r < size);

        return 0;
}

static int write_to_journal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *object_field,
                const char *object,
                const char *extra_field,
                const char *extra,
                const char *buffer) {

        char header[LINE_MAX];

        if (journal_fd < 0)
                return 0;

        log_do_header(header, sizeof(header), level, error, file, line, func, object_field, object, extra_field, extra);

        struct iovec iovec[4] = {
                IOVEC_MAKE_STRING(header),
                IOVEC_MAKE_STRING("MESSAGE="),
                IOVEC_MAKE_STRING(buffer),
                IOVEC_MAKE_STRING("\n"),
        };
        const struct msghdr msghdr = {
                .msg_iov = iovec,
                .msg_iovlen = ELEMENTSOF(iovec),
        };

        if (sendmsg(journal_fd, &msghdr, MSG_NOSIGNAL) < 0)
                return -errno;

        return 1;
}

int log_dispatch_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *object_field,
                const char *object,
                const char *extra_field,
                const char *extra,
                char *buffer) {

        assert_raw(buffer);

        if (log_target == LOG_TARGET_NULL)
                return -ERRNO_VALUE(error);

        /* Patch in LOG_DAEMON facility if necessary */
        if ((level & LOG_FACMASK) == 0)
                level |= log_facility;

        if (open_when_needed)
                (void) log_open();

        do {
                char *e;
                int k = 0;

                buffer += strspn(buffer, NEWLINE);

                if (buffer[0] == 0)
                        break;

                if ((e = strpbrk(buffer, NEWLINE)))
                        *(e++) = 0;

                if (IN_SET(log_target, LOG_TARGET_AUTO,
                                       LOG_TARGET_JOURNAL_OR_KMSG,
                                       LOG_TARGET_JOURNAL)) {

                        k = write_to_journal(level, error, file, line, func, object_field, object, extra_field, extra, buffer);
                        if (k < 0 && k != -EAGAIN)
                                log_close_journal();
                }

                if (IN_SET(log_target, LOG_TARGET_SYSLOG_OR_KMSG,
                                       LOG_TARGET_SYSLOG)) {

                        k = write_to_syslog(level, error, file, line, func, buffer);
                        if (k < 0 && k != -EAGAIN)
                                log_close_syslog();
                }

                if (k <= 0 &&
                    IN_SET(log_target, LOG_TARGET_AUTO,
                                       LOG_TARGET_SYSLOG_OR_KMSG,
                                       LOG_TARGET_JOURNAL_OR_KMSG,
                                       LOG_TARGET_KMSG)) {

                        if (k < 0)
                                log_open_kmsg();

                        k = write_to_kmsg(level, error, file, line, func, buffer);
                        if (k < 0) {
                                log_close_kmsg();
                                (void) log_open_console();
                        }
                }

                if (k <= 0)
                        (void) write_to_console(level, error, file, line, func, buffer);

                buffer = e;
        } while (buffer);

        if (open_when_needed)
                log_close();

        return -ERRNO_VALUE(error);
}

int log_dump_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                char *buffer) {

        PROTECT_ERRNO;

        /* This modifies the buffer... */

        if (_likely_(LOG_PRI(level) > log_max_level))
                return -ERRNO_VALUE(error);

        return log_dispatch_internal(level, error, file, line, func, NULL, NULL, NULL, NULL, buffer);
}

int log_internalv(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *format,
                va_list ap) {

        char buffer[LINE_MAX];
        PROTECT_ERRNO;

        if (_likely_(LOG_PRI(level) > log_max_level))
                return -ERRNO_VALUE(error);

        /* Make sure that %m maps to the specified error (or "Success"). */
        errno = ERRNO_VALUE(error);

        (void) vsnprintf(buffer, sizeof buffer, format, ap);

        return log_dispatch_internal(level, error, file, line, func, NULL, NULL, NULL, NULL, buffer);
}

int log_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *format, ...) {

        va_list ap;
        int r;

        va_start(ap, format);
        r = log_internalv(level, error, file, line, func, format, ap);
        va_end(ap);

        return r;
}

int log_object_internalv(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *object_field,
                const char *object,
                const char *extra_field,
                const char *extra,
                const char *format,
                va_list ap) {

        PROTECT_ERRNO;
        char *buffer, *b;

        if (_likely_(LOG_PRI(level) > log_max_level))
                return -ERRNO_VALUE(error);

        /* Make sure that %m maps to the specified error (or "Success"). */
        errno = ERRNO_VALUE(error);

        /* Prepend the object name before the message */
        if (object) {
                size_t n;

                n = strlen(object);
                buffer = newa(char, n + 2 + LINE_MAX);
                b = stpcpy(stpcpy(buffer, object), ": ");
        } else
                b = buffer = newa(char, LINE_MAX);

        (void) vsnprintf(b, LINE_MAX, format, ap);

        return log_dispatch_internal(level, error, file, line, func,
                                     object_field, object, extra_field, extra, buffer);
}

int log_object_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *object_field,
                const char *object,
                const char *extra_field,
                const char *extra,
                const char *format, ...) {

        va_list ap;
        int r;

        va_start(ap, format);
        r = log_object_internalv(level, error, file, line, func, object_field, object, extra_field, extra, format, ap);
        va_end(ap);

        return r;
}

static void log_assert(
                int level,
                const char *text,
                const char *file,
                int line,
                const char *func,
                const char *format) {

        static char buffer[LINE_MAX];

        if (_likely_(LOG_PRI(level) > log_max_level))
                return;

        DISABLE_WARNING_FORMAT_NONLITERAL;
        (void) snprintf(buffer, sizeof buffer, format, text, file, line, func);
        REENABLE_WARNING;

        log_abort_msg = buffer;

        log_dispatch_internal(level, 0, file, line, func, NULL, NULL, NULL, NULL, buffer);
}

_noreturn_ void log_assert_failed(
                const char *text,
                const char *file,
                int line,
                const char *func) {
        log_assert(LOG_CRIT, text, file, line, func,
                   "Assertion '%s' failed at %s:%u, function %s(). Aborting.");
        abort();
}

_noreturn_ void log_assert_failed_unreachable(
                const char *file,
                int line,
                const char *func) {
        log_assert(LOG_CRIT, "Code should not be reached", file, line, func,
                   "%s at %s:%u, function %s(). Aborting. 💥");
        abort();
}

void log_assert_failed_return(
                const char *text,
                const char *file,
                int line,
                const char *func) {
        PROTECT_ERRNO;
        log_assert(LOG_DEBUG, text, file, line, func,
                   "Assertion '%s' failed at %s:%u, function %s(). Ignoring.");
}

int log_oom_internal(int level, const char *file, int line, const char *func) {
        return log_internal(level, ENOMEM, file, line, func, "Out of memory.");
}

int log_format_iovec(
                struct iovec *iovec,
                size_t iovec_len,
                size_t *n,
                bool newline_separator,
                int error,
                const char *format,
                va_list ap) {

        static const char nl = '\n';

        while (format && *n + 1 < iovec_len) {
                va_list aq;
                char *m;
                int r;

                /* We need to copy the va_list structure,
                 * since vasprintf() leaves it afterwards at
                 * an undefined location */

                errno = ERRNO_VALUE(error);

                va_copy(aq, ap);
                r = vasprintf(&m, format, aq);
                va_end(aq);
                if (r < 0)
                        return -EINVAL;

                /* Now, jump enough ahead, so that we point to
                 * the next format string */
                VA_FORMAT_ADVANCE(format, ap);

                iovec[(*n)++] = IOVEC_MAKE_STRING(m);
                if (newline_separator)
                        iovec[(*n)++] = IOVEC_MAKE((char *)&nl, 1);

                format = va_arg(ap, char *);
        }
        return 0;
}

int log_struct_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *format, ...) {

        char buf[LINE_MAX];
        bool found = false;
        PROTECT_ERRNO;
        va_list ap;

        if (_likely_(LOG_PRI(level) > log_max_level) ||
            log_target == LOG_TARGET_NULL)
                return -ERRNO_VALUE(error);

        if ((level & LOG_FACMASK) == 0)
                level |= log_facility;

        if (IN_SET(log_target,
                   LOG_TARGET_AUTO,
                   LOG_TARGET_JOURNAL_OR_KMSG,
                   LOG_TARGET_JOURNAL)) {

                if (open_when_needed)
                        log_open_journal();

                if (journal_fd >= 0) {
                        char header[LINE_MAX];
                        struct iovec iovec[17];
                        size_t n = 0;
                        int r;
                        bool fallback = false;

                        /* If the journal is available do structured logging.
                         * Do not report the errno if it is synthetic. */
                        log_do_header(header, sizeof(header), level, error, file, line, func, NULL, NULL, NULL, NULL);
                        iovec[n++] = IOVEC_MAKE_STRING(header);

                        va_start(ap, format);
                        r = log_format_iovec(iovec, ELEMENTSOF(iovec), &n, true, error, format, ap);
                        if (r < 0)
                                fallback = true;
                        else {
                                const struct msghdr msghdr = {
                                        .msg_iov = iovec,
                                        .msg_iovlen = n,
                                };

                                (void) sendmsg(journal_fd, &msghdr, MSG_NOSIGNAL);
                        }

                        va_end(ap);
                        for (size_t i = 1; i < n; i += 2)
                                free(iovec[i].iov_base);

                        if (!fallback) {
                                if (open_when_needed)
                                        log_close();

                                return -ERRNO_VALUE(error);
                        }
                }
        }

        /* Fallback if journal logging is not available or didn't work. */

        va_start(ap, format);
        while (format) {
                va_list aq;

                errno = ERRNO_VALUE(error);

                va_copy(aq, ap);
                (void) vsnprintf(buf, sizeof buf, format, aq);
                va_end(aq);

                if (startswith(buf, "MESSAGE=")) {
                        found = true;
                        break;
                }

                VA_FORMAT_ADVANCE(format, ap);

                format = va_arg(ap, char *);
        }
        va_end(ap);

        if (!found) {
                if (open_when_needed)
                        log_close();

                return -ERRNO_VALUE(error);
        }

        return log_dispatch_internal(level, error, file, line, func, NULL, NULL, NULL, NULL, buf + 8);
}

int log_struct_iovec_internal(
                int level,
                int error,
                const char *file,
                int line,
                const char *func,
                const struct iovec input_iovec[],
                size_t n_input_iovec) {

        PROTECT_ERRNO;

        if (_likely_(LOG_PRI(level) > log_max_level) ||
            log_target == LOG_TARGET_NULL)
                return -ERRNO_VALUE(error);

        if ((level & LOG_FACMASK) == 0)
                level |= log_facility;

        if (IN_SET(log_target, LOG_TARGET_AUTO,
                               LOG_TARGET_JOURNAL_OR_KMSG,
                               LOG_TARGET_JOURNAL) &&
            journal_fd >= 0) {

                char header[LINE_MAX];
                log_do_header(header, sizeof(header), level, error, file, line, func, NULL, NULL, NULL, NULL);

                struct iovec iovec[1 + n_input_iovec*2];
                iovec[0] = IOVEC_MAKE_STRING(header);
                for (size_t i = 0; i < n_input_iovec; i++) {
                        iovec[1+i*2] = input_iovec[i];
                        iovec[1+i*2+1] = IOVEC_MAKE_STRING("\n");
                }

                const struct msghdr msghdr = {
                        .msg_iov = iovec,
                        .msg_iovlen = 1 + n_input_iovec*2,
                };

                if (sendmsg(journal_fd, &msghdr, MSG_NOSIGNAL) >= 0)
                        return -ERRNO_VALUE(error);
        }

        for (size_t i = 0; i < n_input_iovec; i++)
                if (memory_startswith(input_iovec[i].iov_base, input_iovec[i].iov_len, "MESSAGE=")) {
                        char *m;

                        m = strndupa_safe((char*) input_iovec[i].iov_base + STRLEN("MESSAGE="),
                                          input_iovec[i].iov_len - STRLEN("MESSAGE="));

                        return log_dispatch_internal(level, error, file, line, func, NULL, NULL, NULL, NULL, m);
                }

        /* Couldn't find MESSAGE=. */
        return -ERRNO_VALUE(error);
}

int log_set_target_from_string(const char *e) {
        LogTarget t;

        t = log_target_from_string(e);
        if (t < 0)
                return t;

        log_set_target(t);
        return 0;
}

int log_set_max_level_from_string(const char *e) {
        int t;

        t = log_level_from_string(e);
        if (t < 0)
                return t;

        log_set_max_level(t);
        return 0;
}

static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {

        /*
         * The systemd.log_xyz= settings are parsed by all tools, and
         * so is "debug".
         *
         * However, "quiet" is only parsed by PID 1, and only turns of
         * status output to /dev/console, but does not alter the log
         * level.
         */

        if (streq(key, "debug") && !value)
                log_set_max_level(LOG_DEBUG);

        else if (proc_cmdline_key_streq(key, "systemd.log_target")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                if (log_set_target_from_string(value) < 0)
                        log_warning("Failed to parse log target '%s'. Ignoring.", value);

        } else if (proc_cmdline_key_streq(key, "systemd.log_level")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                if (log_set_max_level_from_string(value) < 0)
                        log_warning("Failed to parse log level '%s'. Ignoring.", value);

        } else if (proc_cmdline_key_streq(key, "systemd.log_color")) {

                if (log_show_color_from_string(value ?: "1") < 0)
                        log_warning("Failed to parse log color setting '%s'. Ignoring.", value);

        } else if (proc_cmdline_key_streq(key, "systemd.log_location")) {

                if (log_show_location_from_string(value ?: "1") < 0)
                        log_warning("Failed to parse log location setting '%s'. Ignoring.", value);

        } else if (proc_cmdline_key_streq(key, "systemd.log_tid")) {

                if (log_show_tid_from_string(value ?: "1") < 0)
                        log_warning("Failed to parse log tid setting '%s'. Ignoring.", value);

        } else if (proc_cmdline_key_streq(key, "systemd.log_time")) {

                if (log_show_time_from_string(value ?: "1") < 0)
                        log_warning("Failed to parse log time setting '%s'. Ignoring.", value);

        }

        return 0;
}

static bool should_parse_proc_cmdline(void) {
        const char *e;
        pid_t p;

        /* PID1 always reads the kernel command line. */
        if (getpid_cached() == 1)
                return true;

        /* If the process is directly executed by PID1 (e.g. ExecStart= or generator), systemd-importd,
         * or systemd-homed, then $SYSTEMD_EXEC_PID= is set, and read the command line. */
        e = getenv("SYSTEMD_EXEC_PID");
        if (!e)
                return false;

        if (streq(e, "*"))
                /* For testing. */
                return true;

        if (parse_pid(e, &p) < 0) {
                /* We know that systemd sets the variable correctly. Something else must have set it. */
                log_debug("Failed to parse \"$SYSTEMD_EXEC_PID=%s\". Ignoring.", e);
                return false;
        }

        return getpid_cached() == p;
}

void log_parse_environment_variables(void) {
        const char *e;

        e = getenv("SYSTEMD_LOG_TARGET");
        if (e && log_set_target_from_string(e) < 0)
                log_warning("Failed to parse log target '%s'. Ignoring.", e);

        e = getenv("SYSTEMD_LOG_LEVEL");
        if (e && log_set_max_level_from_string(e) < 0)
                log_warning("Failed to parse log level '%s'. Ignoring.", e);

        e = getenv("SYSTEMD_LOG_COLOR");
        if (e && log_show_color_from_string(e) < 0)
                log_warning("Failed to parse log color '%s'. Ignoring.", e);

        e = getenv("SYSTEMD_LOG_LOCATION");
        if (e && log_show_location_from_string(e) < 0)
                log_warning("Failed to parse log location '%s'. Ignoring.", e);

        e = getenv("SYSTEMD_LOG_TIME");
        if (e && log_show_time_from_string(e) < 0)
                log_warning("Failed to parse log time '%s'. Ignoring.", e);

        e = getenv("SYSTEMD_LOG_TID");
        if (e && log_show_tid_from_string(e) < 0)
                log_warning("Failed to parse log tid '%s'. Ignoring.", e);
}

void log_parse_environment(void) {
        /* Do not call from library code. */

        if (should_parse_proc_cmdline())
                (void) proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX);

        log_parse_environment_variables();
}

LogTarget log_get_target(void) {
        return log_target;
}

int log_get_max_level(void) {
        return log_max_level;
}

void log_show_color(bool b) {
        show_color = b;
}

bool log_get_show_color(void) {
        return show_color > 0; /* Defaults to false. */
}

void log_show_location(bool b) {
        show_location = b;
}

bool log_get_show_location(void) {
        return show_location;
}

void log_show_time(bool b) {
        show_time = b;
}

bool log_get_show_time(void) {
        return show_time;
}

void log_show_tid(bool b) {
        show_tid = b;
}

bool log_get_show_tid(void) {
        return show_tid;
}

int log_show_color_from_string(const char *e) {
        int t;

        t = parse_boolean(e);
        if (t < 0)
                return t;

        log_show_color(t);
        return 0;
}

int log_show_location_from_string(const char *e) {
        int t;

        t = parse_boolean(e);
        if (t < 0)
                return t;

        log_show_location(t);
        return 0;
}

int log_show_time_from_string(const char *e) {
        int t;

        t = parse_boolean(e);
        if (t < 0)
                return t;

        log_show_time(t);
        return 0;
}

int log_show_tid_from_string(const char *e) {
        int t;

        t = parse_boolean(e);
        if (t < 0)
                return t;

        log_show_tid(t);
        return 0;
}

bool log_on_console(void) {
        if (IN_SET(log_target, LOG_TARGET_CONSOLE,
                               LOG_TARGET_CONSOLE_PREFIXED))
                return true;

        return syslog_fd < 0 && kmsg_fd < 0 && journal_fd < 0;
}

static const char *const log_target_table[_LOG_TARGET_MAX] = {
        [LOG_TARGET_CONSOLE]          = "console",
        [LOG_TARGET_CONSOLE_PREFIXED] = "console-prefixed",
        [LOG_TARGET_KMSG]             = "kmsg",
        [LOG_TARGET_JOURNAL]          = "journal",
        [LOG_TARGET_JOURNAL_OR_KMSG]  = "journal-or-kmsg",
        [LOG_TARGET_SYSLOG]           = "syslog",
        [LOG_TARGET_SYSLOG_OR_KMSG]   = "syslog-or-kmsg",
        [LOG_TARGET_AUTO]             = "auto",
        [LOG_TARGET_NULL]             = "null",
};

DEFINE_STRING_TABLE_LOOKUP(log_target, LogTarget);

void log_received_signal(int level, const struct signalfd_siginfo *si) {
        assert(si);

        if (pid_is_valid(si->ssi_pid)) {
                _cleanup_free_ char *p = NULL;

                (void) get_process_comm(si->ssi_pid, &p);

                log_full(level,
                         "Received SIG%s from PID %"PRIu32" (%s).",
                         signal_to_string(si->ssi_signo),
                         si->ssi_pid, strna(p));
        } else
                log_full(level,
                         "Received SIG%s.",
                         signal_to_string(si->ssi_signo));
}

void set_log_syntax_callback(log_syntax_callback_t cb, void *userdata) {
        assert(!log_syntax_callback || !cb);
        assert(!log_syntax_callback_userdata || !userdata);

        log_syntax_callback = cb;
        log_syntax_callback_userdata = userdata;
}

int log_syntax_internal(
                const char *unit,
                int level,
                const char *config_file,
                unsigned config_line,
                int error,
                const char *file,
                int line,
                const char *func,
                const char *format, ...) {

        if (log_syntax_callback)
                log_syntax_callback(unit, level, log_syntax_callback_userdata);

        PROTECT_ERRNO;
        char buffer[LINE_MAX];
        va_list ap;
        const char *unit_fmt = NULL;

        if (_likely_(LOG_PRI(level) > log_max_level) ||
            log_target == LOG_TARGET_NULL)
                return -ERRNO_VALUE(error);

        errno = ERRNO_VALUE(error);

        va_start(ap, format);
        (void) vsnprintf(buffer, sizeof buffer, format, ap);
        va_end(ap);

        if (unit)
                unit_fmt = getpid_cached() == 1 ? "UNIT=%s" : "USER_UNIT=%s";

        if (config_file) {
                if (config_line > 0)
                        return log_struct_internal(
                                        level,
                                        error,
                                        file, line, func,
                                        "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
                                        "CONFIG_FILE=%s", config_file,
                                        "CONFIG_LINE=%u", config_line,
                                        LOG_MESSAGE("%s:%u: %s", config_file, config_line, buffer),
                                        unit_fmt, unit,
                                        NULL);
                else
                        return log_struct_internal(
                                        level,
                                        error,
                                        file, line, func,
                                        "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
                                        "CONFIG_FILE=%s", config_file,
                                        LOG_MESSAGE("%s: %s", config_file, buffer),
                                        unit_fmt, unit,
                                        NULL);
        } else if (unit)
                return log_struct_internal(
                                level,
                                error,
                                file, line, func,
                                "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
                                LOG_MESSAGE("%s: %s", unit, buffer),
                                unit_fmt, unit,
                                NULL);
        else
                return log_struct_internal(
                                level,
                                error,
                                file, line, func,
                                "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
                                LOG_MESSAGE("%s", buffer),
                                NULL);
}

int log_syntax_invalid_utf8_internal(
                const char *unit,
                int level,
                const char *config_file,
                unsigned config_line,
                const char *file,
                int line,
                const char *func,
                const char *rvalue) {

        _cleanup_free_ char *p = NULL;

        if (rvalue)
                p = utf8_escape_invalid(rvalue);

        return log_syntax_internal(unit, level, config_file, config_line,
                                   SYNTHETIC_ERRNO(EINVAL), file, line, func,
                                   "String is not UTF-8 clean, ignoring assignment: %s", strna(p));
}

void log_set_upgrade_syslog_to_journal(bool b) {
        upgrade_syslog_to_journal = b;

        /* Make the change effective immediately */
        if (b) {
                if (log_target == LOG_TARGET_SYSLOG)
                        log_target = LOG_TARGET_JOURNAL;
                else if (log_target == LOG_TARGET_SYSLOG_OR_KMSG)
                        log_target = LOG_TARGET_JOURNAL_OR_KMSG;
        }
}

void log_set_always_reopen_console(bool b) {
        always_reopen_console = b;
}

void log_set_open_when_needed(bool b) {
        open_when_needed = b;
}

void log_set_prohibit_ipc(bool b) {
        prohibit_ipc = b;
}

int log_emergency_level(void) {
        /* Returns the log level to use for log_emergency() logging. We use LOG_EMERG only when we are PID 1, as only
         * then the system of the whole system is obviously affected. */

        return getpid_cached() == 1 ? LOG_EMERG : LOG_ERR;
}

int log_dup_console(void) {
        int copy;

        /* Duplicate the fd we use for fd logging if it's < 3 and use the copy from now on. This call is useful
         * whenever we want to continue logging through the original fd, but want to rearrange stderr. */

        if (console_fd >= 3)
                return 0;

        copy = fcntl(console_fd, F_DUPFD_CLOEXEC, 3);
        if (copy < 0)
                return -errno;

        console_fd = copy;
        return 0;
}

void log_setup(void) {
        log_set_target(LOG_TARGET_AUTO);
        log_parse_environment();
        (void) log_open();
        if (log_on_console() && show_color < 0)
                log_show_color(true);
}
