source: MondoRescue/branches/stable/mindi-busybox/sysklogd/syslogd.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Mini syslogd implementation for busybox
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
 *
 * "circular buffer" Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>
 *
 * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

#include "libbb.h"
#include <paths.h>
#include <sys/un.h>

/* SYSLOG_NAMES defined to pull prioritynames[] and facilitynames[]
 * from syslog.h. Grrrr - glibc puts those in _rwdata_! :( */
#define SYSLOG_NAMES
#define SYSLOG_NAMES_CONST /* uclibc is saner :) */
#include <sys/syslog.h>
#include <sys/uio.h>

#if ENABLE_FEATURE_REMOTE_LOG
#include <netinet/in.h>
#endif

#if ENABLE_FEATURE_IPC_SYSLOG
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#endif


#define DEBUG 0

/* MARK code is not very useful, is bloat, and broken:
 * can deadlock if alarmed to make MARK while writing to IPC buffer
 * (semaphores are down but do_mark routine tries to down them again) */
#undef SYSLOGD_MARK

enum { MAX_READ = 256 };

/* Semaphore operation structures */
struct shbuf_ds {
    int32_t size;   /* size of data - 1 */
    int32_t tail;   /* end of message list */
    char data[1];   /* data/messages */
};

/* Allows us to have smaller initializer. Ugly. */
#define GLOBALS \
    const char *logFilePath;                \
    int logFD;                              \
    /* interval between marks in seconds */ \
    /*int markInterval;*/                   \
    /* level of messages to be logged */    \
    int logLevel;                           \
USE_FEATURE_ROTATE_LOGFILE( \
    /* max size of file before rotation */  \
    unsigned logFileSize;                   \
    /* number of rotated message files */   \
    unsigned logFileRotate;                 \
    unsigned curFileSize;                   \
    smallint isRegular;                     \
) \
USE_FEATURE_REMOTE_LOG( \
    /* udp socket for remote logging */     \
    int remoteFD;                           \
    len_and_sockaddr* remoteAddr;           \
) \
USE_FEATURE_IPC_SYSLOG( \
    int shmid; /* ipc shared memory id */   \
    int s_semid; /* ipc semaphore id */     \
    int shm_size;                           \
    struct sembuf SMwup[1];                 \
    struct sembuf SMwdn[3];                 \
)

struct init_globals {
    GLOBALS
};

struct globals {
    GLOBALS
#if ENABLE_FEATURE_IPC_SYSLOG
    struct shbuf_ds *shbuf;
#endif
    time_t last_log_time;
    /* localhost's name */
    char localHostName[64];

    /* We recv into recvbuf... */
    char recvbuf[MAX_READ];
    /* ...then copy to parsebuf, escaping control chars */
    /* (can grow x2 max) */
    char parsebuf[MAX_READ*2];
    /* ...then sprintf into printbuf, adding timestamp (15 chars),
     * host (64), fac.prio (20) to the message */
    /* (growth by: 15 + 64 + 20 + delims = ~110) */
    char printbuf[MAX_READ*2 + 128];
};

static const struct init_globals init_data = {
    .logFilePath = "/var/log/messages",
    .logFD = -1,
#ifdef SYSLOGD_MARK
    .markInterval = 20 * 60,
#endif
    .logLevel = 8,
#if ENABLE_FEATURE_ROTATE_LOGFILE
    .logFileSize = 200 * 1024,
    .logFileRotate = 1,
#endif
#if ENABLE_FEATURE_REMOTE_LOG
    .remoteFD = -1,
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
    .shmid = -1,
    .s_semid = -1,
    .shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024), // default shm size
    .SMwup = { {1, -1, IPC_NOWAIT} },
    .SMwdn = { {0, 0}, {1, 0}, {1, +1} },
#endif
};

#define G (*ptr_to_globals)


/* Options */
enum {
    OPTBIT_mark = 0, // -m
    OPTBIT_nofork, // -n
    OPTBIT_outfile, // -O
    OPTBIT_loglevel, // -l
    OPTBIT_small, // -S
    USE_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,) // -s
    USE_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,) // -b
    USE_FEATURE_REMOTE_LOG(    OPTBIT_remote     ,) // -R
    USE_FEATURE_REMOTE_LOG(    OPTBIT_localtoo   ,) // -L
    USE_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,) // -C

    OPT_mark        = 1 << OPTBIT_mark    ,
    OPT_nofork      = 1 << OPTBIT_nofork  ,
    OPT_outfile     = 1 << OPTBIT_outfile ,
    OPT_loglevel    = 1 << OPTBIT_loglevel,
    OPT_small       = 1 << OPTBIT_small   ,
    OPT_filesize    = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
    OPT_rotatecnt   = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
    OPT_remotelog   = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remote     )) + 0,
    OPT_locallog    = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_localtoo   )) + 0,
    OPT_circularlog = USE_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
};
#define OPTION_STR "m:nO:l:S" \
    USE_FEATURE_ROTATE_LOGFILE("s:" ) \
    USE_FEATURE_ROTATE_LOGFILE("b:" ) \
    USE_FEATURE_REMOTE_LOG(    "R:" ) \
    USE_FEATURE_REMOTE_LOG(    "L"  ) \
    USE_FEATURE_IPC_SYSLOG(    "C::")
#define OPTION_DECL *opt_m, *opt_l \
    USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
    USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
    USE_FEATURE_REMOTE_LOG(    ,*opt_R) \
    USE_FEATURE_IPC_SYSLOG(    ,*opt_C = NULL)
#define OPTION_PARAM &opt_m, &G.logFilePath, &opt_l \
    USE_FEATURE_ROTATE_LOGFILE(,&opt_s) \
    USE_FEATURE_ROTATE_LOGFILE(,&opt_b) \
    USE_FEATURE_REMOTE_LOG(    ,&opt_R) \
    USE_FEATURE_IPC_SYSLOG(    ,&opt_C)


/* circular buffer variables/structures */
#if ENABLE_FEATURE_IPC_SYSLOG

#if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
#error Sorry, you must set the syslogd buffer size to at least 4KB.
#error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
#endif

/* our shared key */
#define KEY_ID ((long)0x414e4547) /* "GENA" */

static void ipcsyslog_cleanup(void)
{
    if (G.shmid != -1) {
        shmdt(G.shbuf);
    }
    if (G.shmid != -1) {
        shmctl(G.shmid, IPC_RMID, NULL);
    }
    if (G.s_semid != -1) {
        semctl(G.s_semid, 0, IPC_RMID, 0);
    }
}

static void ipcsyslog_init(void)
{
    if (DEBUG)
        printf("shmget(%lx, %d,...)\n", KEY_ID, G.shm_size);

    G.shmid = shmget(KEY_ID, G.shm_size, IPC_CREAT | 0644);
    if (G.shmid == -1) {
        bb_perror_msg_and_die("shmget");
    }

    G.shbuf = shmat(G.shmid, NULL, 0);
    if (!G.shbuf) {
        bb_perror_msg_and_die("shmat");
    }

    memset(G.shbuf, 0, G.shm_size);
    G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data) - 1;
    /*G.shbuf->tail = 0;*/

    // we'll trust the OS to set initial semval to 0 (let's hope)
    G.s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
    if (G.s_semid == -1) {
        if (errno == EEXIST) {
            G.s_semid = semget(KEY_ID, 2, 0);
            if (G.s_semid != -1)
                return;
        }
        bb_perror_msg_and_die("semget");
    }
}

/* Write message to shared mem buffer */
static void log_to_shmem(const char *msg, int len)
{
    int old_tail, new_tail;

    if (semop(G.s_semid, G.SMwdn, 3) == -1) {
        bb_perror_msg_and_die("SMwdn");
    }

    /* Circular Buffer Algorithm:
     * --------------------------
     * tail == position where to store next syslog message.
     * tail's max value is (shbuf->size - 1)
     * Last byte of buffer is never used and remains NUL.
     */
    len++; /* length with NUL included */
 again:
    old_tail = G.shbuf->tail;
    new_tail = old_tail + len;
    if (new_tail < G.shbuf->size) {
        /* store message, set new tail */
        memcpy(G.shbuf->data + old_tail, msg, len);
        G.shbuf->tail = new_tail;
    } else {
        /* k == available buffer space ahead of old tail */
        int k = G.shbuf->size - old_tail;
        /* copy what fits to the end of buffer, and repeat */
        memcpy(G.shbuf->data + old_tail, msg, k);
        msg += k;
        len -= k;
        G.shbuf->tail = 0;
        goto again;
    }
    if (semop(G.s_semid, G.SMwup, 1) == -1) {
        bb_perror_msg_and_die("SMwup");
    }
    if (DEBUG)
        printf("tail:%d\n", G.shbuf->tail);
}
#else
void ipcsyslog_cleanup(void);
void ipcsyslog_init(void);
void log_to_shmem(const char *msg);
#endif /* FEATURE_IPC_SYSLOG */


/* Print a message to the log file. */
static void log_locally(char *msg)
{
    struct flock fl;
    int len = strlen(msg);

#if ENABLE_FEATURE_IPC_SYSLOG
    if ((option_mask32 & OPT_circularlog) && G.shbuf) {
        log_to_shmem(msg, len);
        return;
    }
#endif
    if (G.logFD >= 0) {
        time_t cur;
        time(&cur);
        if (G.last_log_time != cur) {
            G.last_log_time = cur; /* reopen log file every second */
            close(G.logFD);
            goto reopen;
        }
    } else {
 reopen:
        G.logFD = device_open(G.logFilePath, O_WRONLY | O_CREAT
                    | O_NOCTTY | O_APPEND | O_NONBLOCK);
        if (G.logFD < 0) {
            /* cannot open logfile? - print to /dev/console then */
            int fd = device_open(_PATH_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
            if (fd < 0)
                fd = 2; /* then stderr, dammit */
            full_write(fd, msg, len);
            if (fd != 2)
                close(fd);
            return;
        }
#if ENABLE_FEATURE_ROTATE_LOGFILE
        {
            struct stat statf;
            G.isRegular = (fstat(G.logFD, &statf) == 0 && S_ISREG(statf.st_mode));
            /* bug (mostly harmless): can wrap around if file > 4gb */
            G.curFileSize = statf.st_size;
        }
#endif
    }

    fl.l_whence = SEEK_SET;
    fl.l_start = 0;
    fl.l_len = 1;
    fl.l_type = F_WRLCK;
    fcntl(G.logFD, F_SETLKW, &fl);

#if ENABLE_FEATURE_ROTATE_LOGFILE
    if (G.logFileSize && G.isRegular && G.curFileSize > G.logFileSize) {
        if (G.logFileRotate) { /* always 0..99 */
            int i = strlen(G.logFilePath) + 3 + 1;
            char oldFile[i];
            char newFile[i];
            i = G.logFileRotate - 1;
            /* rename: f.8 -> f.9; f.7 -> f.8; ... */
            while (1) {
                sprintf(newFile, "%s.%d", G.logFilePath, i);
                if (i == 0) break;
                sprintf(oldFile, "%s.%d", G.logFilePath, --i);
                rename(oldFile, newFile);
            }
            /* newFile == "f.0" now */
            rename(G.logFilePath, newFile);
            fl.l_type = F_UNLCK;
            fcntl(G.logFD, F_SETLKW, &fl);
            close(G.logFD);
            goto reopen;
        }
        ftruncate(G.logFD, 0);
    }
    G.curFileSize +=
#endif
                    full_write(G.logFD, msg, len);
    fl.l_type = F_UNLCK;
    fcntl(G.logFD, F_SETLKW, &fl);
}

static void parse_fac_prio_20(int pri, char *res20)
{
    const CODE *c_pri, *c_fac;

    if (pri != 0) {
        c_fac = facilitynames;
        while (c_fac->c_name) {
            if (c_fac->c_val != (LOG_FAC(pri) << 3)) {
                c_fac++; continue;
            }
            /* facility is found, look for prio */
            c_pri = prioritynames;
            while (c_pri->c_name) {
                if (c_pri->c_val != LOG_PRI(pri)) {
                    c_pri++; continue;
                }
                snprintf(res20, 20, "%s.%s",
                        c_fac->c_name, c_pri->c_name);
                return;
            }
            /* prio not found, bail out */
            break;
        }
        snprintf(res20, 20, "<%d>", pri);
    }
}

/* len parameter is used only for "is there a timestamp?" check.
 * NB: some callers cheat and supply 0 when they know
 * that there is no timestamp, short-cutting the test. */
static void timestamp_and_log(int pri, char *msg, int len)
{
    char *timestamp;

    if (len < 16 || msg[3] != ' ' || msg[6] != ' '
     || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
    ) {
        time_t now;
        time(&now);
        timestamp = ctime(&now) + 4;
    } else {
        timestamp = msg;
        msg += 16;
    }
    timestamp[15] = '\0';

    /* Log message locally (to file or shared mem) */
    if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
        if (LOG_PRI(pri) < G.logLevel) {
            if (option_mask32 & OPT_small)
                sprintf(G.printbuf, "%s %s\n", timestamp, msg);
            else {
                char res[20];
                parse_fac_prio_20(pri, res);
                sprintf(G.printbuf, "%s %s %s %s\n", timestamp, G.localHostName, res, msg);
            }
            log_locally(G.printbuf);
        }
    }
}

static void split_escape_and_log(char *tmpbuf, int len)
{
    char *p = tmpbuf;

    tmpbuf += len;
    while (p < tmpbuf) {
        char c;
        char *q = G.parsebuf;
        int pri = (LOG_USER | LOG_NOTICE);

        if (*p == '<') {
            /* Parse the magic priority number */
            pri = bb_strtou(p + 1, &p, 10);
            if (*p == '>') p++;
            if (pri & ~(LOG_FACMASK | LOG_PRIMASK)) {
                pri = (LOG_USER | LOG_NOTICE);
            }
        }

        while ((c = *p++)) {
            if (c == '\n')
                c = ' ';
            if (!(c & ~0x1f) && c != '\t') {
                *q++ = '^';
                c += '@'; /* ^@, ^A, ^B... */
            }
            *q++ = c;
        }
        *q = '\0';
        /* Now log it */
        timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
    }
}

static void quit_signal(int sig)
{
    timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)"syslogd exiting", 0);
    puts("syslogd exiting");
    if (ENABLE_FEATURE_IPC_SYSLOG)
        ipcsyslog_cleanup();
    exit(1);
}

#ifdef SYSLOGD_MARK
static void do_mark(int sig)
{
    if (G.markInterval) {
        timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)"-- MARK --", 0);
        alarm(G.markInterval);
    }
}
#endif

static void do_syslogd(void) ATTRIBUTE_NORETURN;
static void do_syslogd(void)
{
    struct sockaddr_un sunx;
    int sock_fd;
    fd_set fds;
    char *dev_log_name;

    /* Set up signal handlers */
    signal(SIGINT, quit_signal);
    signal(SIGTERM, quit_signal);
    signal(SIGQUIT, quit_signal);
    signal(SIGHUP, SIG_IGN);
    signal(SIGCHLD, SIG_IGN);
#ifdef SIGCLD
    signal(SIGCLD, SIG_IGN);
#endif
#ifdef SYSLOGD_MARK
    signal(SIGALRM, do_mark);
    alarm(G.markInterval);
#endif
    remove_pidfile("/var/run/syslogd.pid");

    memset(&sunx, 0, sizeof(sunx));
    sunx.sun_family = AF_UNIX;
    strcpy(sunx.sun_path, "/dev/log");

    /* Unlink old /dev/log or object it points to. */
    /* (if it exists, bind will fail) */
    logmode = LOGMODE_NONE;
    dev_log_name = xmalloc_readlink_or_warn("/dev/log");
    logmode = LOGMODE_STDIO;
    if (dev_log_name) {
        int fd = xopen(".", O_NONBLOCK);
        xchdir("/dev");
        /* we do not check whether this is a link also */
        unlink(dev_log_name);
        fchdir(fd);
        close(fd);
        safe_strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
        free(dev_log_name);
    } else {
        unlink("/dev/log");
    }

    sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
    xbind(sock_fd, (struct sockaddr *) &sunx, sizeof(sunx));

    if (chmod("/dev/log", 0666) < 0) {
        bb_perror_msg_and_die("cannot set permission on /dev/log");
    }
    if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
        ipcsyslog_init();
    }

    timestamp_and_log(LOG_SYSLOG | LOG_INFO,
            (char*)"syslogd started: BusyBox v" BB_VER, 0);

    for (;;) {
        FD_ZERO(&fds);
        FD_SET(sock_fd, &fds);

        if (select(sock_fd + 1, &fds, NULL, NULL, NULL) < 0) {
            if (errno == EINTR) {
                /* alarm may have happened */
                continue;
            }
            bb_perror_msg_and_die("select");
        }

        if (FD_ISSET(sock_fd, &fds)) {
            int i;
            i = recv(sock_fd, G.recvbuf, MAX_READ - 1, 0);
            if (i <= 0)
                bb_perror_msg_and_die("UNIX socket error");
            /* TODO: maybe suppress duplicates? */
#if ENABLE_FEATURE_REMOTE_LOG
            /* We are not modifying log messages in any way before send */
            /* Remote site cannot trust _us_ anyway and need to do validation again */
            if (G.remoteAddr) {
                if (-1 == G.remoteFD) {
                    G.remoteFD = socket(G.remoteAddr->sa.sa_family, SOCK_DGRAM, 0);
                }
                if (-1 != G.remoteFD) {
                    /* send message to remote logger, ignore possible error */
                    sendto(G.remoteFD, G.recvbuf, i, MSG_DONTWAIT,
                        &G.remoteAddr->sa, G.remoteAddr->len);
                }
            }
#endif
            G.recvbuf[i] = '\0';
            split_escape_and_log(G.recvbuf, i);
        } /* FD_ISSET() */
    } /* for */
}

int syslogd_main(int argc, char **argv);
int syslogd_main(int argc, char **argv)
{
    char OPTION_DECL;
    char *p;

    PTR_TO_GLOBALS = memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data));

    /* do normal option parsing */
    opt_complementary = "=0"; /* no non-option params */
    getopt32(argv, OPTION_STR, OPTION_PARAM);
#ifdef SYSLOGD_MARK
    if (option_mask32 & OPT_mark) // -m
        G.markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
#endif
    //if (option_mask32 & OPT_nofork) // -n
    //if (option_mask32 & OPT_outfile) // -O
    if (option_mask32 & OPT_loglevel) // -l
        G.logLevel = xatou_range(opt_l, 1, 8);
    //if (option_mask32 & OPT_small) // -S
#if ENABLE_FEATURE_ROTATE_LOGFILE
    if (option_mask32 & OPT_filesize) // -s
        G.logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
    if (option_mask32 & OPT_rotatecnt) // -b
        G.logFileRotate = xatou_range(opt_b, 0, 99);
#endif
#if ENABLE_FEATURE_REMOTE_LOG
    if (option_mask32 & OPT_remotelog) { // -R
        G.remoteAddr = xhost2sockaddr(opt_R, 514);
    }
    //if (option_mask32 & OPT_locallog) // -L
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
    if (opt_C) // -Cn
        G.shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;
#endif

    /* If they have not specified remote logging, then log locally */
    if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_remotelog))
        option_mask32 |= OPT_locallog;

    /* Store away localhost's name before the fork */
    gethostname(G.localHostName, sizeof(G.localHostName));
    p = strchr(G.localHostName, '.');
    if (p) {
        *p = '\0';
    }

    if (!(option_mask32 & OPT_nofork)) {
        bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
    }
    umask(0);
    write_pidfile("/var/run/syslogd.pid");
    do_syslogd();
    /* return EXIT_SUCCESS; */
}