mpm_common.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

     * keep trying because maybe we'll never successfully
     * write again...  but then maybe we'll leave would-be
     * readers stranded (a number of them could be tied up for
     * a while serving time-consuming requests)
     */
    for (i = 0; i < num && rv == APR_SUCCESS; i++) {
        rv = dummy_connection(pod);
    }
}
#endif /* #ifdef AP_MPM_USES_POD */

/* standard mpm configuration handling */
#ifdef AP_MPM_WANT_SET_PIDFILE
const char *ap_pid_fname = NULL;

const char *ap_mpm_set_pidfile(cmd_parms *cmd, void *dummy,
                               const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    if (cmd->server->is_virtual) {
        return "PidFile directive not allowed in <VirtualHost>";
    }

    ap_pid_fname = arg;
    return NULL;
}
#endif

#ifdef AP_MPM_WANT_SET_SCOREBOARD
const char * ap_mpm_set_scoreboard(cmd_parms *cmd, void *dummy,
                                   const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_scoreboard_fname = arg;
    return NULL;
}
#endif

#ifdef AP_MPM_WANT_SET_LOCKFILE
const char *ap_lock_fname = NULL;

const char *ap_mpm_set_lockfile(cmd_parms *cmd, void *dummy,
                                const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_lock_fname = arg;
    return NULL;
}
#endif

#ifdef AP_MPM_WANT_SET_MAX_REQUESTS
int ap_max_requests_per_child = 0;

const char *ap_mpm_set_max_requests(cmd_parms *cmd, void *dummy,
                                    const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    ap_max_requests_per_child = atoi(arg);

    return NULL;
}
#endif

#ifdef AP_MPM_WANT_SET_COREDUMPDIR
char ap_coredump_dir[MAX_STRING_LEN];
int ap_coredumpdir_configured;

const char *ap_mpm_set_coredumpdir(cmd_parms *cmd, void *dummy,
                                   const char *arg)
{
    apr_status_t rv;
    apr_finfo_t finfo;
    const char *fname;
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    fname = ap_server_root_relative(cmd->pool, arg);
    if (!fname) {
        return apr_pstrcat(cmd->pool, "Invalid CoreDumpDirectory path ", 
                           arg, NULL);
    }
    if ((rv = apr_stat(&finfo, fname, APR_FINFO_TYPE, cmd->pool)) != APR_SUCCESS) {
        return apr_pstrcat(cmd->pool, "CoreDumpDirectory ", fname,
                           " does not exist", NULL);
    }
    if (finfo.filetype != APR_DIR) {
        return apr_pstrcat(cmd->pool, "CoreDumpDirectory ", fname,
                           " is not a directory", NULL);
    }
    apr_cpystrn(ap_coredump_dir, fname, sizeof(ap_coredump_dir));
    ap_coredumpdir_configured = 1;
    return NULL;
}
#endif

#ifdef AP_MPM_WANT_SET_ACCEPT_LOCK_MECH
apr_lockmech_e ap_accept_lock_mech = APR_LOCK_DEFAULT;

const char ap_valid_accept_mutex_string[] =
    "Valid accept mutexes for this platform and MPM are: default"
#if APR_HAS_FLOCK_SERIALIZE
    ", flock"
#endif
#if APR_HAS_FCNTL_SERIALIZE
    ", fcntl"
#endif
#if APR_HAS_SYSVSEM_SERIALIZE && !defined(PERCHILD_MPM)
    ", sysvsem"
#endif
#if APR_HAS_POSIXSEM_SERIALIZE
    ", posixsem"
#endif
#if APR_HAS_PROC_PTHREAD_SERIALIZE
    ", pthread"
#endif
    ".";

AP_DECLARE(const char *) ap_mpm_set_accept_lock_mech(cmd_parms *cmd,
                                                     void *dummy,
                                                     const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    if (!strcasecmp(arg, "default")) {
        ap_accept_lock_mech = APR_LOCK_DEFAULT;
    }
#if APR_HAS_FLOCK_SERIALIZE
    else if (!strcasecmp(arg, "flock")) {
        ap_accept_lock_mech = APR_LOCK_FLOCK;
    }
#endif
#if APR_HAS_FCNTL_SERIALIZE
    else if (!strcasecmp(arg, "fcntl")) {
        ap_accept_lock_mech = APR_LOCK_FCNTL;
    }
#endif

    /* perchild can't use SysV sems because the permissions on the accept
     * mutex can't be set to allow all processes to use the mutex and
     * at the same time keep all users from being able to dink with the
     * mutex
     */
#if APR_HAS_SYSVSEM_SERIALIZE && !defined(PERCHILD_MPM)
    else if (!strcasecmp(arg, "sysvsem")) {
        ap_accept_lock_mech = APR_LOCK_SYSVSEM;
    }
#endif
#if APR_HAS_POSIXSEM_SERIALIZE
    else if (!strcasecmp(arg, "posixsem")) {
        ap_accept_lock_mech = APR_LOCK_POSIXSEM;
    }
#endif
#if APR_HAS_PROC_PTHREAD_SERIALIZE
    else if (!strcasecmp(arg, "pthread")) {
        ap_accept_lock_mech = APR_LOCK_PROC_PTHREAD;
    }
#endif
    else {
        return apr_pstrcat(cmd->pool, arg, " is an invalid mutex mechanism; ",
                           ap_valid_accept_mutex_string, NULL);
    }
    return NULL;
}

#endif

#ifdef AP_MPM_WANT_SIGNAL_SERVER

static const char *dash_k_arg;

static int send_signal(pid_t pid, int sig)
{
    if (kill(pid, sig) < 0) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, errno, NULL,
                     "sending signal to server");
        return 1;
    }
    return 0;
}

int ap_signal_server(int *exit_status, apr_pool_t *pconf)
{
    apr_status_t rv;
    pid_t otherpid;
    int running = 0;
    int have_pid_file = 0;
    const char *status;
    
    *exit_status = 0;

    rv = ap_read_pid(pconf, ap_pid_fname, &otherpid);
    if (rv != APR_SUCCESS) {
        if (rv != APR_ENOENT) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, rv, NULL,
                         "Error retrieving pid file %s", ap_pid_fname);
            *exit_status = 1;
            return 1;
        }
        status = "httpd (no pid file) not running";
    }
    else {
        have_pid_file = 1;
        if (kill(otherpid, 0) == 0) {
            running = 1;
            status = apr_psprintf(pconf, 
                                  "httpd (pid %" APR_PID_T_FMT ") already "
                                  "running", otherpid);
        }
        else {
            status = apr_psprintf(pconf,
                                  "httpd (pid %" APR_PID_T_FMT "?) not running",
                                  otherpid);
        }
    }

    if (!strcmp(dash_k_arg, "start")) {
        if (running) {
            printf("%s\n", status);
            return 1;
        }
    }

    if (!strcmp(dash_k_arg, "stop")) {
        if (!running) {
            printf("%s\n", status);
        }
        else {
            send_signal(otherpid, SIGTERM);
        }
        return 1;
    }

    if (!strcmp(dash_k_arg, "restart")) {
        if (!running) {
            printf("httpd not running, trying to start\n");
        }
        else {
            *exit_status = send_signal(otherpid, SIGHUP);
            return 1;
        }
    }

    if (!strcmp(dash_k_arg, "graceful")) {
        if (!running) {
            printf("httpd not running, trying to start\n");
        }
        else {
            *exit_status = send_signal(otherpid, SIGUSR1);
            return 1;
        }
    }

    return 0;
}

void ap_mpm_rewrite_args(process_rec *process)
{
    apr_array_header_t *mpm_new_argv;
    apr_status_t rv;
    apr_getopt_t *opt;
    char optbuf[3];
    const char *optarg;
    int fixed_args;

    mpm_new_argv = apr_array_make(process->pool, process->argc,
                                  sizeof(const char **));
    *(const char **)apr_array_push(mpm_new_argv) = process->argv[0];
    fixed_args = mpm_new_argv->nelts;
    apr_getopt_init(&opt, process->pool, process->argc, process->argv);
    opt->errfn = NULL;
    optbuf[0] = '-';
    /* option char returned by apr_getopt() will be stored in optbuf[1] */
    optbuf[2] = '\0';
    while ((rv = apr_getopt(opt, "k:" AP_SERVER_BASEARGS,
                            optbuf + 1, &optarg)) == APR_SUCCESS) {
        switch(optbuf[1]) {
        case 'k':
            if (!dash_k_arg) {
                if (!strcmp(optarg, "start") || !strcmp(optarg, "stop") ||
                    !strcmp(optarg, "restart") || !strcmp(optarg, "graceful")) {
                    dash_k_arg = optarg;
                    break;
                }
            }
        default:
            *(const char **)apr_array_push(mpm_new_argv) =
                apr_pstrdup(process->pool, optbuf);
            if (optarg) {
                *(const char **)apr_array_push(mpm_new_argv) = optarg;
            }
        }
    }

    /* back up to capture the bad argument */
    if (rv == APR_BADCH || rv == APR_BADARG) {
        opt->ind--;
    }

    while (opt->ind < opt->argc) {
        *(const char **)apr_array_push(mpm_new_argv) =
            apr_pstrdup(process->pool, opt->argv[opt->ind++]);
    }

    process->argc = mpm_new_argv->nelts;
    process->argv = (const char * const *)mpm_new_argv->elts;

    if (dash_k_arg) {
        APR_REGISTER_OPTIONAL_FN(ap_signal_server);
    }
}

#endif /* AP_MPM_WANT_SIGNAL_SERVER */

#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
apr_uint32_t ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;

const char *ap_mpm_set_max_mem_free(cmd_parms *cmd, void *dummy,
	                            const char *arg)
{
    long value;
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }
    
    value = strtol(arg, NULL, 0);
    if (value < 0 || errno == ERANGE)
        return apr_pstrcat(cmd->pool, "Invalid MaxMemFree value: ", 
                           arg, NULL);

    ap_max_mem_free = (apr_uint32_t)value * 1024;

    return NULL;
}

#endif /* AP_MPM_WANT_SET_MAX_MEM_FREE */

#ifdef AP_MPM_WANT_FATAL_SIGNAL_HANDLER

static pid_t parent_pid, my_pid;
apr_pool_t *pconf;

#if AP_ENABLE_EXCEPTION_HOOK

static int exception_hook_enabled;

const char *ap_mpm_set_exception_hook(cmd_parms *cmd, void *dummy,
                                      const char *arg)
{
    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
    if (err != NULL) {
        return err;
    }

    if (cmd->server->is_virtual) {
	return "EnableExceptionHook directive not allowed in <VirtualHost>";
    }

    if (strcasecmp(arg, "on") == 0) {
        exception_hook_enabled = 1;
    }
    else if (strcasecmp(arg, "off") == 0) {
        exception_hook_enabled = 0;
    }
    else {
        return "parameter must be 'on' or 'off'";
    }

    return NULL;
}

APR_HOOK_STRUCT(
    APR_HOOK_LINK(fatal_exception)
)

AP_IMPLEMENT_HOOK_RUN_ALL(int, fatal_exception,
                          (ap_exception_info_t *ei), (ei), OK, DECLINED)

static void run_fatal_exception_hook(int sig)
{
    ap_exception_info_t ei = {0};

    if (exception_hook_enabled &&
        geteuid() != 0 && 
        my_pid != parent_pid) {
        ei.sig = sig;
        ei.pid = my_pid;
        ap_run_fatal_exception(&ei);
    }
}
#endif /* AP_ENABLE_EXCEPTION_HOOK */

/* handle all varieties of core dumping signals */
static void sig_coredump(int sig)
{
    apr_filepath_set(ap_coredump_dir, pconf);
    apr_signal(sig, SIG_DFL);
#if AP_ENABLE_EXCEPTION_HOOK
    run_fatal_exception_hook(sig);
#endif
    /* linuxthreads issue calling getpid() here:
     *   This comparison won't match if the crashing thread is
     *   some module's thread that runs in the parent process.
     *   The fallout, which is limited to linuxthreads:
     *   The special log message won't be written when such a
     *   thread in the parent causes the parent to crash.
     */
    if (getpid() == parent_pid) {
        ap_log_error(APLOG_MARK, APLOG_NOTICE,
                     0, ap_server_conf,
                     "seg fault or similar nasty error detected "
                     "in the parent process");
        /* XXX we can probably add some rudimentary cleanup code here,
         * like getting rid of the pid file.  If any additional bad stuff
         * happens, we are protected from recursive errors taking down the
         * system since this function is no longer the signal handler   GLA
         */
    }
    kill(getpid(), sig);
    /* At this point we've got sig blocked, because we're still inside
     * the signal handler.  When we leave the signal handler it will
     * be unblocked, and we'll take the signal... and coredump or whatever
     * is appropriate for this particular Unix.  In addition the parent
     * will see the real signal we received -- whereas if we called
     * abort() here, the parent would only see SIGABRT.
     */
}

apr_status_t ap_fatal_signal_child_setup(server_rec *s)
{
    my_pid = getpid();
    return APR_SUCCESS;
}

apr_status_t ap_fatal_signal_setup(server_rec *s, apr_pool_t *in_pconf)
{
#ifndef NO_USE_SIGACTION
    struct sigaction sa;

    sigemptyset(&sa.sa_mask);
    
#if defined(SA_ONESHOT)
    sa.sa_flags = SA_ONESHOT;
#elif defined(SA_RESETHAND)
    sa.sa_flags = SA_RESETHAND;
#else
    sa.sa_flags = 0;
#endif

    sa.sa_handler = sig_coredump;
    if (sigaction(SIGSEGV, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, s, "sigaction(SIGSEGV)");
#ifdef SIGBUS
    if (sigaction(SIGBUS, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, s, "sigaction(SIGBUS)");
#endif
#ifdef SIGABORT
    if (sigaction(SIGABORT, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, s, "sigaction(SIGABORT)");
#endif
#ifdef SIGABRT
    if (sigaction(SIGABRT, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, s, "sigaction(SIGABRT)");
#endif
#ifdef SIGILL
    if (sigaction(SIGILL, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, s, "sigaction(SIGILL)");
#endif

#else /* NO_USE_SIGACTION */
    
    apr_signal(SIGSEGV, sig_coredump);
#ifdef SIGBUS
    apr_signal(SIGBUS, sig_coredump);
#endif /* SIGBUS */
#ifdef SIGABORT
    apr_signal(SIGABORT, sig_coredump);
#endif /* SIGABORT */
#ifdef SIGABRT
    apr_signal(SIGABRT, sig_coredump);
#endif /* SIGABRT */
#ifdef SIGILL
    apr_signal(SIGILL, sig_coredump);
#endif /* SIGILL */

#endif /* NO_USE_SIGACTION */

    pconf = in_pconf;
    parent_pid = my_pid = getpid();

    return APR_SUCCESS;
}

#endif /* AP_MPM_WANT_FATAL_SIGNAL_HANDLER */