UNP函数笔记十: 守护进程和inetd超级服务器

第十三章  守护进程和inetd超级服务器:

#include <syslog.h>void syslog(int priority, const char * format, ...);#include <syslog.h>void openlog(const char * ident, int option, int facility);void closelog(void);    option:        LOG_CONS,   LOG_NDELAY, LOG_NOWAIT,         LOG_ODELAY, LOG_PERROR, LOG_PID    facility:        LOG_AUTH,   LOG_AUTHPRIV, LOG_CRON,   LOG_DAEMON,         LOG_FTP,    LOG_KERN,     LOG_LOCAL0, LOG_LOCAL1,         LOG_LOCAL2, LOG_LOCAL3,   LOG_LOCAL4, LOG_LOCAL5,         LOG_LOCAL6, LOG_LOCAL7,   LOG_LPR,    LOG_MAIL,         LOG_NEWS,   LOG_SYSLOG,   LOG_USER,   LOG_UUCP    level:        LOG_EMERG,   LOG_ALERT,  LOG_CRIT, LOG_ERR,         LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG    priority:        facility | level    %m: ("%s", strerror(errno))

示例:

#include <fcntl.h>#include <unistd.h>#include <syslog.h>#include "my_signal.h"#define MAXFD  64int daemon_init(const char * pname, int facility){    int    i;    pid_t  pid;    if ((pid = fork()) < 0) {        return(-1);    }    else if (pid > 0) {        _exit(0);  /* parent terminates */    }    /* child 1 continues... */    if (setsid() == -1) {  /* become session leader */        return(-1);    }    my_signal(SIGHUP, SIG_IGN);    if ((pid = fork()) < 0) {        return(-1);    }    else if (pid > 0) {        _exit(0);  /* child 1 terminates */    }    /* child 2 continues... */    chdir("/");  /* change working directory */    /* close off file descriptors */    for (i = 0; i < MAXFD; i++) {        close(i);    }    /* redirect stdin, stdout, and stderr to /dev/null */    open("/dev/null", O_RDONLY);    open("/dev/null", O_RDWR);    open("/dev/null", O_RDWR);    openlog(pname, LOG_PID, facility);    return (0);  /* success */}

#include <syslog.h>void daemon_inetd(const char * pname, int facility){    openlog(pname, LOG_PID, facility);}

#include <time.h>#include <errno.h>#include <stdlib.h>#include <string.h>#include "sock_ntop.h"#include "tcp_listen.h"#include "daemon_init.h"#define MAXLINE 4096intmain(int argc, char ** argv){    ssize_t           n;    int               listenfd;    int               connfd;    socklen_t         addrlen;    socklen_t         len;    struct sockaddr * cliaddr;    char            * ptr;    char              buff[MAXLINE];    time_t            ticks;    if (argc < 2 || argc > 3) {        printf("usage: daytimetcpsrv2 [ <host> ] <service or port>\n");        exit(1);    }    daemon_init(argv[0], 0);    /* need change "printf" to "syslog" in tcp_listen */    if (argc == 2) {        listenfd = tcp_listen(NULL, argv[1], &addrlen);    }    else {        listenfd = tcp_listen(argv[1], argv[2], &addrlen);    }    if ((cliaddr = (struct sockaddr *)malloc(addrlen)) == NULL) {        syslog(LOG_ERR, "malloc failed: %s", strerror(errno));        exit(1);    }    for ( ; ; ) {        len = addrlen;        if ((connfd = accept(listenfd, cliaddr, &len)) == -1) {            syslog(LOG_ERR, "accept error: %s", strerror(errno));            exit(1);        }        if ((ptr = sock_ntop(cliaddr, len)) == NULL) {            syslog(LOG_ERR, "sock_notp error: %s", strerror(errno));            exit(1);        }        syslog(LOG_INFO, "connection from %s", ptr);        ticks = time(NULL);        snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));        n = strlen(buff);        if (write(connfd, buff, n) != n) {            syslog(LOG_ERR, "write error: %s", strerror(errno));            exit(1);        }        if (close(connfd) == -1) {            syslog(LOG_ERR, "close error: %s", strerror(errno));            exit(1);        }    }}

#include <time.h>#include <errno.h>#include <stdlib.h>#include <string.h>#include "sock_ntop.h"#include "daemon_inetd.h"#define MAXLINE 4096int main(int argc, char ** argv){    ssize_t           n;    socklen_t         len;    struct sockaddr * cliaddr;    char            * ptr;    char              buff[MAXLINE];    time_t            ticks;    daemon_inetd(argv[0], 0);    cliaddr = (struct sockaddr *)malloc(sizeof(struct sockaddr_storage));    if (cliaddr == NULL) {        syslog(LOG_ERR, "malloc failed: %s", strerror(errno));        exit(1);    }    len = sizeof(struct sockaddr_storage);    if (getpeername(0, cliaddr, &len) == -1) {        syslog(LOG_ERR, "getpeername error: %s", strerror(errno));        exit(1);    }    if ((ptr = sock_ntop(cliaddr, len)) == NULL) {        syslog(LOG_ERR, "sock_notp error: %s", strerror(errno));        exit(1);    }    syslog(LOG_INFO, "connection from %s", ptr);    ticks = time(NULL);    snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));    n = strlen(buff);    if (write(0, buff, n) != n) {        syslog(LOG_ERR, "write error: %s", strerror(errno));        exit(1);    }    if (close(0) == -1) {  /* close TCP connection */        syslog(LOG_ERR, "close error: %s", strerror(errno));        exit(1);    }    free(cliaddr);     exit(0);}