cron.c

这是一个我自己仿照linux下cron程序写的精简版的cron

#include <sys/time.h>
#include <time.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdio.h>
#include <syslog.h>
#include <errno.h>
#include <sys/file.h>
#include <pwd.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include "cron.h"


static char ProgramName[]="my_cron";
//static int minute_rec[MINUTE_RANGE];
//static int hour_rec[HOUR_RANGE];
//static int day_of_mon_rec[DAY_OF_MOU_RANGE];
//static int mon_of_year_rec[MONTH_OF_YEAR_RANGE];
//static int day_of_week_rec[MONTH_OF_YEAR_RANGE];
int timerunning;
date_rec *head = NULL;




int daemon_init()
{
        pid_t pid;

        if( (pid = fork()) < 0)
                return -1;
        else if(pid != 0) /* parent exit */
                exit(0);

        setsid();
        chdir("/");
        umask(0);
        /* close stdin, stdout and stderr*/
        freopen("/dev/null", "r", stdin);
        freopen("/dev/null", "w", stdout);
        freopen("/dev/null", "w", stderr);
        return 0;
}




void log_err(char *error)
{
        openlog(ProgramName,LOG_PID,LOG_USER);
        syslog(LOG_ERR, error);
}


static int get_next_token(char *buffer,char *line,int *pt)
{
        int i = 0;
        while (line[*pt] == ' ' || line[*pt] == '\t') {
                (*pt)++;
        }

        if (line[*pt] == ',') {
                (*pt)++;
                return 4;
        } else if (isdigit(line[*pt])) {
                buffer[i++] = line[*pt];
                (*pt)++;
                while (isdigit(line[*pt])) {
                        buffer[i++] = line[*pt];
                        (*pt)++;
                }
                if (line[*pt] == ',') {
                        buffer[i] = '\0';
                        (*pt)++;
                        return 3;
                } else if (line[*pt] == ' ' || line[*pt] == '\t') {
                        buffer[i] = '\0';
                        while(line[*pt] == ' ' || line[*pt] == '\t')
                                (*pt)++;
                        if(line[*pt] == ',') {
                                (*pt)++;
                                return 3;
                        } else
                                return 1;
                } else {
                        return 5;
                }
        } else if (line[*pt] == '*') {
                (*pt)++;
                return 2;
        } else {
                return 5;
        }
}


static int add_rec()
{
        char n[MAX_LINE];
        date_rec * temp;
        snprintf(n,MAX_LINE,"%s: malloc fail to add new record!",ProgramName);
        if((temp = (date_rec *)malloc(sizeof(date_rec))) == NULL) {
                log_err(n);
                return(0);
        }
        memset(temp,0,sizeof(date_rec));
        temp->next = NULL;
        temp->next = head;
        head = temp;
        return 1;
}

static void del_rec()
{
        date_rec * p;
        if(head == NULL)
                return;
        else {
                p = head;
                while(head) {
                        p = head->next;
                        free(head);
                        head = p;
                }
        }
        head = NULL;
}





static int check_number(char *buffer,int i)
{
        int num;
        int value[5][2] = {{0,59},{0,23},{1,31},{1,12},{0,6}};

        num = atoi(buffer);
        if(num >= value[i][0] && num <= value[i][1])
                return num;
        else
                return -1;
}



static void record_it(date_rec * d,int i,int num)
{
        int flag = 1;
        if(num == '*')
                flag = 0;
        switch(i) {
                case 0:
                        if(flag)
                                //d->minute_rec[num] = 1;
                                MARK(d->minute_rec,num);
                        else
                                //memset(d->minute_rec,1,sizeof(d->minute_rec));
                                SET(d->minute_rec);
                        break;
                case 1:
                        if(flag)
                                //d->hour_rec[num] = 1;
                                MARK(d->hour_rec,num);
                        else
                                //memset(d->hour_rec,1,sizeof(d->hour_rec));
                                SET(d->hour_rec);
                        break;
                case 2:
                        if(flag)
                                //d->day_of_mon_rec[num] = 1;
                                MARK(d->day_of_mon_rec,num);
                        else
                                //memset(d->day_of_mon_rec,1,sizeof(d->day_of_mon_rec));
                                SET(d->day_of_mon_rec);
                        break;
                case 3:
                        if(flag)
                                //d->mon_of_year_rec[num] = 1;
                                MARK(d->mon_of_year_rec,num);
                        else
                                //memset(d->mon_of_year_rec,1,sizeof(d->mon_of_year_rec));
                                SET(d->mon_of_year_rec);
                        break;
                case 4:
                        if(flag)
                                //d->day_of_week_rec[num] = 1;
                                MARK(d->day_of_week_rec,num);
                        else
                                //memset(d->day_of_week_rec,1,sizeof(d->day_of_week_rec));
                                SET(d->day_of_week_rec);
                        break;
                default:
                        break;
        }
}


int load_rec()
{
        date_rec * current_date;
        char n[MAX_FNAME];
        char error[MAX_LINE];
        char *User;
        FILE *crontab;
        struct passwd *pw;
        /*----------------------------------------------*/
        char line[MAX_LINE];
        char buffer[MAX_FNAME];
        char * f;
        int pt = 0;
        int i = 0;
        int flag = 0;
        int can_gets = 0;
        int finish = 0;
        int num = 0;
        int temp;


        /* open the crontab */
        if (!(pw = getpwuid(getuid()))) {
                snprintf(error,MAX_LINE,"%s: your UID isn't in the passwd file.\n",
                         ProgramName);
                log_err(error);
                return(0);
        }
        /* dup the user id*/
        if (((User=strdup(pw->pw_name)) == NULL)) {
                snprintf(error,MAX_LINE, "%s: Memory allocation error\n",ProgramName);
                log_err(error);
                return(0);
        }