?? sig3.c
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/********** *sig3.c * **********/#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/stat.h>#include <signal.h>#include <pwd.h>#include <unistd.h>#include <errno.h>#define MAIL_DIR "/var/spool/mail/" #define SLEEP_TIME 10#define MAX_FILENAME 255unsigned char notifyflag=1;long get_file_size(const char *filename){ struct stat buf; if(stat(filename,&buf)==-1) { if(errno==ENOENT)return 0; else return -1; } return (long)buf.st_size;}void send_mail_notify(void){ fprintf(stderr,"New mail has arrived\007\n");}void turn_on_notify(int signo){notifyflag=1;}void turn_off_notify(int signo){notifyflag=0;}int check_mail(const char *filename){ long old_mail_size,new_mail_size; sigset_t blockset,emptyset; sigemptyset(&blockset); sigemptyset(&emptyset); sigaddset(&blockset,SIGUSR1); sigaddset(&blockset,SIGUSR2); old_mail_size=get_file_size(filename); if(old_mail_size<0) return 1; if(old_mail_size>0) send_mail_notify(); sleep(SLEEP_TIME); while(1) { if(sigprocmask(SIG_BLOCK,&blockset,NULL)<0) return 1; while(notifyflag==0) sigsuspend(&emptyset); if(sigprocmask(SIG_SETMASK,&emptyset,NULL)<0) return 1; new_mail_size=get_file_size(filename); if(new_mail_size>old_mail_size) send_mail_notify(); old_mail_size=new_mail_size; sleep(SLEEP_TIME); }}int main(void){ char mailfile[MAX_FILENAME]; struct sigaction newact; struct passwd *pw; if((pw=getpwuid(getuid()))==NULL) { fprintf(stderr,"Get Login Name Error:%s\n\a",strerror(errno)); exit(1); } strcpy(mailfile,MAIL_DIR); strcat(mailfile,pw->pw_name); newact.sa_handler=turn_on_notify; newact.sa_flags=0; sigemptyset(&newact.sa_mask); sigaddset(&newact.sa_mask,SIGUSR1); sigaddset(&newact.sa_mask,SIGUSR2); if(sigaction(SIGUSR1,&newact,NULL)<0) fprintf(stderr,"Turn On Error:%s\n\a",strerror(errno)); newact.sa_handler=turn_off_notify; if(sigaction(SIGUSR1,&newact,NULL)<0) fprintf(stderr,"Turn Off Error:%s\n\a",strerror(errno)); check_mail(mailfile); exit(0); }?? 快捷鍵說明
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