尝试实现信号处理程序，但收到警告：
assignment from incompatible pointer type [enabled by default]
act.sa_sigaction = sigChldHandler;
......我的教授也指出了。
char * argv[3];
argv[0]= GUESSER_PROGNAME;
argv[2]= NULL;
这为3个char指针变量分配内存，但它们并没有特别指向任何地方。＆＃34;但我不确定他的意思是什么。
\ file 1
#include "assign2Headers.h"
pid_t answererPid;
pid_t guesserPid;
int shouldRun = 1;
void sigAlrmHandler(int sig)
{
kill(answererPid,TIME_OVER_SIGNAL);
kill(guesserPid,TIME_OVER_SIGNAL);
shouldRun=0;
}
void sigChldHandler(int sig)
{
wait(NULL);
shouldRun=0;
}
int main(void){
struct sigaction act;
memset(&act, '\0', sizeof(struct sigaction));
act.sa_handler = sigAlrmHandler;
sigaction(SIGALRM, &act, NULL);
act.sa_sigaction = sighldHandler;
sigaction(SIGCHLD, &act, NULL);
char line[LINE_LEN];
char * argv[3];
argv[0]= GUESSER_PROGNAME;
argv[2]= NULL;
answererPid = fork();
if(answererPid == 0){
execl(ANSWERER_PROGNAME,ANSWERER_PROGNAME,(char*)NULL);
}
else{
sleep(1);
snprintf(line,LINE_LEN,"%d",answererPid);
guesserPid=fork();
if(guesserPid==0)
{
execl(GUESSER_PROGNAME,GUESSER_PROGNAME,argv[0],line,(char*)NULL);
}
else
{ alarm(NUM_SECONDS);
while(shouldRun)
sleep(1);
sleep(1);
sleep(1);
printf("launcher finished\n");
return (EXIT_SUCCESS);
}
}
}
\ file 2
#include "assign2Headers.h"
int shouldRun = 1;
void timeoverhandler(int sig)
{ sleep(1);
printf("\nOh no! The time is up!\n");
printf("guesser finished\n");
shouldRun=0;
exit(EXIT_SUCCESS);
}
void winsignalhandler(int sig)
{
printf("\nCongratulations! You found it!\n");
shouldRun=0;
signal(WIN_SIGNAL,winsignalhandler);
}
void correctsignalhandler(int sig)
{
printf("Yay! That was right!\n");
signal(CORRECT_SIGNAL,correctsignalhandler);
}
void incorrectsignalhandler(int sig)
{
printf("Oops! That was wrong. Please restart from the beginning.\n"
"\nRe-starting from the beginning:\n");
signal(INCORRECT_SIGNAL,incorrectsignalhandler);
}
int main(int argc,char* argv[])
{
pid_t answererPid=atoi(argv[1]);
signal(TIME_OVER_SIGNAL,timeoverhandler);
signal(WIN_SIGNAL,winsignalhandler);
signal(CORRECT_SIGNAL,correctsignalhandler);
signal(INCORRECT_SIGNAL,incorrectsignalhandler);
while(shouldRun)
{ int guess;
printf("What would you like your next guess to be: 0 or 1? ");
scanf("%d",&guess);
if(guess==0)
kill(answererPid,ZERO_SIGNAL);
if(guess==1)
kill(answererPid,ONE_SIGNAL);
sleep(2);
}
printf("guesser finished\n");
return (EXIT_SUCCESS);
}
\ file 3
//--- Common standard header files ---//
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
////--- Common constants: ---//
#define ZERO_SIGNAL SIGUSR1
#define ONE_SIGNAL SIGUSR2
#define CORRECT_SIGNAL SIGUSR1
#define INCORRECT_SIGNAL SIGUSR2
#define WIN_SIGNAL SIGINT
#define TIME_OVER_SIGNAL SIGTERM
#define GUESSER_PROGNAME "guesser"
#define ANSWERER_PROGNAME "answerer"
#define LINE_LEN 256
#define NUM_SECONDS 30
\ file 4
//--- Inclusion of header files ---//
#include "assign2Headers.h"
//--- Definition of constants: ---//
#define PATTERN_LEN 4
//--- Definition of global vars: ---//
int answer;
int numCorrect = 0;
int shouldRun = 1;
//--- Definition of global fncs: ---//
void timeUpHandler (int sig
)
{
shouldRun = 0;
}
void guessHandler (int sig,
siginfo_t* infoPtr,
void* dataPtr
)
{
int toSendBack;
int userBit = (sig == ONE_SIGNAL);
int correctBit = ((answer >> numCorrect) & 0x1);
int isCorrect = (correctBit == userBit);
printf("position %d: userBit %d, correctBit %d\n",
numCorrect,userBit,correctBit
);
if (isCorrect)
{
numCorrect++;
if (numCorrect >= PATTERN_LEN)
toSendBack = WIN_SIGNAL;
else
toSendBack = CORRECT_SIGNAL;
}
else
{
numCorrect = 0;
toSendBack = INCORRECT_SIGNAL;
}
kill(infoPtr->si_pid,toSendBack);
}
int main (int argc,
char* argv[]
)
{
// I. Application validity check:
// II. Run program:
// II.A. Initialize random number generator and choice:
srand(getpid());
answer = rand() % (1 << PATTERN_LEN);
printf("(The answer is %d)\n",answer);
// II.B. Install signal handlers:
struct sigaction act;
memset(&act,'\0',sizeof(act));
act.sa_handler = timeUpHandler;
sigaction(TIME_OVER_SIGNAL,&act,NULL);
act.sa_flags = SA_SIGINFO;
act.sa_sigaction = guessHandler;
sigaction(ZERO_SIGNAL,&act,NULL);
sigaction(ONE_SIGNAL,&act,NULL);
// II.C. Hand out while game still active:
while ( (numCorrect < PATTERN_LEN) && shouldRun )
sleep(1);
// III. Finished, return answer:
printf("answerer finished\n");
return(EXIT_SUCCESS);
}
如何删除此警告以及他的意思是什么？有人帮帮我。
答案 0 :(得分：4)
我猜你正在研究Linux。来自sigaction联机帮助页：
struct sigaction {
void (*sa_handler)(int);
void (*sa_sigaction)(int, siginfo_t *, void *);
sigset_t sa_mask;
int sa_flags;
void (*sa_restorer)(void);
};
原型void sigChldHandler(int sig)与sa_sigaction不匹配。因此警告。
您可以使用
sa_handler设置信号处理函数或指定SIG_IGN / SIG_DFL操作。 sa_sigaction设置信号处理函数 - 如果用户需要访问更多细节，如用户上下文和siginfo结构（发送者进程详细信息，信号类型等）。需要在SA_SIGINFO中为此用法设置sa_flags。 对于您的情况，设置sa_handler可能就足够了。
在main()：
struct sigaction act;
act.sa_handler = sigChldHandler;
act.sa_flags = SA_RESTART;
sigaction(SIGCHLD, &act, NULL);
另外，
sigaction结构，除非您需要相同的处理程序。 sigaction()＆amp; signal()用法。坚持一个。也许，sigaction因为它是新的＆amp;提供的功能多于signal()。答案 1 :(得分：1)
此段：
char * argv[3];
argv[0]= GUESSER_PROGNAME;
argv[2]= NULL;
argv[0]无效。由于argv是一个指针数组，因此在使用它们之前，需要确保这些指针指向某个位置。
这可以通过strdup()：
argv[0]= strdup(GUESSER_PROGNAME);
argv[0]= malloc(strlen(GUESSER_PROGNAME)+1);
strcpy(argv[0], GUESSER_PROGNAME);
注意： malloc()也应该检查，失败时可以返回NULL。堆上分配的任何内存最后也应该是free()。
就清晰度而言，您可以替换：
#define GUESSER_PROGNAME "guesser"
使用：
const char *guesser_progname = "guesser";