I am trying to run a program that does following actions:
Here are the two programs, draw.out works fine (Tetris game) but isn't getting input from pipe, what is my mistake?
File 1:
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdlib.h>
#include <curses.h>
#include <string.h>
int main(void)
{
int fd[2], childpid;
//pid_t childpid;
char input = 'o';
char readbuffer[80];
pipe(fd);
if ((childpid = fork()) == -1)
{
perror("fork");
exit(1);
}
if (childpid == 0)
{
close(0);
dup(fd[0]);
execl("draw.out", NULL);
}
else
{
close(fd[0]);
while (input != 'q')
{
input = getch();
if (input == 'a' || input == 's' || input == 'd' || input == 'w' || input == 'q')
{
write(fd[1], &input, 1);
kill(getpid() + 1, SIGUSR2);
}
}
exit(0);
}
return 1;
}
File 2:
#include <signal.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
void print_screen(int a, int b, int c, int t, int flat);
void my_handler(int signum);
int a = 9, b = 10, c = 11, t = 0, flat = 1;
int newfd = 0;
int main(void)
{
if (signal(SIGUSR2, my_handler) == SIG_ERR)
{
printf("Pærent: Unable to create handler for SIGUSR2\n");
}
while (t < 20)
{
system("clear");
print_screen(a, b, c, t, flat);
sleep(1);
t++;
}
}
void my_handler(int signum)
{
if (signum == SIGUSR2)
{
printf("signal arrived");
char input;
fgets(&input, sizeof(input), stdin);
switch (input)
{
case 'a':
if (a > 1)
{
a--;
b--;
c--;
}
break;
case 's':
t++;
break;
case 'd':
if (c < 18)
{
a--;
b--;
c--;
}
case 'w':
if (flat == 1)
{
flat = 0;
}
else
{
if (b<18 && b>1)
{
flat = 1;
}
}
break;
case 'q':
exit(0);
}
}
}
void print_screen(int a, int b, int c, int t, int flat)
{
char str[420] = "\n";
int i, j;
for (i = 0; i < 20; i++)
{
for (j = 0; j < 20; j++)
{
if (i != 19 && !(j>0 && j < 19))
{
strcat(str, "*");
}
else if (i == 19)
{
strcat(str, "*");
}
else
{
if (flat == 1 && i == t && (j == a || j == b || j == c))
{
strcat(str, "-");
}
else if (flat == 0 && j == b && (i == t || i == t - 1 || i == t + 1))
{
strcat(str, "-");
}
else
{
strcat(str, " ");
}
}
}
strcat(str, "\n");
}
puts(str);
}
答案 0 :(得分：2)
首先：你不能用fgets读取一个字节。来自man fgets：
fgets（）从流
中读取最多一个小于大小的字符
sizeof（输入）是1＆＃34;比size＆＃34;是0.因此，足球将不会读。例如，将其更改为fgetc。
第二：kill(getpid() + 1, SIGUSR2);陈述显然是错误的，因为你认为你的孩子将拥有你的过程的pid + 1.这是错误的假设，并且不需要这样的构造，因为你有{{1} }变量正确设置。
第三：你没有childpid使用ncurses，所以initscr()不会工作。因为这也将重新配置您的终端添加＆＃34; \ n \ r＆＃34;在每一行的末尾而不是＆＃34; \ n＆＃34;。并且在退出之前不要忘记取消初始化调用getch()的ncruses。
第四：做一些比在信号处理程序中获取/设置简单变量更复杂的事情通常是一个非常糟糕的主意。您应该endwin()使用poll函数在主循环中输入，如下所示：
select第五：您在案例中错过了struct timeval time;
time.tv_sec = 0;
time.tv_usec = 0;
fd_set set;
FD_ZERO(&set);
FD_SET(0, &set);
if (select(1, &set, NULL, NULL, &time) > 0) {
handle_input();
}
语句，同时break和d键都是递减变量，而a应该递增I {}猜测。
以下是有效的代码：
d第二档：
#include <signal.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
void print_screen(int a, int b, int c, int t, int flat);
void handle_input(void);
int a = 9, b = 10, c = 11, t = 0, flat = 1;
int newfd = 0;
int main(void) {
int t = 0;
while (t < 20) {
system("clear");
print_screen(a, b, c, t, flat);
sleep(1);
struct timeval time;
time.tv_sec = 0;
time.tv_usec = 0;
fd_set set;
FD_ZERO(&set);
FD_SET(0, &set);
if (select(1, &set, NULL, NULL, &time) > 0) {
handle_input();
}
t++;
}
return 0;
}
void handle_input() {
char input;
input = fgetc(stdin);
switch (input) {
case 'a':
printf("a\n");
if (a > 1) {
a--;
b--;
c--;
}
break;
case 's':
t++;
break;
case 'd':
if (c < 18) {
a++;
b++;
c++;
}
break;
case 'w':
if (flat == 1) {
flat = 0;
} else {
if (b<18 && b>1) {
flat = 1;
}
}
break;
case 'q':
exit(0);
}
}
void print_screen(int a, int b, int c, int t, int flat) {
char str[4200] = "\n";
int i, j;
for (i = 0; i < 20; i++) {
for (j = 0; j < 20; j++) {
if (i != 19 && !(j>0 && j < 19)) {
strcat(str, "*");
}
else if (i == 19) {
strcat(str, "*");
} else {
if (flat == 1 && i == t && (j == a || j == b || j == c)) {
strcat(str, "-");
} else if (flat == 0 && j == b && (i == t || i == t - 1 || i == t + 1)) {
strcat(str, "-");
} else {
strcat(str, " ");
}
}
}
strcat(str, "\n\r");
}
puts(str);
}