init commit

3sem/cnts/contest14/04a.c

@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/wait.h>
+
+volatile sig_atomic_t sigusr1_received = 0;
+
+void
+sigusr1_handler(int signum)
+{
+    sigusr1_received = 1;
+}
+
+int
+main(int argc, char **argv)
+{
+    int n = (int) strtol(argv[1], NULL, 10);
+
+    int fd[2];
+    pipe(fd);
+
+    signal(SIGUSR1, sigusr1_handler);
+
+    if (!fork()) {
+        close(fd[0]);
+        FILE *out = fdopen(fd[1], "w");
+
+        int i = 1;
+        while (i <= n) {
+            printf("1 %d\n", i);
+            fflush(stdout);
+            fprintf(out, "%d\n", i);
+            fflush(out);
+            kill(getppid(), SIGUSR1);
+            pause();
+            if (i >= n) {
+                break;
+            }
+            i++;
+        }
+
+        fclose(out);
+        return 0;
+    } else if (!fork()) {
+        close(fd[1]);
+        FILE *in = fdopen(fd[0], "r");
+
+        int i;
+        while (1) {
+            if (i >= n) {
+                break;
+            }
+            i++;
+            printf("2 %d\n", i);
+            fflush(stdout);
+            kill(getppid(), SIGUSR1);
+            pause();
+        }
+
+        fclose(in);
+        return 0;
+    }
+
+    close(fd[0]);
+    close(fd[1]);
+
+    while (wait(NULL) != -1)
+        ;
+
+    printf("Done\n");
+
+    return 0;
+}