init commit

3sem/cnts/contest13/04.c

@@ -0,0 +1,71 @@
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+
+void
+ex(void)
+{
+    // разослать SIGKILL
+    // а некому.
+
+    exit(1);
+}
+
+void
+swap(int *a, int *b)
+{
+    int tmp = *a;
+    *a = *b;
+    *b = tmp;
+
+    return;
+}
+
+int
+main(int argc, char **argv)
+{
+    int fd1[2];
+    int fd2[2];
+    if (close(2) == -1 || pipe(fd1) == -1 || pipe(fd2)) {
+        ex();
+    }
+
+    for (int i = 1; i < argc; ++i) {
+        pid_t pid = fork();
+        if (pid == 0) {
+
+            if (i != 1 && i != argc - 1) {
+                if (dup2(fd2[1], 1) == -1 || dup2(fd1[0], 0) == -1) {
+                    ex();
+                }
+            } else if (i == 1) {
+                if (dup2(fd2[1], 1) == -1) {
+                    ex();
+                }
+            } else {
+                if (dup2(fd1[0], 0) == -1) {
+                    ex();
+                }
+            }
+
+            close(fd1[0]);
+            close(fd1[1]);
+            close(fd2[0]);
+            close(fd2[1]);
+
+            execlp(argv[i], argv[i], NULL);
+            _exit(1);
+        } else if (pid == -1) {
+            ex();
+        }
+
+        swap(&fd1[0], &fd2[0]);
+        swap(&fd1[1], &fd2[1]);
+        wait(NULL);
+    }
+
+    return 0;
+}