study

Author: wenjun1055

10.22.c

@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+
+
+#define BUFFSIZE 1024
+
+static void sig_tstp(int);
+
+int main(void)
+{
+    int     n;
+    char    buf[BUFFSIZE];
+
+    if (signal(SIGTSTP, SIG_IGN) == SIG_DFL) {
+        signal(SIGTSTP, sig_tstp);
+    }
+
+    while ((n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0) {
+        if (write(STDOUT_FILENO, buf, n) != n) {
+            printf("write error\n");
+            exit(-1);
+        }
+    }
+
+    if (n < 0) {
+        printf("read error\n");
+        exit(-1);
+    }
+
+    return 0;
+}
+
+static void sig_tstp(int signo)
+{
+    sigset_t    mask;
+
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGTSTP);
+    sigprocmask(SIG_UNBLOCK, &mask, NULL);
+
+    signal(SIGTSTP, SIG_DFL);
+
+    kill(getpid(), SIGTSTP);
+
+    signal(SIGTSTP, sig_tstp);
+}