[hackers] [scroll] ptty: add event loop to handle input and output for future tests || Jan Klemkow

[git]

commit 6010f1f28817ad49ed50eca2a0b3a8a90126fd95
Author:     Jan Klemkow <j.klem...@wemelug.de>
AuthorDate: Wed Apr 15 22:07:56 2020 +0200
Commit:     Jan Klemkow <j.klem...@wemelug.de>
CommitDate: Wed Apr 15 22:07:56 2020 +0200

    ptty: add event loop to handle input and output for future tests

diff --git a/ptty.c b/ptty.c
index c0f81d9..475c8ef 100644
--- a/ptty.c
+++ b/ptty.c
@@ -3,6 +3,7 @@
 #include <errno.h>
 #include <inttypes.h>
 #include <limits.h>
+#include <poll.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -88,16 +89,42 @@ main(int argc, char *argv[])
        }
 
        /* parent */
-       FILE *fh = fdopen(mfd, "rw");
-       if (fh == NULL)
-               die("fdopen");
 
        if (closeflag && close(mfd) == -1)
                die("close:");
 
-       char buf[BUFSIZ];
-       while (fgets(buf, sizeof buf, fh) != NULL)
-               fputs(buf, stdout);
+       struct pollfd pfd[2] = {
+               { STDIN_FILENO, POLLIN, 0},
+               { mfd,          POLLIN, 0}
+       };
+
+       for (;;) {
+               char buf[BUFSIZ];
+               ssize_t n;
+               int r;
+
+               if ((r = poll(pfd, 2, -1)) == -1)
+                       die("poll:");
+
+               if (pfd[0].revents & POLLIN) {
+                       if ((n = read(STDIN_FILENO, buf, sizeof buf)) == -1)
+                               die("read:");
+                       if (n == 0) break;
+                       if (write(mfd, buf, n) == -1)
+                               die("write:");
+               }
+
+               if (pfd[1].revents & POLLIN) {
+                       if ((n = read(mfd, buf, sizeof buf)) == -1)
+                               die("read:");
+                       if (n == 0) break;
+                       if (write(STDOUT_FILENO, buf, n) == -1)
+                               die("write:");
+               }
+
+               if (pfd[0].revents & POLLHUP || pfd[1].revents & POLLHUP)
+                       break;
+       }
 
        int status;
        waitpid(pid, &status, 0);