only select for write, if it was not possible before

1 files changed, 14 insertions, 4 deletions

diff --git a/src/vpn/gnunet-vpn-helper.c b/src/vpn/gnunet-vpn-helper.c
index 0577173b0..928ede4c6 100644
--- a/src/vpn/gnunet-vpn-helper.c
+++ b/src/vpn/gnunet-vpn-helper.c
@@ -139,6 +139,9 @@ int main(int argc, char** argv) {
 
         int rea = 1;
         int wri = 1;
+
+        int write_fd_possible = 0;
+        int write_stdout_possible = 0;
 outer:
         while(rea != 0 && wri != 0 && running == 1) {
                 FD_ZERO(&fds_w);
@@ -146,18 +149,24 @@ outer:
 
                 if (rea) {
                         FD_SET(fd_tun, &fds_r);
-                        FD_SET(1, &fds_w);
+                        if (!write_stdout_possible)
+                                FD_SET(1, &fds_w);
                 }
 
                 if (wri) {
                         FD_SET(0, &fds_r);
-                        FD_SET(fd_tun, &fds_w);
+                        if (!write_fd_possible)
+                                FD_SET(fd_tun, &fds_w);
                 }
 
                 int r = select(fd_tun+1, &fds_r, &fds_w, (fd_set*)0, 0);
 
                 if(r > 0) {
-                        if (FD_ISSET(0, &fds_r) && FD_ISSET(fd_tun, &fds_w)) {
+                        if (FD_ISSET(fd_tun, &fds_w)) write_fd_possible = 1;
+                        if (FD_ISSET(1, &fds_w)) write_stdout_possible = 1;
+
+                        if (FD_ISSET(0, &fds_r) && write_fd_possible) {
+                                write_fd_possible = 0;
                                 struct suid_packet *pkt = (struct suid_packet*) buf;
                                 r = read(0, buf, sizeof(struct suid_packet_header));
                                 if (r < 0) {
@@ -190,7 +199,8 @@ outer:
                                         }
                                         r += t;
                                 }
-                        } else if (FD_ISSET(1, &fds_w) && FD_ISSET(fd_tun, &fds_r)) {
+                        } else if (write_stdout_possible && FD_ISSET(fd_tun, &fds_r)) {
+                                write_stdout_possible = 0;
                                 r = read(fd_tun, buf, 65600);
                                 if (r < 0) {
                                         fprintf(stderr, "read-error: %m\n");