fds: Make many fds nonblocking

Introduce iswouldblock to cope with POSIX not specifying which of
EAGAIN or EWOULDBLOCK you get).  In various subsystems, make more fds
nonblocking and handle errors appropriately.  Specifically:

* Logging self-pipe reading end.
* Signal self-pipe reading end.
* SLIP both ends.  Fixing the writing end involves breaking out a new
  function slip_write.  We have to set these nonblocking after reading
  the confiramation byte.
* tun's network interface fd.

In various of these we add code to handle EINTR, too.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/log.c b/log.c
index 3748f9157d15dc7778847201c0eaed777f39fdc5..cbe4a85bf013fd8d2c432ba510b1f9ac301bb1d6 100644 (file)
--- a/log.c
+++ b/log.c
@@ -579,6 +579,7 @@ static void log_from_fd_afterpoll(void *sst, struct pollfd *fds, int nfds)
                    i=-1;
                }
            }
+       } else if (errno==EINTR || iswouldblock(errno)) {
        } else {
            Message(M_WARNING,"log_from_fd: %s\n",strerror(errno));
            st->finished=True;
@@ -598,6 +599,8 @@ void log_from_fd(int fd, cstring_t prefix, struct log_if *log)
     st->i=0;
     st->finished=False;
 
+    setnonblock(st->fd);
+
     register_for_poll(st,log_from_fd_beforepoll,log_from_fd_afterpoll,
                      prefix);
 }

diff --git a/process.c b/process.c
index 12e2caac5fc6d7d2749422434af2cda54245d056..a15e3a6357f385dbd76115283699b7656ade439a 100644 (file)
--- a/process.c
+++ b/process.c
@@ -302,6 +302,7 @@ void start_signal_handling(void)
     spw=p[1];
     spr=p[0];
     setnonblock(spw);
+    setnonblock(spr);
 
     register_for_poll(NULL,signal_beforepoll,signal_afterpoll,"signal");
     signal_handling=True;

diff --git a/slip.c b/slip.c
index 3f7935a008ad16e483a3aaee72af8795b033147a..4c0cac12ee635685ea9e7a1085cd884767cb2d51 100644 (file)
--- a/slip.c
+++ b/slip.c
@@ -31,6 +31,27 @@ struct slip {
 
 /* Generic SLIP mangling code */
 
+static void slip_write(int fd, const uint8_t *p, size_t l)
+{
+    while (l) {
+       ssize_t written=write(fd,p,l);
+       if (written<0) {
+           if (errno==EINTR) {
+               continue;
+           } else if (iswouldblock(errno)) {
+               lg_perror(0,"slip",0,M_ERR,errno,"write() (packet(s) lost)");
+               return;
+           } else {
+               fatal_perror("slip_stuff: write()");
+           }
+       }
+       assert(written>0);
+       assert((size_t)written<=l);
+       p+=written;
+       l-=written;
+    }
+}
+
 static void slip_stuff(struct slip *st, struct buffer_if *buf, int fd)
 {
     uint8_t txbuf[DEFAULT_BUFSIZE];
@@ -56,16 +77,12 @@ static void slip_stuff(struct slip *st, struct buffer_if *buf, int fd)
            break;
        }
        if ((j+2)>DEFAULT_BUFSIZE) {
-           if (write(fd,txbuf,j)<0) {
-               fatal_perror("slip_stuff: write()");
-           }
+           slip_write(fd,txbuf,j);
            j=0;
        }
     }
     txbuf[j++]=SLIP_END;
-    if (write(fd,txbuf,j)<0) {
-       fatal_perror("slip_stuff: write()");
-    }
+    slip_write(fd,txbuf,j);
     BUF_FREE(buf);
 }
 
@@ -195,7 +212,7 @@ static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds)
     if (fds[1].revents&POLLIN) {
        l=read(st->rxfd,rxbuf,DEFAULT_BUFSIZE);
        if (l<0) {
-           if (errno!=EINTR)
+           if (errno!=EINTR && !iswouldblock(errno))
                fatal_perror("%s: userv_afterpoll: read(rxfd)",
                             st->slip.nl.name);
        } else if (l==0) {
@@ -366,6 +383,8 @@ static void userv_invoke_userv(struct userv *st)
                  st->slip.nl.name,confirm);
        }
     }
+    setnonblock(st->txfd);
+    setnonblock(st->rxfd);
 }
 
 static void userv_kill_userv(struct userv *st)

diff --git a/tun.c b/tun.c
index 6ecde61794a3e3ea2821f6ebe185003c6ea07b4c..2c84ed0dace4d51a35c16071a7926e59859159be 100644 (file)
--- a/tun.c
+++ b/tun.c
@@ -118,6 +118,7 @@ static void tun_afterpoll(void *sst, struct pollfd *fds, int nfds)
        buffer_init(st->buff,calculate_max_start_pad());
        l=read(st->fd, st->buff->start, buf_remaining_space(st->buff));
        if (l<0) {
+           if (errno==EINTR || iswouldblock(errno)) return;
            fatal_perror("tun_afterpoll: read()");
        }
        if (l==0) {
@@ -353,6 +354,7 @@ static void tun_phase_hook(void *sst, uint32_t newphase)
        our networks. */
 
     setcloexec(st->fd);
+    setnonblock(st->fd);
 
     hostaddr=ipaddr_to_string(st->nl.local_address);
     secnetaddr=ipaddr_to_string(st->nl.secnet_address);

diff --git a/util.h b/util.h
index 33b2b2bd865e0cb81c3e2d2d5c4a2a4706da7296..c52c5b324002d65ddad3d1bdd5a1856b700b6702 100644 (file)
--- a/util.h
+++ b/util.h
@@ -95,4 +95,7 @@ void string_item_to_iaddr(const item_t *item, uint16_t port, union iaddr *ia,
 #define MAX(a,b) MINMAX((a),(b),>)
 #define MIN(a,b) MINMAX((a),(b),<)
 
+static inline bool_t iswouldblock(int e)
+    { return e==EWOULDBLOCK || e==EAGAIN; }
+
 #endif /* util_h */