New option sitout-eio

CHANGES

@@ -45,6 +45,11 @@ Features:
 	before exit. Signal USR1 logs actual values.
 	Tests: OPTION_STATISTICS SIGUSR1_STATISTICS
 
+	Added option sitout-eio to specify a timerange in which EIO on the pty
+	of a sub process is tolerated.
+	Red Hat issue 1853102 related.
+	Thanks to Jonathan Casiot for sending an initial patch.
+
 Corrections:
 	When a sub process (EXEC, SYSTEM) terminated with exit code other than
 	0, its last sent data might have been lost depending on timing of read/

doc/socat.yo

@@ -2823,6 +2823,12 @@ label(OPTION_PTY_INTERVAL)dit(bf(tt(pty-interval=<seconds>)))
    periodically checks the HUP condition using tt(poll()) to find if the pty's
    slave side has been opened. The default polling interval is 1s. Use the
    pty-interval option [link(timeval)(TYPE_TIMEVAL)] to change this value.
+label(OPTION_SITOUT_EIO)dit(bf(tt(sitout-eio=<timeval>)))
+   The login program in Linux closes its tty/pty and reopens it for security
+   reasons. During this time the pty master would get EIO on I/O operations and
+   might terminate. With this option socat() tolerates EIO for the specified
+   time. Please note that in this state socat() blocks traffic in both
+   directions, even when it is not related to this channel.
 enddit()
 
 

sycls.c

@@ -547,7 +547,11 @@ ssize_t Read(int fd, void *buf, size_t count) {
    _errno = errno;
    if (!diag_in_handler) diag_flush();
 #if WITH_SYCLS
-   Debug1("read -> "F_Zd, result);
+   if (result < 0) {
+      Debug2("read -> "F_Zd" (errno=%d)", result, _errno);
+   } else {
+      Debug1("read -> "F_Zd, result);
+   }
 #endif /* WITH_SYCLS */
    errno = _errno;
    return result;

xio-progcall.c

@@ -21,6 +21,7 @@ const struct optdesc opt_openpty = { "openpty",   NULL, OPT_OPENPTY,     GROUP_P
 #if HAVE_DEV_PTMX || HAVE_DEV_PTC
 const struct optdesc opt_ptmx    = { "ptmx",      NULL, OPT_PTMX,        GROUP_PTY,   PH_BIGEN, TYPE_BOOL, 	OFUNC_SPEC };
 #endif
+const struct optdesc opt_sitout_eio = { "sitout-eio", NULL, OPT_SITOUT_EIO, GROUP_PTY, PH_INIT, TYPE_TIMEVAL, OFUNC_OFFSET, XIO_OFFSETOF(para.exec.sitout_eio), XIO_SIZEOF(para.exec.sitout_eio) };
 
 #if WITH_EXEC || WITH_SYSTEM
 

xio-progcall.h

@@ -10,6 +10,7 @@ extern const struct optdesc opt_fdout;
 extern const struct optdesc opt_path;
 extern const struct optdesc opt_pipes;
 extern const struct optdesc opt_pty;
+extern const struct optdesc opt_sitout_eio;
 extern const struct optdesc opt_openpty;
 extern const struct optdesc opt_ptmx;
 extern const struct optdesc opt_stderr;

xio.h

@@ -234,6 +234,7 @@ typedef struct single {
       struct {
 	 pid_t pid;		/* child PID, with EXEC: */
 	 int fdout;		/* use fd for output if two pipes */
+	 struct timeval sitout_eio;
       } exec;
 #if WITH_READLINE
       struct {

xioopts.c

@@ -1482,6 +1482,7 @@ const struct optname optionnames[] = {
 #ifdef SIOCSPGRP
 	IF_SOCKET ("siocspgrp",	&opt_siocspgrp)
 #endif
+	IF_PTY    ("sitout-eio", 	&opt_sitout_eio)
 	IF_TUN    ("slave",	&opt_iff_slave)
 	IF_SOCKET ("sndbuf",	&opt_so_sndbuf)
 	IF_SOCKET ("sndbuf-late",	&opt_so_sndbuf_late)

xioopts.h

@@ -644,6 +644,7 @@ enum e_optcode {
 #ifdef SIOCSPGRP
    OPT_SIOCSPGRP,
 #endif
+   OPT_SITOUT_EIO,
 #ifdef SO_ACCEPTCONN
    OPT_SO_ACCEPTCONN,
 #endif /* SO_ACCEPTCONN */

xioread.c

@@ -75,23 +75,48 @@ ssize_t xioread(xiofile_t *file, void *buff, size_t bufsiz) {
       break;
 
    case XIOREAD_PTY:
-      do {
+   {
+       int eio = 0;
+       bool m = false; 	/* loop message printed? */
+      while (true) {
+       do {
 	 bytes = Read(pipe->fd, buff, bufsiz);
-      } while (bytes < 0 && errno == EINTR);
-      if (bytes < 0) {
+       } while (bytes < 0 && errno == EINTR);
+       if (bytes < 0) {
 	 _errno = errno;
-	 if (_errno == EIO) {
-	    Notice4("read(%d, %p, "F_Zu"): %s (probably PTY closed)",
-		    pipe->fd, buff, bufsiz, strerror(_errno));
-	    return 0;
-	 } else {
-	    Error4("read(%d, %p, "F_Zu"): %s",
-		   pipe->fd, buff, bufsiz, strerror(_errno));
+	 if (_errno != EIO) {
+	    Error4("read(%d, %p, "F_Zu"): %s", pipe->fd, buff, bufsiz, strerror(_errno));
+	    errno = _errno;
+	    return -1;
 	 }
-	 errno = _errno;
-	 return -1;
+	 if (pipe->para.exec.sitout_eio.tv_sec == 0 &&
+	     pipe->para.exec.sitout_eio.tv_usec == 0) {
+		Notice4("read(%d, %p, "F_Zu"): %s (probably PTY closed)",
+			pipe->fd, buff, bufsiz, strerror(_errno));
+		return 0;
+	 }
+	 if (!m) {
+		 /* Starting first iteration: calc and report */
+		 /* Round up to 10ms */
+		 eio = 100*pipe->para.exec.sitout_eio.tv_sec +
+			    (pipe->para.exec.sitout_eio.tv_usec+9999)/10000;
+		 Notice3("xioread(fd=%d): EIO, sitting out %u.%02lus for recovery", pipe->fd, eio/100, (unsigned long)eio%100);
+		 m = true;
+	 }
+	 poll(NULL, 0, 10);
+	 if (--eio <= 0) {
+		 /* Timeout */
+		 Error4("read(%d, %p, "F_Zu"): %s", pipe->fd, buff, bufsiz, strerror(_errno));
+		 errno = _errno;
+		 return -1;
+	 }
+	 /* Not reached */
+       } else
+	       break; 	/* no error */
       }
-      break;
+   }
+   return bytes;
+   break;
 
 #if WITH_READLINE
    case XIOREAD_READLINE: