bind: Check for POLLRDHUP on the server if available

This is a feature on modern Linux.

Thanks to Ludovic Courtès <ludo@gnu.org> for the pointer.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

src/CMakeLists.txt

@@ -300,7 +300,10 @@ if (WITH_SYMBOL_VERSIONING AND HAVE_LD_VERSION_SCRIPT AND ABIMAP_FOUND)
 endif (WITH_SYMBOL_VERSIONING AND HAVE_LD_VERSION_SCRIPT AND ABIMAP_FOUND)
 
 add_library(${LIBSSH_SHARED_LIBRARY} SHARED ${libssh_SRCS})
-target_compile_options(${LIBSSH_SHARED_LIBRARY} PRIVATE ${DEFAULT_C_COMPILE_FLAGS})
+target_compile_options(${LIBSSH_SHARED_LIBRARY}
+                       PRIVATE
+                           ${DEFAULT_C_COMPILE_FLAGS}
+                           -D_GNU_SOURCE)
 
 target_link_libraries(${LIBSSH_SHARED_LIBRARY} ${LIBSSH_LINK_LIBRARIES})
 
@@ -348,7 +351,10 @@ install(
 
 if (BUILD_STATIC_LIB)
   add_library(${LIBSSH_STATIC_LIBRARY} STATIC ${libssh_SRCS})
-  target_compile_options(${LIBSSH_STATIC_LIBRARY} PRIVATE ${DEFAULT_C_COMPILE_FLAGS})
+  target_compile_options(${LIBSSH_STATIC_LIBRARY}
+                         PRIVATE
+                            ${DEFAULT_C_COMPILE_FLAGS}
+                            -D_GNU_SOURCE)
 
   if (MSVC)
     set(OUTPUT_SUFFIX static)

src/bind.c

@@ -345,11 +345,18 @@ static int ssh_bind_poll_callback(ssh_poll_handle sshpoll,
  */
 ssh_poll_handle ssh_bind_get_poll(ssh_bind sshbind)
 {
+    short events = POLLIN;
+
     if (sshbind->poll) {
         return sshbind->poll;
     }
+
+#ifdef POLLRDHUP
+    events |= POLLRDHUP;
+#endif /* POLLRDHUP */
+
     sshbind->poll = ssh_poll_new(sshbind->bindfd,
-                                 POLLIN,
+                                 events,
                                  ssh_bind_poll_callback,
                                  sshbind);