Plugin context check: check termios settings

CHANGELOG.md

@@ -70,6 +70,7 @@ Developers may need to change their code
 
 * Plugin context check before and after all callbacks.
   * Check blocked signals and signal handlers
+  * Check termios settings
   * Any changes to context are logged at loglevel WARNING
 * Added set/get pointer API to clixon_data:
    * clicon_ptr_get(), clicon_ptr_set(), 

apps/cli/cli_common.c

@@ -562,9 +562,10 @@ cli_start_shell(clicon_handle h,
     int            retval = -1;
     char           bcmd[128];
     cg_var        *cv1 = cvec_i(vars, 1);
+    sigset_t       oldsigset;
+    struct sigaction oldsigaction[32] = {0,};
     
     cmd = (cvec_len(vars)>1 ? cv_string_get(cv1) : NULL);
-
     if ((pw = getpwuid(getuid())) == NULL){
 	clicon_err(OE_UNIX, errno, "getpwuid");
 	goto done;
@@ -575,6 +576,9 @@ cli_start_shell(clicon_handle h,
 	goto done;
     }
     endpwent();
+
+    if (clixon_signal_save(&oldsigset, oldsigaction) < 0)
+	goto done;
     cli_signal_flush(h);
     cli_signal_unblock(h);
     if (cmd){
@@ -598,6 +602,8 @@ cli_start_shell(clicon_handle h,
 	goto done;
     }
 #endif
+    if (clixon_signal_restore(&oldsigset, oldsigaction) < 0)
+	goto done;
     retval = 0;
  done:
     return retval;

lib/clixon/clixon_sig.h

@@ -47,6 +47,8 @@ typedef void (*sigfn_t)(int);
  * Prototypes
  */ 
 int  set_signal(int signo, void (*handler)(int), void (**oldhandler)(int));
+int  clixon_signal_save(sigset_t *sigset, struct sigaction sigaction_vec[32]);
+int  clixon_signal_restore(sigset_t *sigset, struct sigaction sigaction_vec[32]);
 void clicon_signal_block(int);
 void clicon_signal_unblock(int);
 

lib/src/clixon_event.c

@@ -48,6 +48,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
+#include <signal.h>
 #include <syslog.h>
 #include <sys/types.h>
 #include <sys/time.h>

lib/src/clixon_plugin.c

@@ -47,7 +47,8 @@
 #include <dlfcn.h>
 #include <dirent.h>
 #include <syslog.h>
-
+#include <unistd.h>
+#include <termios.h>
 #include <sys/stat.h>
 #include <sys/param.h>
 
@@ -71,12 +72,13 @@
  * Private types
  */
 /*! Structure for checking status before and after a plugin call
- * Currently signal settings: blocked and handlers, could be extended to more
+ * Currently signal settings: blocked and handlers, and termios
  * @see plugin_context_check
  */
 struct plugin_context {
     sigset_t         pc_sigset;            /* See sigprocmask(2) */
     struct sigaction pc_sigaction_vec[32]; /* See sigaction(2) */
+    struct termios   pc_termios;           /* See termios(3) */
 };
 
 /* Internal plugin structure with dlopen() handle and plugin_api
@@ -518,6 +520,7 @@ plugin_context_get(void)
 	goto done;
     }
     memset(pc, 0, sizeof(*pc));
+
     if (sigprocmask(0, NULL, &pc->pc_sigset) < 0){
 	clicon_err(OE_UNIX, errno, "sigprocmask");
 	goto done;
@@ -536,6 +539,10 @@ plugin_context_get(void)
 	pc->pc_sigaction_vec[i].sa_flags &= ~0x04000000;
 #endif
     }
+    if (isatty(0) && tcgetattr(0, &pc->pc_termios) < 0){
+	clicon_err(OE_UNIX, errno, "tcgetattr %d", errno);
+	goto done;
+    }
     return pc;
  done:
     if (pc)
@@ -564,15 +571,48 @@ plugin_context_check(plugin_context_t *oldpc0,
     		     const char       *fn)
 {
     int                    retval = -1;
-    int                    failed;
+    int                    failed = 0;
     int                    i;
     struct plugin_context *oldpc = oldpc0;
     struct plugin_context *newpc = NULL;
 
     if ((newpc = plugin_context_get()) == NULL)
 	goto done;
+    if (oldpc->pc_termios.c_iflag != newpc->pc_termios.c_iflag){
+	clicon_log(LOG_WARNING, "%s Plugin context %s %s: Changed termios input modes from 0x%x to 0x%x", __FUNCTION__,
+		   name, fn,
+		   oldpc->pc_termios.c_iflag,
+		   newpc->pc_termios.c_iflag);
+	failed++;
+    }
+    if (oldpc->pc_termios.c_oflag != newpc->pc_termios.c_oflag){
+	clicon_log(LOG_WARNING, "%s Plugin context %s %s: Changed termios output modes from 0x%x to 0x%x", __FUNCTION__,
+		   name, fn,
+		   oldpc->pc_termios.c_oflag,
+		   newpc->pc_termios.c_oflag);
+	failed++;
+    }
+    if (oldpc->pc_termios.c_cflag != newpc->pc_termios.c_cflag){
+	clicon_log(LOG_WARNING, "%s Plugin context %s %s: Changed termios control modes from 0x%x to 0x%x", __FUNCTION__,
+		   name, fn,
+		   oldpc->pc_termios.c_cflag,
+		   newpc->pc_termios.c_cflag);
+	failed++;
+    }
+    if (oldpc->pc_termios.c_lflag != newpc->pc_termios.c_lflag){
+	clicon_log(LOG_WARNING, "%s Plugin context %s %s: Changed termios local modes from 0x%x to 0x%x", __FUNCTION__,
+		   name, fn,
+		   oldpc->pc_termios.c_lflag,
+		   newpc->pc_termios.c_lflag);
+	failed++;
+    }
+    /* XXX pc_termios.cc_t  c_cc[NCCS] not checked */
+#if 0
+	/* In case you want early detection and crash. But otherwise it is recommended that
+	 * the caller looks for retval == 0 */
+	assert(failed == 0);
+#endif
     for (i=1; i<32; i++){
-	failed = 0;
 	if (sigismember(&oldpc->pc_sigset, i) != sigismember(&newpc->pc_sigset, i)){
 	    clicon_log(LOG_WARNING, "%s Plugin context %s %s: Changed blocking of signal %s(%d) from %d to %d", __FUNCTION__,
 		       name, fn, strsignal(i), i,
@@ -600,10 +640,10 @@ plugin_context_check(plugin_context_t *oldpc0,
 	 * the caller looks for retval == 0 */
 	assert(failed == 0);
 #endif
+    }
     if (failed)
 	goto fail;
 
-    }
     retval = 1; /* OK */
  done:
     if (newpc)

lib/src/clixon_sig.c

@@ -121,6 +121,58 @@ clicon_signal_unblock(int sig)
 	sigprocmask(SIG_UNBLOCK, &set, NULL);
 }
 
+/*! Save complete signal context
+ */
+int
+clixon_signal_save(sigset_t        *sigset,
+		   struct sigaction sigaction_vec[32])
+{
+    int retval = -1;
+    int i;
+    
+    if (sigprocmask(0, NULL, sigset) < 0){
+	clicon_err(OE_UNIX, errno, "sigprocmask");
+	goto done;
+    }
+    for (i=1; i<32; i++){
+	if (sigaction(i, NULL, &sigaction_vec[i]) < 0){
+	    clicon_err(OE_UNIX, errno, "sigaction");
+	    goto done;
+	}
+    }
+    retval = 0;
+ done:
+    return retval;
+}
+
+/*! Restore complete signal context
+ *
+ * Note: sigaction may not restore SIGKILL or SIGSTOP, which cannot be caught or ignored.
+ */
+int
+clixon_signal_restore(sigset_t        *sigset,
+		      struct sigaction sigaction_vec[32])
+{
+    int retval = -1;
+    int i;
+    
+    if (sigprocmask(0, sigset, NULL) < 0){
+	clicon_err(OE_UNIX, errno, "sigprocmask");
+	goto done;
+    }
+    for (i=1; i<32; i++){
+	if (i == SIGKILL || i == SIGSTOP)
+	    continue;
+	if (sigaction(i, &sigaction_vec[i], NULL) < 0){
+	    clicon_err(OE_UNIX, errno, "sigaction");
+	    goto done;
+	}
+    }
+    retval = 0;
+ done:
+    return retval;
+}
+
 /*! Read pidfile and return pid using file descriptor
  *
  * @param[in]  pidfile  Name of pidfile