Error handling for CLI

Continue, do not exit on read/expand errors
Accept -1 error without clicon_err in callbacks / expand
C-API: Three-value return of clicon_cliread

apps/cli/cli_main.c

@@ -156,7 +156,6 @@ cli_history_save(clicon_handle h)
     return retval;
 }
 
-
 /*! Clean and close all state of cli process (but dont exit). 
  * Cannot use h after this 
  * @param[in]  h  Clixon handle
@@ -236,17 +235,22 @@ cli_interactive(clicon_handle h)
     char         *cmd;
     char         *new_mode;
     cligen_result result;
+    int           ret;
 
     /* Loop through all commands */
     while(!cligen_exiting(cli_cligen(h))) {
         new_mode = cli_syntax_mode(h);
         cmd = NULL;
-        if (clicon_cliread(h, &cmd) < 0)
+        /* Read a CLI string, including expand handling */
+        if ((ret = clicon_cliread(h, &cmd)) < 0)
             goto done;
+        if (ret == 0)
+            continue;
         if (cmd == NULL) { /* EOF */
             cligen_exiting_set(cli_cligen(h), 1);
             continue;
         }
+        /* Here errors are handled */
         if (clicon_parse(h, cmd, &new_mode, &result, NULL) < 0)
             goto done;
         /* Why not check result? */
@@ -815,7 +819,6 @@ main(int    argc,
             goto done;
     }
 
-
     /* Go into event-loop unless -1 command-line */
     if (!once){
         retval = cli_interactive(h);

apps/cli/cli_plugin.c

@@ -516,8 +516,9 @@ cli_plugin_finish(clicon_handle h)
 int 
 cli_handler_err(FILE *f)
 {
-    if (clicon_errno &&
-        (clicon_get_logflags() & CLICON_LOG_STDERR) == 0){
+    if (clicon_errno){
+        /* Check if error is already logged on stderr */
+        if ((clicon_get_logflags() & CLICON_LOG_STDERR) == 0){
             fprintf(f,  "%s: %s", clicon_strerror(clicon_errno), clicon_err_reason);
             if (clicon_suberrno)
                 fprintf(f, ": %s", strerror(clicon_suberrno));
@@ -525,6 +526,7 @@ cli_handler_err(FILE *f)
         }
         else
             fprintf(f, "CLI command error\n");
+    }
     return 0;
 }
 
@@ -596,7 +598,7 @@ clicon_parse(clicon_handle  h,
         switch (*result) {
         case CG_EOF: /* eof */
         case CG_ERROR: 
-            fprintf(f, "CLI parse error: %s\n", cmd);
+            fprintf(f, "CLI parse error: %s\n", cmd); // In practice never happens
             break;
         case CG_NOMATCH: /* no match */
             fprintf(f, "CLI syntax error: \"%s\": %s\n", cmd, reason);
@@ -741,7 +743,8 @@ cli_prompt_get(clicon_handle h,
 /*! Read command from CLIgen's cliread() using current syntax mode.
  * @param[in]  h       Clicon handle
  * @param[out] stringp Pointer to command buffer or NULL on EOF
- * @retval     0       OK
+ * @retval     1       OK
+ * @retval     0       Fail but continue
  * @retval    -1       Error
  */
 int
@@ -776,15 +779,22 @@ clicon_cliread(clicon_handle h,
     }
     cligen_ph_active_set_byname(cli_cligen(h), mode->csm_name);
 
+    clicon_err_reset();
     if (cliread(cli_cligen(h), stringp) < 0){
-        clicon_err(OE_FATAL, errno, "CLIgen");
+        cli_handler_err(stdout);
+        if (clicon_suberrno == ESHUTDOWN)
             goto done;
+        goto fail;
     }
-    retval = 0;
+
+    retval = 1;
  done:
     if (pfmt)
         free(pfmt);
     return retval;
+ fail:
+    retval = 0;
+    goto done;
 }
 
 /*

lib/src/clixon_err.c

@@ -155,6 +155,10 @@ clicon_err_reset(void)
 }
 
 /*! Find error category struct given name
+ *
+ * @param[in] category Error category
+ * @retval    cec      error category callback structs
+ * @retval    NULL     Not found
  */
 static struct clixon_err_cats *
 find_category(int category)
@@ -181,6 +185,13 @@ find_category(int category)
  * - Logs to syslog with LOG_ERR
  * - Set global error variable name clicon_errno
  * - Set global reason string clicon_err_reason
+ * Typically a call to clicon_err() is followed by a return -1 (or NULL) that signals 
+ * a fatal error that fails early and loud.
+ * However there are some cases where such an error does not cause an exit. This includes
+ * CLI operations of callbacks and expand functions. The reason is that user-defined errors
+ * should just signal an error and not terminate. To override this one can set a suberr to 
+ * ESHUTDOWN.
+ *
  * @note: err direction (syslog and/or stderr) controlled by clicon_log_init()
  *
  * @param[in]    fn       Inline function name (when called from clicon_err() macro)
@@ -227,7 +238,6 @@ clicon_err_fn(const char *fn,
     }
     va_end(args);
     strncpy(clicon_err_reason, msg, ERR_STRLEN-1);
-
     /* Check category callbacks as defined in clixon_err_cat_reg */
     if ((cec = find_category(category)) != NULL &&
         cec->cec_logfn){