expr: Check for missing operand to operator

Reported-by: Ryan Whitworth <me@ryanwhitworth.com>
Signed-off-by: Steve Bennett <steveb@workware.net.au>

2 files changed, 19 insertions, 0 deletions

diff --git a/jim.c b/jim.c
index e69d4c0..cf9b758 100644
--- a/jim.c
+++ b/jim.c
@@ -8899,12 +8899,26 @@ noargs:
 
             if (op->arity >= 3) {
                 node->ternary = Jim_StackPop(&builder->stack);
+                if (node->ternary == NULL) {
+                    goto missingoperand;
+                }
             }
             if (op->arity >= 2) {
                 node->right = Jim_StackPop(&builder->stack);
+                if (node->right == NULL) {
+                    printf("missing right term to operator %s\n", op->name);
+                    goto missingoperand;
+                }
             }
             if (op->arity >= 1) {
                 node->left = Jim_StackPop(&builder->stack);
+                if (node->left == NULL) {
+missingoperand:
+                    Jim_SetResultFormatted(interp, "missing operand to %s in expression: \"%#s\"", op->name, builder->exprObjPtr);
+                    builder->next--;
+                    return JIM_ERR;
+
+                }
             }
 
             /* Now push the node */
diff --git a/regtest.tcl b/regtest.tcl
index aae22d5..0833b39 100644
--- a/regtest.tcl
+++ b/regtest.tcl
@@ -340,6 +340,11 @@ puts "TEST 48 PASSED"
 catch {format %1.9999999999f 1.0}
 puts "TEST 49 PASSED"
 
+# REGTEST 50
+# expr missing operand
+catch {expr {>>-$x}}
+puts "TEST 50 PASSED"
+
 # TAKE THE FOLLOWING puts AS LAST LINE
 
 puts "--- ALL TESTS PASSED ---"