awk: disallow "str"++, closes bug 12981

function                                             old     new   delta
parse_expr                                           887     896      +9

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 11 insertions, 1 deletions

diff --git a/editors/awk.c b/editors/awk.c
index 70df2fdb4..f7451ae32 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -1359,8 +1359,10 @@ static node *parse_expr(uint32_t iexp)
                                         v = cn->l.v = xzalloc(sizeof(var));
                                         if (tc & TC_NUMBER)
                                                 setvar_i(v, t_double);
-                                        else
+                                        else {
                                                 setvar_s(v, t_string);
+                                                xtc &= ~TC_UOPPOST; /* "str"++ is not allowed */
+                                        }
                                         break;
 
                                 case TC_REGEXP:
diff --git a/testsuite/awk.tests b/testsuite/awk.tests
index b5008290f..87f6b5007 100755
--- a/testsuite/awk.tests
+++ b/testsuite/awk.tests
@@ -390,5 +390,13 @@ testing 'awk negative field access' \
         '' \
         'anything'
 
+# was misinterpreted as (("str"++) i) instead of ("str" (++i))
+# (and was executed: "str"++ is "0", thus concatenating "0" and "1"):
+testing 'awk do not allow "str"++' \
+        'awk -v i=1 "BEGIN {print \"str\" ++i}"' \
+        "str2\n" \
+        '' \
+        'anything'
+
 
 exit $FAILCOUNT