Don't try to compile a pattern known to be in error

Regular expression patterns are parsed by the lexer/toker, and then
compiled by the regex compiler.  It is foolish to try to compile one
that the parser has rejected as syntactically bad; assumptions may be
violated and segfaults ensue.  This commit abandons all parsing
immediately if a pattern had errors in it.  A better solution would be
to flag this pattern as not to be compiled, and continue parsing other
things so as to find the most errors in a single attempt, but I don't
think it's worth the extra effort.

Making this change caused some misleading error messages in the test
suite to be replaced by better ones.

diff --git a/t/re/re_tests b/t/re/re_tests
index f210202..410fcea 100644 (file)
--- a/t/re/re_tests
+++ b/t/re/re_tests
@@ -1464,13 +1464,10 @@ abc\N   abc\n   n
 # Verify get errors.  For these, we need // or else puts it in single quotes,
 # and bypasses the lexer.
 /\N{U+}/       -       c       -       Invalid hexadecimal number
-# Below currently gives a misleading message
-/[\N{U+}]/     -       Sc      -       Unmatched
-/[\N{U+}]/     -       sc      -       Syntax error in (?[...])
+/[\N{U+}]/     -       c       -       Invalid hexadecimal number
 /abc\N{def/    -       c       -       Missing right brace
 /\N{U+4AG3}/   -       c       -       Invalid hexadecimal number
-/[\N{U+4AG3}]/ -       Sc      -       Unmatched
-/[\N{U+4AG3}]/ -       sc      -       Syntax error in (?[...])
+/[\N{U+4AG3}]/ -       c       -       Invalid hexadecimal number
 
 # And verify that in single quotes which bypasses the lexer, the regex compiler
 # figures it out.

diff --git a/toke.c b/toke.c
index 383203a..880ac53 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -5021,7 +5021,16 @@ Perl_yylex(pTHX)
            s = PL_bufend;
        }
        else {
+            int save_error_count = PL_error_count;
+
            s = scan_const(PL_bufptr);
+
+            /* Quit if this was a pattern and there were errors.  This prevents
+             * us from trying to regex compile a broken pattern, which could
+             * lead to segfaults, etc. */
+            if (PL_lex_inpat && PL_error_count > save_error_count) {
+                yyquit();
+            }
            if (*s == '\\')
                PL_lex_state = LEX_INTERPCASEMOD;
            else