Nasm lexer: Don't read past end of passed string.

This was because the re2c-generated code always reads the next character
prior to user code being executed.  Instead, check for the \0 marker prior
to entering the re2c code.  Retain the re2c check just for sanity.

Reported by: Samuel Thibault (on yasm-devel@)

svn path=/trunk/yasm/; revision=2122

1 files changed, 38 insertions, 47 deletions

diff --git a/modules/parsers/nasm/nasm-token.re b/modules/parsers/nasm/nasm-token.re
index 931dbdc4..cc589b18 100644
--- a/modules/parsers/nasm/nasm-token.re
+++ b/modules/parsers/nasm/nasm-token.re
@@ -139,6 +139,8 @@ nasm_parser_lex(YYSTYPE *lvalp, yasm_parser_nasm *parser_nasm)
 
 scan:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
         /* standard decimal integer */
@@ -387,10 +389,7 @@ scan:
 
         ws+                     { goto scan; }
 
-        [\000]                  {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\000]                  { goto endofinput; }
 
         any {
             yasm_warn_set(YASM_WARN_UNREC_CHAR,
@@ -403,6 +402,8 @@ scan:
     /* %line linenum+lineinc filename */
 linechg:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
         digit+ {
@@ -414,10 +415,7 @@ linechg:
             RETURN(INTNUM);
         }
 
-        [\000] {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\000] { goto endofinput; }
 
         "+" {
             RETURN(s->tok[0]);
@@ -441,14 +439,13 @@ linechg:
 
 linechg2:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
-        [\000] {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\000] { goto endofinput; }
 
-        "\r" { }
+        "\r" { goto linechg2; }
 
         (any \ [\000])+ {
             parser_nasm->state = LINECHG;
@@ -460,12 +457,11 @@ linechg2:
     /* directive: [name value] */
 directive:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
-        [\]\000] {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\]\000] { goto endofinput; }
 
         [a-zA-Z_][a-zA-Z_0-9]* {
             lvalp->str_val = yasm__xstrndup(TOK, TOKLEN);
@@ -488,6 +484,8 @@ directive:
     /* section directive (the section name portion thereof) */
 section_directive:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
         [a-zA-Z0-9_$#@~.?-]+ {
@@ -508,15 +506,7 @@ section_directive:
             goto section_directive;
         }
 
-        "]" {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
-
-        [\000]          {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\]\000]        { goto endofinput; }
 
         any {
             yasm_warn_set(YASM_WARN_UNREC_CHAR,
@@ -529,6 +519,8 @@ section_directive:
     /* inner part of directive */
 directive2:
     SCANINIT();
+    if (*cursor == '\0')
+        goto endofinput;
 
     /*!re2c
         /* standard decimal integer */
@@ -589,10 +581,7 @@ directive2:
         [-+|^*&/%~$():=,\[]     { RETURN(s->tok[0]); }
 
         /* handle ] for directives */
-        "]" {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        "]"                     { goto endofinput; }
 
         /* forced identifier; within directive, don't strip '$', this is
          * handled later.
@@ -625,10 +614,7 @@ directive2:
 
         ws+                     { goto directive2; }
 
-        [\000]                  {
-            parser_nasm->state = INITIAL;
-            RETURN(s->tok[0]);
-        }
+        [\000]                  { goto endofinput; }
 
         any {
             yasm_warn_set(YASM_WARN_UNREC_CHAR,
@@ -646,23 +632,15 @@ stringconst:
 
 stringconst_scan:
     SCANINIT();
+    if (*cursor == '\0')
+        goto stringconst_error;
 
     /*!re2c
-        [\000]  {
-            yasm_error_set(YASM_ERROR_SYNTAX, N_("unterminated string"));
-            strbuf[count] = '\0';
-            lvalp->str.contents = (char *)strbuf;
-            lvalp->str.len = count;
-            RETURN(STRING);
-        }
+        [\000]  { goto stringconst_error; }
 
         any     {
-            if (s->tok[0] == endch) {
-                strbuf[count] = '\0';
-                lvalp->str.contents = (char *)strbuf;
-                lvalp->str.len = count;
-                RETURN(STRING);
-            }
+            if (s->tok[0] == endch)
+                goto stringconst_end;
 
             strbuf[count++] = s->tok[0];
             if (count >= strbuf_size) {
@@ -673,4 +651,17 @@ stringconst_scan:
             goto stringconst_scan;
         }
     */
+
+stringconst_error:
+    yasm_error_set(YASM_ERROR_SYNTAX, N_("unterminated string"));
+
+stringconst_end:
+    strbuf[count] = '\0';
+    lvalp->str.contents = (char *)strbuf;
+    lvalp->str.len = count;
+    RETURN(STRING);
+
+endofinput:
+    parser_nasm->state = INITIAL;
+    RETURN(s->tok[0]);
 }