Fix INTEGER_OVERFLOW in gen_tables64.h

Implemented the same signed-midpoint fix in the 64-bit helpers (s2i_64__, i2s_64_bsearch__) by changing mid from size_t to ssize_t, preventing mid - 1 unsigned wraparound in binary search bound updates.

Added the edge-case guard for empty tables (n == 0) before right = n - 1 in both 32-bit and 64-bit search helpers, avoiding underflow when n is zero.

Author: stevegrubb

lib/gen_tables.h

@@ -1,5 +1,5 @@
 /* gen_tables.h -- Declarations used for lookup tables.
- * Copyright 2008 Red Hat Inc., Durham, North Carolina.
+ * Copyright 2008 Red Hat Inc.
  * All Rights Reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ -33,6 +33,10 @@ inline static int s2i__(const char *strings, const unsigned *s_table,
 			const int *i_table, size_t n, const char *s, int *value)
 {
 	size_t lo = 0, hi = 0;
+
+	if (n == 0)
+		return 0;
+
 	ssize_t left = 0, right = n - 1;
 
 	while (left <= right) {	/* invariant: left <= x <= right */
@@ -85,6 +89,9 @@ inline static const char *i2s_bsearch__(const char *strings,
 {
 	ssize_t left, right;
 
+	if (n == 0)
+		return NULL;
+
 	left = 0;
 	right = n - 1;
 	while (left <= right) {	/* invariant: left <= x <= right */

lib/gen_tables64.h

@@ -48,10 +48,14 @@ inline static int s2i_64__(const char *strings, const unsigned *s_table,
 		const int64_t *i_table, size_t n, const char *s, int64_t *value)
 {
     size_t lo = 0, hi = 0;
+    if (n == 0)
+	    return 0;
+
     ssize_t left = 0, right = n - 1;
 
     while (left <= right) {	   /* invariant: left <= x <= right */
-        size_t mid, off, i;
+        ssize_t mid;
+        size_t off, i;
         const char *t;
         int r;
 
@@ -103,10 +107,13 @@ inline static const char *i2s_64_bsearch__(const char *strings,
 {
     ssize_t left, right;
 
+    if (n == 0)
+	    return NULL;
+
     left = 0;
     right = n - 1;
     while (left <= right) {    /* invariant: left <= x <= right */
-        size_t mid;
+        ssize_t mid;
         int64_t mid_val;
 
         mid = (left + right) / 2;