Fix undefined behavior in TUI's TAB expansion

[deliverable/binutils-gdb.git] / gdb / tui / tui-io.c

diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index c8b85672c0fb529fcf0d04c20b021b3f9dd202ab..97906ceb45eaefb7d5fea9f38e73616ffb80153b 100644 (file)
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -668,20 +668,20 @@ tui_getc (FILE *fp)
 char *
 tui_expand_tabs (const char *string, int col)
 {
-  int n_adjust;
+  int n_adjust, ncol;
   const char *s;
   char *ret, *q;
 
   /* 1. How many additional characters do we need?  */
-  for (n_adjust = 0, s = string; s; )
+  for (ncol = col, n_adjust = 0, s = string; s; )
     {
       s = strpbrk (s, "\t");
       if (s)
        {
-         col += (s - string) + n_adjust;
+         ncol += (s - string) + n_adjust;
          /* Adjustment for the next tab stop, minus one for the TAB
             we replace with spaces.  */
-         n_adjust += 8 - (col % 8) - 1;
+         n_adjust += 8 - (ncol % 8) - 1;
          s++;
        }
     }
@@ -690,7 +690,7 @@ tui_expand_tabs (const char *string, int col)
   ret = q = xmalloc (strlen (string) + n_adjust + 1);
 
   /* 2. Copy the original string while replacing TABs with spaces.  */
-  for (s = string; s; )
+  for (ncol = col, s = string; s; )
     {
       const char *s1 = strpbrk (s, "\t");
       if (s1)
@@ -699,12 +699,12 @@ tui_expand_tabs (const char *string, int col)
            {
              strncpy (q, s, s1 - s);
              q += s1 - s;
-             col += s1 - s;
+             ncol += s1 - s;
            }
          do {
            *q++ = ' ';
-           col++;
-         } while ((col % 8) != 0);
+           ncol++;
+         } while ((ncol % 8) != 0);
          s1++;
        }
       else