Fix GDBHISTSIZE test failure on i686

The test

  test_histsize_history_setting "99999999999999999999999999999999999" "unlimited"

was failing on i686 because the condition in init_history() for
determining whether to map a large GDBHISTSIZE value to infinity was

  long var = strtol (tmpenv);
  if (var > INT_MAX)
    history_size = unlimited;

but this condition is never true on i686 because INT_MAX == LONG_MAX.
So in order to properly map large out-of-range values of GDBHISTSIZE to
infinity on targets where LONG_MAX > INT_MAX as well as on i686, we have
to instead change the above condition to

  if (var > INT_MAX
      || (var == INT_MAX && errno == ERANGE))
    history_size = unlimited;

gdb/ChangeLog:

	* top.c (init_history): Look at errno after calling strtol to
	properly map large GDBHISTSIZE values to infinity.

1 files changed, 9 insertions, 1 deletions

diff --git a/gdb/top.c b/gdb/top.c
index 6ae84ab..77fe096 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -1685,10 +1685,13 @@ init_history (void)
   if (tmpenv)
     {
       long var;
+      int saved_errno;
       char *endptr;
 
       tmpenv = skip_spaces (tmpenv);
+      errno = 0;
       var = strtol (tmpenv, &endptr, 10);
+      saved_errno = errno;
       endptr = skip_spaces (endptr);
 
       /* If GDBHISTSIZE is non-numeric then ignore it.  If GDBHISTSIZE is the
@@ -1700,7 +1703,12 @@ init_history (void)
 	;
       else if (*tmpenv == '\0'
 	       || var < 0
-	       || var > INT_MAX)
+	       || var > INT_MAX
+	       /* On targets where INT_MAX == LONG_MAX, we have to look at
+		  errno after calling strtol to distinguish between a value that
+		  is exactly INT_MAX and an overflowing value that was clamped
+		  to INT_MAX.  */
+	       || (var == INT_MAX && saved_errno == ERANGE))
 	history_size_setshow_var = -1;
       else
 	history_size_setshow_var = var;