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Re: [RFA/mips] Fix crash trying to print long double float
- From: Andrew Cagney <cagney at gnu dot org>
- To: Joel Brobecker <brobecker at gnat dot com>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Fri, 06 Aug 2004 16:23:50 -0400
- Subject: Re: [RFA/mips] Fix crash trying to print long double float
- References: <20040806181603.GQ1203@gnat.com>
Because the gdbarch vector tells GDB that TARGET_LONG_DOUBLE_BIT = 64bit,
we end up returning a NULL floatformat. And unfortunately for us, we
immediatly use that NULL floatformat to feed it to floatformat_is_valid(),
which dereferences it without checking that it's not NULL before hand.
This causes the SEGV. See values.c:unpack_double():
if (!floatformat_is_valid (floatformat_from_type (type), valaddr))
{
*invp = 1;
return 0.0;
}
Does the attached stop the crash?
Andrew
2004-08-06 Andrew Cagney <cagney@gnu.org>
* doublest.c: Update copyright.
(floatformat_from_length): Call error when floatformat is NULL.
(extract_floating_by_length): Remove NULL fmt check.
(store_floating_by_length): Ditto.
Index: doublest.c
===================================================================
RCS file: /cvs/src/src/gdb/doublest.c,v
retrieving revision 1.18
diff -p -u -r1.18 doublest.c
--- doublest.c 29 Jul 2004 19:33:22 -0000 1.18
+++ doublest.c 6 Aug 2004 20:20:14 -0000
@@ -1,8 +1,8 @@
/* Floating point routines for GDB, the GNU debugger.
Copyright 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
- 1996, 1997, 1998, 1999, 2000, 2001, 2003 Free Software Foundation,
- Inc.
+ 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004 Free Software
+ Foundation, Inc.
This file is part of GDB.
@@ -618,8 +618,8 @@ floatformat_from_doublest (const struct
/* Return a floating-point format for a floating-point variable of
- length LEN. Return NULL, if no suitable floating-point format
- could be found.
+ length LEN. If no suitable floating-point format is found, an
+ error is thrown.
We need this functionality since information about the
floating-point format of a type is not always available to GDB; the
@@ -633,12 +633,13 @@ floatformat_from_doublest (const struct
static const struct floatformat *
floatformat_from_length (int len)
{
+ const struct floatformat *format;
if (len * TARGET_CHAR_BIT == TARGET_FLOAT_BIT)
- return TARGET_FLOAT_FORMAT;
+ format = TARGET_FLOAT_FORMAT;
else if (len * TARGET_CHAR_BIT == TARGET_DOUBLE_BIT)
- return TARGET_DOUBLE_FORMAT;
+ format = TARGET_DOUBLE_FORMAT;
else if (len * TARGET_CHAR_BIT == TARGET_LONG_DOUBLE_BIT)
- return TARGET_LONG_DOUBLE_FORMAT;
+ format = TARGET_LONG_DOUBLE_FORMAT;
/* On i386 the 'long double' type takes 96 bits,
while the real number of used bits is only 80,
both in processor and in memory.
@@ -646,9 +647,13 @@ floatformat_from_length (int len)
else if ((TARGET_LONG_DOUBLE_FORMAT != NULL)
&& (len * TARGET_CHAR_BIT ==
TARGET_LONG_DOUBLE_FORMAT->totalsize))
- return TARGET_LONG_DOUBLE_FORMAT;
-
- return NULL;
+ format = TARGET_LONG_DOUBLE_FORMAT;
+ else
+ format = NULL;
+ if (format == NULL)
+ error ("This GDB does not support %d-bit floating-point values.",
+ len & TARGET_CHAR_BIT);
+ return format;
}
const struct floatformat *
@@ -675,12 +680,6 @@ extract_floating_by_length (const void *
const struct floatformat *fmt = floatformat_from_length (len);
DOUBLEST val;
- if (fmt == NULL)
- {
- warning ("Can't extract a floating-point number of %d bytes.", len);
- return NAN;
- }
-
floatformat_to_doublest (fmt, addr, &val);
return val;
}
@@ -699,13 +698,6 @@ store_floating_by_length (void *addr, in
{
const struct floatformat *fmt = floatformat_from_length (len);
- if (fmt == NULL)
- {
- warning ("Can't store a floating-point number of %d bytes.", len);
- memset (addr, 0, len);
- return;
- }
-
floatformat_from_doublest (fmt, &val, addr);
}