+2016-02-01 Andrew Burgess <andrew.burgess@embecosm.com>
+
+ * value.c (max_value_size): New variable.
+ (MIN_VALUE_FOR_MAX_VALUE_SIZE): New define.
+ (set_max_value_size): New function.
+ (show_max_value_size): New function.
+ (check_type_length_before_alloc): New function.
+ (allocate_value_contents): Call check_type_length_before_alloc.
+ (set_value_enclosing_type): Likewise.
+ (_initialize_values): Add set/show handler for max-value-size.
+ * NEWS: Mention new set/show command.
+
2016-01-31 Simon Marchi <simon.marchi@polymtl.ca>
* varobj.h (struct varobj): Fix typos in comments.
Control whether parameter types and return types are displayed in overloads
selection menus. It is activaled (@code{on}) by default.
+set max-value-size
+show max-value-size
+ Controls the maximum size of memory, in bytes, that GDB will
+ allocate for value contents. Prevents incorrect programs from
+ causing GDB to allocate overly large buffers. Default is 64k.
+
* The "disassemble" command accepts a new modifier: /s.
It prints mixed source+disassembly like /m with two differences:
- disassembled instructions are now printed in program order, and
+2016-02-01 Andrew Burgess <andrew.burgess@embecosm.com>
+
+ * gdb.texinfo (Value Sizes): New section.
+ (Data): Add the 'Value Sizes' node to the menu.
+
2016-01-26 John Baldwin <jhb@FreeBSD.org>
* gdb.texinfo (Debugging Output): Fix subject verb disagreements.
character set than GDB does
* Caching Target Data:: Data caching for targets
* Searching Memory:: Searching memory for a sequence of bytes
+* Value Sizes:: Managing memory allocated for values
@end menu
@node Expressions
$2 = (void *) 0x8049560
@end smallexample
+@node Value Sizes
+@section Value Sizes
+
+Whenever @value{GDBN} prints a value memory will be allocated within
+@value{GDBN} to hold the contents of the value. It is possible in
+some languages with dynamic typing systems, that an invalid program
+may indicate a value that is incorrectly large, this in turn may cause
+@value{GDBN} to try and allocate an overly large ammount of memory.
+
+@table @code
+@kindex set max-value-size
+@itemx set max-value-size @var{bytes}
+@itemx set max-value-size unlimited
+Set the maximum size of memory that @value{GDBN} will allocate for the
+contents of a value to @var{bytes}, trying to display a value that
+requires more memory than that will result in an error.
+
+Setting this variable does not effect values that have already been
+allocated within @value{GDBN}, only future allocations.
+
+There's a minimum size that @code{max-value-size} can be set to in
+order that @value{GDBN} can still operate correctly, this minimum is
+currently 16 bytes.
+
+The limit applies to the results of some subexpressions as well as to
+complete expressions. For example, an expression denoting a simple
+integer component, such as @code{x.y.z}, may fail if the size of
+@var{x.y} is dynamic and exceeds @var{bytes}. On the other hand,
+@value{GDBN} is sometimes clever; the expression @code{A[i]}, where
+@var{A} is an array variable with non-constant size, will generally
+succeed regardless of the bounds on @var{A}, as long as the component
+size is less than @var{bytes}.
+
+The default value of @code{max-value-size} is currently 64k.
+
+@kindex show max-value-size
+@item show max-value-size
+Show the maximum size of memory, in bytes, that @value{GDBN} will
+allocate for the contents of a value.
+@end table
+
@node Optimized Code
@chapter Debugging Optimized Code
@cindex optimized code, debugging
+2016-02-01 Andrew Burgess <andrew.burgess@embecosm.com>
+
+ * gdb.base/max-value-size.c: New file.
+ * gdb.base/max-value-size.exp: New file.
+ * gdb.base/huge.exp: Disable max-value-size for this test.
+
2016-01-28 Iain Buclaw <ibuclaw@gdcproject.org>
* gdb.dlang/demangle.exp: Sync tests from libiberty testsuite.
return -1
}
+gdb_test_no_output "set max-value-size unlimited"
+
gdb_test "print a" ".1 = .0 .repeats \[0123456789\]+ times.." "print a very large data object"
set timeout $prev_timeout
--- /dev/null
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright (C) 2016 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+char one;
+char ten[10];
+char one_hundred[100];
+
+int
+main (void)
+{
+ return 0;
+}
--- /dev/null
+# Copyright (C) 2016 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+standard_testfile
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile debug]} {
+ untested $testfile.exp
+ return -1
+}
+
+if ![runto_main] then {
+ fail "Can't run to main"
+ return 0
+}
+
+# Run "show max-value-size" and return the interesting bit of the
+# result. This is either the maximum size in bytes, or the string
+# "unlimited".
+proc get_max_value_size {} {
+ global gdb_prompt
+ global decimal
+
+ gdb_test_multiple "show max-value-size" "" {
+ -re "Maximum value size is ($decimal) bytes.*$gdb_prompt $" {
+ return $expect_out(1,string)
+ }
+ -re "Maximum value size is unlimited.*$gdb_prompt $" {
+ return "unlimited"
+ }
+ }
+}
+
+# Assuming that MAX_VALUE_SIZE is the current value for
+# max-value-size, print the test values. Use TEST_PREFIX to make the
+# test names unique.
+proc do_value_printing { max_value_size test_prefix } {
+ with_test_prefix ${test_prefix} {
+ gdb_test "p/d one" " = 0"
+ if { $max_value_size != "unlimited" && $max_value_size < 100 } then {
+ gdb_test "p/d one_hundred" \
+ "value requires 100 bytes, which is more than max-value-size"
+ } else {
+ gdb_test "p/d one_hundred" " = \\{0 <repeats 100 times>\\}"
+ }
+ gdb_test "p/d one_hundred \[99\]" " = 0"
+ }
+}
+
+# Install SET_VALUE as the value for max-value-size, then print the
+# test values.
+proc set_and_check_max_value_size { set_value } {
+ if { $set_value == "unlimited" } then {
+ set check_pattern "unlimited"
+ } else {
+ set check_pattern "${set_value} bytes"
+ }
+
+ gdb_test_no_output "set max-value-size ${set_value}"
+ gdb_test "show max-value-size" \
+ "Maximum value size is ${check_pattern}." \
+ "check that the value shows as ${check_pattern}"
+
+ do_value_printing ${set_value} "max-value-size is '${set_value}'"
+}
+
+# Check the default value is sufficient.
+do_value_printing [get_max_value_size] "using initial max-value-size"
+
+# Check some values for max-value-size that should prevent some
+# allocations.
+set_and_check_max_value_size 25
+set_and_check_max_value_size 99
+
+# Check values for max-value-size that should allow all allocations.
+set_and_check_max_value_size 100
+set_and_check_max_value_size 200
+set_and_check_max_value_size "unlimited"
+
+# Check that we can't set the maximum size stupidly low.
+gdb_test "set max-value-size 1" \
+ "max-value-size set too low, increasing to \[0-9\]+ bytes"
+gdb_test "set max-value-size 0" \
+ "max-value-size set too low, increasing to \[0-9\]+ bytes"
+gdb_test "set max-value-size -5" \
+ "only -1 is allowed to set as unlimited"
return val;
}
+/* The maximum size, in bytes, that GDB will try to allocate for a value.
+ The initial value of 64k was not selected for any specific reason, it is
+ just a reasonable starting point. */
+
+static int max_value_size = 65536; /* 64k bytes */
+
+/* It is critical that the MAX_VALUE_SIZE is at least as big as the size of
+ LONGEST, otherwise GDB will not be able to parse integer values from the
+ CLI; for example if the MAX_VALUE_SIZE could be set to 1 then GDB would
+ be unable to parse "set max-value-size 2".
+
+ As we want a consistent GDB experience across hosts with different sizes
+ of LONGEST, this arbitrary minimum value was selected, so long as this
+ is bigger than LONGEST on all GDB supported hosts we're fine. */
+
+#define MIN_VALUE_FOR_MAX_VALUE_SIZE 16
+gdb_static_assert (sizeof (LONGEST) <= MIN_VALUE_FOR_MAX_VALUE_SIZE);
+
+/* Implement the "set max-value-size" command. */
+
+static void
+set_max_value_size (char *args, int from_tty,
+ struct cmd_list_element *c)
+{
+ gdb_assert (max_value_size == -1 || max_value_size >= 0);
+
+ if (max_value_size > -1 && max_value_size < MIN_VALUE_FOR_MAX_VALUE_SIZE)
+ {
+ max_value_size = MIN_VALUE_FOR_MAX_VALUE_SIZE;
+ error (_("max-value-size set too low, increasing to %d bytes"),
+ max_value_size);
+ }
+}
+
+/* Implement the "show max-value-size" command. */
+
+static void
+show_max_value_size (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c, const char *value)
+{
+ if (max_value_size == -1)
+ fprintf_filtered (file, _("Maximum value size is unlimited.\n"));
+ else
+ fprintf_filtered (file, _("Maximum value size is %d bytes.\n"),
+ max_value_size);
+}
+
+/* Called before we attempt to allocate or reallocate a buffer for the
+ contents of a value. TYPE is the type of the value for which we are
+ allocating the buffer. If the buffer is too large (based on the user
+ controllable setting) then throw an error. If this function returns
+ then we should attempt to allocate the buffer. */
+
+static void
+check_type_length_before_alloc (const struct type *type)
+{
+ unsigned int length = TYPE_LENGTH (type);
+
+ if (max_value_size > -1 && length > max_value_size)
+ {
+ if (TYPE_NAME (type) != NULL)
+ error (_("value of type `%s' requires %u bytes, which is more "
+ "than max-value-size"), TYPE_NAME (type), length);
+ else
+ error (_("value requires %u bytes, which is more than "
+ "max-value-size"), length);
+ }
+}
+
/* Allocate the contents of VAL if it has not been allocated yet. */
static void
allocate_value_contents (struct value *val)
{
if (!val->contents)
- val->contents = (gdb_byte *) xzalloc (TYPE_LENGTH (val->enclosing_type));
+ {
+ check_type_length_before_alloc (val->enclosing_type);
+ val->contents
+ = (gdb_byte *) xzalloc (TYPE_LENGTH (val->enclosing_type));
+ }
}
/* Allocate a value and its contents for type TYPE. */
void
set_value_enclosing_type (struct value *val, struct type *new_encl_type)
{
- if (TYPE_LENGTH (new_encl_type) > TYPE_LENGTH (value_enclosing_type (val)))
- val->contents =
- (gdb_byte *) xrealloc (val->contents, TYPE_LENGTH (new_encl_type));
+ if (TYPE_LENGTH (new_encl_type) > TYPE_LENGTH (value_enclosing_type (val)))
+ {
+ check_type_length_before_alloc (new_encl_type);
+ val->contents
+ = (gdb_byte *) xrealloc (val->contents, TYPE_LENGTH (new_encl_type));
+ }
val->enclosing_type = new_encl_type;
}
Usage: $_isvoid (expression)\n\
Return 1 if the expression is void, zero otherwise."),
isvoid_internal_fn, NULL);
+
+ add_setshow_zuinteger_unlimited_cmd ("max-value-size",
+ class_support, &max_value_size, _("\
+Set maximum sized value gdb will load from the inferior."), _("\
+Show maximum sized value gdb will load from the inferior."), _("\
+Use this to control the maximum size, in bytes, of a value that gdb\n\
+will load from the inferior. Setting this value to 'unlimited'\n\
+disables checking.\n\
+Setting this does not invalidate already allocated values, it only\n\
+prevents future values, larger than this size, from being allocated."),
+ set_max_value_size,
+ show_max_value_size,
+ &setlist, &showlist);
}
projects / binutils-gdb.git / commitdiff