binutils-gdb/gdb/testsuite/gdb.mi/mi-vla-fortran.exp
Andrew Burgess 37a8db1a33 gdb: Guard against undefined behaviour in mi-vla-fortran.exp
The test gdb.mi/mi-vla-fortran.exp reveals an issue with the DWARF
generated by gfortran.

In the test a pointer variable 'pvla2' is created:
    real, pointer :: pvla2 (:, :)

Initially this variable will be unassociated, so something like this:
    l = associated(pvla2)

should return false.

In the test gdb stops at a point _before_ pvla2 is associated with
anything, and we then try to print pvla2, the expectation is that gdb
should reply <not associated>.

The problem is that the data the DWARF directs gdb to read (to identify
if the variable is associated or not) is not initialised until the first
time pvla2 is accessed.

As a result gdb ends up reading uninitialised memory, sometimes this
uninitialised memory indicates the variable is associated (when it's
not).  This first mistake can lead to a cascade of errors, reading
uninitialised memory, with the result that gdb builds an invalid type to
associate with the variable pvla2.

In some cases, this invalid type can be very large, which when we try to
print pvla2 causes gdb to allocate a large amount of memory.

A recent commit added a new gdb variable 'max-value-size', which
prevents gdb from allocating values of extreme size.  As a result
directly trying to print pvla2 will now now error rather than allocate a
large amount of memory.

However, some of the later tests create a varobj for pvla2, and then
ask for the children of that varobj to be displayed.  In the case where
an invalid type has been computed for pvla2 then the number of children
can be wrong, and very big, in which case trying to display all of these
children can cause gdb to consume an excessive amount of memory.

This commit first detects if printing pvla2 triggers the max-value-size
error, if it does then we avoid all the follow on tests relating to the
unassociated pvla2, which avoids the second error printing the varobj
children.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-vla-fortran.exp: Add XFAIL for accessing unassociated
	pointer.  Don't perform further tests on the unassociated pointer
	if the first test fails.
2016-02-01 18:05:35 +00:00

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# Copyright 2015-2016 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/>.
# Verify that, using the MI, we can evaluate a simple C Variable Length
# Array (VLA).
load_lib mi-support.exp
set MIFLAGS "-i=mi"
gdb_exit
if [mi_gdb_start] {
continue
}
standard_testfile vla.f90
if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable \
{debug f90}] != "" } {
untested mi-vla-fortran.exp
return -1
}
mi_delete_breakpoints
mi_gdb_reinitialize_dir $srcdir/$subdir
mi_gdb_load ${binfile}
set bp_lineno [gdb_get_line_number "vla1-not-allocated"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 1 "del" "vla" \
".*vla.f90" $bp_lineno $hex \
"insert breakpoint at line $bp_lineno (vla not allocated)"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "500-data-evaluate-expression vla1" \
"500\\^done,value=\"<not allocated>\"" "evaluate not allocated vla"
mi_create_varobj_checked vla1_not_allocated vla1 "<not allocated>" \
"create local variable vla1_not_allocated"
mi_gdb_test "501-var-info-type vla1_not_allocated" \
"501\\^done,type=\"<not allocated>\"" \
"info type variable vla1_not_allocated"
mi_gdb_test "502-var-show-format vla1_not_allocated" \
"502\\^done,format=\"natural\"" \
"show format variable vla1_not_allocated"
mi_gdb_test "503-var-evaluate-expression vla1_not_allocated" \
"503\\^done,value=\"\\\[0\\\]\"" \
"eval variable vla1_not_allocated"
mi_list_array_varobj_children_with_index "vla1_not_allocated" "0" "1" \
"real\\\(kind=4\\\)" "get children of vla1_not_allocated"
set bp_lineno [gdb_get_line_number "vla1-allocated"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 2 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno (vla allocated)"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "510-data-evaluate-expression vla1" \
"510\\^done,value=\"\\(.*\\)\"" "evaluate allocated vla"
mi_create_varobj_checked vla1_allocated vla1 "real\\\(kind=4\\\) \\\(5\\\)" \
"create local variable vla1_allocated"
mi_gdb_test "511-var-info-type vla1_allocated" \
"511\\^done,type=\"real\\\(kind=4\\\) \\\(5\\\)\"" \
"info type variable vla1_allocated"
mi_gdb_test "512-var-show-format vla1_allocated" \
"512\\^done,format=\"natural\"" \
"show format variable vla1_allocated"
mi_gdb_test "513-var-evaluate-expression vla1_allocated" \
"513\\^done,value=\"\\\[5\\\]\"" \
"eval variable vla1_allocated"
mi_list_array_varobj_children_with_index "vla1_allocated" "5" "1" \
"real\\\(kind=4\\\)" "get children of vla1_allocated"
set bp_lineno [gdb_get_line_number "vla1-filled"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 3 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "520-data-evaluate-expression vla1" \
"520\\^done,value=\"\\(1, 1, 1, 1, 1\\)\"" "evaluate filled vla"
set bp_lineno [gdb_get_line_number "vla1-modified"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 4 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "530-data-evaluate-expression vla1" \
"530\\^done,value=\"\\(1, 42, 1, 24, 1\\)\"" "evaluate filled vla"
mi_gdb_test "540-data-evaluate-expression vla1(1)" \
"540\\^done,value=\"1\"" "evaluate filled vla"
mi_gdb_test "550-data-evaluate-expression vla1(2)" \
"550\\^done,value=\"42\"" "evaluate filled vla"
mi_gdb_test "560-data-evaluate-expression vla1(4)" \
"560\\^done,value=\"24\"" "evaluate filled vla"
set bp_lineno [gdb_get_line_number "vla1-deallocated"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 5 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "570-data-evaluate-expression vla1" \
"570\\^done,value=\"<not allocated>\"" "evaluate not allocated vla"
set bp_lineno [gdb_get_line_number "pvla2-not-associated"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 6 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
set test "evaluate not associated vla"
send_gdb "580-data-evaluate-expression pvla2\n"
gdb_expect {
-re "580\\^done,value=\"<not associated>\".*${mi_gdb_prompt}$" {
pass $test
mi_create_varobj_checked pvla2_not_associated pvla2 "<not associated>" \
"create local variable pvla2_not_associated"
mi_gdb_test "581-var-info-type pvla2_not_associated" \
"581\\^done,type=\"<not associated>\"" \
"info type variable pvla2_not_associated"
mi_gdb_test "582-var-show-format pvla2_not_associated" \
"582\\^done,format=\"natural\"" \
"show format variable pvla2_not_associated"
mi_gdb_test "583-var-evaluate-expression pvla2_not_associated" \
"583\\^done,value=\"\\\[0\\\]\"" \
"eval variable pvla2_not_associated"
mi_list_array_varobj_children_with_index "pvla2_not_associated" "0" "1" \
"real\\\(kind=4\\\)" "get children of pvla2_not_associated"
}
-re "580\\^error,msg=\"value contents too large \\(\[0-9\]+ bytes\\).*${mi_gdb_prompt}$" {
# Undefined behaviour in gfortran.
xfail $test
}
-re "${mi_gdb_prompt}$" {
fail $test
}
timeout {
fail "$test (timeout)"
}
}
set bp_lineno [gdb_get_line_number "pvla2-associated"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 7 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "590-data-evaluate-expression pvla2" \
"590\\^done,value=\"\\(\\( 2, 2, 2, 2, 2\\) \\( 2, 2, 2, 2, 2\\) \\)\"" \
"evaluate associated vla"
mi_create_varobj_checked pvla2_associated pvla2 \
"real\\\(kind=4\\\) \\\(5,2\\\)" "create local variable pvla2_associated"
mi_gdb_test "591-var-info-type pvla2_associated" \
"591\\^done,type=\"real\\\(kind=4\\\) \\\(5,2\\\)\"" \
"info type variable pvla2_associated"
mi_gdb_test "592-var-show-format pvla2_associated" \
"592\\^done,format=\"natural\"" \
"show format variable pvla2_associated"
mi_gdb_test "593-var-evaluate-expression pvla2_associated" \
"593\\^done,value=\"\\\[2\\\]\"" \
"eval variable pvla2_associated"
set bp_lineno [gdb_get_line_number "pvla2-set-to-null"]
mi_create_breakpoint "-t vla.f90:$bp_lineno" 8 "del" "vla" ".*vla.f90" \
$bp_lineno $hex "insert breakpoint at line $bp_lineno"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "vla" "" ".*vla.f90" "$bp_lineno" \
{ "" "disp=\"del\"" } "run to breakpoint at line $bp_lineno"
mi_gdb_test "600-data-evaluate-expression pvla2" \
"600\\^done,value=\"<not associated>\"" "evaluate vla pointer set to null"
mi_gdb_exit
return 0