This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
[PATCH 1/7] Emit a query when writing to a readonly section and trust_readonly is true
- From: Yao Qi <yao at codesourcery dot com>
- To: <gdb-patches at sourceware dot org>
- Date: Fri, 20 Sep 2013 10:47:00 +0800
- Subject: [PATCH 1/7] Emit a query when writing to a readonly section and trust_readonly is true
- Authentication-results: sourceware.org; auth=none
- References: <1378641807-24256-1-git-send-email-yao at codesourcery dot com> <1379645226-8719-1-git-send-email-yao at codesourcery dot com>
If users write readonly section, such as .text, the contents of the inferior
and of the executable become out of sync. It is better to emit a query
to ask users to "set trust-readonly-sections off".
(gdb) set trust-readonly-sections on
(gdb) p /x* (char *) 0x080484c1 = 0xcc
Address is read-only and trust-readonly-sections is set to "on".
Set it to "off" and write to a read-only section? (y or n) y
$1 = 0xcc
gdb:
2013-09-20 Yao Qi <yao@codesourcery.com>
* target.c (memory_xfer_partial_1): Emit a query if GDB
writes to a readonly section and 'trust_readonly' is true.
gdb/testsuite:
2013-09-20 Yao Qi <yao@codesourcery.com>
* gdb.base/trust-readonly.exp: New.
---
gdb/target.c | 35 +++++++++---
gdb/testsuite/gdb.base/trust-readonly.exp | 85 +++++++++++++++++++++++++++++
2 files changed, 111 insertions(+), 9 deletions(-)
create mode 100644 gdb/testsuite/gdb.base/trust-readonly.exp
diff --git a/gdb/target.c b/gdb/target.c
index d55712d..37db36b 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1471,11 +1471,13 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,
}
}
- /* Try the executable files, if "trust-readonly-sections" is set. */
- if (readbuf != NULL && trust_readonly)
+ /* If "trust-readonly-sections" is set, read from the executable
+ files. When GDB writes to a readonly section of the inferior,
+ emit a warning that option 'trust-readonly-sections' should be
+ turned off. */
+ if (trust_readonly)
{
struct target_section *secp;
- struct target_section_table *table;
secp = target_section_by_addr (ops, memaddr);
if (secp != NULL
@@ -1483,12 +1485,27 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,
secp->the_bfd_section)
& SEC_READONLY))
{
- table = target_get_section_table (ops);
- return section_table_xfer_memory_partial (readbuf, writebuf,
- memaddr, len,
- table->sections,
- table->sections_end,
- NULL);
+
+ if (readbuf != NULL)
+ {
+ struct target_section_table *table;
+
+ table = target_get_section_table (ops);
+ return section_table_xfer_memory_partial (readbuf, writebuf,
+ memaddr, len,
+ table->sections,
+ table->sections_end,
+ NULL);
+ }
+
+ if (writebuf != NULL)
+ {
+ if (query (_("Address is read-only and trust-readonly-sections\
+ is set to \"on\".\nSet it to \"off\" and write to a read-only section? ")))
+ trust_readonly = 0;
+ else
+ return -1;
+ }
}
}
diff --git a/gdb/testsuite/gdb.base/trust-readonly.exp b/gdb/testsuite/gdb.base/trust-readonly.exp
new file mode 100644
index 0000000..8627800
--- /dev/null
+++ b/gdb/testsuite/gdb.base/trust-readonly.exp
@@ -0,0 +1,85 @@
+# Copyright 2013 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 start.c
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+ untested "Could not compile $binfile."
+ return -1
+}
+
+clean_restart ${binfile}
+
+if ![runto_main] then {
+ return -1
+}
+
+set main_address ""
+set test "Extract main address"
+gdb_test_multiple "print *main" $test {
+ -re "\} ($hex) .*$gdb_prompt $" {
+ pass $test
+ set main_address $expect_out(1,string)
+ }
+ -re ".*$gdb_prompt $" {
+ # Unable to extract address of main. Bail out.
+ fail $test
+ return -1
+ }
+}
+
+set main_contents ""
+set test "Extract main contents"
+gdb_test_multiple "print/x *(char *) $main_address" $test {
+ -re "\\$$decimal = ($hex).*$gdb_prompt $" {
+ pass $test
+ set main_contents $expect_out(1,string)
+ }
+ -re ".*$gdb_prompt $" {
+ # Unable to extract contents of main. Bail out.
+ fail $test
+ return -1
+ }
+}
+
+# Set option "trust-readonly-sections" off, write one byte and read it
+# back.
+
+gdb_test_no_output "set trust-readonly-sections off" ""
+gdb_test "print /x* (char *) $main_address = 0xcc" "\\$$decimal = 0xcc" \
+ "write to main (off)"
+gdb_test "print /x * (char *) $main_address" "\\$$decimal = 0xcc" \
+ "read from main (off) 1"
+
+gdb_test_no_output "set trust-readonly-sections on" ""
+gdb_test "print /x* (char *) $main_address = 0x11" "\\$$decimal = 0x11" \
+ "write to main (on)" \
+ "Address is read-only and trust-readonly-sections is set to \"on\"\..*y or n. $" \
+ "y"
+
+# Option "trust-readonly-sections" is turned off as answer "y" is
+# entered above.
+gdb_test "show trust-readonly-sections" \
+ "Mode for reading from readonly sections is off\."
+
+gdb_test "print /x * (char *) $main_address" "\\$$decimal = 0x11" \
+ "read from main (off) 2"
+
+# Set option "trust-readonly-sections" on, and test GDB read data from
+# the executable file instead of the inferior.
+
+gdb_test_no_output "set trust-readonly-sections on" ""
+gdb_test "print /x * (char *) $main_address" "\\$$decimal = ${main_contents}" \
+ "read from main (on)"
--
1.7.7.6