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gdb: Fix "info os <unknown>" command

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Running `info os someUnknownOsType` is crashing when gdb is built with
-D_GLIBCXX_DEBUG:

	/usr/include/c++/5/debug/vector:439:error: attempt to
	access an element in an empty container.

In target_read_stralloc from target.c, the call to
target_read_alloc_1 can return an empty vector, we then call vector::back on
this vector, which is invalid.

This commit adds a check for emptiness before trying to call
vector::back on it. It also adds test to check for `info os <unknown>`
to return the proper error message.

This is a regression in gdb 8.2 and this patch restores the behavior of
previous versions.

gdb/ChangeLog:

	PR gdb/23974
	* target.c (target_read_stralloc): Check for empty vector.

gdb/testsuite/ChangeLog:

	PR gdb/23974
	* gdb.base/info-os.exp: Check return for unknown "info os" type.
This commit is contained in:
Paul Marechal
2018-12-21 12:02:33 -05:00
committed by Simon Marchi
parent 9a67ecf9e9
commit 6ef08cc9a8
4 changed files with 14 additions and 1 deletions
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5
gdb/ChangeLog
View File

@@ -1,3 +1,8 @@
2018-12-21 Paul Marechal <paul.marechal@ericsson.com>
PR gdb/23974
* target.c (target_read_stralloc): Check for empty vector.
2018-12-19 Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
PR gdb/23999:

2
gdb/target.c
View File

@@ -1875,7 +1875,7 @@ target_read_stralloc (struct target_ops *ops, enum target_object object,
if (!buf)
return {};
if (buf->back () != '\0')
if (buf->empty () || buf->back () != '\0')
buf->push_back ('\0');
/* Check for embedded NUL bytes; but allow trailing NULs. */

5
gdb/testsuite/ChangeLog
View File

@@ -1,3 +1,8 @@
2018-12-21 Paul Marechal <paul.marechal@ericsson.com>
PR gdb/23974
* gdb.base/info-os.exp: Check return for unknown "info os" type.
2018-11-21 Benno Fünfstück <benno.fuenfstueck@gmail.com>
PR python/23714

3
gdb/testsuite/gdb.base/info-os.exp
View File

@@ -175,6 +175,9 @@ expect_multiline "info os semaphores" "$semkey +$semid +666 +1 .*" "get semaphor
# key msqid perm num used bytes num messages last msgsnd() command last msgrcv() command user group creator user creator group last msgsnd() time last msgrcv() time last msgctl() time
expect_multiline "info os msg" "$msgkey +$msqid +666 .*" "get message queues"
gdb_test "info os unknown_entry" [multi_line \
"warning: Empty data returned by target. Wrong osdata type\\\?" \
"Can not fetch data now."]
# The SysV IPC primitives linger on after the creating process is killed
# unless they are destroyed explicitly, so allow the test program to tidy