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[PATCH] gdb: Fix "info os <unknown>" command
- From: Paul Marechal <paul dot marechal at ericsson dot com>
- To: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Cc: Paul Marechal <paul dot marechal at ericsson dot com>
- Date: Mon, 17 Dec 2018 22:13:16 +0000
- Subject: [PATCH] gdb: Fix "info os <unknown>" command
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.
---
gdb/target.c | 2 +-
gdb/testsuite/gdb.base/info-os.exp | 3 +++
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/gdb/target.c b/gdb/target.c
index 80b8453176..6c63255d03 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1793,7 +1793,7 @@ 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. */
diff --git a/gdb/testsuite/gdb.base/info-os.exp b/gdb/testsuite/gdb.base/info-os.exp
index 8d7eab9c53..c44e6b27c3 100644
--- a/gdb/testsuite/gdb.base/info-os.exp
+++ b/gdb/testsuite/gdb.base/info-os.exp
@@ -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
--
2.20.1