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Fix GDB crash when registers cannot be modified.

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This crash was detected when using GDB with the valgrind gdbserver.
To reproduce:

valgrind sleep 10000

In another window:
gdb
target remote | vgdb
p printf("make sleep print something\n")
=>
terminate called after throwing an instance of 'gdb_exception_error'
Aborted

The problem is that the valgrind gdbserver does not allow to change
registers when the inferior is blocked in a system call.
GDB then raises an exception.  The exception causes the destructor
of
 typedef std::unique_ptr<infcall_suspend_state, infcall_suspend_state_deleter>
    infcall_suspend_state_up;
to be called.  This destructor itself tries to restore the value of
the registers, and fails similarly.  We must catch the exception in
the destructor to avoid crashing GDB.
If the destructor encounters a problem, no warning is produced if
there is an uncaught exception, as in this case, the user will already
be informed of a problem via this exception.

With this change, no crash anymore, and all the valgrind 3.15 tests
pass succesfully.

gdb/ChangeLog
2019-04-19  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* inferior.h (struct infcall_suspend_state_deleter):
	Catch exception in destructor to avoid crash.
This commit is contained in:
Philippe Waroquiers 2019-04-13 10:22:41 +02:00
parent d563b95314
commit ee3c5f8968
1 changed files with 12 additions and 1 deletions
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13
gdb/inferior.h
View File

@ -68,7 +68,18 @@ struct infcall_suspend_state_deleter
{
void operator() (struct infcall_suspend_state *state) const
{
restore_infcall_suspend_state (state);
try
{
restore_infcall_suspend_state (state);
}
catch (const gdb_exception_error &e)
{
/* If we are restoring the inferior state due to an exception,
some error message will be printed. So, only warn the user
when we cannot restore during normal execution. */
if (!std::uncaught_exception ())
warning (_("Failed to restore inferior state: %s"), e.what ());
}
}
};