Currently, when parsing a stream of tokens we make a copy of the token
list at the beginning of each level of recursion so that we do not
modify the original list in cases where we need to fall back to an
earlier state.
In the worst case, we will only read 1 or 2 tokens off the list before
recursing again, which means an upper bound of roughly N^2 token allocations.
For a "reasonably" sized QMP request (in this a QMP representation of
cirrus_vga's device state, generated via QIDL, being passed in via
qom-set), this caused my 16GB's of memory to be exhausted before any
noticeable progress was made by the parser.
This patch works around the issue by using single copy of the token list
in the form of an indexable array so that we can save/restore state by
manipulating indices.
A subsequent commit adds a "large_dict" test case which exhibits the
same behavior as above. With this patch applied the test case successfully
completes in under a second.
Tested with valgrind, make check, and QMP.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Currently a NULL token list will crash the parser, instead we have it
pass back a NULL QObject.
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
When input some invalid word 'unknowcmd' through QMP port, qemu outputs
this error message:
"parse error: invalid keyword `%s'"
This patch makes qemu output the content of invalid keyword, like:
"parse error: invalid keyword `unknowcmd'"
Signed-off-by: Amos Kong <akong@redhat.com>
Acked-by: Richard Henderson <rth@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
If the parser fails to parse the key in parse_pair, it will access a NULL
pointer. A simple way to trigger this is sending {foo} via QMP. This patch
turns the segfault into a syntax error reply.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
OK we are fooled by the json lexer and parser. As we use %I64d to
print 'long long' variables in Win32, but lexer and parser only deal
with %lld but not %I64d, this patch add support for %I64d and solve
'info pci', 'powser_reset' and 'power_powerdown' assert failure in
Win32.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This is the third and final stage of the JSON parser. It parses lexical tokens
performing grammar validation and creating the final QObject representation. It
uses a recursive decent parser.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Michael Roth
Anthony Liguori
Stefan Weil
Paul Brook
Luiz Capitulino
Amos Kong
Kevin Wolf
Roy Tam
Amit Shah