Leak introduced in commit 0436d32. If we allocate an actions array,
but fail early enough to never consume it with the qemu monitor
transaction call, we leaked memory.
But our semantics of making the transaction command free the caller's
memory is awkward; avoiding the memory leak requires making every
intermediate function in the call chain check for error. It is much
easier to fix things so that the function that allocates also frees,
while the call chain leaves the caller's data intact. To do that,
I had to hack our JSON data structure to make it easy to protect a
portion of an arbitrary JSON tree from being freed.
* src/util/json.h (virJSONType): Name the enum.
(_virJSONValue): New field.
* src/util/json.c (virJSONValueFree): Use it to protect a portion
of an array.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONTransaction): Avoid
freeing caller's data.
* src/qemu/qemu_driver.c (qemuDomainSnapshotCreateDiskActive):
Free actions array on failure.
These VIR_XXXX0 APIs make us confused, use the non-0-suffix APIs instead.
How do these coversions works? The magic is using the gcc extension of ##.
When __VA_ARGS__ is empty, "##" will swallow the "," in "fmt," to
avoid compile error.
example: origin after CPP
high_level_api("%d", a_int) low_level_api("%d", a_int)
high_level_api("a string") low_level_api("a string")
About 400 conversions.
8 special conversions:
VIR_XXXX0("") -> VIR_XXXX("msg") (avoid empty format) 2 conversions
VIR_XXXX0(string_literal_with_%) -> VIR_XXXX(%->%%) 0 conversions
VIR_XXXX0(non_string_literal) -> VIR_XXXX("%s", non_string_literal)
(for security) 6 conversions
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Version 2.0.0 or yajl changed API. It is fairly trivial for us to
cope with both APIs in libvirt, so adapt.
* configure.ac: Probe for yajl2 API
* src/util/json.c: Conditional support for yajl2 API
Problem:
"parser.head" is not NULL even if it's free'ed by "virJSONValueFree",
returning "parser.head" when "virJSONValueFromString" fails will cause
unexpected errors (libvirtd will crash sometimes), e.g.
In function "qemuMonitorJSONArbitraryCommand":
if (!(cmd = virJSONValueFromString(cmd_str)))
goto cleanup;
if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
goto cleanup;
......
cleanup:
virJSONValueFree(cmd);
It will continues to send command to monitor even if "virJSONValueFromString"
is failed, and more worse, it trys to free "cmd" again.
Crash example:
{"error":{"class":"QMPBadInputObject","desc":"Expected 'execute' in QMP input","data":{"expected":"execute"}}}
{"error":{"class":"QMPBadInputObject","desc":"Expected 'execute' in QMP input","data":{"expected":"execute"}}}
error: server closed connection:
error: unable to connect to '/var/run/libvirt/libvirt-sock', libvirtd may need to be started: Connection refused
error: failed to connect to the hypervisor
This fix is to:
1) return NULL for failure of "virJSONValueFromString",
2) and it seems "virJSONValueFree" uses incorrect loop index for type
of "VIR_JSON_TYPE_OBJECT", fix it together.
* src/util/json.c
* src/util/json.c, src/util/json.h: Declare returned strings
to be const
* src/qemu/qemu_monitor.c: Wire up JSON mode for qemuMonitorGetPtyPaths
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h: Fix
const correctness. Add missing error message in the function
qemuMonitorJSONGetAllPCIAddresses. Add implementation of the
qemuMonitorGetPtyPaths function calling 'query-chardev'.
configure: yajl: no
CC libvirt_util_la-json.lo
util/json.c:32:27: error: yajl/yajl_gen.h: No such file or directory
util/json.c:33:29: error: yajl/yajl_parse.h: No such file or directory
* src/util/json.c: remove the includes if yajl not configured in
This introduces simple API for handling JSON data. There is
an internal data structure 'virJSONValuePtr' which stores a
arbitrary nested JSON value (number, string, array, object,
nul, etc). There are APIs for constructing/querying objects
and APIs for parsing/formatting string formatted JSON data.
This uses the YAJL library for parsing/formatting from
http://lloyd.github.com/yajl/
* src/util/json.h, src/util/json.c: Data structures and APIs
for representing JSON data, and parsing/formatting it
* configure.in: Add check for yajl library
* libvirt.spec.in: Add build requires for yajl
* src/Makefile.am: Add json.c/h
* src/libvirt_private.syms: Export JSON symbols to drivers
